[fdandrews]

Here are my current OB speaks. MCM 21" woofer in U-frame with cotton insulation stuffing. Fostex 166en full range speaks in U-frames with cotton insulation stuffing. (I think it is called "Ultratouch") Nelson Pass designed crossover. 80 hz/12db per octave with 6 db of boost at 20 hz. No crossover on the Fostex, but a small output cap in the preamp limits output below 30 hz to them. Woofers are driven by a Citation 5 with SDS labs PS board. (highly recommended) Fostex speaks driven by a single ended parallel feed 6L6GC amp with 404a driver tubes. I have included a photo of "the rack."











 

[richidoo]

Cool! Thanks for sharing your project with us! Nice woodwork 

That's a lot of damping! Ultratouch is a very powerful acoustic absorber. Why did you do it that way? What did they sound like without the insulation?
Rich

[Poultrygeist]

open baffles?

[matevana]

open baffles?

Wouldn't be surprised if it functions a little like an aperiodic design. The few that I've played with sound like a cross between OB and a transmission line.

[gils]

 

21 " !?

Thiele-Small Parameters:

Resonance Frequency Fs: 25.9 Hz
DC Resistance Re: 6.3ohm
Mechanical Q Factor Qms: 3.51
Electrical Q Factor Qes: 0.43
Total Q Factor Qts: 0.38
Equivalent Cas air load Vas: 705.0 liters
Voice Coil Over Hang X-max 7mm

green is good , red is bad .

[fdandrews]

How about "sort of open baffle". I don't have the space in my room to bring the speakers out more than 18" or so from the back wall. Whatever you think of the woofer, this is the best bass response that I have gotten in my room. Doesn't get very loud before the woofers start complaining, but I don't listen very loud anymore. I meant to try them with and without stuffing, but it sounds so good as is that I haven't been motivated to unstuff the full range boxes. Since I cross over the woofers at 80 hz, I don't believe that the stuffing of the woofer boxes is doing much except filtering out any higher frequency sounds from the rear radiation.