Damping factor or watts?

Not exactly INefficient though, are they? So tell me: Were you, by any chance, using any kind of auto-xformer between the OTLs and your speakers? Gotta keep digging for factors here before I give up any ground!

Rodman99999, on just about every speaker that I can think of, the suspension gets stretched as the speaker diaphragm moves away from the resting point. Furthermore, the speakers that have the most back EMF, i.e. the ones that are the most reactive, tend to be high efficiency designs, not low efficiency. In most high efficiency designs, the speaker is usually moving less, not more, due to the nature of the design.

The back EMF of such speakers is often the reason that amplifiers with large amounts of feedback (and often higher 'damping factors') usually sound more shrill on these speakers, as the back EMF becomes an unintended part of the feedback signal.

This is probably not what you would have initially thought. I know it was not for me! It turns out to get highly reactive speakers to calm down, you need an amp without feedback, i.e. low damping factor. In fact what you start to get about this is that the damping factor is for the most part irrelevant, whereas the amount of loop feedback is (the less the better).

So anyway, the issue of stopping the mass of the speaker is almost non-existant, unless you intend to amplify non-linear /non-musical signals. An example of that might be a linear motor in a disk drive. Damping in a situation like that would be quite important as the driving signal is not a function. But for audio, the amplifier is always sending the speaker a signal (power), and this power is always moving the cone incrementally in a new place.

To be otherwise suggests that the signal is not a function (which it has to be by definition). Like I mentioned before, the amp does not push the speaker to full excursion and then 'let go'. Since the signal is a function the cone is literally under power all the way back to zero and then beyond.

When I started this business I believed in damping and a lot of other things that I later found to be made up. I was fortunate though that I had enough exposure to the right classes in college and had read enough texts from the 'old days' that I was encouraged to look past the 'company line' to see what was really up. Turns out there have been two design paradigms in conflict in audio for a long time:

http://www.atma-sphere.com/papers/paradigm_paper2.html

And I definitely subscribe to one and not the other, just like everyone else in audio :)

I don't know anything about the technical stuff, I do know that my speakers need low damping to sound their best 9they are almost universally used with tube amps), preferably around 10, much higher and the bass sounds choked, with pther speakers you need high[er] damping or the bass sounds loose and out of control -- so I imagine the answer depends very much on your speakers and how they are designed.

Hi Rodman99999,

I don't blame you one bit for fighting to keep the family farm.

92 dB is higher than average efficiency, I'll admit. Whether or not it qualifies as true "high efficiency" is a judgment call - over on Audio Asylum they discussed at length where to draw the line, and if I recall correctly the consensus was 96 dB. You and I will probably have to hire lawyers and go to court to settle this issue. Or maybe we could have a cage-fight? We could sell tickets and split the proceeds, maybe both be able to buy some new gear (allow me to recommend a nice low-damping-factor amplifer...).

Sorry, couldn't resist.

Okay, back to the RMAF rooms. No autoformers were used. The only things that made the speakers "low damping-factor friendly" were a smooth impedance curve and a fairly low port tuning. The port tuning is actually user-adjustable, so the speakers can be adapted to different room acoustic situations, but this feature is also useful in amplifier matching. With a solid state amp, a higher tuning frequency would probably work better.

Duke

Audiokinesis- It's been a few years(like maybe 26) since anyone threw any Thiele-Small parameters at me, so I'm still picking up the pieces of my shattered brain here! From what you're describing: I'm going to guess the woofers are about 8" based on the Vas? If that's so: with a fairly high mechanical(11.69) and electrical(.35) system loss, they sound like they might have a relatively stiff compliance. The moving mass isn't all that high, so I'm thinking a fairly short throw(or single/flat wound) voice coil. If I'm all wet here, I'm certain you'll let me know. I don't expect any mercy!!