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04-28-2009 Post mapped to one branch of Knowledge Tree
haralanov


Bulgaria
Posts 130
Joined on 05-20-2008

Post #: 1
Post ID: 10371
Reply to: 10371
Constructing LF modules to the limits
fiogf49gjkf0d
It is well known fact that all loudspeaker enclosures contribute to the sound of a given acoustic system to some degree. Unfortunately the resonances of the baffles have constant monochrome character and if they are too prominent there is always some kind of sound signature coming from the vibrating walls. It’s the same as someone puts sugar on everything he eats. In the case of loudspeakers it’s even worse because the resonances need some time to settle down below audible level, so the reproduced notes become time distorted . There are some ways which tries to overcome the resonances but the result is not always positive. If the walls are made stronger using very hard material combined with extensive bracing, the resonance frequency gets higher but the Q of that resonance also gets higher and it’s character is very prominent if someone sticks his ear to the enclosure. Ping-ping-ping says the box Smile

waterfall 1.jpg


The key is damping the vibrations with huge amount of sand, preferably quartz sand. The wider the contact area with the walls is, the better damping. The other side of the problem are the air-born resonances inside the enclosure. There are only two ways to eliminate them completely – with proper geometry of the box and using “soft walls”, because the standard damping materials are not efficient at low frequencies.

waterfall 2.jpg

I used thin velveteen layer to hold the sand at proper position without leakage inside the enclosure. The result is amazing – first effectively damping the vibrations of the baffles and second – absorbing all the energy from the back wave inside the box. As we Bulgarians say: “One shot – two rabbits” Smile

1.jpg



2.jpg



3.jpg



4.jpg



5.jpg



This way the only sound I get comes from the cone of my modified ScanSpeak 25W/8565-00s taking the box 99% out of sonic equation. I definitely know why Romy likes so much this driver even I do not have proper amplification at the moment. It is capable to throw absolutely wonderful tone, it makes the Sound full of body and weight, very harmonically rich and the same time very transparent. I listened to the box before the sand filling and the sound was different – the bass was stronger, but not so defined and with less finesse (I do not mean blurred), definitely there was some kind of sonic fog. Now the bass notes are much more meaningful, allowing me to consume musical content more easily. Almost forgot – one of the secrets for proper low bass is having the front baffle as wide as one could afford Wink




"If you can't explain it simply, you don't understand it well enough." -A.E.
04-28-2009 Post does not mapped to Knowledge Tree
RonyWeissman
Lyon, France
Posts 138
Joined on 05-29-2004

Post #: 2
Post ID: 10378
Reply to: 10371
Scanspeak bass enclosure
fiogf49gjkf0d
Hi,

Thanks for pictures, that looks interesting.  You are using one driver per side for your system it looks like?
R Weissman
04-28-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 3
Post ID: 10379
Reply to: 10371
Some comments about the bass inclosure.
fiogf49gjkf0d

Haralanov,

Here some raw cements of my on it, without any particular order of importance….

1)      Sand damping it beautiful, it is well-recognized, but you do pay cost for it, in your case the cost is space. Sand is very little compressible damping and if you have the same volume with no sand then you would have  the resonance of the whole enclosure a few dB lower, or you would have almost twice smaller enclosure for the same bass. It is important to understand that when I say “the same bass” I mean the bass in term of SPL pleasure per power. However it is very much not complete or even overlay important characteristics as it has no indication about the quality of bass that is much more complex category.

2)      Would the positive results you report be different if you have hermetic wood made compartments filed with sand without using the fabrics to hold the sand? Sure, the fabric walls is good as it has “some” elasticity but I do not think that the 25W/8565-00 driver might in this volume develop the pressure to be able to stress the fabrics-shaped sand walls.

3)      You need to take under consideration the not only the sand walls were beneficial but the face that you have the internal cavities of irregular shape – very good for Sound. Kharma Exquisite used the same idea of the internal irregular cavities…

4)      I wonder if the effectiveness of your dumping will change with time.  In a few months, when the sand in your enclosure will be settled, try to flip the enclosure upside down and see if the un-compressed, disturbed sand will have a new effect to sound.

5)      If you feel that 25W/8565-00 is a good driver then try many of 25W/8565-00. I have single driver enclosure, 2-drivers enclosure, 4-drivers enclosure  and 6-drivers enclosure . If I have space I would have 20 of the 25W/8565-00 drivers enclosure. More drivers- mean less exertions of each driver and – oh boy ! they do sound phenomenally with little power… You might try it using both channels on one side and playing mono recordings…

6)      The  25W/8565-00 are superbly sensitive to damping by amp, and a fraction of Ohm here and there do make a lot of difference.

7)      Why do you feel that the front baffle shall be as wide as possible? Where and how you cross them?

8)      Did you try to use a regular pressed wood board as you use but to pile up a 75 pounds bag of sand atop?

9)      What driver over 10kHz you use with this LF section?

10)   Do you know that you might not feel some of the compartments to the full capacity and to to shape sound in own way? You might try to bare into the sand some plastic air bubbles from packing material…. If you feel that you are too crazy then I need to disappoint you saying that I know people who pressurize the enclosure and pump inside of the box a replenishable inert gas…

11)   I see you put some kind of condom atop of the driver basket. What is it?

12)   Try to put a foam wrapper around the center poll of your enclosure.

13)   What is your feeling before and after the sane when you scratch the surface of the driver with your nail (my favorite test). The scratching the driver surface it like playing cello – by listening the harmonics of that “scratch” one can say a LOT about the bass quality…

14)   Are you planning to drive this thing with SET? Be advised that I never was able to find a SS PP amp that was able to do proper bass….

The Cat

PS: I renamed your images, when you upload your mages then try to name them more or less uniquely and identifiable.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-28-2009 Post does not mapped to Knowledge Tree
tuga


Posts 174
Joined on 12-26-2007

Post #: 4
Post ID: 10380
Reply to: 10371
Sand and... polystyrene beads
fiogf49gjkf0d
Hello Haralanov,

That's a nice strong heavy box you have there.
You might want to check and add some more sand in the future because vibration helps the grains to adjust which in turn reduces volume.
 Romy the Cat wrote:

10)   Do you know that you might not feel some of the compartments to the full capacity and to to shape sound in own way? You might try to bare into the sand some plastic air bubbles from packing material…. If you feel that you are too crazy then I need to disappoint you saying that I know people who pressurize the enclosure and pump inside of the box a replenishable inert gas…


As an alternative to Romy's suggestion you could try a mixture of sand and polystyrene beads as this will prevent the sand to become a compact mass.


Cheers,

Tuga


"Science draws the wave, poetry fills it with water" Teixeira Pascoaes
04-28-2009 Post does not mapped to Knowledge Tree
haralanov


Bulgaria
Posts 130
Joined on 05-20-2008

Post #: 5
Post ID: 10381
Reply to: 10379
Different factors affecting bass quality
fiogf49gjkf0d
 Romy the Cat wrote:
Sand damping it beautiful, it is well-recognized, but you do pay cost for it, in your case the cost is space.

I know that Romy… but without the massive amounts of sand, there are always some vibrations felt when I touch the baffles with my hand. In my case I intentionally made the enclosures that big because the need of wider front baffle for purely sonic reasons.

 Romy the Cat wrote:
Would the positive results you report be different if you have hermetic wood made compartments filed with sand without using the fabrics to hold the sand?

My original idea was to use double walls with sand between them, so I made some experiments and came to the conclusion that the air volume inside the box has some disturbing sound signature which “speaks’ through the cone and I was clearly able to hear it.

 Romy the Cat wrote:
Sure, the fabric walls is good as it has “some” elasticity but I do not think that the 25W/8565-00 driver might in this volume develop the pressure to be able to stress the fabrics-shaped sand walls.

Romy, its not about the pressure. There is a huge difference in sound with hard and soft (sand based) walls even at 1mm excursion from the driver.

 Romy the Cat wrote:
I wonder if the effectiveness of your dumping will change with time.  In a few months, when the sand in your enclosure will be settled, try to flip the enclosure upside down and see if the un-compressed, disturbed sand will have a new effect to sound.

I already made that experiment before gluing the top of the enclosures. I was not able to hear any differences when the sand is hard pressed in the cavities. Actually it was very hard to compress down the sand because it is very homogenius and it is very difficult to raise its density.

 Romy the Cat wrote:
If you feel that 25W/8565-00 is a good driver then try many of 25W/8565-00. You might try it using both channels on one side and playing mono recordings…

That was the first thing I made when I finished the enclosures. Wow. The difference is really huge. The authority of sound, the weight of bass notes they give, the ability to portray the real size of the instruments, the sense of scale to all recordings, the evenness of the bass in the room…. I am really motivated to use 4 drivers per side, up to the ceiling, in the way you use them, but with freedom to time align all 4 enclosures because they will be separated from each other.

 Romy the Cat wrote:
The  25W/8565-00 are superbly sensitive to damping by amp, and a fraction of Ohm here and there do make a lot of difference.

I know that and for this reason I use maximally short cables as I can, which are also very thick. They are amazing at very low frequencies – fast and harmonically potent. The drivers are wired directly to the power amp (of course not solid state amp)- there is no coil of any kind.
I read your comments about the supersensitivity of 25W:

http://www.goodsoundclub.com/GetPost.aspx?PostID=1619

It is not my experience. I realize it is sensitive to some degree, but not that much. I tried to find the reason why they behave in this way in the context of your acoustic system and I think I know the reason if it is the wiring diagram of your LF section:

LF wiring illustration.JPG

 Romy the Cat wrote:
Why do you feel that the front baffle shall be as wide as possible? Where and how you cross them?

I do not “feel” that – it is what my ears said at the time when I stick the back sides of two loudspeakers next to the L&R sides of the tiny experimental enclosure (30cm wide) ScanSpeaks were mounted to. The sound have totally different influence to the listener this way. The sense of scale just doubled when the front baffle became twice as wide. The feeling is like you horn load the driver, but the horn has very very little gain. I don’t know how to explain this in English…. It is easy to try this with your bass towers. They are line-level crossed at 64Hz, first order.

 Romy the Cat wrote:
Did you try to use a regular pressed wood board as you use but to pile up a 75 pounds bag of sand atop?

Yep. The side walls of the enclosures are vibrating too much for my taste, even the sand filled bag was over 50kg. It helped a little to control the vibrations – but they were still there.

 Romy the Cat wrote:
What driver over 10kHz you use with this LF section?

I use small Bulgarian made ribbon tweeter from 80’s with alnico magnet system and ribbon size 55x10mm. The model is called “ВЛД 40”.

 Romy the Cat wrote:
If you feel that you are too crazy then I need to disappoint you saying that I know people who pressurize the enclosure and pump inside of the box a replenishable inert gas…

I have my reasons to believe this not too effective method to allow 25W show its potential…
In past I have tried with almost all imaginable damping materials to see what will happen. Dynamat Extreme, natural wool, memory foam (Tempur) and many others. Nothing is as efficient as the sand.

 Romy the Cat wrote:
I see you put some kind of condom atop of the driver basket. What is it?

It is soft polymer which damps the micro vibrations of the driver’s chassis and at the same time gives the driver aerodynamic share to allow the back wave of the cone to be radiated undisturbed. The outеr layer is from velveteen again because purely sonic reasons.

 Romy the Cat wrote:
Try to put a foam wrapper around the center poll of your enclosure.

Good idea, thanks.

 Romy the Cat wrote:
What is your feeling before and after the sane when you scratch the surface of the driver with your nail (my favorite test). The scratching the driver surface it like playing cello – by listening the harmonics of that “scratch” one can say a LOT about the bass quality…

You are absolutely correct about this test. I usually tap the cone first to determine the low frequency behavior of the driver/enclosure as a whole and the second part of the test is scratching the cone – this gives me an idea of the upper spectrum of the driver.
Before the sand filling there was some kind of sonic boom coming from the inside of the box when I tapped the cone with my middle finger, even the speaker walls were lined with natural wool. Have in mind without sand Q of the enclosure is lower because the bigger net volume of the box. With the sand applied I quickly understood what was the pure tone of my 25W/8565 drivers – deep, rich and full of body.

 Romy the Cat wrote:
Be advised that I never was able to find a SS PP amp that was able to do proper bass….

Solid state amps are out of my scope and they should be used only in context of powerful DJ installations Wink

Best regards,
P. Haralanov




"If you can't explain it simply, you don't understand it well enough." -A.E.
04-28-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 6
Post ID: 10382
Reply to: 10381
More stopping wall ideas.
fiogf49gjkf0d

 haralanov wrote:
  There is a huge difference in sound with hard and soft (sand based) walls even at 1mm excursion from the driver.

If it so ten it is an interesting found. As I understand it is about the “stopping wall”. I wonder if the positive effect you report would be identically favoriteable for 100Hz and for 30Hz. That way I asked you where and how you cross your LF section. I think if to think further in this direction then it is possible to use the “hard wall” but to make the surface of the wall not flat but with high indentation textile, like a high bas-relief. Then the leading edge of the pressure of wave will not hard-bounce from the wall but will be time-damped, mimicking what you do with you soft wall. I think it is a cool idea and I never seen it done in hard surface inside the speakers. Pretend that you have the profile of the inners wall of enclosure like on the image below, with irregular high of the peaks, and made not with soft foam but with hard wood. That would be very cool to experiment with….

foam-acoustic.jpg

 haralanov wrote:
 
It is not my experience. I realize it is sensitive to some degree, but not that much. I tried to find the reason why they behave in this way in the context of your acoustic system and I think I know the reason if it is the wiring diagram of your LF section:

LF wiring illustration.JPG

Yes, it is my wiring diagram only I have all 6 drivers 25W or the 10”.  Sure, I would need to go for all parallel connections and rewind the transformer for 0.8R secondary. It is somewhere at the bottom of my list to do… sometimes….  BTW, one of the reasons why you might have less sensitivity to the damping change because your SET amp might use some global feedback, does it?

 haralanov wrote:
The sound have totally different influence to the listener this way. The sense of scale just doubled when the front baffle became twice as wide.

Interesting! I never looked into it.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-21-2011 Post does not mapped to Knowledge Tree
oxric
Posts 184
Joined on 02-12-2010

Post #: 7
Post ID: 17036
Reply to: 10381
Scanspeak, sand and sound.
fiogf49gjkf0d
 haralanov wrote:
 Romy the Cat wrote:
If you feel that 25W/8565-00 is a good driver then try many of 25W/8565-00. You might try it using both channels on one side and playing mono recordings…

That was the first thing I made when I finished the enclosures. Wow. The difference is really huge. The authority of sound, the weight of bass notes they give, the ability to portray the real size of the instruments, the sense of scale to all recordings, the evenness of the bass in the room…. I am really motivated to use 4 drivers per side, up to the ceiling, in the way you use them, but with freedom to time align all 4 enclosures because they will be separated from each other.

...
 Romy the Cat wrote:
Be advised that I never was able to find a SS PP amp that was able to do proper bass….

Solid state amps are out of my scope and they should be used only in context of powerful DJ installations Wink

Best regards,
P. Haralanov



Hi Haralanov,

A couple of years ago you posted about your special woofer, or rather subwoofer solution but I think you had not quite finished that ambitious and what you termed 'constructing LF modules to the limit' project.

I am sure there are many others like me who have wondered whatever happened to your experiment with the Scanspeak 25W/8565-00 as you said that eventually you were planning to have four of these per side as you had experienced the improvement in low bass that you get with multiple such drivers. I know you may have completely stopped at that point but if you have continued or completed that project, maybe you might care to share your experience on this thread you started. It is not only curiosity that motivates me to ask as in the long term, I may try to go down this route myself, and I do not need to be told about the effectiveness of sand in this application. I think that the attention you have paid to damping should pay huge rewards in the LF applications.

I was recently talking to a friend about the Scanspeak 25W/8565-00s and mentioned your installation to him. He feels that his simulations show that the 25W would have difficulty reaching down to 30Hz. Would that fit in with your experience of the 25W? And whilst we are at it you mentioned using tube amplification for this channel; would you mind saying how you drive this channel?

Best regards
Rakesh


.
09-22-2011 Post does not mapped to Knowledge Tree
haralanov


Bulgaria
Posts 130
Joined on 05-20-2008

Post #: 8
Post ID: 17038
Reply to: 17036
Shift in direction
fiogf49gjkf0d
Rakesh, during the last year, there were some very important moments in my own realizations about the methods of low frequency reproduction.
I totally abandoned my Scanspeak bass modules and now they are resting in my garage. I intentionally have my listening without the low bass channels, because I first have to make the rest of the audio-band to sound just the way I want it to sound. During the last couple of months practically all of my efforts are concentrated towards the construction of my wide-range 12” channel, because it is the core of my system.
 
Now let’s get back to the topic. There are some things that my 25W woofers cannot do, no matter how much of them one is going to use. This is also true for any 10” woofer existing on this planet. The restriction is entirely due to the cone size. The behavior of a 10” cone is very different in comparison to a much bigger, lets say 23” cone, because the bigger cone couples very effectively with the surrounding air (just like horns!) because of its large radiating area for a given voice coil. When you have larger area, you have better control over the cone movement, because now there is more “attached” air which causes this control. But the moving mass must be as little as possible! Make some very simple experiment: Take a piece of cardboard with a size of approximately 22”x22. It must weight around 80-100 grams. Now try to make some wind, while waving it back and forth. You have to note it is not so easy to move it, because you feel high air resistance against your attempts to move it easily. Now take your phone (its weight must be approximately the same) and perform exactly the same movements with in the air, while holding it in your hand. Is there any wind? No? That’s for a reason. Do you think it is harder to control your hand movement because there is no air resistance that damps the inertia of the phone in your hand? Congratualtions! Now you know how the voice coil feels while pushing a small cone :-)

This very effectively flattens the impedance peak at Fs, and one has much more accurate tone at the range where the Fs of the system occur. It considerably lowers (nearly removes) the monochrome bass taste. The improperly reproduced range at and around Fs kills the entire sound of that channel. What happens at Fs? Usually the cone continues to radiate AFTER the signal passes. Everybody knows what it means. Imagine you are a box trainer (he is in the role of a voice coil) and you tell your boxer (he is the cone) you want him to demonstrate how fast he is able to kick. But imagine that boxer is lazy just in that moment, so he says to himself: "Why should I hurry, I’m so lazy – I will not kick fast and while I’m kicking, I’m gonna eat some sandwitches”. That’s what one gets from small coned woofers. They are not well controlled by the driving force, coming from the voice coil and they smear the accuracy of the bass notes. Using 4, 6, 10 or 20 ten inch woofers per side, does not improve the cone behavior of any of them – it only allows higher sensitivity and better dynamic range due to the raised total radiating area. But the whole trick is to keep the control at woofer’s Fs without using hard suspensions and too much electrical damping (because it makes the bass notes to sound dry and atonal). As a second benefit of all this, the big woofer will be very phase linear in the audible range of the bass, because there are no impedance anomalies which shift the phase of the signal (if the Fs of the woofer is out of the audible range, so it must be 16-17-18Hz). So now you have proper harmonic structure across the bass range and the bass channels are very easily integrated with the upper bass channels. But one have to high-pass his upper bass channel at least one octave higher than the Fs of that channel to keep it phase linear too. If one avoids phase anomalies, he will be rewarded with very realistic sounding system.

My bass channels will use 2x23” underhung woofers per side. The scale and authority of the big woofers (if they are properly made!) is absolutely unmatched by a stack of several smaller ones due to the above mentioned reasons. Take a look at the cones:

IMG_4187.jpg
 
The second reason why I switch to considerably bigger woofer units is because they have much better tone (if properly made!). It is the same as reproducing a midrange with an optimized for midrange reproduction driver, instead of array of 10 tweeters. Well, using 10-20 tweeters to reproduce midrange will give you some midrange sound, but that sound is very far behind the sound of the dedicated midrange driver in context of tonal department.
   
There is another reason why I switch to bigger woofers, but this reason is indirect, because I can get the same effect by using a lot of 10 inchers. This is because sometimes I really love to listen at ultra loud levels, and I don’t want to have compression, distortion and dynamic restrictions in the low bass range when listening at 110-115dB. There will be around 2500 (there is no mistake in the number) liters of air behind EACH of the 4 woofers. May be in future I will add another pair of 23 inchers per side in order to have better dynamic reserve when listening at 120dB levels.
And not at the last place, I kicked the 25W woofers out of the system, because they tend to have just a slight taste of very soft rubber in the bass tone. This taste is very delicate, because the soft rubber is not directly in your mouth, but you feel the rubber as some kind of after taste after eating rubber in the previous day (just like eating garlic) but you can still feel it in your mouth/ear...
 
Best regards,
Petar Haralanov



"If you can't explain it simply, you don't understand it well enough." -A.E.
09-22-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 9
Post ID: 17039
Reply to: 17038
Big vs. small.
fiogf49gjkf0d

This is very interesting observation. I am in away envy that Petar went for a set of large woofers (4x23”!). This is the way to go! Unfortunately I did not experiment with it even I had the drivers and means to do it. My problem was with the fact that I need the woofers to be in time alight position and faced directly to the listening location. Pilling up the boxes of multiple 18” or 24” footer in the mid of my room would be very destructive to the way how my room “feels”. So I juts can afford to do it from decor perceive, so I never went there.  Still, the biggest reason however was not the decor consideration but that I feel very satisfied with the 25W drivers. I would like to add even more of 25W drivers, in fact I did plan to rebuild my woofer towers, putting 8-10 drivers per channel and increasing the depth of the boxes: I do not want to ad width of the baffle that I would like to keep at 12”. I never went anywhere with this project and I do not know if I will.

 haralanov wrote:
The second reason why I switch to considerably bigger woofer units is because they have much better tone (if properly made!). It is the same as reproducing a midrange with an optimized for midrange reproduction driver, instead of array of 10 tweeters. Well, using 10-20 tweeters to reproduce midrange will give you some midrange sound, but that sound is very far behind the sound of the dedicated midrange driver in context of tonal department.

With my very enthusiastic support of the haralanov’s bass move I would like to tone that the above quite is not truly accurate presentation of what is going on. First off all the collection of 10 tweeters are not the same of the collection of 10 woofers. Woofers do not suffer from HF lobbing and Woofers can form line-array that has a LOT of benefits at LF. It is not only about the better or worse individual woofer but about using the line-array benefits as well. Also, about the “tonal department” – it is depends how the woofers are used. In my case I cross then at 3rd and 4th order (different for L and R channels) at 20Hz. There is truly no “tonal department” in those frequencies and with such a steep orders.  I would say that it more colors the midbass channel then indicate own tone. So, I presume that in this context we can talk about tone of woofers. It of cause would be very different if the woofers are cross as 40Hz or at 80Hz… I do not insist that 25W drivers are great tonal drivers at any range and I do admit the there are many other woofers with paper suspension that are much more tonally capable.

 haralanov wrote:
There is another reason why I switch to bigger woofers, but this reason is indirect, because I can get the same effect by using a lot of 10 inchers. This is because sometimes I really love to listen at ultra loud levels, and I don’t want to have compression, distortion and dynamic restrictions in the low bass range when listening at 110-115dB. There will be around 2500 (there is no mistake in the number) liters of air behind EACH of the 4 woofers. May be in future I will add another pair of 23 inchers per side in order to have better dynamic reserve when listening at 120dB levels.
And not at the last place, I kicked the 25W woofers out of the system, because they tend to have just a slight taste of very soft rubber in the bass tone. This taste is very delicate, because the soft rubber is not directly in your mouth, but you feel the rubber as some kind of after taste after eating rubber in the previous day (just like eating garlic) but you can still feel it in your mouth/ear...

I am with you with the dynamic restrictions at 115dB. I do feel that 25W have it but are you sure that it is drivers but not your amplification? To drive them to 115dB at 20Hz would take an immense amount of power. What I observe is that with multiplication of 25W driver the effect of dynamic restrictions much softening and become very malleable, up to the point to be addictive in a way. I kind of like that very sort of “soft clipping”. It might not “impressive” but it is more forgiving and more naturally sounding to me.

About the “taste of very soft rubber in the bass tone”. At wish range? If you use then at 150Hz then they do sound like rubber garbage and nothing else. With drop of crossover point the rubber tone is gone and get converted to own very interesting infection of almost 2 harmonics. If you use them at let say 60Hz and sharp filter then I would not disagree that they have rubber sound. I do know rubber sound and it is not what it is as Sound of 25W does have differences that usually are eaten by the rubber suspension in the rubber sounding drivers. I would call it not “taste of very soft rubber in the bass tone” but rather the “driver own character” and I would like to note that I am not hate this character and differences of the bass notes are still well exposed though the 25W own character.

In the end I think the real test would be to make the an array with 8 or 10 ScanSpeak 25W drivers per side and to make two boxed with large woofer and compare at 20Hz. If one would ask me then I would bet on the large woofers. Still I do not think that line-array of the small drivers will be uncontestable. I do feel that line-array of the small drivers might be “enough”.

I know that it sounds like by saying all of it I justify my laziness not to going for large woofers. Still, I would like to remind you folks that among many of my diagnoses I am very prone to undertake some crazy audio projects. I have drivers, I have machines in the basements and I have a carpenter who only expects the command “fetch” as he will start to cut the wood in my basement -  when I get back from work the woofer boxed would be sitting there. I never went for it as I feel that the even my current small-array of 25W drivers is enough and does not give me a any frustrations for now.

Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-22-2011 Post does not mapped to Knowledge Tree
oxric
Posts 184
Joined on 02-12-2010

Post #: 10
Post ID: 17040
Reply to: 17038
A LF solution of seismic proportions then!
fiogf49gjkf0d
 haralanov wrote:


Rakesh, during the last year, there were some very important moments in my own realizations about the methods of low frequency reproduction.
I totally abandoned my Scanspeak bass modules and now they are resting in my garage. I intentionally have my listening without the low bass channels, because I first have to make the rest of the audio-band to sound just the way I want it to sound. During the last couple of months practically all of my efforts are concentrated towards the construction of my wide-range 12” channel, because it is the core of my system. 
 


Hi Haralanov,

Thanks for the response. Very scary.

 I wish you good luck with the wide-range effort. You certainly sound like you know what you are doing and I for one would like the opportunity to hear your driver once you have completed its construction. My own personal exposure to widerange drivers has never been very positive but the theoretical benefits of such a design cannot be denied.

Sorry to hear you abandoned the Scanspeaks though as at the time you sounded very pleased with the direction of that project. It is certainly the sort of LF solution that 99% of people might just be able to accomodate after all.



 haralanov wrote:
 

 
Now let’s get back to the topic. There are some things that my 25W woofers cannot do, no matter how much of them one is going to use. This is also true for any 10” woofer existing on this planet. The restriction is entirely due to the cone size. The behavior of a 10” cone is very different in comparison to a much bigger, lets say 23” cone, because the bigger cone couples very effectively with the surrounding air (just like horns!) because of its large radiating area for a given voice coil. When you have larger area, you have better control over the cone movement, because now there is more “attached” air which causes this control. But the moving mass must be as little as possible! Make some very simple experiment: Take a piece of cardboard with a size of approximately 22”x22. It must weight around 80-100 grams. Now try to make some wind, while waving it back and forth. You have to note it is not so easy to move it, because you feel high air resistance against your attempts to move it easily. Now take your phone (its weight must be approximately the same) and perform exactly the same movements with in the air, while holding it in your hand. Is there any wind? No? That’s for a reason. Do you think it is harder to control your hand movement because there is no air resistance that damps the inertia of the phone in your hand? Congratualtions! Now you know how the voice coil feels while pushing a small cone :-)
 




With regard to the practical aspect of your LF project, I am both shocked and spellbound. Well, without being an expert, and at the expense of stating the obvious, an 18" driver is equivalent to roughly 3x10" and a 23" driver to 5x10" drivers in terms of cone area, so I can see the benefit of going for 4 such drivers equivalent to 21 10" drivers no less. But a 10" driver can be used in a 100 litre enclosure to good effect, which one can build fairly easily. But how does one accomodate four 2500 litre enclosures? I hope that your driver, if you mean for it to be commercialised can be used to good effect in a smaller enclosure!

Just to be clear four 2500 litre enclosures (ie. 70cmx70cmx500cm to accomodate your drivers or variations such as 100x100x250cm) is a really huge volume which would take up 10m3, that is 8 percent of a decent 6x7x3m room. To put this in perspective, I calculate one channel of my horn system to take up about 1m3 of total space.

This is not to mention either the material cost and complexity of controlling internal vibrations in such huge enclosures or the problems in terms of positioning such massive structures in a listening room where their large surfaces become yet another area where one has to be careful with reflections from the MF drivers.



 haralanov wrote:


My bass channels will use 2x23” underhung woofers per side. The scale and authority of the big woofers (if they are properly made!) is absolutely unmatched by a stack of several smaller ones due to the above mentioned reasons. Take a look at the cones...The second reason why I switch to considerably bigger woofer units is because they have much better tone (if properly made!). It is the same as reproducing a midrange with an optimized for midrange reproduction driver, instead of array of 10 tweeters. Well, using 10-20 tweeters to reproduce midrange will give you some midrange sound, but that sound is very far behind the sound of the dedicated midrange driver in context of tonal department.
   
There is another reason why I switch to bigger woofers, but this reason is indirect, because I can get the same effect by using a lot of 10 inchers. This is because sometimes I really love to listen at ultra loud levels, and I don’t want to have compression, distortion and dynamic restrictions in the low bass range when listening at 110-115dB. There will be around 2500 (there is no mistake in the number) liters of air behind EACH of the 4 woofers. May be in future I will add another pair of 23 inchers per side in order to have better dynamic reserve when listening at 120dB levels.
And not at the last place, I kicked the 25W woofers out of the system, because they tend to have just a slight taste of very soft rubber in the bass tone. This taste is very delicate, because the soft rubber is not directly in your mouth, but you feel the rubber as some kind of after taste after eating rubber in the previous day (just like eating garlic) but you can still feel it in your mouth/ear...
 


You must must have a very understanding family to play that loud and your tympana must have been soaked in titanium at birth! But seriously, if the 23" inchers are really that good, let me know when I can try a pair.

Best regards
Rakesh



09-22-2011 Post does not mapped to Knowledge Tree
haralanov


Bulgaria
Posts 130
Joined on 05-20-2008

Post #: 11
Post ID: 17042
Reply to: 17040
My direction is 2x4" + 12" + 2x15" + 4x23"
fiogf49gjkf0d
Romy, I do agree with all your comments.
It is true that the magnitude of the rubber taste very much depends on the crossover frequency. I used them below 64Hz, but with first order filter, implemented before the amp that drives them. With that kind of setting there is very slight rubber taste, and it is absolutely not annoying, but it is there and I’m able to hear it. I intentionally do not use steeper filters. I very much like the way how bass arrays portray the low frequency scale and size. A pair of woofers listened at 90dB are far below the level of sonic 3D effect (sorry for the stupid phrase, but I cannot describe it accurately in English) which one gets by listening to an array of 4 woofer pairs, listened again at 90dB. With arrays, bass has size and physicality – not only SPL level, as is the case with only one pair of woofers. But you know all that much better than me, because you are listening at bass arrays for years. The point is to have as much radiating surface through the vertical plane as possible.
I will move to live in my house in the province and I have quite a big room there, which I will use only for listening (it has solid floor and quite a good acoustics) so I can afford to put as much woofers as I want, and may be I will end up with 8 x 23” woofers in order to have very even bass response at my listening chair.
 
 oxric wrote:
I wish you good luck with the wide-range effort

Thanks, I will need it :-)
I had 12” wideranger that sounded almost the way I like, but unfortunately I blew it up. It was 102dB sensitive, but the feeling was it is 122+dB sensitive. A couple of months ago I was in very good mood and I had desire to listen very enjoyable big band music at very loud levels. After 10 minutes of listening at these levels, my mood got even higher and I turned up the volume until the sound became so loud, that my brain refused to believe it is possible. Generally speaking, most of the drivers distort before they burn, but it was not the case. The sound was ultra loud, with absolutely no stress or distortion and with absolutely no sign it will burn. But there was a fragment, where there were playing simultaneously several sub trombones, several trumpets, tuba, double bass and suddenly the voice coil literally flied out of the magnetic gap disentagled in the air and the former went in fire. I was listening at more than 120dB…
Then I made second attempt to make such a driver, with the intention to improve it further:

IMG_6219.jpg__IMG_6234.jpg__IMG_6204.jpg
 
I made several mistakes, but unfortunately I realized them after I finished the driver. It does not have that sense of unlimited effortlessness and freedom of sound and even more important – it doesn’t have the fresh breeze effect that I’m looking for. Now I prepare third version of that driver. I hope it will be the last one……….
 
 oxric wrote:
My own personal exposure to widerange drivers has never been very positive but the theoretical benefits of such a design cannot be denied.

That’s because there are no good widerange drivers out there, for any amount of money. And I wish I was kidding…
 
 oxric wrote:
an 18" driver is equivalent to roughly 3x10" and a 23" driver to 5x10" drivers in terms of cone area, so I can see the benefit of going for 4 such drivers equivalent to 21 10" drivers no less.

Rakesh, what you said is accurate, but I’m switching to 23” drivers, not because they have big radiating area, but because of the more accurate behavior of that big radiating area. It may sound childish, but I really want my bass drivers to do strictly what my bass amplifiers tell them to do. I simply prefer speakers which do not have their own “intelligence” at/around their Fs.
 
 oxric wrote:
I hope that your driver, if you mean for it to be commercialised can be used to good effect in a smaller enclosure!

It will never be commercialized. What I’m doing in audio is with only one purpose – to make the sound in my room closer to the sound in my imagination. I will not sell anything.
Second of all, I will intentionally make its T/S parameters to be optimized for a very big enclosure. I know someone is going to tell me I am stupid to do so, when I have a chance to make it to work with much smaller enclosures. Well, as you might have guesses – there is a reason behind that decision. The reason is that the loading in front of the cone will be symmetrical to the air loading behind the cone. This technique lowers the distortion a lot and prevents impedance and phase anomalies. This is important.
The size of the enclosures is not a real problem for me and when I find the place in my room where these woofers sound at their best, I will construct the enclosures from double brick walls with 4-5” sand filling between the walls. And of course they will be fixed with absolutely no option to be moved because of the several ton of weight. But I truly hate to speak in “future time”, so when everything is done and ready for listening, I can eventually post my impressions here.
 
Best regards,
Haralanov


"If you can't explain it simply, you don't understand it well enough." -A.E.
09-22-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 12
Post ID: 17043
Reply to: 17042
It is not only about volume displacement.
fiogf49gjkf0d

 haralanov wrote:
Romy, I do agree with all your comments.
It is true that the magnitude of the rubber taste very much depends on the crossover frequency. I used them below 64Hz, but with first order filter, implemented before the amp that drives them. With that kind of setting there is very slight rubber taste, and it is absolutely not annoying, but it is there and I’m able to hear it. I intentionally do not use steeper filters. I very much like the way how bass arrays portray the low frequency scale and size. A pair of woofers listened at 90dB are far below the level of sonic 3D effect (sorry for the stupid phrase, but I cannot describe it accurately in English) which one gets by listening to an array of 4 woofer pairs, listened again at 90dB. With arrays, bass has size and physicality – not only SPL level, as is the case with only one pair of woofers. But you know all that much better than me, because you are listening at bass arrays for years. The point is to have as much radiating surface through the vertical plane as possible.
I will move to live in my house in the province and I have quite a big room there, which I will use only for listening (it has solid floor and quite a good acoustics) so I can afford to put as much woofers as I want, and may be I will end up with 8 x 23” woofers in order to have very even bass response at my listening chair.
Lived for 10 years with first order and 78Hz, The room was in small and used 6 driver per side. I drive them single full bloated 6C33C with 5.3:1 if I am not mistaken. The woofer cabinets were a bit on over-damped side, the way how John Dunlavy used to like. I need to say that I did like the way bass sound a lot and I do not feel that it had any rubber taste. I truly did not. Among all drivers that I heard I would rather say that 25W has some foam suspension coloration but not exactly that. The 25W is strange driver and in my estimation it has no analogy. When it go into the “distortion mode” being overdriven then it sound in own manner, distorted buy pleasantly.  I honestly say that I never consider the 25W driver as the weekend past of my playback and BTW my bass always was quite at high respect from anyone who hear my playback. It might not mean anything but I do feel that I have quite high expectation from bass. Sure the 8 x23” woofers would be much more interestng solution for ULF, particularly if the drivers are good but you see, the lower bass is NOT ONLY volume displacement but many other factors. Considering many of those factors and managing all of those factors are the key in proper bass reproduction. If you in your room can accommodate 8 x23” woofers in time align position and face them straight forward then  you do have a hell of a listening room…

 haralanov wrote:
I simply prefer speakers which do not have their own “intelligence” at/around their Fs.

This is a noble but controversial desire. If you true would like to accomplish it then dive your woofer with negative output impedance. But… you will feel a need to EQ drivers as no one makes the drivers that can work without reliance upon the Fs.

PS: haralanov, and everyone, I constantly ask people to do it. In the top of my gallery where you input imaged there is a note: “Attentions: before uploading, please, name your images identifiably.” Would you be so kind to comply? It is not my administrative wish, it is a necessity. The images are being uploaded to Site_Images directory if my server and as they accumulated it is getting too slow to open the gallery. So, I have a process that moves the User Images to the Site Images directory and updates the reference in the user posts. If you name your image too generic, in the way how your camera does it, like “DSC_1417.JPG” for instance, then when the image is moved to the Site Images directory with many thousands images then it might meet the existed image with the same name.  I did not write a provision for it and I feel it is not too difficult for posters to mane own images with  own unique name.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-23-2011 Post does not mapped to Knowledge Tree
be
Copenhagen, Denmark
Posts 86
Joined on 02-12-2007

Post #: 13
Post ID: 17044
Reply to: 17038
Rubber sound
fiogf49gjkf0d
Hi, I have spoken to a few guys here, who had used the 8 inch version of the Scanspeak woofers for the low frequency channel they agreed about the somewhat rubbery sound of them in the higher range.
The solution was quite easy and logical: They removed the rubber suspension and replaced it with half roll foam suspension from some loudspeaker part suplier.
This together with perforations of the back spider had the added bennefit of lowering the Fo to below 20Hz.
They claimed that the improvement was considerable.
I have not heard it before and after, so I cant comment, but in the one setup I heard them in, the result was superb.
The crossover was arround 400Hz and I did not hear anny rubbery sound.

Rgds.
09-23-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 14
Post ID: 17045
Reply to: 17044
I do not agree with "Rubber Sound".
fiogf49gjkf0d

Again, I do not agree with all notion of Rubber sound that Haralanov seeded.  I can not speak what was in the situation that “be” described and 400Hz crossover. I do have the 8” version of 25W driver (I think it is 21W) and my feeling that it sound along the line with 25W driver. I would say that from what I heard in the sound of 21W it has more rubbery sound then 25W. The problem is that I do not attribute or associate the character that 25W or 21W drivers have to Rubber at all. It might “feel” that it is sort of like rubber and looking at the driver it is very easy to conclude that the rubber is the guilty party. I do not feel this way.

The 25W footers are made with Styrene-Butadiene rubber wish is synthetic polymer and frequently used for many different things. SkanSpeak calls the suspension ofthe 25W woofer as "non-inertia" suspension. Sure this is just marketing things BUT when I first touched the 25W woofers I did get a feeling the it is not a regular rubber as SkanSpeak probably used much thinner rubber on those drivers, Put in this way: many other drivers the I touched did not impress me with this feeling of suspension non-not intensive softness. For a first time I touched them it was when John Dunlavy upgraded his SC-IV model in end of 90s to the SC-IVA replacing whatever woofer the model SC-IV had with the 25W. It was very good move for those speakers and I did noted that SC-IVA had much more interesting bass then SC-V or even the SC-VI. This  thin rubber suspension on the 25W driver does not feel like rubber to me when I touch it and it more feel like ailed foam or even leather.  In my view it does has different feel to touch when I move the driver by hand.

Now about the allegations of the rubber sound. Well, we all understand that word “allegations” is not literal here but still let talk about it a bit more. In my assessment what you guys call rubber sound of the 25W driver (and I do know what you are talking about) is not rubber sound but the sound of the driver compression. This driver is 88dB sensitive and it behaves like any other 88dB driver. If you take let say a good 15-18” woofer then they would be 97-101dB sensitive, the 12-13dB difference in sensitivity got to be heard. OK, let see how the 25W woofer compresses sound.

In my past I had a number of powerful SS amps (BAT, Spectral, PassLab, etc) that I was experimenting to drive my woofer towers. The best SS amp that I had was Lamm M1.1. Lamm M1.1 was very interesting amp and I have seen a number of commercial ported speakers that never were famous for their bass performance and Lamm M1.1 transformed them into very different bass. So, I was trying in my past to drive my woofer towers with different SS amps. It was OK but ultimately I did not like it and I do concur that it had very sever dynamic restriction and did sound almost like rubber. 

It was in 2000-2001, and I use a pair of Lamm ML2.0 to drive my speakers.  One day I took one of my Lamm ML2.0 from left channel and put it to drive bass towers of my right channel, listening it in mono version. It was truly fantastic as all, absolutely all problems that I hear in the woofer towers with 4x25W driver were gone. It was so wonderful that I immediately played to Lamm for another pair of ML2.0 SETs and frankly I never looked back.

If you look further down the line of my past, the period that is well covered already in my site then at the time when I made my first 3 Channels Melquiades DSET ( at that time I called it Super Melquiades) I was not satisfied with the sound of the bass transformer I had after I added extra two woofers. The impedance of the woofers dropped from 8R to 4R and the new transformer that I has was 6.1R or something like this. I order another transformer that I think was 5.3R. I might be mistaken with the numbers but what I am not mistaken hat there was HUGE difference in the sound of my woofers between 5.3R and 6.1R transformers. You understand that we are taking about very minor change in loading that in most of the cases shall not be auditable. At that time I use 100Hz second order and the difference in sound moderated by loading was VERY substantial.

So, what I am trying to say, BTW, I do remember that I did said it before. There is something in the 25W driver that is very nice. I think that combination of that cone (I use the pimpled cones only), that soft suspension, the masses and anything else makes it very sensitive to loading. My woofers boxes are overtrumped, that makes them even more sensitive to loading.  The soft “saturation” of the SET amps looks like makes the dynamic limitations of 25W drivers to sound very human and very none annoying. In the end with properly SET loaded and many drivers in line-array I truly report that I had no negative qualities you guys associated with this driver and I did liked it a lot. I do concur that it was not the perfect in absolute send but I do not associated it with rubber suspicion but with other factors: low reverberation time in the room, restricted power of my bass amp, inability to put another 16 2W driver in use and so on.

 I do sincerely feel that in that in that time in that small room I had the best bass I heard in audio anywhere. It is very much not ego thing but just my testimony. From certain perspective it was in a way even bass-better then what I have now in my current listening room (not all together but from only certain restrictive perspective). Do I recognize the 25W problems? Of cause I do but I would not name the rubber suspension but rather the dynamic restrictions. If the 25W was let say 10dB sensitive then it would be much more interesting.

So, in the end of the day I feel that you guys call the dynamic restrictions of the driver as “rubber sound”.  In reality with a good SET bass amp those dynamic restrictions are very pleasant and very transparent.

For sure using the larger driver with very different topology is other way to go and there is nothing wrong with it. However, the different sound of the larger woofers is not necessarily is an indication that there is something wrong with 25W woofers, particularly if the efforts were not spent to make the 25W to sound properly. If I have an option to go for 8x24” woofers or 32x25W woofers (or whatever will be an equivalent in volume displacement) and if I had no other considerations (room, location, positions, boxes… etc…) then I truly do not know what I would select. I know that if 25W woofers had extra 10dB sensitively and had extra 10-15dB of compression point then I would not doubt about my choice as I feel that there is something very nice, very organic, very pleasant and very sort of speaking human in the sound of the 25W driver. Not it is NOT the tone-wealthy driver (like some others) but it still has that “something” that makes it to be loved my me.

Rgs,
Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-23-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 15
Post ID: 17046
Reply to: 17045
Here is the idea that I had.
fiogf49gjkf0d
Here is the idea that I had for the “ultimate bass” for my room. Below is the picture of Macondo one channel as it is now from my listening position. So, if I find a way to deal with the wall edge at my ceiling  then I might replace the current 72” woofer tower with 110” woofer tower of identical width (marked in red at the photo), make it 4 deeper and put in there 8x25W driver per channel.  One 18” driver has as much air displacement as 3.2 ten inch drivers. So, 8 drivers in term of displacement are the same as two and half 18 inchers….

LeftChennal_BassIdeas.JPG

The ides is not only to get extra 9dB sensitivity from set of 8 drivers but the most important to get extra 18dB max dynamic pressure (9 from sensitivity and 9 from power handling). This would be my version of “Constructing LF modules to the limits”, considering my desire to keep the footprint to minimum, to have as driver side and time aligned and make an attempt to organize them in line-array (even though I question if it would be effective at the frequencies I use them)

Would be more effective to go for large drivers?  Possible but I do not think that anyone would ever give more or less objective and definitive answer. Building the theories I see some advantages in use of large drivers and I see some advantages to use small drivers.  I know that if I go for my 16-drivers scenario then I will stay with my 25W woofers that I happened like a lot. Surprisingly the biggest obstacle in me not going for the 16-drivers is my current boxes that I also like. If someday would take my current woofers from my hands then I would call my carpenter and commission him to built for me the taller boxes. I have also the boxes for 2 driver, also very good footers that can’t use  in my room and probably somebody would… I hate to sell my unused any more projects but I also hate to collect all of this, my basemen looks like speakers graveyard….

Rgs, Romy the Cat
 


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-23-2011 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,130
Joined on 10-12-2006

Post #: 16
Post ID: 17047
Reply to: 17046
Situational Ethics
fiogf49gjkf0d
Setting aside the small drivers for LF, while the rest of us have been all ga-ga about the vertical array, the pros have long since moved to the "horizotal array" for LF.  Although I plan for several large drivers in large "modified IB" cabinets, I think I will make them so they can either stand up or lie down, hoping I can stand them up!

Regardless, headroom  - all by itself - is ALWAYS a good thing, and especially at LF.

I have mentioned it before, but i love to re-tell Gordon Holt's allusion to the sound of the long strings in an orchestra as "...a fully-loaded semi pulling away from the curb."

Best regards,
Paul S
09-24-2011 Post does not mapped to Knowledge Tree
noviygera


Chicago, IL
Posts 137
Joined on 06-12-2009

Post #: 17
Post ID: 17050
Reply to: 10371
Better tone
fiogf49gjkf0d
>> The second reason why I switch to considerably bigger woofer units is because they have much better tone (if properly made!)

Haralanov,
This statement is interesting to me because I am embarking on a similar scale LF project and I am very curious what "properly made" means when perusing the tonal attributes of LF. What properties or specifications other than driver diameter do you evaluate when perusing a better tone?

Herman
09-24-2011 Post does not mapped to Knowledge Tree
oxric
Posts 184
Joined on 02-12-2010

Post #: 18
Post ID: 17051
Reply to: 17046
Spacing between drivers in vertical bass array.
fiogf49gjkf0d
 Romy the Cat wrote:
Here is the idea that I had for the “ultimate bass” for my room. Below is the picture of Macondo one channel as it is now from my listening position. So, if I find a way to deal with the wall edge at my ceiling  then I might replace the current 72” woofer tower with 110” woofer tower of identical width (marked in red at the photo), make it 4 deeper and put in there 8x25W driver per channel.  One 18” driver has as much air displacement as 3.2 ten inch drivers. So, 8 drivers in term of displacement are the same as two and half 18 inchers…. 

 


Romy,

I have always felt that if I went for a vertical array of 10" drivers, I would keep the drivers closer spaced than you do in your 'Dunlavy' made enclosure.

Based on the 110" height of the tower, I see that you would be doing this by reducing the distance between eight drive units to about 5cm with the planned 110" tower. I was planning to try and use 8 drivers myself if I went for such a configuration but I would try to find a way to reduce the distance between the drivers to virtually nothing.

In fact, if I could talk Scanspeak into it, I would have two cutouts at opposing ends of the frames. This would possibly in your case enable you even to have 12 drivers per tower.

Best regards
Rakesh

   
09-24-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 19
Post ID: 17052
Reply to: 17046
Here is pretty much the idea that I had.
fiogf49gjkf0d
Here is pretty much the idea that I had – a very tall line array with min footprint and with more of less corrected timing error by angling the front baffle. At the picture below the curvature of positioning of Macondo channels is not depicted (for sake of graphic simplicity) but the idea is well exposed. 

BassTower2011Front.jpg


BassTower2011Back.jpg
 


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-24-2011 Post does not mapped to Knowledge Tree
oxric
Posts 184
Joined on 02-12-2010

Post #: 20
Post ID: 17053
Reply to: 17052
Using modules for time alignment
fiogf49gjkf0d
 Romy the Cat wrote:
Here is pretty much the idea that I had – a very tall line array with min footprint and with more of less corrected timing error by angling the front baffle. At the picture below the curvature of positioning of Macondo channels is not depicted (for sake of graphic simplicity) but the idea is well exposed. 



I like the idea of angling the enclosure, although I am not sure about the idea of the lowest drivers firing at the floor...I would use a series of modules each containing two tightly fit drivers which would fire parallel to the floor, and achieve a very similar approximate time alignment by positioning.

http://www.etnow.com/news/2007/10/alcons-qb363-arrayable-bass

You can find above a link to a company that offers(maybe offered I don't know) such modules and you can also see that here they have also gone for minimum spacing between the drivers.

Best regards
Rakesh
09-24-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 21
Post ID: 17054
Reply to: 17051
Do your own experiments.
fiogf49gjkf0d
 oxric wrote:

I have always felt that if I went for a vertical array of 10" drivers, I would keep the drivers closer spaced than you do in your 'Dunlavy' made enclosure.

Based on the 110" height of the tower, I see that you would be doing thisare doing this by reducing the distance between eight drive units to about 5cm with the planned 110" tower. I was planning to try and use 8 drivers myself if I went for such a configuration but I would try to find a way to reduce the distance between the drivers to virtually nothing.

In fact, if I could talk Scanspeak into it, I would have two cutouts at opposing ends of the frames. This would possibly in your case enable you even to have 12 drivers per tower.

I am not sure what drives you: a desire to but a speaker of a desire to initiate a new group buy for ScanSpeak drivers. Knowing you I am pretty sure that if I do not put a stupid smiley face in the end of the last sentance then you will not be able to “get” that it meant to be sarcastic.

Anyhow, for sure you are right – the more drivers the merrier. When I went a few years from 4 drivers to 6 drives it was not a minor change. It is also explainable. The boost of 3dB sensitivity with doubling driver is not as important as the boost of 6dB max dynamic range (via more power handeling). In reality the boost of max dynamic range might be even more and multiple coils have better cooling options and minimize the thermal compression. There are many other advantages as well. I would fit the font baffle as you said with as many drivers as I might but you need to be sensitive to the volume of the box. If I would like to keep the width no more than 12” then more drivers means larger depth of the box. Do not forget that you need to provide the min volume of the air for each driver. I do not insist that the volume I use is right or wrong, at might be smaller or larger; in fact I do prefer it to be a little bit larger then what I have now. All of those things are well predictable for sealed boxes by using the T/S data. Anyhow, more driver = more depth of the box….

BTW, if you would like to think about the my solution then get a pair of those drivers, put then in 2-3 cub feet boxes and experiment with them. They for sure have own sound, you might or might not like them. I kind of like them and I very much use to them but I am very much might be ignorant in what large drivers or betters drivers might do.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-24-2011 Post does not mapped to Knowledge Tree
oxric
Posts 184
Joined on 02-12-2010

Post #: 22
Post ID: 17055
Reply to: 17054
A Group Buy for Scanspeak? Now you mention it!
fiogf49gjkf0d
 Romy the Cat wrote:


I am not sure what drives you: a desire to but a speaker of a desire to initiate a new group buy for ScanSpeak drivers. Knowing you I am pretty sure that if I do not put a stupid smiley face in the end of the last sentance then you will not be able to “get” that it meant to be sarcastic.

The Cat


Hi Romy,

I think that in this case what drives me at the moment with regard to my LF solution is nothing other than the intellectual process of deciding on which route to eventually follow. Sure I will experiment once I make that first step.

And why did you not mention a Group Buy for ScanSpeak drivers earlier? I would have started one ages ago!

Best regards
Rakesh
09-24-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 23
Post ID: 17056
Reply to: 17053
I would not fight for tight space too much.
fiogf49gjkf0d
 oxric wrote:
I like the idea of angling the enclosure, although I am not sure about the idea of the lowest drivers firing at the floor...I would use a series of modules each containing two tightly fit drivers which would fire parallel to the floor, and achieve a very similar approximate time alignment by positioning.

http://www.etnow.com/news/2007/10/alcons-qb363-arrayable-bass

You can find above a link to a company that offers(maybe offered I don't know) such modules and you can also see that here they have also gone for minimum spacing between the drivers.
 What they do is fine but I would not kill myself too much in hoses fights for a fraction of inch in the front baffle. First off all mounding the drivers with no space you do compromise the structural integrity of front baffle but I guess that might be conceded during the design stage and the front baffle might be made from aluminum or something like this. The most important is that it not truly significant from line-array perspective. The line-array doctrine are applicable if the array less than the wavelength. If I cross my woofer at 20Hz then you understand that all my conversations about array is only conversations.
 
The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-24-2011 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,495
Joined on 05-28-2004

Post #: 24
Post ID: 17058
Reply to: 17055
Your Group Buys is an indication of your simplicity.
fiogf49gjkf0d
 oxric wrote:
And why did you not mention a Group Buy for ScanSpeak drivers earlier? I would have started one ages ago!
  
This is all because you are a primitive person with very simplistic and amateurish understanding of many things. You need to learn from much more sophisticated people, of cause I mean myself.  Take a look: I do not run like a wounded in the ass antelope across web, soliciting drivers, negotiating with dealers, forming group buys, shipping those heavy boxes and printing labels. I am much more classy then that. I am blabbering at my site about some kind of drivers, make a few pictures and drop the names of Bruckner, Gurdjieff and Kant along the lines. The simple audio people out there get scared, run to snatch the drivers. In a few months or years they come to me, complain that it was shit. Then I am making that companionably-suffering face and "agree" to take the drivers from their hands. This way I have half of the price and free delivery. You see, THAT is the way how the real professionals are operating.
 
The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
09-24-2011 Post does not mapped to Knowledge Tree
oxric
Posts 184
Joined on 02-12-2010

Post #: 25
Post ID: 17059
Reply to: 17058
Classy and sophisticated Romy.
fiogf49gjkf0d
 Romy the Cat wrote:


This is all because you are a primitive person with very simplistic and amateurish understanding of many things. You need to learn from much more sophisticated people, of cause I mean myself.  Take a look: I do not run like a wounded in the ass antelope across web, soliciting drivers, negotiating with dealers, forming group buys, shipping those heavy boxes and printing labels. I am much more classy then that. I am blabbering at my site about some kind of drivers, make a few pictures and drop the names of Bruckner, Gurdjieff and Kant along the lines. The simple audio people out there get scared, run to snatch the drivers. In a few months or years they come to me, complain that it was shit. Then I am making that companionably-suffering face and "agree" to take the drivers from their hands. This way I have half of the price and free delivery. You see, THAT is the way how the real professionals are operating.
 
The Cat


Romy,


I have never doubted for one little moment that you were one of the most sophisticated, classy individual I have not had the pleasure to meet!

I would like to say something about being called simplistic and amateurish. I like simplicity of purpose and elegance of solutions and in many ways a multi-channel system enables one to combine, paradoxically, sophistication and simplicity. So being simplistic and seeking simple solutions as opposed to being a simpleton which you clearly are when it comes to normal human interaction, is for me worthy praise indeed. That is why I started to explore this avenue only last year as opposed to you who have spent thousands of hours developing and posting about your audio system. I have no such time, will never have it and so must accept grudgingly the accusation of being and intending to remain an amateur.

I do not see the relevance of the Fane Group Buy to this thread which was if you remember about the use of the Scanspeak drivers in Haralanov's system. My query was adressed to him, and my intention was to find out what were the results of his project. You decided to jump in with your slanted configuration for LF in Macondo, maybe a post which really ought to have been made at a more appropriate location on your forum.

So to go back, clearly we are not talking about a line array at the relevant frequencies we are dealing with. See the part on your website where you describe your LF module:

"The Macondo’s Bass Channel is line arrays. The arrays employ religiously-sealed enclosures with six “spotted” Scan Speak 25W/8565-00 drivers per channel... "

Clearly you had written this at a time when you did not really understand or appreciate the concept of line arrays, or you were not able to express yourself very clearly. In any case, the construction aspects of mounting drivers in a tight space whilst maintaining rigidity are perfectly within the building skills of any good carpenter or talented diyer such as yourself. I do not think one would need to go to the expense of using aluminium whether one uses modules or not but certainly in the case of modules construction is evidently that much easier. And since you mentioned a tower height of 110" I thought it made sense to have 12 drivers where you were planning to have 8. Anyway, that's what I would do. And with regard to slanting the front baffle, I find the idea slightly odd because of the reflections at floor level for the lowest drivers.

Best regards
Rakesh



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