dumptruck is finally building ewaves for real

It would be cool if you could use a passive baffle step on the woofer to get the high end 9of the woof) down level with where it measures at 30hz, then crank the HF down to match.....you would be basically flat to 25hz!!!

Here is a measurement of what I'm pretty sure this is the best sound I've achieved so far. LF is active, HF is active plus passive CD-comp. and a broadish passive notch at ~1400Hz. Measurements are accurate above approx. where the vertical yellow line is. I believe the bass actually levels off at what is 110dB on this graph:

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The acoustic slopes end up like 5th order Bessel on the woofer and 6th order Bessel on the tweeter, not quite at the same point. In other words, there ain't much overlap. I will be trying a 2nd notch on the 2.5k peak to see if that's audible at all.
 
What effective baffle thickness did you end up with? Looking at the photos the waveguide is flush mounted and the woofer is rear mounted so I'm guessing 3/4" between front of the woofer frame and the rear of the waveguide flange.
A bit less. It's 18mm thick wood, woofer mounted to the rear with no recess/rabbit or anything, waveguide flush-mounted to the front.

Would using electrolytic caps on the woofer be a problem? They are almost free. Though it does seem a little pointless to save $ on the crossover for $400 of drivers :yes:
For the one I just posted? Should be fine. You could always upgrade or bypass later. I have been using Jantzen p-core DCR values for the woofer inductors, btw, and 18-20-guage air cores for the HF.

P.S. that crossover is for NO L-pad on the HF, if that wasn't clear. It won't work right with one installed.
 
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Finally got my pair TD15M-4 from the group buy :banana:

Ordered crossover parts and decided to skip the electrolytics. You're right about the not cheap part. Oh well, might be last speaker upgrade for many years.

I've got a bunch of 0.01 uF bypass caps I could use. Any reason not to?

Now I just have to decide if (passive) bi-amping with my Yamaha AVR offers any benefit :scratch2:

Many thanks for posting the results of all your work! :thmbsp:
 
Good luck Don! Some people think bypass caps are detrimental when using high quality poly caps to begin with, and should only be used for large electrolytics. I have no opinion. Are you saying you're using the DE250 and QSC as well, and you bought the crossover I posted above? If so, I'd be happy to come up with revisions and buy your extra crossover parts at cost minus shipping should it not work out or meet your taste. I can use 'em.
 
Yep, DE250 and the QSC waveguide. With a little luck I'll have them up and running in a week or two. The cabs are ~5 ft^3 (net) and I think the tuning target was 42Hz.
 
A while back, I promised to try some measurements of the changes when adding the insulation to the cabinets. Here are a few.

This CSD cycles from no insulation, to the same speaker with the same insulation strategy as the the other, but about 1/2 as much material, to the other speaker with maximum insulation applied. It is taken as nearfield because that's the only way I can get any data to compare into the lower mids. Basically, it's totally invalid as far as amplitude, but you can get an idea of the relative changes happening between the three measurements.

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Here are some nearfield FR measurements, set up for the best bass/midbass resolution. First, maximum-absorption versus none. As you can see the port tuning and function changes significantly, whereas I claimed it hardly changed at all back when I originally added the absorption. Well, that's because the ports are now just holes in the box. When they were tubes, the effect on tuning was different.

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Next, zero absorption (still orange) vs. the more conservatively-lined 2nd cabinet:
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Conclusions? I think it seems likely the more moderately-lined box is functioning better in the bass reflex department without much sacrifice elsewhere. Calls for some A/B listening tests with crossovers, which hasn't been done yet.
 

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Excellent graphs!
To my eye, absorption 2 looks better.
Nice to see that the material is doing what is expected.
Thanks for posting those, DT.
 
Yep, DE250 and the QSC waveguide. With a little luck I'll have them up and running in a week or two. The cabs are ~5 ft^3 (net) and I think the tuning target was 42Hz.

5ft^3 is what I built to also, golden ratio internals as well. Works great in-room with my low 32Hz tuning. 42Hz is on the money if you plan to use subwoofers and have a somewhat larger room than mine, minus variations in taste... :) Good luck and start a thread with pictures!

Dumptruck, nice graphs showing the effect of lining. I guess mine falls in the light/medium lining category.

As a little on-topic aside, I programmed a -2dB HF shelf filter centered at 200Hz, Q=1, in my miniDSP, been listening to that for a few days. I don't truly need the baffle-step correction in my small room along with the placement, but figured it would not hurt to try and it's so easy with DSP. 2dB does not sound like much, but this covers the whole bass range, it's noticeable and I like it so far, overall sound is more solid and it does not alter the fundamental characteristic of the bass. I intend to keep it that way for now. I could see going for 3 or 4dB in a larger room, away from walls.

az
 
Yeah, 1-2dB is pretty noticeable when it's a trend spanning octaves. I've really been dragging my feet finalizing the bass response on these. It's a lot of effort/time both making changes and testing when it comes to that aspect. Much faster messing with the crossover design.
 
What do the insides of your cabs with conservative padding look like? Curious to compare to what you showed before.
 
Making progress....had to hack out a section of the box bracing to fit the deeper AE woofer. Got one installed and breaking in. Will leave the 2226 in the other side for something of a comparison.

You can't really tell from the photo but the woofer is flush-mounted and the waveguide is on a ~3/4" thick gasket

Crossover will be wired for bi-amping and mounted externally to backside of speaker cabinet.
 

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Hey Don, if there's too much treble, increase the 4Ω resistor in the high pass to 6-8Ω or so. Any other troubles, please report. I'm doing my best to annoy you by coming up with a completely new crossover, but nothing yet ;).
 
My Yamaha has the multi-point automatic EQ capability and a 7-band (?) parametric EQ for each channel so I can do a bit of tweaking without melting solder. I've got Friday off so I'll be able to wrap it up and do the high-power tests before the wife gets home.
 
I finally got them up and running yesterday. At first I thought they were a bit on the bright side. After listening for a while I concluded that it may have been a result of excessive volume...I was running at -10 dB (relative to reference level) which is rocking the house. Also that was using the YPAO "flat" auto EQ setting. I'll have to re-run it and see if the "natural" setting takes the edge off.
 
Hey Don, I think I had the treble excessive. I'd highly recommend changing the 4Ω in the high pass to 6Ω.

I've done some more messing about, and based on some more measurement attempts, I've gone back to thinking mine need baffle step compensation. I've come up with a new crossover to try that passively, haven't tried it yet. The low pass is a nasty beast, although I did simplify the high pass for it a lot, at least. Anyway, outside BSC the response, phase, xover point are all close to what I gave you (if you up that resistor a tad), so if you wanna try to approximate with EQ and see what you think, bring everything up approx. +3dB starting around 150-200Hz and on down from there (stop around 40).
 
Making progress....had to hack out a section of the box bracing to fit the deeper AE woofer. Got one installed and breaking in. Will leave the 2226 in the other side for something of a comparison.

You can't really tell from the photo but the woofer is flush-mounted and the waveguide is on a ~3/4" thick gasket

Crossover will be wired for bi-amping and mounted externally to backside of speaker cabinet.

Nice going! What's your internal cabinet volume and tuning? What HF driver are you using?

az
 
How's it going Don? Ready to sell me those xovers yet? ;) I spent all afternoon Saturday trying to better nail down a target response, the "voicing" as they say. Still have to go back and listen again - make sure I agree with myself on a different day. Here's the difference vs. my current iteration (black line). The 500-1000Hz sag in filtered and unfiltered response is not real. I'm all the way up to 4mH for the main inductor now, which requires cabinet tuning to be kept on the low side to avoid too much interaction with the crossover, but seems to be what's right for my cabinets.. The other changes are less obvious tweaks that came from lots of A/B with other speakers, with test signals and music.

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