The Stereo Subs Project

[chessman]

Originally Posted by doggiehowser

http://thielaudio.com/THIEL_Site05/P..._TechPaper.pdf

This white paper covers some of that discussion of integrating the subwoofer with main speakers. It's a bit technical though.

This review covers an interview with the late Jim Thiel which is a bit more layman in comparison
Thiel SmartSub SS1 subwoofer | Stereophile.com

"Take a speaker like, let's say, a CS1.6," said Thiel—"a two-way speaker with a pretty good crossover. Even a relatively unsophisticated observer would probably hesitate to remove that crossover and use it in a completely different loudspeaker with different drivers, a different-sized enclosure, and so on—and that's the kind of situation that subwoofers are in with processor-based management or the generic crossovers built into the backs of most of them. And, as you know, crossovers are something I have strong opinions about.

"Instead of trying to figure out the filter characteristics you want, I thought we should start with the signal that represents the output you want from the combination of the sub plus the main speaker. To oversimplify, that would be the input signal, and you subtract from it the part that the main speakers will reproduce—you electronically construct an analog of your main speakers that has the same [low-frequency] output characteristics, the same rolloff characteristics, and you take that signal and subtract it from the main input signal. What you are left with, by definition, is whatever the subwoofer will need to put out to blend with the main speakers to produce the desired result. That's the insight that got me excited about the subwoofer project."

Another review
SoundStage! Equipment Review - Thiel Audio SmartSub SS2 Subwoofer and SI 1 Integrator Crossover/Controller (11/2004)

doggiehowser, the Thiel white paper was very interesting - thanks for posting that.

The Thiel Subwoofer Integrator looks awesome. I was gratified to learn that I had correctly assessed most of the issues at play. The F113's are high extension, strong magnet, and high powered subs capable of loud, accurate, low bass without distortion. I had addressed the boundary effect issues by placement on a single wall, using two subs, and bass traps. I was able to get close to an "ideal" curve using the frequency display of the SMS-1 to overcome what the white paper called the "counter-intuitive needed adjustments" (they certainly are). I was able to use the F113's E.L.F. control to, in effect, augment some of the missing response. I was not able to hit a perfect curve like the Thiel displayed, but I think I did pretty well. I will have to study the paper a bit to see if there are any hints for some additional tweaking. Maybe I can level out that 3dB hump a bit.

[doggiehowser]

Have fun

I've always hated how subs sounded in a stereo setup and always disabled it unless I was watching a movie.

But the Thiels changed all that. I ended up getting two SS2s which have been upgraded to SS2.2s and they integrate superbly with no complex measurements.

I still use an f113 for home theater duties because those things move mountains of air like nobody's business :P I still find the 13" woofer a tad slower than the Thiels tho. Those are just lightning fast. They just don't push out volumes of air (hence the use of two of them) and they really shouldn't be tasked to go down below 20Hz because they will try to do it linearly but the cabinets and power just aren't enough).

[chessman]

After reading the Thiel whitepaper I tried some further tweaking, which yielded a surprising fact: you have to trust your ears over the frequency graphs. Don't get me wrong, a bad graph probably sounds bad. The problem is that a good graph does not necessarily sound better than a less good graph.

I have attached some pics as examples. The 40 H High Pass, normal polarity, +1 ELF is where I left it the other night. The hump in the response looked iffy, but sounded good. (Or did it, since burn in is not completed? ). Today I tried many variations on settings. The second pic is 50H HP, inverted polarity, no ELF. The curve looks better than the prior one, but sounded terrible - just thud, thud, thud. The third pic is 40H HP, inverted polarity, no ELF. Looks almost the same as the 50H, but sounds much better.

Now I am struggling with which sounds better: regular polarity, +1 ELF v. inverted polarity, no ELF. One thing is for sure, I will have to follow Dan's advice and trust my ears over my eyes. Fun problem to have.

P.S. No signal is going through the Velodyne SMS-1 to be EQ'd or otherwise adjusted. I am just using its sweep, measure and display abilities as a tool.

[chessman]

Listening has put me back to non-inverted (0 polarity). The graph is not as pretty, but bass has a more natural resonance. Before the scientists break out slide rules and attack I would make two observations. First, tonal quality is more than frequency response. I do not have the ability to do water fall graphs, but I have the feeling that the "bad" frequency response graph has a more equal decay pattern (hence, the more natural sounding bass). Second, move a measuring microphone an inch and you may have wildly different results. You live in a world of aggregate readings, not a head vise.

The graphs help weed out bad choices and really help you narrow choices at a broad level, but the fine choices are best left to your ears.

[chessman]

The system is settling in more and more with more playing time. The improvements keep coming. The sense of "presence" in the sound stage is improved and it is a bit bigger. The signature sound of many musical instruments is improved in two ways - a horn might have more growl in a jazz riff, but you also hear triangle strikes in songs where you never knew before that they were there. I think the extra octave is giving some weight to some instruments sound (drums are much better). I also think that cleaning up some distortion in the low end has quieted the mid-range to the point that I am hearing even more detail (the hitherto unnoticed triangle strikes). Best of all the sound is completely integrated and effortless, the speakers and the subs disappear, and there is no graininess or edge at all. If the Bryston is adversely affecting the sound I cannot hear it. To the contrary, I think it sounds noticeably better.

[chessman]

Thus far this thread has been about using "stereo" subs for music only. I have been beyond happy with the improvement to the two channel experience.

Of course, one sub matched to each of the right and left main signals (via the magnificent Bryston 10B-Sub) meant that I had no sub at all receiving the LFE signal for Home Theater. Of course the Bryston would have allowed one sub to supplement both mains leaving the other for LFE duty, but I was too in love with the smooth frequency response of two subs for music to do that. So, I bought a third JL Audio F113 to use for the LFE signal.

The current lineup, then, is one F113 for the left, one F113 for the right, and one F113 for LFE only. Thus, it is stereo subs (i.e., only two) for music and three subs for HT (i.e., mains run as large, the other five speakers as small, with two subs helping the mains run as full range and the third as LFE).

Setup was much easier than expected. I ran the onboard ARO on the F113, placed it at the same distance from the listening position as the other two (but at 90 degrees to them), consequently left relative phase at zero, used the Oppo for movie bass management (crossed at 80 H), used the Emotiva for TV bass management (crossed at 80 H), disabled the LP filter on the F113 and I was good to go. I am not using the SMS-1 at all in the signal path, nor did I use it for this set up.

Today I watched all or part of J.J. Abrams' "Star Trek," "Transformers," "Master and Commander," "Open Range," and the Ohio State basketball game. I have been sitting here with a silly grin on my face because it sounds so awesome!!

[bart]

Randy, it's a joy to follow your journey!

[chessman]

Gee, thanks Bart.

[trek737]

Originally Posted by chessman

Thus far this thread has been about using "stereo" subs for music only. I have been beyond happy with the improvement to the two channel experience.

Of course, one sub matched to each of the right and left main signals (via the magnificent Bryston 10B-Sub) meant that I had no sub at all receiving the LFE signal for Home Theater. Of course the Bryston would have allowed one sub to supplement both mains leaving the other for LFE duty, but I was too in love with the smooth frequency response of two subs for music to do that. So, I bought a third JL Audio F113 to use for the LFE signal.

The current lineup, then, is one F113 for the left, one F113 for the right, and one F113 for LFE only. Thus, it is stereo subs (i.e., only two) for music and three subs for HT (i.e., mains run as large, the other five speakers as small, with two subs helping the mains run as full range and the third as LFE).

Setup was much easier than expected. I ran the onboard ARO on the F113, placed it at the same distance from the listening position as the other two (but at 90 degrees to them), consequently left relative phase at zero, used the Oppo for movie bass management (crossed at 80 H), used the Emotiva for TV bass management (crossed at 80 H), disabled the LP filter on the F113 and I was good to go. I am not using the SMS-1 at all in the signal path, nor did I use it for this set up.

Today I watched all or part of J.J. Abrams' "Star Trek," "Transformers," "Master and Commander," "Open Range," and the Ohio State basketball game. I have been sitting here with a silly grin on my face because it sounds so awesome!!

Randy,

Just found this thread and have read it from front to back. Really excited that the two sub setup as worked well for you. It took my system to another level and it looks like it has done the same for you! Enjoy... & a big

Congrats !!!

[chessman]

Jim, thanks! This has been a major upgrade for music and HT.