AE TD12H woofers complete

[mazurek]

I just finished a modification to my system where I replaced 4x Dayton RSS 265HF with 4x Acoustic Elegance TD12H 4ohm woofers. My wife was a big part of this project and helped me with gluing. She also lobbied for hardwood corners and wheels.

[mazurek]

Here is a picture of the build in progress.



The hardwood corners are made of maple and abused all of my tools. The way I did them was to build a molding with an inset to glue the birch plywood in. I glued the cabinet in stages: first the tops and bottoms were assembled with molding, then the frame (top, bottom and sides), then the fronts and backs were assembled with molding, then the fronts and backs were glued on. In retrospect, I think tolerances would have been better if I just build a square cabinet and then cut the corners out, but then I would have to route the holes after full assembly.

[mazurek]

I love Neutrik speak-on connectors!

[mazurek]

The axles for the wheels are press fit into the base. I was a little worried about vibration, but the woofers are heavy enough that solid contact is made and there is no evidence of vibration from the wheels (which have sleeve bearings). They were a good idea because fully assembled, each box with drivers is about 100 lbs.

[mazurek]

The boxes are stuffed with 50% foam and 50% fiberglass according to a good combination I saw in Vance Dickason's loudspeaker cookbook. Final closed system parameters end up being about Fc = 55Hz, Q=0.7 (each woofer has roughly 1.1CF of volume in the cabinet). This is part of my experiment, the Dayton woofers have Fc=38Hz for roughly the same volume per driver. The difference is not as bad as it sounds though because the new woofers are more efficient at higher frequencies, so at 20Hz they only have 2dB less voltage sensitivity. Models predicted actually for them to have similar power sensitivity at 20Hz, but I ordered a non-standard voice coil configuration (4ohm rather than the published 8ohm). I may remove stuffing just to check the efficiency issue though.

These are set to Q=0.5, F=20Hz electronically. Each driver gets about 200watts and is highpassed at 10Hz so they should avoid destroying themselves. The experiment of using a driver-box combination with higher Fs and sensitivity worked in my opinion because overall power output is roughly the same due to higher sensitivity.

[mazurek]

I did some measurements of the Dayton RSS265HF versus the AE TD12H. The AE TD12H wins hands down in terms of linear frequency response. It is very extended with no obvious inductive hump and extends up to a kHz flat. The harmonic distortion story is more mixed. For straightforward harmonic distortion, the drivers are roughly comparable, with the TD12H slightly higher at 20Hz and comparable up to 100Hz. The TD12H wins in terms of inter-modular distortion for two tone excitation signals below 100Hz. Ultimately, it is nearly impossible to beat the value of the Dayton products. Subjectively, when equalized to a similar low frequency response these integrate a little better probably because the flat frequency response at high frequencies ( I may not have adequately accounted for the inductive rolloff of the daytons's in their crossover). They also sound quite clean, but the phase plug does have some air noise at high excursions (somewhat comparable to the air noise many drivers have at high excursions).

And my wife likes them and will be staining them in spring.

[krips]

Looks good . Are you going to finish them the same as your other cabs?

[blue934]

will you be adding subwoofers to your setup? kidding.
looks like a fun build. they should give some visceral impact.

david

[mazurek]

It seems it would be a shame to finish them in flat black like my old ones. I will give my wife some samples to experiment with, I think she wants to stain them some dark shade. I don't have much experience with staining, will staining birch/maple dark turn out ok? I'd rather not veneer them because they already have a veneer face.

The new drivers have plenty of impact. They have just as much low authority as the old ones, and slightly more punch, probably because the phase effects of the inductive lowpass are slightly easier to deal with correctly in the crossover (the old ones had a very good magnitude response in the passband and I took some effort to adjust the delay, but the new ones still are subjectively slightly punchier). I thought it might be some fun to corner load the old subwoofers for a <20Hz or <40Hz subwoofer, but I'm not sure for those gigantic wavelengths whether the corner will give them that much more gain.

[Txgrizzly]

Ebony stain on maple looks nice, you will have to put a few coats on it though to get it really dark though.

[Dean100]

Those look great! :T Are you using an active crossover or passive between the MT's and the Woofers. If active, can you tell us more about it.

[mazurek]

I will plan on doing a test piece with ebony then.

It is fully active. The circuits are similar to those listed at linkwitz's site: http://www.linkwitzlab.com/filters.htm. I use Simetrix to simulate and http://www.expresspcb.com/ to prototype my 2-layer active filter boards and use a custom +/-15 V LM337/317 regulated power supply. Op amps are LM4562, bypassed with a small capacitor at each opamp power line, I used to use OPA2134, I think they are about the same and either way they are low noise and dc offset.

The midwoofer section is linkwitz transformed out from 70Hz to 140Hz and highpassed to get an effective 140Hz LR4 highpass. The subwoofer section is lowpassed LR4 at 140Hz.