GoodSoundClub - Romy the Cat's Audio Site

09-15-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	1
Post ID:	14457
Reply to:	14457

Macondo’s lowest channel.

Ok, “unless something goes terribly wrong” the new Macondo’s midbass horns will be built and I am sure that I will find ways for them to sound properly. As you remember I do not believe in horns for lowers octaves and I do have plan to construct a dedicated sub 35Hz channel that will do the necessary for me sonic kill.

I do not anticipate that it will be a complex project; the only slick moment would be that I do not what to see any woofers or large boxes in my listening room and the LF channel shall be in some kind of more or less time arrival sanity.

In this there I will be posting my considerations, idea, and contemplations, report about the progress of the project and follow up with the results. At this point I am juts strategizing as I do not think that that my sub 35Hz channel will be starting too soon. I think I might render the projects during winter as for now I will have my bass towers that are left from my old listing rooms. It is possible that my Danlavy-built bass towers will be good enough to stay but I think that 4 18” drivers will be better. But who knows. If not then I will get rid of Danlavys (I never thought that I might sell them as I do love them hugely) and will build my new 35Hz channel. Whatever I will and will get you will hear about it right here in this thread.

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

09-19-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	2
Post ID:	14496
Reply to:	14457

A mono LF channel – I do not like it.

While the aftermath of the midbass horn project is not over I am strategizing how I might implement Macondo’s LF section. The leading idea is to bolt a triangular shape sealed enclosure juts behind the small wall that cover the load bearing beam from the midbass horns. The space is phenomenal from many perspectives. It will be absolutely not visible in listening room and will not impede my normal living stile in the home. The space is about 18cub feet that would be perfect for one high displacement driver of 18”-24”, the type that would be nice to use foe sun 35Hz channel. The fact that the channel will be arriving-wise closer then the MF channels is not a big deal as well – it is not difficult to delay LF on analog level. However, it will be just one mono channel… this makes the whole idea a bit moot….

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

09-19-2010

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Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #:	3
Post ID:	14498
Reply to:	14496

LF Results

It is hard to get used to the idea of 1 or 3 LF channels supporting a "stereo" hi-fi. But the way it winds up working is that the "wrong number" of channels, or sources in the "wrong spots" can make things sound worse, because of cancellation and/or augmentation. So who knows what the "right number" would be in your big, framed house at this point? Maybe 1 channel would work better than 2; or maybe 3 would work better than 2. Just as interesting to me will be the new requirements for mid-upper bass, to go with your new ceiling horns, and watching how you will get the whole low end integrated in the large space (without EQ?).

BTW, congratulations and mazel tov for safe and tidy insertion of the big ceiling horns! I see now it was not so high as I had thought; but still too far to drop something like that!

And did you say, "240' of speaker cable"!?!

Best regards,
Paul S

09-20-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	4
Post ID:	14505
Reply to:	14496

The size maters

Well, I figures that while I am not sure what to do with LF section and where to locate it I will live with my woofer tower from my old listening room. They did not work well as Lower-Upper-bass channel installed next to Macondo but in odd place, handling under 35Hz then might do OK.
I have 12 drivers, 6 per channel and it is lot of LF displacement. One 18” woofer has surface of 255 square inch. The 6 driver of 10” has aria of 468 square inch, or almost as 2x18 woofers. If I go mono (something that I do not want to do) them it will be 936 sq inch, or a bit less than 4 fill 18” woofers. This is a LOT of displacement and it will require lot of power. If I run it with a powerful SS amp with high gain (perhaps my B2 amp or similar) then I might have something.

The advantage of my woofer towers that they are already here and I need to spent zero efforts to make them to work. Also they use drivers with 19Hz resonance – good lock to find 18” driver with sub 25Hz resonance. The arrays did work femininely food in my old much smaller room but I never used then at dedicated lowest octave – this will be first for me to try it with those drivers. My concern is excursion. The Scan-Speak woofers are light and relatively low excursion. In my old room they did not move a lot and it was very good. My new room from bass perspective has over 1400 sq feet space and to pump 30Hz pressure at THAT volume would require a lot. I’m even afraid that my Yamaha B2’s power will not be enough and I would feel much more comfortable with a good 400-800W power amp.

Anyhow, I think to setup my Scan-Speak arrays with B2 would be a good thing to start… The key would be to find out how low my midbass horns go. If they go to 40Hz then the LF section would pick up at 35Hz-40Hz. If the cathedral ceiling would do the trick and the midbass would spread down to 30Hz (I think possible) then the LF section will pick up from 25Hz and this would be much more preferable configuration. Let see, I am a week away from starting all listening and measurement tests.

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

09-20-2010

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Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #:	5
Post ID:	14507
Reply to:	14505

Response Curve

Three problems with the Scan-Speak are the low X-max, the built-in response curve, and limited power handling. It will be interesting to see how you juggle these issues if you do use these guys for LF. Obviously, if you bias against the natural rising response, then you begin to run up against the excursion and power handling limits. Will all that surface area save the day? I wonder.

Somewhere in the LF pages on this site, someone mentioned and/or gave me a link to a couple of big, contemporary LF drivers that did not look too bad. One looked like another modern re-make of the old 1808 (and I think it was NOT the one you're thinking...), and the other was just a big, nasty LF machine. Both looked acceptable to me.

At some future date, when I begin my own LF project, I hope others will remind me not to even start without the proper test equipment on hand. LF is just too frustrating to deal with by trail and error, "by ear". And while it would be nice to get by without narrow EQ, I have rolled over on this, conceptually, before I even begin.

Best regards,
Paul S

09-20-2010

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jessie.dazzle

Paris, France
Posts 456
Joined on 04-23-2006

Post #:	6
Post ID:	14508
Reply to:	14457

ULF placement and power

Romy wrote:

"...The leading idea is to bolt a triangular shape sealed enclosure juts behind the small wall that cover the load bearing beam from the midbass horns..."

For a lot of reasons, I'd vote for an alternate placement. You've got that basement, so why not use it as a rear chamber? You might be able to use the volume "as is", without building a proper rear chamber. In this case, assuming stereo configuration, do you think it would be necessary to separate the basement into two volumes so the drivers do not communicate with each other via the basement?

With regard to power; In my case, in a room that appears larger than your current space, 100 watts for each driver (2 x M1.1) seems to be more than enough; driver sensitivity is nothing special; 94db. I'd expect the amps could run 4 of these drivers with no problem; it would be easy enough to connect the pair to a single amp and find out. I can do it if you want.

"...good luck to find 18” driver with sub 25Hz resonance..."

I only know of one; if we can believe the specs, the McCauley 6174 has Fs at 20Hz.

jd*

How to short-circuit evolution: Enshrine mediocrity.

09-20-2010

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oxric
Posts 194
Joined on 02-12-2010

Post #:	7
Post ID:	14510
Reply to:	14508

Wishful thinking and the Maelstrom-21

Romy wrote:

While the aftermath of the midbass horn project is not over I am strategizing how I might implement Macondo’s LF section. The leading idea is to bolt a triangular shape sealed enclosure juts behind the small wall that cover the load bearing beam from the midbass horns. The space is phenomenal from many perspectives. It will be absolutely not visible in listening room and will not impede my normal living stile in the home.

Romy:

It appears to me that hoping that the first aesthetically pleasing location for your LF driver will actually work in practice is an extreme form of wishful thinking on your part, but I may be wrong and the laws of probability may well be working in your favour.

On the other hand, a driver that will probably meet with contempt by many but nonetheless looks on paper quite promising is the Maelstrom-21, with a Fs of around 16.3Hz, if that can be believed. At a price of under $600 apiece, it gives you the option of creating a Geddes based array or a 2-3 driver set-up for very little expense and frees more time and energy analysing and optimising their placement in your room. You can follow the link below.

http://www.diycable.com/main/pdf/M21.pdf

A speaker designer that I know in the UK has also pointed me to the Volt Radial RV4504 from a reputable manufacturer which seems to be beautifully designed/built and with plenty of thought given to addressing the heat issues, see below, albeit with a Fs of 33Hz. But the designer might be willing to do something fairly custom for you if you want to push the boat out here.

http://www.voltloudspeakers.co.uk/About_Us/about_us.html

Regards
Rakesh

09-20-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	8
Post ID:	14511
Reply to:	14510

I will need a direct radiator under the bottom…

jessie.dazzle wrote:
For a lot of reasons, I'd vote for an alternate placement. You've got that basement, so why not use it as a rear chamber? You might be able to use the volume "as is", without building a proper rear chamber. In this case, assuming stereo configuration, do you think it would be necessary to separate the basement into two volumes so the drivers do not communicate with each other via the basement?

Yes, there are many reasons why I'd vote for an alternate placement for LF section/s as well. Still the location I describe has some very important benefits at this moment: 1) It will not stress the suspended floor in my listening room 2) I need to do nothing to make it work as I do have the enclosures and amplification.

jessie.dazzle wrote:
With regard to power; In my case, in a room that appears larger than your current space, 100 watts for each driver (2 x M1.1) seems to be more than enough; driver sensitivity is nothing special; 94db. I'd expect the amps could run 4 of these drivers with no problem; it would be easy enough to connect the pair to a single amp and find out. I can do it if you want.

I do not know anything about your LF section. What do you use and where does it crossed?

jessie.dazzle wrote:
I only know of one; if we can believe the specs, the McCauley 6174 has Fs at 20Hz.

The McCauley 6174 looks like a good driver; I wonder how long the motor if this driver is. I kind of sorry that at my time I did buy the Leviathan woofer. It was 14Hz in underhang mode – those types of the drivers never will be available again….

oxric wrote:
I appears to me that hoping that the first aesthetically pleasing location for your LF driver will actually work in practice is an extreme form of wishful thinking on your part, but I may be wrong and the laws of probability may well be working in your favour.

On the other hand, a driver that will probably meet with contempt by many but nonetheless looks on paper quite promising is the Maelstrom-21, with a Fs of around 16.3Hz, if that can be believed. At a price of under $600 apiece, it gives you the option of creating a Geddes based array or a 2-3 driver set-up for very little expense and frees more time and energy analysing and optimising their placement in your room. You can follow the link below.

http://www.diycable.com/main/pdf/M21.pdf

A speaker designer that I know in the UK has also pointed me to the Volt Radial RV4504 from a reputable manufacturer which seems to be beautifully designed/built and with plenty of thought given to addressing the heat issues, see below, albeit with a Fs of 33Hz. But the designer might be willing to do something fairly custom for you if you want to push the boat out here.

http://www.voltloudspeakers.co.uk/About_Us/about_us.html

Rakesh, thanks, I never heard those drivers I will look into them. My wishful thinking was not only wishful thinking but also a desire to use an existing solution for modeling or ay least temporary use of what I already have. I kind of sick for now building the things and I want this stage to pass. I need a little break from construction phase. The life is going away and I keep building the things… I am too tired from this. My playback in disabled mode for moths and for some time did not have quality time at my home with Sound. I kind of am missing it…. I kind of knew that it will come when I bought the new house but I think I am at final stage. I am planning to make the playback to work with midbass horn and place my woofers in the place behind the middle poll. I might even use the digital EQ to drive it.

I would like to live with it for a while, to get good sound, to setup my analog, to setup electricity, setup speaker positioning… I will research the subject of killer drivers and strategies with LF channels but I think that my existing LF sections will be good to prototype of what I might get. I never had 42Hz horn and I do not know how the 30Hz LF channel need to work in context of horn. I do feel that will need a direct radiator under the bottom but I at this point I do not know specifics….

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

09-21-2010

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jessie.dazzle

Paris, France
Posts 456
Joined on 04-23-2006

Post #:	9
Post ID:	14513
Reply to:	14511

ULF experience: Drivers & power considerations cont'd

Romy wrote:

"...I do not know anything about your LF section. What do you use and where does it crossed?..."

I have 2 ULF "boxes"; each has an 18" McCauley 6174.

The enclosures are sealed and each measures 14 cubic feet. They are made from 70mm thick concrete blocks.

Power is from a pair of M1.1 amps (100 Watts each).

Crossover frequency (set high until I get the mid-bass horns done) is 60Hz, 6 dB/Oct, and is for now done via a Velodyne SMS 1 (this is the only place I use an active crossover).

Since the last round of modifications to the system¹, I no longer use any electronic EQ for these channels. I never did use the phase correction feature, as the boxes are positioned such that I don't need it. This all means that the SMS 1 now serves only as a 6 dB filter. If I were not moving, I'd replace it with a simple passive crossover.

However, I recently bought a house in the US and will at some point be moving (its complicated). The house has a basement which might be exploited as a rear chamber. For this reason I am debating weather or not to move the ULF boxes, as they are extremely heavy. This is what's behind the questions in my previous post.

"...The McCauley 6174 looks like a good driver; I wonder how long the motor if this driver is..."

Their spec sheet does not give this information, however, this driver is capable of a full 2 inches of excursion, so the motor is certainly designed for long travel. They are intended for use in live public concerts; in the context of a home system, with the volume really turned up loud, playing deep bass, I've never seen the cones go beyond maybe 3/16" total excursion (at this point, small items start falling off the shelves in my neighbor's house). So it is fair to assume that for our purposes, the coil operates well within the saturated zone.

The 100 Watts per driver as supplied by the M1.1s is more than enough to get me arrested... I can only assume it has something to do with this amp's capacity to deliver high current. At some point I will compare them to a 1000 Watt class D amp that I have; It would be intersting to learn what, if any sacrifice this entails. If I could get away using the class D amp, I'd save quite a lot on electricity.

"...I kind of sorry that at my time I did buy the Leviathan woofer. It was 14Hz in underhang mode – those types of the drivers never will be available again…"

I once looked into this driver and ended up speaking with someone who was involved with their modification... According to what I was told, converting the Aura driver into a Leviathan involved loading on weight to increase the moving mass... I don't like this approach.

jd*

¹Changed drivers in the upper bass horns from 8 to 4 Ohms (using what I guess is a custom-ordered pair of Fane 8Ms in 4 Ohm), and added more damping materials between and behind all horns.

How to short-circuit evolution: Enshrine mediocrity.

09-21-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	10
Post ID:	14514
Reply to:	14513

To experiment during the New England winter

jessie.dazzle wrote:
I have 2 ULF "boxes"; each has an 18" McCauley 6174.

The enclosures are sealed and each measures 14 cubic feet. They are made from 70mm thick concrete blocks.

Power is from a pair of M1.1 amps (100 Watts each).

Presumably that the McCauley drivers are fine I think would be the very ultimate ULF channel. The 100 Watts of M1.1 is a bit tricky as Vladimir very conservatively grade them as 100W. Generally in what I seen Lamms are able to pump more than this. I did not measure where they clip but it felt as they are more powerful than some other amps rated at 100W

jessie.dazzle wrote:
However, I recently bought a house in the US and will at some point be moving (its complicated). The house has a basement which might be exploited as a rear chamber. For this reason I am debating weather or not to move the ULF boxes, as they are extremely heavy. This is what's behind the questions in my previous post.

I am bit skeptical for use basement as a rear chamber in my case. My floor is suspended and I do not want any bone vibration take palace when ULF is working. This is why I am trying to put my ULF in another room that does not share the same suspended floor as my listening room. I have Sunfire cub sub that is horrible sonically but able to pump very high pressure, placing it in deferent locations is it very easy to model what and how will vibrate. This is what I will be experimenting when my midbass project will be over. The only viable use of basemen, at least in my case would be if I make woofer sitting in some kind of sealed pipe that goes from basemen floor to basemen ceiling and exhaust into the listening room, but decoupled from the listening room’s floor. I am contemplating it but cutting two 20 holes in listening room floor would require me to be absolutely confident that it is what I want. At this time I do not have this confidence as I am still do not have a clear visualization of what kind ULF sound I would like to make. I do know very precise what I would NOT to have in lowest octave but it is not enough for me.

jessie.dazzle wrote:
I've never seen the cones go beyond maybe 3/16" total excursion …

That is very good. I do not like the drivers that excurt too much. What kind outer suspension it has, is it rubber? The web site does not say anything about it. Anyhow, the amount of pressure McCauley does is not a key factor. I think the key factor would be the degree to which the driver is able to decimate the LF pitches.

jessie.dazzle wrote:

I once looked into this driver and ended up speaking with someone who was involved with their modification... According to what I was told, converting the Aura driver into a Leviathan involved loading on weight to increase the moving mass... I don't like this approach.

Actually it was not increase the moving mass but using much softer suspension (what I was told). If the subject were only about mass then we can do it today with any of the Auras. At that time North Creek had access to made-to-order inner suspension (spider) that was much softer. This combining with the fact that it was the only one 18” woofer with underhang motor and the fact that it has cloth outer suspension in my view made the driver very exclusive. I have 4 of my Auras but they I think stock versions. I need to measure them to see what they are. But I still will try my arrays of the 10” scan-speaks first. Anyhow, this ULF chals will be a very interesting thing to experiment during the long NE winter….

The Cat

PS: BTW, in which part of US are you planning to return?

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

09-21-2010

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jessie.dazzle

Paris, France
Posts 456
Joined on 04-23-2006

Post #:	11
Post ID:	14519
Reply to:	14514

Pitching pitch

Romy wrote:

"...What kind outer suspension it has, is it rubber?..."

Correct (I know I know...)

"...I think the key factor would be the degree to which the driver is able to decimate the LF pitches..."

Pitch: The property of sound that varies with variation in the frequency of vibration.... I decided to look it up and double check my understanding of the word.

On the first day I received the drivers, I set them face-up in their packing tubes (a sort of small improvised rear chamber) and let them play full-range. Yes they were polluting the mids and highs coming from the rest of the system, but I was sucked in by something I had only ever heard in mid and upper-bass.

I grew up around old tubed electronics driving paper cones. Until building this system, certain qualities of mid and upper-bass existed only as a memory; one I found more true to life and pleasant, and one I did not forget. These massive drivers were making sound that had this quality, though lower down the scale; this is something I had never heard from home audio. I don't know what to call it (tone+dynamics+nonaggressiveness), but it is what I heard from the AK drivers as well, and it is what motivated me to build the 40Hz horns.

People have grown accustomed to abbreviated LF, delivered via shorthand or code, which then must be decoded as bass. It is analogous to a mode of delivery that relies on squirting under high pressure to get the job done; exactly like electricity delivered as high voltage (high SPL), versus flooding via high current (high spatial capacity).

There's something in bass that makes people feel physically good; even the high-pressure, abbreviated bass has this effect in the short term, but I find the human body is much more responsive to bass delivered in copious, flooding longhand, especially over extended periods. This is the case regardless of the type of music (including bass-centric synthesized electro).

Once in the large enclosures, they made my old ported subs sound like they had a cold.

"...I am bit skeptical for use basement as a rear chamber in my case. My floor is suspended and I do not want any bone vibration take palace when ULF is working. This is why I am trying to put my ULF in another room that does not share the same suspended floor as my listening room...The only viable use of basement, at least in my case would be if I make woofer sitting in some kind of sealed pipe that goes from basemen floor to basemen ceiling and exhaust into the listening room, but decoupled from the listening room’s floor. I am contemplating it but cutting two 20 holes in listening room floor would require me to be absolutely confident that it is what I want..."

That's what I was expecting you'd say, and what I was expecting to have to do.

"...BTW, in which part of US are you planning to return?..."

To Southeast Michigan (a suburb north of Detroit); you know, a crisis is a terrible thing to waste!

jd*

How to short-circuit evolution: Enshrine mediocrity.

09-21-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	12
Post ID:	14520
Reply to:	14519

There are many key points….

jessie.dazzle wrote:
Romy wrote:
"...I think the key factor would be the degree to which the driver is able to decimate the LF pitches..."

Pitch: The property of sound that varies with variation in the frequency of vibration.... I decided to look it up and double check my understanding of the word.

Ironically my misspelling and use the word “decimate” instead of “discriminate” (the automated check speller always do it to me) did not change the meaning of my statement too much. We all undusted that a large cone diameter and high exertion imply high pressure at LF. Still there are other considerations that I find are superbly important to me. The discrimination of pitches is one of them for instance. Most of the woofers do not have high discrimination (recognition of differences) between similar notes. If you have an upper bass in your hands then you hardly will be able to take two notes that would have the same character. Many woofers however do not discriminate those characters and play all notes as some kind of generic LF note. All ported speakers sound this way and many other topologies, particularly badly implemented. My Sunfire cube sun that might literally destroy my house with acoustic pressure is always produces just one single LF note – it is not a generic note – it is literally one single LF tone – no matter what was given to it. Another of many factors that are superbly important to me is an ability of the bass driver to demonstrate bass contrast while the driver is stressed. Many drivers produce OK slam from silence but very few of them can do the same from elevated sustained tone. Let for instance an orchestra to hold high volume sustained tone (pedal point) and then you have a bass event. The contrast and texture with wish this superimposed bass event is presented by bass channel says a LOT about the driver and its enclosure. The way how the driver plays at very low dynamic levels is also is very important. Many big powerful bass drivers with very powerful motors have very strong own outer suspension to assure that the driver will be able to handle this motor’s force. This super strong outer suspension make the driver do not comply well to an excitement by low currents…. I mean I can go on, there are many key factors but I still think that the decimations of bass event encompassed a LOT. In some cases it is not a driver it but the way how it used: enclosure, damping, amplification….

jessie.dazzle wrote:
To Southeast Michigan (a suburb north of Detroit); you know, a crisis is a terrible thing to waste!

Yes, driving a Peugeot for a couple years would do it to a person... :-)

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

10-07-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	13
Post ID:	14667
Reply to:	14457

A first true bass test

Since my left channel along with midbass horn is more or less configured I made today a first rest of the full assembly - with LF section. The midbass does somewhere hear 40Hz and I set the LF section for 34Hz, drove it from B2 via the SMS crossover. I very fast find a right phase and it felt like the arrival time was not a problem. However, it look like to set the ULF section would take a bit most taste to get LF channels to sound as I want then just to set then up by simple measurements and to drive big woofers from powerful amps. The character of bas was very unpleasant it did in a way ruined the lower end of midbass. Sure it will be many experiments with LF, the SMS toy make it very simple, but it is not so straight forward. It will take for a while to learn how to play lower bass in this 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

10-28-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	17
Post ID:	14804
Reply to:	14457

What to expect from ULF channel?

Since I finalized how my midbass horn handles decay the only things left in my playback is to set the right level and cut off point of my ULF channel. Formerly I did set it up for 35Hz, second order and it was fine as a temporary setting. However in the light of improvements in midbass upper knee decay the new way to use ULF need to be devised. Last night I span some time to run ULF channel up and down in frequency and volume but frankly I did not find the configuration that I feel comfortable.

I need to admit that I never ever heard any properly implemented ULF channels. Yes, I have seen very good ULF channels but if I had change to hear them then they sound always too low to me. I know very much how I would like ULF to sound but I do not get this effect with my ULF so far. It feels like second order is too shallow for my ULF but if I go higher then I lose proper integration between ULF and midbass.

I think the whole idea of how I use the ULF and what my ULF is needed to be de reviewed. I do know what sound I would like to get but I do not know all expressive tools of ULF. My former experiments with ULF were very successful but then I was playing with tratrix upperbass. Now my lower horn is not tratrix but hyperbolic and I need to say that hyperbolic curves decays much slower and with much more integration complexity then tratrix. So, I need to think and to revise how I think my ULF might be used.

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

10-29-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	18
Post ID:	14815
Reply to:	14804

OK, it is something.

I guess I have found a more or less usable new configuration for ULF channel. It is 28Hz, second order, with slightly raised ULF on the transition slope. It sounds quite good. Well, I am not supposed to say this. It doesn’t sound good but it sound properly. I mean the bass is absolutely properly integrated and present a very rare setting of how a playback bass shall sound. I say very rare because any other setup I heard had too much bass of bass tock over the upper channels. My setup now has absolutely proper “talk” between lower bass, midbass and upperbass, letting all low end channels to shine where they shall. I am absolutely confident that that way how my playback not render bass is how the best orchestra shall sound from the best sits on a house. Do I like the quality of bass that I am getting; do I consider it as a good quality bass? No, I do not.

Even though quantivly and structurally bass is correct but it is not what I am looking. I am looking for “winter frost bass”. I do not know how to explain it but if you were high in mounts and remeber this feeling of early morning burning frost then you know what I mean. My current bass is sourced from one channel, hopefully when I engage the second it will do better. I do not know how bass transparent the Velodyne crossover. I presume that it is the one that east all bass quality. My next step will be to make the 28Hz, second order, passive, line-level before the ULF amp. I hope my preamp will be able to drive it, 7 reactive filter to drive – it is a LOT – very few preamps would handle it.

The location of my ULF channel and not good and I do feel the time alignment discrepancy. I can correct it by phase regulator on the Velodyne crossover but I will not have this option in line-level passive crossover. I have some options and some tricks how I can deal with the situation, it will be later. Still, as now, I have very much usable setting with very proper bass. It is not the bass of my dream but it is not wrong bass and this already a LOT.

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

11-05-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	19
Post ID:	14851
Reply to:	14815

The new ULF scenario experiments.

Romy the Cat wrote:
Even though quantivly and structurally bass is correct but it is not what I am looking.

Last night I got rid the SMS crossover. I built in the 28Hz, 12dB per octave crossover in the Yamaha B2 amp that I use for ULF channels. Then I place an extra bass modules to the another active spot at the room and connected it all together.

The bass presentce is fine. I have enough bass and I was very fast found the right balance between ULF and midbass. The B2 amp has enough gain and power to handle that ULF- I run B2 with 7db attenuation. The quality of this bass is still not what I would like it to be. Comparing very fine differences between upper knew of ULF and lower knee of midbass I do feel that midbass is more articulate and coherent. In fact I am not sure if I like the result of “distributed bass”. The second bass module is located at different distance then the first one and I feel it mads the ULF quality. I might do so measurements and to see the arrival phase but with line-level passive crossover I do not think I will be able to do anything with it. The alternative would be to drive ULF location #2 from line level direct but the ULF location #1 from a digital devise with precise phase dialing. This would imply a different amplification and will be too much all together.

Generally the popular idea that at LF the time arrival becomes non-critical look absolutely ridicules as far as my experiments show. In fact the wrong arrivals of my ULF are the thing that bothers ma a lot in my current setup.

Anyhow, I am planning to close the book on the ULF channels this weekend. The pane is to measure and to calibrate bass with ULF firing from two locations. If it does not work then get rid of the location #2 and keep the location #1. Then adding a speaker level coil to the bass modules in the location #1 I will be trying to align the bass arrival to the rest of the sound. This might be an interesting solution as I would not mind if bass filter will be a bit sharper but the experiment with SMS crossover show that a full third order is too sharp and the arrival time become too far behind. I might try the trick with a fraction order crossover that was so successful with midbass. The problem that extra coil’s DCR driving the ULF is usually not very good idea. I was able to avoid punishment with it in midbass channel but I do not know if it will work in ULF. I need to hear how it will turn out….

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

11-05-2010

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scooter
Posts 161
Joined on 07-17-2008

Post #:	20
Post ID:	14854
Reply to:	14851

Time coherence of ULF - my experience

Time coherence of ULF may be less important than that of higher frequencies and that seems to make sense in theory and jibes with my own experience. However, I still think ULF timing matters a lot with respect to a) higher frequency drivers and b) other ULF drivers.

Thus, I never really understood the placement of the two ULF units from the above diagram (aesthetics and boost aside). I thought the explanation would eventually appear on the board - and it did today.

ULF-1 does not seem to be a problem but I can't see anything but time alignment issues a) and b) with ULF-2. Also, despite expert views that one can not locate ULF, I'll bet you are consciously or unconsciously locating that ULF-2 off to the "far right." If I were you, despite room aesthetics, I would consider placing the ULF units near your main horns just for experimental purposes; that might help you diagnose problems and move forward. That could be a bit of a root canal at this stage now that you have pulled out the electronic x-over and are trying to close this chapter but it would be a shame to spoil all of this effort with ULF that should be relatively easy to improve.

In any case, your mileage will vary due to acoustics of your particular room.

11-05-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	22
Post ID:	14864
Reply to:	14862

Why I like the like the location #1

JJ Triode wrote:
Romy,How about putting bass tower #2 directly behind#1, but facing the opposite direction from #1? This would keep #2 away from the turntable, yield a symmetrical setup and enable #2 to energize the hot spot around your chair.Note, I'm not sure which tower carries the right and which the left signal, you might need to experiment with that if you take my suggestion.Regards,JJ

This would violate livability in the room, if it exists. The idea is to place LF in the locations what it will have no impact to living environment. The location in the position #1 is not perfect acoustically but it has absolutely no impact the living in my room/home, that is why I so much like this location. Also, the bass is not heard practically no where except the listening spot – and this is HUGE. The listening spot has from +15 +20dB compare to the rest of the room – how do not take advantage of it!

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

11-13-2010

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	23
Post ID:	14936
Reply to:	14864

I need to find another ULF solution.

Romy the Cat wrote:

As successful I am with the midbass horns as problematic the situation with the lower frequency channel. I do have the good location for my LF channel and I setup the DC SS amp with line-level filter at 28Hz. The midbass horns do get benefited by ULF but the problem that I have is that as soon the ULF become effective it take over the sound of midbass horns and clearly vandalizes it. I am not one of those fools who would say that “horns are faster”. It has nothing to do with speed.

Anyhow, I did the measurements today and what I saw shocked me. Of the ULF sections has nice 20Hz at MF level then they have +12dB at 60Hz level. That explains everything but it also absolutely clearly indicates that the selected location must not be used for ULF. That sucks as I have no other space in the room that can accommodate 80sq feet of sealed enclosure without ruining the room feel. Well, I need to find another solution; this is what I will be concentrated upon.

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

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