Damping factor or watts?

Rodman99999, I chose those woofers based on low thermal compression, suitable combination of bass extension and efficiency in a size box that I could live with, and sufficiently smooth response between 1 kHz and 2 kHz. I'd have liked higher voice coil DC resistance in both cases, but went with what was available. These woofers were not picked out as being uniquely "low damping factor friendly".

The heavier-cone woofer is a 12" with plus or minus 7 mm of linear excursion, and the lighter-cone one is a 10" with plus or minus 6 mm of linear excursion. Both are prosound drivers with unusually low efficiency (and consequently good bass extension) for prosound units of that size; most prosound 10" and 12" woofers are really midranges with efficiencies in the upper 90's.

Duke

Audiokinesis

Thanks for the info on Atma-Sphere S-30 - I checked and it looks very very interesting.

Thanks, Kijanki.

One other thing I should mention: I don't intend to give the impression that a low damping factor amp will work with just any speaker. I'd want to see the impedance curve and possibly the frequency response curve before making that call.

That being said, a couple of weeks ago a friend of mine wanted to try a low damping factor amp on his 89 dB, 5-to-20 ohm two-way monitors. I was skeptical because of the impedance curve. He liked the sound, but there was a lower treble emphasis associated with an impedance peak in the crossover region (which I had predicted, having seen the curve). So I calculated and assembled a circuit that smoothed the impedance peak, and that solved the problem. Maybe that would work with other speakers as well. I'd like to adjust the bass tuning in his speakers also, but we haven't gotten to that point yet.

Duke

It's interesting to note that the highly regarded Pass X350, X600 and X1000 all have damping factors well below 100. Thanks, Duke, for your insight.

Audikinesis

DF=1 is a little extreme. On the other hand Atma-Spere design does not have transformers and capacitors in the signal path !!!. I would stay away from amps with DF>500. Icepower, I use, is a different beast and has inherently high DF (speaker always connected to V+ and GND - only direction changes). In addition TIM is a result of the charge traped on the junction of output transistors when overdiven momentarily - does not happen in Icepower.

Some amps with high DF (suggesting deep feedback) don't sound harsh or bright but make you tired after a while. It is because our brain fills the gaps when amp is choked-up after transitions (TIM). I would stay away from very good spects - something has to give. TIM was uknown 40 years ago!

As I remember, long long time ago 16 Ohm or even 32 Ohm speakers were typical and damping was easier. Lower impedance came with solid state's (I suspect) desire for higher power. Also, underhung speakers (narrow coil in wide gap) are rare inspite of their lower distortions - is it cost?