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04-11-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,283
Joined on 05-28-2004

Post #: 1
Post ID: 7180
Reply to: 7180
The loudspeakers for a powerful SET

The Lamm ML3 made me to think about this subject. Since my negative expectations about the ML3’s Class A2 operation turned out to be wrong  and since we go into expense and efforts (totally unnecessary in my view as DSET make it worthless) and make a powerful full-range SET then what speakers that or those SET might be using?

Do exist any full rage good loudspeakers with mid 90s dB sensitivity that would be full-range-worthy of a powerful SET? Are any 4 sections acoustic systems with sensitivity of LF section compatible to the sensitivity of MF section? Lamm ML2.0 was screwed by the fact that any single commercial loudspeaker that it was used/demoed with was essentially not good enough for that amp. I wonder, if the ML3 is an interestingly sounding amp, then what acoustic system it might be used. With 1200V on plate ML3 has enough spare voltage on the GM70’s grid to allow passing a lot of SET power (I think it should be 35W in A1 rather than 28W). There are some other SETs with 200-250V on output tube grid and able to push 50W-100W if SET power.  I wonder what speakers are out there to mate those amps with.

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
04-11-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,283
Joined on 05-28-2004

Post #: 2
Post ID: 7183
Reply to: 7180
What I would like to see…

What I would like to see is as usually does not exist but I would like to see a regular cone full-range loudspeaker objectionably made for use with a single powerful SET.

What I have in mind is a sealed enclosure the size of Dunlavy V or VI, 4-5 ways, with first order crossover only, with curved-indented front baffle to time-align drivers ( like the Evolution Audio does) , with sensitivity of sub-near 100dB (like Coincident use to be), with paper cones and with all efforts in the speaker "wasted" on the quality of the drivers.  It might be an interesting project for someone to undertake… That type of monster would be interesting to driver with a powerful SET…

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
04-11-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,051
Joined on 10-12-2006

Post #: 3
Post ID: 7184
Reply to: 7183
People say
There are those who claim to drive some of the big vintage speakers with SETs at AA.  Like those ancient top models from University, Wharfdale, Tannoy, etc., etc.  Not that this is the same as an objective approach.

I've heard it tried with small SETs, but it's fearsome the way those big speakers gobble power as SPL and complexity rise and frequency drops.

I can see someone trying the ML3 with the big, fancy Audio Classics speakers; but they are horns.

One would think the toffs are thinking, Wilson.

I think it would be intewresting to come up with a list of drivers that would make up what would probably have to be a 4 or 5-way speaker.  One might use a single 15" to get down to 60 Hz and then go to paralleled 15" or 18" below that.

I have not tried the bi-wiring for a long time.  Some guys use more than one OPT tap for this.

The big Dunlavys I have heard have sounded serious to me, but I only heard them with giant SS.  Certainly on par with big Wilsons.

Best,
Paul S
04-12-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,283
Joined on 05-28-2004

Post #: 4
Post ID: 7186
Reply to: 7184
That ideas behind 'breathing' cone loudspeaker

All those vintage speakers are not interesting. Among the contemporary loudspeakers, I also to do not know anything that I would consider unarguably worthy.

The main point off of this exercise is to let people to think about the opportunity or possibility to have a SET-friendly full-range cone loudspeaker. When I say SET-friendly I do not mean only impedance requirement (that is in many cases blown up out of proportion) and sensitivity of the load. A high SET power and low sensitivity is not necessarily a good thing. 10W and 100dB is not the same as 300W and 90dB – it never will be the same, and none of the low power SETs that I have seen, driving low sensitivity loads at A1 and at very low volumes sounded acceptable.

Anyhow, despite that all of it blows up in the face of my DSET inclination and some of my views about loudspeakers but the ‘live’ cone full-range loudspeaker for SET is a cool idea for someone to attack.

Somehow, David Wilson does his largest loudspeaker that they have no dynamic limitations of cones in boxes. Somehow some of the drivers do have very tone, like LE8. Somehow some of the roofers do have great “bite” at low resonant frequency and high sensitivity, like 505B.  I think if to invest some money and efforts then it is possible to come up with something.

The shape-wise I very much like what Evolution Audio does in this top model.

http://evolutionacoustics.com/mmthree.html

It should be extra one or two channels and the LF section should be twice-trice larger. The drivers of course should be totally different. If it possible to make something like this as a whole speaker at 99-100dB sensitivity then I think it might be a good candidate to somebody who peruse a powerful SET idea. In fact I feel that there is a deficit on the market and no one supply this demand…

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
04-12-2008 Post does not mapped to Knowledge Tree
Antonio J.
Madrid, Spain
Posts 269
Joined on 08-16-2004

Post #: 5
Post ID: 7187
Reply to: 7186
I'd be content with much less
I could live happily with a 2 or 3 way system which were above 95dB/w to be used with some SET amp in the 20-30wpc range, covering just from about 60Hz to 16KHz, provided it fits a domestic, shared-purpose room. I'd only ask for right tone, effortless dynamics, and some of the real space that the TU-X1 can deliver. Probably the right tone is the most difficult thing to achieve.

In fact I'm living with a way more handicapped system, but this doesn't mean I know what would make me happier hahahaha.

Rgrds
04-12-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,051
Joined on 10-12-2006

Post #: 6
Post ID: 7188
Reply to: 7186
Test Bed
Being both fairly lazy and fairly cheap with respect to audio, I remain very interested in the
FR SET/dynamic speaker dream.  Also, I am generally both weary and wary of the extreme complexity/difficulty engendered/entailed by other FR approaches.

When I first started the DEBZ project, I admit I was not sure if they (at 97 dB) could be driven FR with garden variety SETs, especially considering the 15" woofer.  As it turned out, there were some problems I anticipated and some that emerged as the stark contrast between what the DEBZ/Wright 2A3 SETs did right versus what they did wrong or just could not do. I have written of these things in other posts.

The bar was certainly raised with the ML2s, and they also introduced some amazing experiencess that I never saw coming.  BUT: some of the old issues remain, such as ultimate dynamics and, of course, true LF, and not all of the issues are due to the speakers, per se.  Sure, there's lots more with the ML2s than with other SETs I've tried; but there's nothing like orchestral music to put things back into proper perspective...

Anyway, I agree that rated efficiency should be about as high as reasonably possible if there is to be any hope of FR SET.  However, there is another issue I am thinking about with rated-high-efficiency speakers that also have very high "allowable power" input ratings.  Namely, most of these speakers just eat up amplifier power at an alarming rate, much faster than the 3 dB/double power rule suggests, and this sort of speaker IMO invariably winds up needing big amplifiers to deliver its best.  This means that driver choice is critically important for use with SETs, not to mention crossover logistics.  I know that atomic scientist Dick Olsher used a LEAP program and then his own ears to work out the DEBZs, and I think this sort of "objective" modeling is a worthwhile preliminary step.  But in the real world, and as we hear it, crossovers are a sombitch to design and implement, and they invariably act a lot weirder than any model would suggest, including acting as non-linear "sinks", not to mention the reactive elements.

I am thinking that even in the case of a 4-way system I like the idea of a wide range driver in the mix, if only to circumvent crossovers and driver matching.  I have thought for a while that the biggest problem with the DEBZ is the usual loudspeaker Achilles heel, namely weight (setting aside for the moment ultimate dynamics).  Based on previous experience, I still imagine that a 10" driver just does better in the lower mids, other factors being equal.  Now, if I could just find a 10" "wide range" driver half as fast as the Lowther...

If anyone has tried the ML3 it would be interesting to hear what with and how its power unspooled.  I think this will be the crux of any FR SET/speaker project.

If we assume that the ML3 is a more powerful ML2, then it MIGHT open the door for a 4-way system, and MAYBE even 5-way, although it is still hard for me to imagine 4-way and bass from 1 SET.

Best regards,
Paul S
04-14-2008 Post does not mapped to Knowledge Tree
miab
Canada
Posts 46
Joined on 02-07-2008

Post #: 7
Post ID: 7193
Reply to: 7183
Why Paper?
I'm curious as to why the preference to paper cones as opposed to carbon/poly/kevlar/ceramic/.... With weight and stiffness advantages of other materials, would advancing technology not be well implemented towards drivers?  

Does it have to be one box? What about seperating the cabinets for lower frequencies altogether for a two box solution? Not in the Watt/Puppy (over/under) style but altogether seperate placement. I'm thinking room placement and lower frequency issues.
04-14-2008 Post does not mapped to Knowledge Tree
Gregm
Greece
Posts 91
Joined on 02-16-2005

Post #: 8
Post ID: 7194
Reply to: 7193
I vote Paper for warmth & tone
 miab wrote:
I'm curious as to why the preference to paper cones as opposed to carbon/poly/kevlar/ceramic/.... With weight and stiffness advantages of other materials, would advancing technology not be well implemented towards drivers?
For lower frequencies, I too would vote for paper: the tonality is pleasant, "humanly intelligible" (to coin a phrase) and the way the actual sounds are reproduced sounds to me "correct within its limitations". What I'm trying to say is, reproduced sound sounds "recognisable", more akin to a real life... it's difficult to explain.

I would use paper for everything but the tweet & upper mids perhaps.

 miab wrote:
Does it have to be one box? What about seperating the cabinets for lower frequencies altogether for a two box solution? Not in the Watt/Puppy (over/under) style but altogether seperate placement. I'm thinking room placement and lower frequency issues.
I would agree with you. The link Romy gave above leads to a visual example of such a construction, although i'm not sure the bottom can be separated fm the top.


I would like to see an experiment where first consideration is to get 15k to ~80Hz right. Here, the big trick will be to get 2kHz-15kHz acceptable, a range which seems to elude the best designers presently (for reasons unknown). Then, we have to go from ~80 down and keep the sensitivity high and the sound acceptable. Also the region 15k up will have to be tackled and that would require some different "research" because of the very important "tonality" matching aspects...

Overall I think it's difficult to pull through: one amp driving one multi-channel speaker from dc to daylight... Tall order!

04-14-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,283
Joined on 05-28-2004

Post #: 9
Post ID: 7195
Reply to: 7193
The objectives of the exercise.

 miab wrote:
I'm curious as to why the preference to paper cones as opposed to carbon/poly/kevlar/ceramic/.... With weight and stiffness advantages of other materials, would advancing technology not be well implemented towards drivers? 

My preferences are to the drivers that sound properly and they much not necessary be papers. However, speaker designers invented for themselves an idiotic notion of piston-like uniform movement of driver’s diaphragm, with no break-ups. So, many of today’s “granite drivers” are the illustration of this concept. I do not support the idea of stiff drivers. However, if someone is able to get a right sound from non-stiff drivers then it is good for them. I am not saying it imposable but it is highly unlikely to see in a typically-senseless commercial implementation as the commercial modals are made to fulfill the generic public demand, the demand that is hugely corrupted and tainted.

 miab wrote:
I'm Does it have to be one box? What about seperating the cabinets for lower frequencies altogether for a two box solution? Not in the Watt/Puppy (over/under) style but altogether seperate placement. I'm thinking room placement and lower frequency issues.

Well, there in doubts in my mind that for more or less objectionable acoustic system the MF and LF should be separated in different locations a they serve functionally different purpose. I have written about it in multiple places of my site. However for the sake of the given exercise the separate cabinets are no acceptable as it would defeat the whole purpose.  If a person put the LF section into a separate enclosure then you’re not restricted by design limitation of a full range loudspeaker and you can go more aggressive and tougher with your design decisions.  Having a separate LF section would instantaneously imply multiamping, the concept that contradicts the idea of a powerful full-range SET. In any powerful full-range SET I would say 85% of the amp’s efforts and money are wasted for the bottom two-tree octaves. If there is no need for it in the amp then it should not be powerful full-range SET but a DSET (the concept that kills any powerful full-range SET). So, if we accept on the market the army of 30W-100W SETs that are trying to be full-range amplifiers than I think the only rational way to use them is to have just one full-range box. If you go for two box solution with different sensitivity and different loading need then why you would need a powerful full-range SET.

BTW, there is in this subject a “kink” – a powerful full-range SET with the sections of output transformer exposed, allowing driving multiple loudspeaker’ segment by different transformer’s section. However, it becomes complex in term of loading, crossovering and few other subjects that would be too difficult for an ordinary user to care.  In case the powerful full-range SET is many by the same company as the loudspeakers. Then a single amp might have HF and LF outputs.

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
04-14-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,051
Joined on 10-12-2006

Post #: 10
Post ID: 7204
Reply to: 7195
LF: the fly in the ointment
Maybe we should just start by trying to think of a viable way to get down to 20 Hz in a reasonably sized enclosure driven by an SET that must also drive the rest of the system.  This was always the sticker for me, and this was a major consideration in my choice of the DEBZ compromises.

I especially like the idea of a melded speaker/amp, with taps appropriate to each section.  The LF section will have to be HEAVY, that's for sure, and I suppose this will also mean amorphous core for LF, as silicon steel or M3, etc. are not optimal above LF.

I agree with paper drivers below HF, except Harbeth seems to have figured out a nice alternative for their 40, some sort of petro/paper, I don't know.  And who knows how this driver type might adapt outside their propritary set of compromises?  I also do not accept - at all - the practical implementations I have heard of the "rigid piston" theory.  Ceramics and metal cones I have heard are all so far out there that I really wouldn't know where to start with one.  No, I think paper, "flexion" nothwithstanding, is the easiest and most fruitful path.  Not to mention that paper can be doped, if desired.

Best regards,
Paul S
04-15-2008 Post does not mapped to Knowledge Tree
Gregm
Greece
Posts 91
Joined on 02-16-2005

Post #: 11
Post ID: 7210
Reply to: 7204
The project seen in context
It doesn't seem prudent to look at the speaker without considering the amplifier at all. We would be designing a speaker that would work with a theoretical amp -- but not one that's available.

I propose the following:
  • Characteristics of many commercial SETs should be recensed & a "standard" SET should be made or chosen, corresponding  to these characteristics. Things like output vs frequency should be taken into account.
  • The drive units should be chosen, not only for their sonic performance but also their compatibility with the "standard SET" performance characteristics. {To give a silly illustration: if the amp sounds shrill in a specific frequency bracket -- say 1-4kHz -- then we shouldn't choose a ceramic or metallic drive unit for this bracket, etc.}
  • The design should start from the bottom frequency up, rather than the other way round. I think it's better to start getting the 25-50Hz part right and then move upward -- rather than the other way 'round as it's usually done. That way the extra low octave is part of the whole rather than an afterthought. In many commercial speakers the 20-¬60 region sounds like an afterthought. Itherwise, the bottom 8ve becomes active which is outside our scope.
  • Let's begin the excercise with a "reasonably-priced" experimental model. I propose Eminence A or B 15" for the bottom 8ve (s) as follows: either 2/ or 4/ side. If two, then the "ripol" arrangmenent. If four, then two in front & one on either side.


04-15-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,051
Joined on 10-12-2006

Post #: 12
Post ID: 7211
Reply to: 7210
Working with parallel woofers
Greg, do you have any experience with the Eminence drivers?

When the Audax PR380M2 I use (8 Ohm) became unavailable, Dick Osher specified the 15" Eminence driver as a drop-in substitute for the BZ series.

I happen to use a single 15 " Audax  in a BR enclosure per side, to keep real world efficiency up (97 dB); but impedance still drops to 4 Ohms at one sharp drop point, right below a 40 Ohm spike.  FYI, the FR ML2 is not at its best with this.  Where would impedance go with 2 or 4 drivers, and how much real world power would this require?  The "ripol" link re-linked into a home/advertisement page when I checked it, and as this is written I still don't know what "ripol" means.  I did buy my Audaphon JP2 naked ribbons from those guys, however, and it is a nice stock unit, when that time comes.

So, has anyone following actually tried the 15" Eminence or similar in parallel?  How big would such a cabinet have to be to get 20 Hz?  This seems important when we figure total cabinet/baffle size for the whole thing.  This is the part that always got me chewing my pencil.

As I said up the thread, my experience with "pro" type drivers has been that they are power sinks.  By this I mean to say that even if they are rated 98 dB or even higher, if they also allow 600 watts input, then they are likely to wind up actually demanding lots of power, which is to say more than SET could provide.

There are a couple of Gm70 SET amps out there that have 50 watts.  Of those, I am guessing that the Wavac and the Lamm might make enough USEFUL power.  Kron may also have something out there that might work.  I don't know about how any of these sound, but the crux is likely to be iron rather than the tube, and I assume that if the amp is not outright terrible then it might be massaged to sound better.

Best regards,
Paul S
04-15-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,283
Joined on 05-28-2004

Post #: 13
Post ID: 7212
Reply to: 7211
Following ....

 Gregm wrote:
It doesn't seem prudent to look at the speaker without considering the amplifier at all. We would be designing a speaker that would work with a theoretical amp -- but not one that's available.

You are right but the opposite is true as well:  it is difficult to design an objectionably performing powerful full-range SET without considering speaker, particularly the moment of LF section damping. It is not always the case the MF, HF and LF would require the same loading but it said by the person spoiled with DSET. So, in a case of powerful full-range SET we need to determine loading only by LF. Lamm ML3 had for those exercises adjustable feedback. I see it as a half-ass solution. My idea for my large amorphous LF DSET was to run tryfilar coil with one coil cares main impedance transformation and two smaller coils care 2% of impedance with ability to connect the supplements coils in phase and out of phase. BTW, it would be able a half-ass solution….

What actually might be fun to deal is some kind of impedance conversion mechanism on the speaker side. Pretend a large speaker with bass driver that has interchangeable voice coils. Scratch it - it would lead to crossover alternation but it might be some kind of impedance transformation devise on the speaker side… My point is that today large speakers are very expensive monster with 50K-100K price tags. Our cars cost as much, or perhaps even half of it but our cars have huge amount of on-board intelligence permitting us to get a lot of use from our cars under different conditions. The damn loudspeakers have 3-4 drivers and a wooden box. Why not to load the loudspeaker with some sound not-degrading intelligence? Why loudspeaker? I feel because if we put some intelligence to our powerful full-range SETs then SET imidetaly get converted into DSET and the idea of “powerful full-range” evaporates….

 Paul S wrote:
There are a couple of Gm70 SET amps out there that have 50 watts.

I do not think so. None of the commercial amps that I have seen use GM70 over 900V and it was the subject of my bitching for a while. With typical (and foolish) for GM70 use of 750-800 and 35-40W, the conventional 95dB sensitivity of load and average room size the GM70 will run deep into grid currents. In fact it is might be interesting to look how different powerful SETs deal with the A2 problems and with the compelling recharging. I just never looked careful in this direction as I tend to look toward higher sensitivity then toward to more power.

BTW, Lamm did some tricks most likely in his new amps. If you look at the pictures then ML3 has coupling capacitors between second and third stage rated at 1000V. This is kind of interesting. The GM70 let say minus 200V on grid and the 6H30 let say 200V on plate. That makes 400V necessary for the cap. The Electrocube that Lamm uses has 400V, 600V and 1000V caps. Why Lamm did not use 600V? Vladimir is a frugal guy and he would never go for overboard cap as he needs to keep the price of the amp under $136.000.

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
04-15-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,051
Joined on 10-12-2006

Post #: 14
Post ID: 7215
Reply to: 7212
A2-capable is OK in A1
Some of the more powerful SETs (including some of the Gm70s, I think) run parallel output tubes, and some go into A2.  I know parallel output can work at line levels, but no experience I can recall with parallel output at high levels.

My Wright 2A3 SETs went well into A2, and the DEBZs put them there a lot.  Distortion is quite present and obnoxious in A2, but oddly, A1 actually seems to benefit from the "headroom", meaning I still had more acceptable power than from typical A1-only 2A3 SETs.

Paul S
04-16-2008 Post does not mapped to Knowledge Tree
Gregm
Greece
Posts 91
Joined on 02-16-2005

Post #: 15
Post ID: 7218
Reply to: 7212
A few clarifications
 Romy the Cat wrote:
...it is difficult to design an objectionably performing powerful full-range SET without considering speaker, particularly the moment of LF section damping. It is not always the case the MF, HF and LF would require the same loading but it said by the person spoiled with DSET. So, in a case of powerful full-range SET we need to determine loading only by LF. The caT
That is exactly what I am proposing further up. In fact, I went further daring to propose that we help the matter of loading through judicious choice of driver...
 Romy the Cat wrote:
Well, there in doubts in my mind that for more or less objectionable acoustic system the MF and LF should be separated in different locations a they serve functionally different purpose. I have written about it in multiple places of my site. However for the sake of the given exercise the separate cabinets are no acceptable as it would defeat the whole purpose.
Not necessarily: they could be separate boxes, interconnected by short cable. This allows some freedom of movement between top & bottom (like some of Wilson's products or A-Physic's et aliae).

 Paul S wrote:
Greg, do you have any experience with the Eminence drivers?
Yes, I used 2 Alphas and 2 Betas per side in a double W config, and I had an impedance drop somewhere (25??) -- which was insignificant in practical terms since the woofs were in connected in series-parallel and I was driving them separately anyway with a PLL xover.
As to the ripol thingy, it's here: http://www.lautsprechershop.de/hifi/aka_sub_sonder_en.htm It just gives an idea of how it's done. I'm sorry the link didn't work for you. Linkwitz also has an explanation of the W & H configs on his site.

As you note, size does matter of course. Not to damp any enthusiasm, but the w construction with 2 x 15" is quite large: nearly 3' high in the first place, not to mention the width. In practical terms, getting to 20Hz in passive mode will take up real estate -- except for the ripol where, purportedly, the footprint is slightly smaller while, allegedly, the sound is... just as good. Whatever. The points with size are:
  • We all seem to be doggedly pursuing ~20Hz as if our lives depended on itSmile
  • We're passive, so tricky electronic short-cuts are out of scope; the construction will be big.
  • The 15" are already quite large; add to this that if you use a couple, you need to play with the actual audible radiating distance between the two to determine cancellations & resonances (spikes, etc)

As a side question -- and please forgive my idiocy: what is a DEBZ?
04-16-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,283
Joined on 05-28-2004

Post #: 16
Post ID: 7219
Reply to: 7218
The sensitivity vs. exertion – a constant battle.

 Gregm wrote:
Not necessarily: they could be separate boxes, interconnected by short cable. This allows some freedom of movement between top & bottom (like some of Wilson's products or A-Physic's et aliae).

Actually I consider the “separate boxes, interconnected by short cable” (like Wilson's and other) being still a single box loudspeaker. When I imply “two box” I meant the boxed do not share footprint and LF section might be used and discreet location from MF section, similar to how it made in Marten Coltrane and in few others.

The catch in here is that as soon we isolate the LF section then we stop to think about sensitivity and begin to think about resonance frequency. There is not reason do not go in a dedicated LF section for lover resonance frequency. But the Fs is always conflicts with sensitivity… so we end up with multiamping. I am not saying that it could not be optimized somehow but I did not see it done.

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
04-16-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,051
Joined on 10-12-2006

Post #: 17
Post ID: 7223
Reply to: 7218
Compared to what we have already done
Greg, I have written about my "DEBZ" speakers several times at this site, including Post ID 3269, early in my original Lamm ML2 thread.  I mention these speakers now to compare what we are aiming at here to what I have already done, which is 38 Hz  up to bat radar region, flat, driven by single ML2 per side.  My BR bins do great solo bass, jazz, etc., but they drop fast below 38 Hz and they become inarticulate and a litle soft (kitty's furry belly) with complex peaks, such as orchestral tutti.   I would love to have that next octave down, or most of it, because I am already close enough to hear quite clearly what I'm missing.  But, as I noted above, the ML2s are already stretched as it is, at 1/channel, so we can use this as a guide.

If I were to do the DEBZ concept right now, I would tune the BR bins higher and cross over/high-pass (to) the Lowther DX4s higher.  This would give me a better "tilt" up to the low end.  Or - much easier - I might first just eff with the low-pass network to allow the woofers to come up just a little.  One way or the other, I would (and still might) add separately-amped boom boxes, either "too-large" sealed, or carefully-tuned BR, just for that bottom octave.  Who knows if this would make the original woofers "identifiable" (which they are not at this time)?  That could be a problem in my case, and it is certainly something to consider when choosing/matching drivers for this FR speaker/amp excercise.

Greg, what did you use to drive the woofers and how did they do; how low, how loud and how musical?   This would help as a frame of reference for the "W"  and/or "double-W" set-ups.  If it took 100 dedicated watts to get this set-up to relax, then perhaps we are already pissing up a rope.

Anyway, at this point I think it would take more than double ML2 power to get to 20 Hz as part of decent FR with 97 dB speakers.  Not that we NEED 20 Hz; but why not aim there, at least to start?  Maybe 3 dB down at 20 Hz...

Best,
Paul S
04-17-2008 Post does not mapped to Knowledge Tree
Gregm
Greece
Posts 91
Joined on 02-16-2005

Post #: 18
Post ID: 7227
Reply to: 7223
Deep in the well of lower frequencies
 Paul S wrote:
Greg, I have written about my "DEBZ" speakers several times at this site,
D. Olsher's Basszilla -- of course! Sorry, Paul, I forgot.

 Paul S wrote:
If I were to do the DEBZ concept right now, I would tune the BR bins higher and cross over/high-pass (to) the Lowther DX4s higher.  This would give me a better "tilt" up to the low end.  Or - much easier - I might first just eff with the low-pass network to allow the woofers to come up just a little.  One way or the other, I would (and still might) add separately-amped boom boxes, either "too-large" sealed, or carefully-tuned BR, just for that bottom octave.  Who knows if this would make the original woofers "identifiable" (which they are not at this time)?
I would expect a tweet / super/tweet to make the lower freq drive unit identifiable (if identifiable it becomes) -- but you might try any old separate "sub woof" & check it out for effects, I suppose.

As you suggest, an despite the added complexity, maybe just adding another drive unit for the extra 8ve is indicated...
 Paul S wrote:
Greg, what did you use to drive the woofers and how did they do; how low, how loud and how musical?   This would help as a frame of reference for the "W"  and/or "double-W" set-ups.  If it took 100 dedicated watts to get this set-up to relax, then perhaps we are already pissing up a rope.
No, nowhere near that much power. I was using a tired ~60W/ 8ohm rated ss integrated fm the early '80s (arcam? something) which didn't even get warm. The unfortunate point is I never tried a tube on the bass -- or don't remember doing so. I probably didn't since to do so I would need a different PLLX (for the different amp).
No problems with spl which was fine even for full Mahler 2 or 4/Klemperer -- it's that as spl went up, the lower freq seemed to take ascendance over the rest, requiring me to turn to the volume control. And no, this wasn't a matter of positioning -- it was different voodoo that I never bothered to analyse. Anyway, the sensitivity of this thing at the usual useless test-bench conditions (2,8V -- 1kHz or thereabouts) was ~100dB with an annoying peak at 55 or so (which is easy to tame).

 Paul S wrote:
Anyway, at this point I think it would take more than double ML2 power to get to 20 Hz as part of decent FR with 97 dB speakers.  Not that we NEED 20 Hz; but why not aim there, at least to start?  Maybe 3 dB down at 20 Hz...

Best,
Paul S
Paul -- do you offer any discounts upwards of 20HzSmile? I found that even 5Hz higher help, i.e. 25Hz -2/3dB helps. I propose 25 Hz even though, admittedly, it is a big compromise.
04-17-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,051
Joined on 10-12-2006

Post #: 19
Post ID: 7237
Reply to: 7227
No Discounts!!!
Well, FWIW, my Audax LF units started life at ~100 dB and wound up closer to 96 dB to get ~40 Hz from them via  ~ 4.75 cu. ft. BR boxes.  Computer tuning was very close, only a strip of rubber weatherstripping in the vent opening between best bass and typical BR "whoosh".

So, as a place to start:  FR ML2 = ~ 18 watts = 40 Hz from 4.75 cu. ft. BR box DEBZ+

Ironically, I suppose that the ML3s might drive something quite like the DEBZ - with slightly re-thought LF compromise - down to near 30 Hz, if you're looking for "discounts".

However, this would include the DEBZs' inherent dynamic limitations, which I suppose are below the big and multi-tower Wilsons, even though I have never heard the big Wilsons optimized.  I also assume that optimizing the big Wilsons (or any of their ilk, for that matter) to exploit/explore their dynamic limits would mean lots more power than even the ML3s can provide.

And so again:  To make greater dynamics than ML3 with hypothetical DEBZ++, then even higher efficiency drivers are required, and insertion losses would have to be lowered.  And I don't know of such drivers.

Re-thinking the DEBZ-ish design again, I think the un-Zobeled Lowther DX4 is about 99.5 dB.  IF Budification obviates the need for notch filters, as some insist, then paralleled/series 100 dB woofers might set up circa 99 dB in a "Super DEBZ++", and this MIGHT be OK with the same 97 dB Audaphon JP2 ribbon on top that my present DEBZ+s use.  This might actually work to get the thing closer to the very elusive SET/FR goal.

How's that?

And given the above, what exactly does the 99 dB LF section look/act like?  My limited experience with paralleled woofers was not at this level at all; we were just sticking them in big boxes and pouring power into them to make them loud, like cheap-o Meyer units.

Best regards,
Paul S
04-18-2008 Post does not mapped to Knowledge Tree
Gregm
Greece
Posts 91
Joined on 02-16-2005

Post #: 20
Post ID: 7244
Reply to: 7237
OK, but hold yer horses...
...we'll have to compromise somewhere. So, since it isn't the spkr's range, then it must be the amplifier.
Forget the ML's 18W. We must have ~38-40, so let's say our machine is using a 45 / 211 / 610 /g70 type of tube.
Also I don't suggest we conclude with the Baszilla type of bass/upper bass section which is one 15" in a box -- difficult to make this work even with ~35W. Lets get some

It's not that you need anything special to get 96dB from 4 dual paralleled woofs. That achievable. It's that by the time you provide the current they need to operate you're running out of "gas" for the rest of the spkr, in particular, the midrange.

 Paul wrote:
Re-thinking the DEBZ-ish design again, I think the un-Zobeled Lowther DX4 is about 99.5 dB.  IF Budification obviates the need for notch filters, as some insist, then paralleled/series 100 dB woofers might set up circa 99 dB in a "Super DEBZ++", and this MIGHT be OK with the same 97 dB Audaphon JP2 ribbon on top that my present DEBZ+s use.  This might actually work to get the thing closer to the very elusive SET/FR goal.
Seriously, I've been thinking along these lines too, but:
  1. I wouldn't play the Lowther unzobeled preferring to tame the low freq unit instead, and if necessary which it probably isn't. (I.e. in my previous playing around, it wasn't really necessary, I had just screwed up something somewhere.)
  2. I would like to break yr Lowther's range into two -- adding a lower mid unit in-between Lowther & bass.
  3. But I know that breaking this up means using up even more power...
Basically I'm worried about a Lowther playing down to 150 and, if I cut the L higher, I'm worried about the woof trying to play up to say 200.
I'll try this W-E to play a EX-4 down to 150 & up to 200, coupled to a Beyma 15". See what happens. I'll probably have to bi-amp because asaik the only set available is a 300b. Regards
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