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.

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…

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…

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?

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.

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.

• 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.
  

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.

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

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.

Paul S wrote:

Greg, do you have any experience with the Eminence drivers?

• We all seem to be doggedly pursuing ~20Hz as if our lives depended on it
• 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)

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.

Paul S wrote:

Greg, I have written about my "DEBZ" speakers several times at this site,

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)?

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.

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 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.

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...

Greg, did you use 1st order X-overs?

I happen to use 2nd order at this time, to keep LF out of the Lowther.

At this point I have a pretty seamless transition.

Of course, the real test will be with the true LF (ie, way below 50 Hz).
 
In fact, I thought that's what you set out to do?

Best regards,
Paul S