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  »  New  Romy The Cat's new Listening Room..  Won't be the last time he makes that trip!...  Audio Discussions  Forum     478  2779433  03-28-2010
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10-03-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 126
Post ID: 22803
Reply to: 22800
A ULF solution for my new listening room
fiogf49gjkf0d
It looks to me that I will be able to live with my 6 driver line array. Again no measurements were made but it is what it “looks”.  Sound-wise it is very reputable and I just might leave it as is. My current room is 6 larger to what I had in downtown Boston and running the identical configuration I will have fine result. I had slightly more solid lower bass in my Boston apartment. It is not something that is notable under normal circumstances but it rather something that I know knowing what I want to hear. It is not bass notes that are missing but a reference to the infinite “space” information at the bottom. In my Boston apartment I had it by having smaller room and in my Woburn house I had it employing ULF (Ultra Low Frequency) sections that were sitting on transition slope at 20Hz. My new room is 6 time larger for MF and perhaps 12 time larger at ULF as it has an open clearance to the rest of the house and share the same ULF space with my office, which in the same Romy’s Wing.  
 
So, I am slowly begun to wondering what kind ULF solution I might look into. I am not a stage where I certain that I will go for it. I would like to have my playback to setup perfectly (it is not yet) and then I will make a decisions. Still, it does not prohibit me to think and to strategize. 
 
First is the objective. I do not need my new ULF to operate in auditable region, so I am taking about sub 20 Hz. To stay with sealed configuration and to use let say 2x 18” driver per channel I will end up with 10-12 feet enclosures, something that I would not put in my room per esthetic reasons.  To stick with ported configurations would give me some yield with size but it also will be prohibitly large and will end up with two refrigerators in the room. Even if I agree to use ports and deal with all crap that comes with it then the question would be how to power the thing and what the drivers to use. There is no good driver out there with Fs of 10-14 but to do it with 25Hz driver is pain. I can make driver to go 10hz in open air but this will be large and expensive project, I do not know if I have time and the important zeal to undertake it.  
 
Alternative would be to mount a few drivers in sealant as I initials proposed in this thread, creating an infinite baffle. Again I will be faced the selection of driver, amplification, render everything and I do not know what would be the results and I did not deal with infinite baffles. I do not think that I will hit the numbers lower then my drivers free air resonance.
   
I might pooh- pooh resonance and the whole idea of mass-centricity and switch to pure velocity, driving the infinite baffle with negative output impedance. That would require doing a LOT of equalization and a lot of power to dissipate and I still have no knowledge to predict the result.
 
A promising alternative would be to use small enclosures with a lot of power, something similar to what Bob Carver did with his Sunfire subs. Bob Carver in a way a charlatan and his subs sound accordingly horrible but it might be dirty water where I could fish something. There is company out there that makes fully active devise that are small.  
 
https://www.powersoundaudio.com/products/t18ht?variant=10539398788 
 
I am sure that the T18HT will hit the right specification numbers but will it produce the proper ULF feeling that I need? This is the Carver’s technology + digital amplification = I naturally scare.  
 
So, I am not sure what I want and not sure if I like what is out there and I do not know if I even need to look in this direction. Still, looking at my walls and sealant I am kind of drooling. If anyone dealt infinite baffle in regular house then I would like to hear from you. It is not a big deal to cut a few joists and to mount drivers in there but I am afraid if I load to the drivers 0.5kW then they will excite any lousy piece of wood in the house and I will end up with disaster… 

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
10-08-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 127
Post ID: 22807
Reply to: 22803
Ok, a first objective look.
fiogf49gjkf0d
Today I spent a few hours to calibrate the Macondo and Milq. One of the drivers from Macondo was gunner and the rest was more of less stable. I did some initial measurements. It was not impressive. I do have approximately 3-4 db deficiency on left channel in bass and 6-8 db deficiency in bass of the right channel. So, my hope that 6 drivers per line array would be enough did not work. I would need 10 drivers array on right and 14-16 on left to linearize bass region. Obviously I do not have this luxury. The character of the response is kind of what I predicted. Since the sound feels that it is “enough” bass and the bass is more or less one note then I was presuming that it is some kind of +10-12dB room mode at 40-50Hz. It turned out to be true.  So, I need to deal with +10dB 50Hz mode and overall deficiency of upperbass, middle bass and lower bass. In the lower bass I am down 16-20 dB from where I would like to be. So, I am considering to add a midbass direct radiator channel and then put my current ULF array at sub 40Hz transition slop. So, I need to experiment with enclosures for midbass drivers.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-09-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 128
Post ID: 22808
Reply to: 22807
Some room dealing basics

Two of my local audio folks asked me to put online my thoughts process about my listening room. Here are some basics. Yesterday, messuring my room I got the following response in lower octaves. That is a typical response in rondom rooms, or what audio people have in 80% or all cases. 

NewRoom_CurentRTA.jpg

The room ironically sounds with “good bass” and I had last night an audio friend visited me and he did not complain about bass. I am not kidding, it is “enough bass”.  Now we are going into quality of bass. Just looking at the response (in reality it is +12dB at 50Hr) and correlating with what is auditable it is not hard to recognize that system has tendency to produce one generic bass note. The diversity of all bass notes had the same “coloration” or rather the same unified common characteristics. That is obviously not good but why my last night friend did not complain about bass? Well, there is an explanation for that. I played to him mostly jazz and what he asked me to play to him classical muse I plays an adagio with no bass. The jazz music by nature pretty much has very few bass notes and they are all the same to begin with. In addition” properly reproduced 50Hz is not bad thing. It is not ported crap with marble driver but nice 6 drivers array with very linear motors, driver with good DSET – it is ended very nice sounding. Still. We know that we have in bass a very strong harmonic coloration. How to deal with it? Obviously we need to linearize the response; we need to get extension down to teen hertz, and we need to get VERY accurate amount of upper and mid bass – something that to a great degree identifies high end audio reproduction. There is a key in all of it – the above mentioned things need to be done by proper means, by natural way, not to fighting with the room but using the room as a friend rather than a foe.

NewRoom_CurentRTA1.jpg

Well, if you look at the image just above then it briefly depicts the plan how I would like to start attacking the problem. I declare 50Hz as a dangers zone and I will wright low-pass and high-pass filters against 50Hz using the transitional slopes, offsetting the natural room problem by decaling filter slopes. On the left of the 50Hz I think I will implement 15Hz 18db/octave filter, which shall fill the room with lower bass and will arrive flat or near flat at 50Hz. I plan to use my line arrays for this channel and in order this filter to work I would need to drive a lot of power over it, so I would need over 100W at least. On the right from 50hz it will be a mid-bass channel probably from sub 150hz. That would be tricky as the filter shall die at 50Hz with minus 10dB. So I would need to play with it and figure out how not to you high order roll off. I think I would drive it with Milq’s bas channel, it means it needs to be over 100dB sensitive. I do not have a decision now about topology of the channel. The midbass horn would be nice but I do not know if I can afford to do it time-wise. I line array with 15” vintage driver might work well and would not be expletive, also it would be response tweakable, not like horn. Anyhow, in context of what I said above I am contemplating my options.
 

What is very important to observe in all of it is that I do not fight with the room but I rather USE the room in my design objective, that is one of my Macondo Axioms and I would like this to me the lesson of this post. 

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
10-10-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 129
Post ID: 22809
Reply to: 22808
Thinking about the forthcoming experiment.
fiogf49gjkf0d
I have order 4cu feet sealed enclosure for two 15 drivers. It is relatively small box but I need to hit minus 6-8 dB at 50Hz. The collection of the drivers I have would be following: Vitavox AK51 and 15/40, Altec 416B and 515B. I like Vitavox tone (a lot) and I love now 416B runs across dynamic range with good SS amplification. The 416B has dynamic advantage in ported configuration and I have no idea how the sealed box compression might hurt it. Vitavox has great tone but it is paper-suspended driver and loaded in air spring it might just stop “ringing”. The 515 is wonderful and has extra 3-4 dB sensitivity but with extra magnetic force it a bit wrong sounding driver. You do not want to have a woofer with 1.7T in gap… The most important is how to get the midbass channel to get me 0dB at 100Hz and minus 12dB one octave lower. Sure a sharp filter would do but can I do something more intelligent? It would be nice to tune the enclosure size and thigh the pneumatic spring until I have proper SPL drop, however, how will it affect the compression?  The ultimate fan would be if I were able to combine the Injection channel with Midbass channel. Pretend a time-aligned enclosure with 10” and 15 drivers siting in own spaces. I might even would consider in this configuration to go for ported topology for midbass.
NewMidbadIdea_Box.png



"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-11-2016 Post does not mapped to Knowledge Tree
oxric
Posts 194
Joined on 02-12-2010

Post #: 130
Post ID: 22810
Reply to: 22809
Slighly mad suggestion! Ignore accordingly
fiogf49gjkf0d
I would have been tempted to maximise space above for use by 4 midbass 15" drivers, 2 per side maybe in separate enclosures you can can move each module independently of the other.
But probably too late for that as you have ordered the enclosures. And would require compromising location of Injection channel (I was thinking alongside your Raal tweeter).
I am sure your solution is infinitely better...
RgdsRakesh
10-11-2016 Post does not mapped to Knowledge Tree
noviygera


Chicago, IL
Posts 177
Joined on 06-12-2009

Post #: 131
Post ID: 22811
Reply to: 22809
Bass trap
fiogf49gjkf0d
Romy,
I tried non-symmetric crossovers (freq and slopes different for channels) but had to go back to symmetric because the phase response sounded very wrong to my ears. I learned that I could get used to a bad frequency response but I could not get used to a non-linear phase response.   I think the crossover you are proposing will introduce this "step" in the phase response.
Is there anything bad about using a tubed bass trap in your room?
10-11-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 132
Post ID: 22812
Reply to: 22810
I will see...
fiogf49gjkf0d
 oxric wrote:
I would have been tempted to maximise space above for use by 4 midbass 15" drivers, 2 per side maybe in separate enclosures you can can move each module independently of the other.
But probably too late for that as you have ordered the enclosures. And would require compromising location of Injection channel (I was thinking alongside your Raal tweeter).
I am sure your solution is infinitely better...
RgdsRakesh
The enclosure (one single box) for one channel that I have order is a test enclosure – a $50 car dual 15” sealed box. This will give me an idea what amount of the drivers I would need to use. The box has 2 section by 2cub feet per driver. I still do not know how to kill the output from the 15” driver so fast and without losing dynamics. So I will be doing experimentation with it and I do not think that the box that I ordered for test will be the final one.



"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-11-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 133
Post ID: 22813
Reply to: 22811
Pure arrival time minus reflection or....
fiogf49gjkf0d
 noviygera wrote:
Romy,  I tried non-symmetric crossovers (freq and slopes different for channels) but had to go back to symmetric because the phase response sounded very wrong to my ears. I learned that I could get used to a bad frequency response but I could not get used to a non-linear phase response.     I think the crossover you are proposing will introduce this "step" in the phase response.   Is there anything bad about using a tubed bass trap in your room?  

I do not use tubed bass trap as I do not like the sound they produce.  To have any more or less sensitive absorption at 50Hz you knee to put a lot of trap in the room and they shorten reverberation time at upper bass very aggressively as they have much higher absorption rate at 300-500Hz. 
 
Regarding the phase response. Yes, I very much agree with you and I am for years a curator of the idea that we do not hear amplitude but hear only phase. As I will be introducing a very narrow bandwidth channel I am wondering myself how to organize the things phase-wise and the most important how to calibrate the phase performance. I have my problem with pulse response and with LMS analyses. So, I need to find a matrix how I will be align the new midbass channel. I am not sure if I need to do it by pure arrival time minus reflection or I need to factor in the reverberations. I need to experiment and to listen it.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-11-2016 Post does not mapped to Knowledge Tree
anthony
Posts 335
Joined on 08-18-2014

Post #: 134
Post ID: 22814
Reply to: 22813
Other absorbtion methods
fiogf49gjkf0d
 Romy the Cat wrote:

I do not use tubed bass trap as I do not like the sound they produce.  To have any more or less sensitive absorption at 50Hz you knee to put a lot of trap in the room and they shorten reverberation time at upper bass very aggressively as they have much higher absorption rate at 300-500Hz. 
 


What about Helmholtz Resonators?  This looks like an application ideal for their use where they only absorb over a spectrum of 10-20Hz.  Apparently they are simple to design and build.

Diaphragmatic absorbers may also be applicable, but I think they will also have a little absorbtion outside the target range.
10-12-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 135
Post ID: 22815
Reply to: 22814
Converting acoustic problems into acoustic paybacks.
fiogf49gjkf0d
Anthony, the Helmholtz Resonators for 50Hz are huge and will work ONLY for a very narrow location, presumably the listening position. This is not an ultimate objective and it is not about EQ the response at the sweat spot but rather to normalize the response in the whole room. You see, the horn loading topology and using SET amplification with no feedback implies high amp’s output impedance and high microphone sensitivity of the speakers. The acoustic room feedback is very active with such topology and you want to load the acoustic feedback evenly, not only to create flat response at your listening position. This and many other reasons makes me to discard the room treatment as active problem correction ceremony but rather embrace the approach when an acoustic system is designed using the room aberrations and the initial input parameters. For sure I deal with open walls and the rest of the typical acoustic problem but I try do not fight the room but rather embrace the room problems into my design idea, converting the problem into benefits.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-19-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 136
Post ID: 22823
Reply to: 22459
Evolution of my rooms sound quality.
fiogf49gjkf0d
A local audio friend sent me a few days back a feedback after visiting my new listening room: 
 
“When we used to listen to music at your Woburn house I could come home and still enjoy my playback. But listening to playback at the Boxwood house was so much like Marlborough street it messed up my mind with home playback.” 

 
I disagree with my fend comment and I feel that sound I am getting in my new listening room not even remotely where is I would like it to be. This, however made me to think about the evolution of my sound. 
 
The best sound I ever had with my Boston small listening rooms was a short two weeks in 1999 when I was running modified AvantGard Trio and driving it with Lamm SS amps. Yep, it was not near a sane configuration and one would notice in there a zillion problems with sound but it was one of the experiments after which my AvantGards accidently landed to DPoLS and it make everything sound very much beyond from what might be expected from audio. It was so hypnotizing that I took two days off and just was sitting in my room not believing that it might be happened. Considering that I do consulting and at that time billed $125 per you understand that my voluntary withhold from work cost me a lot of money. Still, it was the happiest time in my audio life as I got an audio reverence that seldom, if ever, come to a person life. In two weeks or so I moved slightly AvantGard and the sound got destroyed. I could write 300 pages book of what I heard during those 10 or so days but there are very few people in audio who would understand it or will be able to relate to it. To the rest of my living in that Boston listening room it was OK sound with many interesting hi-endish tricks, very good but not extraordinary. 
 
The next best sound I have was end of December 2011. It was my first year I made up my suburbia listening room and I spent good 6 months to work on the room and on the playback. The sound was spectacular. It was not even closed to what I had when I had AvantGards at DPoLS (it was probably 10% of it). Still, in context of no DPoLS it was stunningly good sound. I was so impressed and so pound then that I even send invitation to many bizarre and adversary people  from my past (Lamm, and a few alike), inviting them to my listening room and witness “what might be done”. In a few months Amy moved with me and she is in a way destroyed the sound with her decoration efforts and the sound in my Woburn listening room never was “great” after the winter of 2011. 
 
In my current new suburban listening room I am nowhere near the sound I was able to get in Woburn or in Boston. I do think that the room that I have here is way friendlier then Woburn room and the space sound VERY complimentary. The playback is not there and the LF region is not there. I am juts learning now how to configure my time-window to reject from my system pulse response the screams of my twins. As I have some time I will finish the Macondo setup and calibration and I will see where it will bring me.  I have some advanced ideas for this installation that I am also willing to try, so it might be interesting where I will lend. The new room has also much better electricity then what I had before – it will help a bit for sure…


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-19-2016 Post does not mapped to Knowledge Tree
xandcg


Rio de Janeiro, BR.
Posts 218
Joined on 09-07-2014

Post #: 137
Post ID: 22824
Reply to: 22823
Why not pentode or push-pull instead solid state.
fiogf49gjkf0d
Romy,

I would like to know, if you do not mind to explain, since you cannot drive your bass modules using SET, why you use Solid State amplifiers instead Pentode or Push-Pull Triode?

Thanks!



Think for yourself, do not be sheep.
10-21-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 138
Post ID: 22825
Reply to: 22824
I do not know powerful pentodes in output.
fiogf49gjkf0d
 xandcg wrote:
I would like to know, if you do not mind to explain, since you cannot drive your bass modules using SET, why you use Solid State amplifiers instead Pentode or Push-Pull Triode?

Well, I need to say that I never heard any good bass from other amps then SET. No SS amp I even heard produced proper bass and a number of Push-Pull Triodes that I was exposed to did not sound acceptable. They were just OK but SET, or more accurately say DSET, was always better. So, this is pretty much an empirical standing then then some kind my private believe system. I do not have a lot of exposure to Pentodes in output stage, so I am not able to say anything. I heard some low power pentodes SET but they were just not so impressive amps all together. Anyhow, I do not have any experience on the subject to make any generalization. 
 
The issue is that I use my ULF on transitional slope with open bottom which requires a LOT of power. Pretend that I need -3dB at 40Hz in the room. I can write slope from let say 10Hz +3dB that would arrive to 40Hz where I need to be (let forget for the sake of illustration about room modes and pretend that it is all linear). To pump +3dB at 10Hz  you would need a lot of power and if you are in DSET world where OPT inductance and frequency are a part of power capacity then you end up with VERY expensive implantation and OPT is the size of a refrigerator. Considering that of you use the triode that might give to you let say 100-200W then you would be at 2000-3000V on plate and your refrigerator OPT need to be isolated for 5000V. That all makes it very demanding. If one know what and how he wants to do with Pentode SET then it is fine but not knowing how to kook it would be too inconvenient to try, at least to me.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
10-21-2016 Post does not mapped to Knowledge Tree
xandcg


Rio de Janeiro, BR.
Posts 218
Joined on 09-07-2014

Post #: 139
Post ID: 22826
Reply to: 22825
I thought on tetrodo and write pentodo.
fiogf49gjkf0d
Hi,

I thought on tetrodo (KT-88, KT-120, KT150) and  write pentodo, sorry. Wherever the tetrodo sound were nothing special I personally find them a lot of better than solid state, that why I was asking, and these days one can have 300W with to KT150 PP.

Anyway, I think I got your point. I feel you are waiting/looking to find the right solution where you can use triode instead of experiment/integrate other things.

Also, as already said, I am not a technical person. I shall investigate the «Transitional Slope» technique because by your explanation I feel it bring a very interesting sound.

If I understood correctly, the bass on this configuration may be something that start from down to up what I imagine should be like a volcanic style bass.

Do it would also apply (have the same effect) on tapped horns, have you how to predict?

Thanks for your reply.



Think for yourself, do not be sheep.
10-25-2016 Post does not mapped to Knowledge Tree
shannon
Posts 23
Joined on 08-08-2014

Post #: 140
Post ID: 22829
Reply to: 22825
Zarathustra
fiogf49gjkf0d
Congrats on the new brats. And family.  How things have changed.  Even though Amy has introduced sound problems I appreciate the decoration efforts.  Also the Angels playing strings tapestry is magnificent.  
So did you ever get Zarathustra functional.  Myself I have it sitting mostly finished, after a few years.  I got trapped up in cosmetics and the zeal evaporated.  

Seems like it can provide the power does it sound interesting
11-13-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 141
Post ID: 22836
Reply to: 22823
Very very nice.
fiogf49gjkf0d
It took for me a few weeks to put up a new direct radiator Midbass channels. Each channel has 2 of Vitavox 15/40 drivers is seals 2 cu foot enclosures. No filtration of any kind on speaker level and Vitavoxes juts are driver from Milq LF channel that has first order 78Hz low pass filter. You know, I just connected everything and I am surprised how nice it is and how accidently the sensitivity of the Vitavox tandem match the gain of Macondo rest channels. I did not do measurements yet but the Vitavox tandem shall do ~50Hz. I think it will go a bit lower as the driver soft out but I am not sure that I need them to do lower as I have that 50Hz room mode. If everything will be as I plan then I will have 0dB flat at 50Hz with my midbass and I will have the whole 6-driver line array to form ULF that I will probably put at 20Hz on transition slope. The funny part is that the playback is so nicely positioned in the room that it swallowed two big 20” by 40” boxes and they are not even visible among the forest of the rest Macondo. 
 
Subjectively the Vitavox direct radiator Midbass sound surprisingly fine. There is no “glow” that I had with my horns but I will get other interesting effects when I put my ULF in use. The articulation, tonal and contrast integrity of the direct mounted Vitavox is very fine. I think I do prefer the dynamic transience in open air better but it would be impossible to have a practical channel with open baffle.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-13-2016 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,570
Joined on 10-12-2006

Post #: 142
Post ID: 22837
Reply to: 22836
OB (etc.) at Midbass
fiogf49gjkf0d
You have said that you want to keep the channel relatively small, and sealed is one way to do it.  I don't know your Vitavox, but a larger ("IB") box might have more of the dynamic transcience you mention, and it probably would not be a step back in terms of the other qualities you've mentioned. Others may be scratching their heads, but, as I reported here, I have recently heard "FR" OB sounding OK down to maybe 50Hz, and it was done with electronic wizardry, along with the amp power to push the curve.  By the way, with 3 little kids, it amazes me that you've gotten this far so quickly!

Best regards,
Paul S
11-15-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 143
Post ID: 22850
Reply to: 22837
Theoretically possible?
fiogf49gjkf0d
Well, I do not like any none-sealed enclosure. From my perspective IB box is also sealed and I am not against it. It is not about the sealing of encloses but about absence of contra-phase feedback that is always there in any other topologies. There are many scenarios how the baffle could be opened in one way or another and it is kind of ironic that the quality of the sound (with right driver) above the baffle cut off frequency might be very good. The problem that almost all open baffle devotees fail to understand that somewhere a baffle ends and within the octave where is does an acoustic shortage take place. The acoustic shortage itself is survivable and might be even pleasurable. The problem begins if you want to add an additional channel under the acoustic shortage. I never heard any good result of it and I do not think that I is theoretically possible


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-16-2016 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,570
Joined on 10-12-2006

Post #: 144
Post ID: 22851
Reply to: 22850
So True
fiogf49gjkf0d
Yes, the "bottom drops out" of the "IB" depending on whether or how it's "opened", and one way or another, the cabinet may or may not "assist" the driver at some point. This is where one has to decide how much to ask from the particular driver or drivers. It seems like 50Hz is not too much to ask from some 15" drivers, and one "should" have some options, including IB or "modified IB", that best allow a given driver to "sing". With a fairly large box, it seems like there can be less "contribution" from either "stored energy" or "released energy" than there is from  "strategically released", vented boxes, for sure. Of course, in theory, a typical sealed box simply "eats" the energy that goes into the smaller box, and there "is no penalty" from the cabinet. Too bad about driver membranes. Sure, it has to do with the particular driver, the particulars of the box, the amp or amps, and the room, not to mention system integration and personal preference. There are usually problems with adding significant deep bass under any musical mid-bass, if only because a new level of energy is required, and the extra power often requires a different approach than the rest of the system. I think most of the old IB speakers that people associate with the designation never had anything under them!

Best regards,
Paul S
11-27-2016 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 145
Post ID: 22866
Reply to: 22779
This kid has a strange genes or “Papa, how to measure twins impedance?”.
fiogf49gjkf0d



"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-02-2016 Post does not mapped to Knowledge Tree
oxric
Posts 194
Joined on 02-12-2010

Post #: 146
Post ID: 22868
Reply to: 22866
Are they Brucknerised yet?
fiogf49gjkf0d
Romy,

That's a great photo and so funny. Your children are just so adorable. 

I do wonder though. Whilst Thomas seems to rather enjoy the multiple wonders of operating dad's multimeter, the little twins look like they are ready to pull the plug and say no more Bruckner until we have left for college...Enjoy the good times.

regards
Rakesh
04-02-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 147
Post ID: 23093
Reply to: 22459
7 moths and one event...
The twins were born in mid of august last year. Since then I had time and strength to finicky with my playback here and there. It is not set ups up to my standard yet and the playback is not properly imbedded into my new listening room. The people who know me know how important it is and do know that it take some time even if one know what he is doing. Still with all randomness of Sound in my room yesterday took place in a way an extraordinary event. I actually spent an hour sitting in my comfy chair and juts enjoying the music. It was the last movement of Bruckner 8 and I started as target listening after I just connected my ULF. And then it got me and it was quite wonderful ride. Believe me or not it was first “no worry” time spending in front of my playback since mid-august last year. 
 
So, aside from the music what I observed in audio. The musical events were not time aligned. It has nothing to do with channels time alignment but rather with musical phrases were not presented with proper timing. Usually it happens because the R and L of ULF channels are reversed but they were not. I do not know what is going on. It feels like there are to recording playing at the same time and one is offset time wise. So, far I do not know what is going on but I think I do need to calibrate the playback before move further.
 


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-04-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 148
Post ID: 23094
Reply to: 23093
The next day
The last night I “locked” Thomas to watch Masha and Bear in my office and spent some time with playback trying to answers a few questions in my head.
   
First, I needed to discover what was the source of the ridicules double-sound that I experienced another day. Doing more listening I realized that my overall system balance moved to right channel. I went to check the Macondo calibration (gain by individual channel) and very quick realized that it was criminally off. Apparently someone, I do think that it was Thomas as neither my wife nor cleaning ladies allow to touch amplifiers, turned each single knob of both Melquiades. The worth thing was that that Thomas max out the Injection Channels at both amps, what a little rag rat! I remember all calibrations with no measurement (count clicks on step attenuators) and as I put the Macondo back to a proper working order I did get a nice result. 

 
Second is that I still not clear how to deal with my video vs audio dilemma. As the way how it is setup now I might play audio or video via Macondo or via a crap alternative SS pilot playback that I made available (4 ugly Cambridge Sound satellite speakers and Sunfire sub). All of it driven from preamp, so the connection is not a problem. I use the pilot sound to play sports on the big screen for friends (I do not watch sports). The sound is very ugly, plus it is cold-running SS setup. A few times wify and me sit to watch some films and she was explicitly complaining that “sound was not beautiful”. Trust me, with my MASS-grown wife, raised upon the principles of extreme-left political correctness it meant a lot of expressed negativism…   

So, I was wondering last night if it possible to make my pilot playback a bit more palatable. It was Yamaha B2 and I was trying Dunlavy II and Celestion 600 that I had sitting in basement. Bothe speaker did deliver survivable result in small rooms before but in context of my current, relatedly large room it was very bad. The proper solution would be to drag my Cetla 91 from the basement but Cetla 91 are large. I can accommodate Cetla AND Macondo and the rest playback together within 22 feet but it will be not elegant and I would like not to do it. So, I am kind of at lost. I have an idea to compliment 4 ugly Cambridge Sound satellite speakers and Sunfire sub with own upper midrange channel (and I have plenty of it in basement). I think it will make it a bit friendlier. I have the leftover Macondo’s MiniMe’s little bass tower and it might do. 

http://www.GoodSoundClub.com/TreeItem.aspx?PostID=9564 
 
I have no idea how it will work when I will drive it very hard to fill the whole room…

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
04-04-2017 Post does not mapped to Knowledge Tree
clarkjohnsen
Boston, MA, US
Posts 298
Joined on 06-02-2004

Post #: 149
Post ID: 23095
Reply to: 23094
I don't understand the video problem. . .
. . . because I haven't seen the setup. All in the same room? (No opera room?) Why can't the main system be used? Etc. etc.
04-04-2017 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,049
Joined on 05-28-2004

Post #: 150
Post ID: 23096
Reply to: 23095
Choose your poisons
 clarkjohnsen wrote:
. . . because I haven't seen the setup. All in the same room? (No opera room?) Why can't the main system be used? Etc. etc.

Yep, they are in the same room. No opera room anymore. The reason why I would like do not use the main system all time is because the mains system is 14 amplifiers and 12 of them are tubes. The heat and longentivity are a factors for sure. Plus the glowing tubes attract the kids attention of we are not in a room. What I am saying is that the integrated “opera room” is not opera room anymore. In the opera room we mostly watch some movies, musical programs like concerts and operas. In our new listening room the projector is being used for many other activities. Amy’s dad sometime watches football in there, Tomas watches his cartons and there are a lot of other happenings that do not need to have a full Macondo-Milq are running. During those activities is it nice to have a SS playback running with just OK sound. Stop by, you will see how it feels, it is in face a very nice both video and audio room. I do not have yet the sound in here up to my former standards but in your case I can compensate it with Glenlivet 1972 :-) 


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
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