My living room "make over" (aka the "surrounded by bass" project)

[Kvalsvoll]

...

Then I put it all together.  The problem is entirely acoustic.  The dip in the response around 165 Hz at the listening position is most likely due to a series of primary and secondary reflections involving the floor and ceiling, and these reflections are creating a deep dip that's broad in both frequency response and space (as confirmed by moving around the space). 

...

 

Yes.

It is the sound pressure acting on surfaces and objects in the room that makes the rattles and buzzing and noise.

By using common sense and a scientific approach you found out, instead of chasing problems in the wrong direction, which is the common approach still used in hifi.

 

Lots of good information in your thread here, I like it. 

[SME]

Yes.

It is the sound pressure acting on surfaces and objects in the room that makes the rattles and buzzing and noise.

By using common sense and a scientific approach you found out, instead of chasing problems in the wrong direction, which is the common approach still used in hifi.

 

Lots of good information in your thread here, I like it. 

 

Thanks for the compliment.

 

In retrospect, sound acting on surfaces/objects should have been obvious, but I mostly noticed it with sub bass frequencies.  Conversely, with my old speakers, I did observe transmission of vibrations at around 265 Hz directly to the floor, to the wall, and to the chassis of the flat-screen TV which buzzed.  Isolation fixed that issue.  So it happens both ways.  Too bad I never did before/after response measurements at the listening position when I isolated the old speakers.  There might have been a real difference in that case.

[SME]

I updated my posts for the DNA-360 + SEOS-15 horn and the TD12M woofer (with and without cabinet) to add impedance plots, update some of the polar plots, and add notes to indicate where there's clipping within the 2D maps.  In this case, clipping refers not to audio clipping but clipping of the data to the maximum value available in the color range of the map.  I also added a horizontal 2D polar map plot for the TD12M in-box normalized to 0 degrees instead of 30 degrees because it doesn't clip and gives a better indication of the polar response pattern.

 

Edit: I also put up a DNA-360 harmonic distortion plot (measured up close) at the level of output required for 98 dB SPL at my MLP.

Edited May 26, 2016 by SME

[3ll3d00d]

There is a switch to the script that lets you set the spl used as 0 for the z scale (colour range). You can also fiddle with the gnuplot script if required. There is ultimately a limited dynamic range in that colour scheme though so you do have to choose where to focus.

 

Having said that it sounds like normalisation bit of the script is a bit simple to handle this case correctly

[SME]

There is a switch to the script that lets you set the spl used as 0 for the z scale (colour range). You can also fiddle with the gnuplot script if required. There is ultimately a limited dynamic range in that colour scheme though so you do have to choose where to focus.

 

Having said that it sounds like normalisation bit of the script is a bit simple to handle this case correctly

 

Thanks!  Yeah, I think I tried switch ("-r" ?) to set the SPL 0 point, but I don't think it did anything with normalization turned on.  I did find a way to hack the script to set the relative SPL that everything is normalized to.  I used that to re-do the TD12M/cabinet vertical polar map.  That trick isn't so helpful for the SEOS-15+DNA-360 horizontal map because the break-up peak is so strong on-axis compared to off-axis.  I'm sure other tweaks are possible, but I haven't fiddled with it enough. 

[3ll3d00d]

It is probably because I hardcoded the z axis range to get a consistent colour scheme. IIRC it used to vary with the data but that made graphs hard to compare visually. A simple fix is likely to be offsetting the data to bring that the level of the peak down to +3, a lot of info fades away into the blue when that happens though. It is quite a hacky script to put it mildly but does the job most of the time!

[SME]

Yay for cut wood:

 

[SME]

I got passive circuits bulit for my compression drivers and integrated over the last week.  My planned design didn't actually work corrected because I made a conceptual error in my script.  Actually, I originally did it the right way but I changed the sign on capacitance after getting a non-intuitive result.  Bzzt, wrong.

 

Thankfully, once I found and fixed the error, I was able to come up with a valid design with parts I already had on hand.  The result isn't perfect, but it's very close to what I was hoping for:

 

 

These measurements were taken with the horn and mic in the exact same location before and after the test.  It cuts the sensitivity by about 2 dB at the top and 10 dB at the bottom.  This ensures that the CD will never see more power from my amp than it's rated for, yet I still retain enough headroom to hit 110 dB at the listening position absent any compression.

 

This circuit reduces the background hiss a lot.  I now struggle to hear the hiss at my seats when the room is dead quiet and my ears have adjusted to the silence.  This seems to have improved low level listening somewhat as well.

 

There's no high pass filtering here except for the 40 uF capacitance in-line for DC protection, which cuts in around 500 Hz.

 

I also have an impedance measurement and picture of the assembled board but I didn't get these items transferred over yet.  I'll try to post them soon.

[SME]

I've been meaning to post an update for a while, and I still haven't put up the pictures of my DNA-360+SEOS-15 passive circuit.  Instead, I got preoccupied by a bunch of other things, and my health hasn't been 100% lately, either.

 

After my last posts, I spent a long time listening and making fine adjustments to the speaker voicing.  Over the mid-range, I decided to give more weight to a flat power response (using REW spectrogram and decay plots to get a close guess) than to a flat response at the MLP.  This involved boosting the lower and middle mid-range (250-1000 Hz or so) by a couple dB.  It took a few iterations of careful listening to tweaking by 0.5 dB here and there to get the mid-range balanced right to my ears.  The middle mids (500-1000Hz) are still a bit peaky because of ceiling and floor reflections, but the sound is much improved again.  The improvement was most noticeable with female vocals, but lots of stuff in that range, particularly percussion, really came to life.  Especially noticeable was the improvement in tonal balance of ambient and "surround-panned" content in 2 channel recordings.

 

Another change I did was to shelf up the top end to try to reduce the amount of roll-off above the 17 kHz break-up mode.  It takes quite a bit of boost to get 20 kHz up to -6 dB, but I figured I'd give it a shot and at least listen to the difference.  I was surprised by how much the extra output contributed to the treble.  Despite the fact that few people (including myself) can hear loud sine waves much above 17 kHz, extensions seems to be a lot more audible with transients and what I would describe as textured sounds.  (Think of the sound of rain falling, which is not like white or pink noise but is like a pseudorandom procession of a whole bunch of tiny impulses as each drop hits the ground.)  This change made the speakers sound a lot brighter, so I had to adjusted the roll-off to have a much lower Q.  The high frequency part of my target curve is now fairly close to the ATSC 2013 recommendations on page 34 here, except that I'm a tiny bit more rolled-off at the top.  Even with that, I think things may be a tad too bright, but it takes a lot of listening to ascertain that.  I'm at the point where 0.25 dB makes a pretty noticeable change.

 

So now the speakers sound even better.  They left my old speakers in the dust long ago, and yet I know I can improve things a lot more once they are installed more permanently and I have the software work I need done to take measurements at multiple seat locations quickly.  At least once my center speaker is done, I shouldn't have to do many tweaks to its tonal balance to make it sound great right out of the gate.

 

=====================

 

Apart from this fine tuning, I have spent a good bit of time iterating on designs for other speakers.  I'll be doing a lot of exciting work on that front soon.  I have TD6H woofers ordered for my surrounds, but the real fun to be had will be with the subs.  I have ordered the subwoofers for sealed boxes at the front of my room.  Sorry, it'll be a while before I can go into specifics about the drivers, but I will say that they will be powered by a SpeakerPower SP2-12k, which I hope to order early next week.  Oh, and, these do make me worry for my house.  I hope to receive these items within a month or two, but we shall see.

 

I haven't yet committed to the design for subs behind my sofa, but I think I'm close.  While it's tempting to go sealed for these subs to supplement the ULF, I'm thinking I will optimize them for output at 40 Hz and up.  In my room, the area behind the sofa is pretty much crap for subs playing in the 25-40 Hz range, and the response at the seats is already quite smooth with just two subs up front.  So 40 Hz and up is where it's at.  For these super-MBMs, I'm contemplating 4 dual-opposed cabinets, each with a pair of Acoustic Elegance TD10S and a down-firing 6" port.  They'll be designed to match the height of the seat back so they can be used as rear sofa tables.  The smaller woofer minimizes the depth, and the sims suggest these should play wicked loud with a fairly modest amount of power.  (Yay, cheaper amps!)  Each cabinet will get its own amp channel and DSP so that I can have fine grained control over the bass and possibly the lower mid-range response throughout the listening area and room.  This will be especially powerful when used for bass management because I can send different signals to the different subs for each mains channel that gets bass managed.  It'll probably take a lot of effort to figure out the best way to optimize these and to build the required tools, but it'll be fun trying.

 

With all the speakers I'm planning, I'll be using all 16 outputs from my Motu A16, including 6 independent sub outputs.  Yet I'll still technically only be "5.1", or maybe it's "5.6".  (Who needs Atmos when you can just add subwoofer channels?)

[Kvalsvoll]

Interesting thoughts about the hf roll-off and how flat to 20k makes a difference.

 

My experience correlates well with your findings - flat all the way up makes for better transients and texture.

And it does sound a little brighter.

I decided that this has to do with changes inside the audible range - up to 16k for me now, and not only level, but also radiation and power response.

If the hf is rolled off, and also beams above say 10k, there will be very little energy left up around the very highest you can hear.

 

Working on the F2 with this huge amt driver with very bad radiation in the upper range I notice high frequency sounds are less realistic and kind of appears smaller in size.

Increasing the dispersion in the upper end and also eq to flat all the way up improved this a lot, but it is still not up with the smaller horns with the ribbon drivers.

It sound analytic and very refined, but lacks realism.

[lukeamdman]

SME,

 

Sorry, just getting caught up on this thread, but so far your experiences have already answered some questions I had!

 

First, it's too bad the OpenDRC-AN has a loud noise floor.  I tried to go full active with a 10x10HD and the noise floor was just too much.  I could hear the hiss outside the room!  I've been trying to think of how to get that last 1% of performance out of my mains, and I was contemplating FIR EQ, but the OpenDRC-AN has now been scratched off the list...

 

Second, the Motu 16A is on my list to replace the 10x10, but it has some downsides.  From what I've gathered, it does have 4 bands of PEQ on both the input and output of each channel (so really 8 total), but it doesn't have low-pass filters?  Since you're fully active, how have you been implementing a LPF with the Motu?

[SME]

Hi Luke,

 

The DSP built-in to the Motu A16 unit itself is very limited.  Instead, it is intended to be connected to a PC as an audio interface.  I built a PC running Linux and run my custom DSP software on it.  I don't have FIR capability at the moment, but I can configure delays and use pretty much as many biquads as I want.  Biquads are very flexible and can be used to implement a variety of specific filter types.  The MiniDSP units and probably most pro gear use biquads for the PEQ and crossover settings they provide, but they offer a very limited flexibility compared to what I can do with a beefy x86 CPU.

 

Alas, the software is still quite primitive.  If I want to make a change, I literally edit lines of code in a Python DSP control script that look like "EQPeakFilter(f0=61.0, gain=-10.0, Q=8.0)," (that's for my worst room mode) and then restart the script.  It starts and stops running pretty much instantly and has so far worked without any clicks, pops, thumps, or drop-outs (so far, fingers crossed).  This is in total contrast to the MiniDSP units.  The full-scale DC thump that my MiniDSP 2x4 emits upon losing power is scary.  The firmware glitches that cause the OpenDRC-AN to intermittently emit loud pops under certain circumstances are also scary.  I hope most pro devices are more forgiving, and I guess you get what you pay for in that sense.  In my case, I'm gone the way I have, despite the immense effort so far.  Now I have a platform that I can build on, and I have ambitious plans for a user interface that integrates the activities of measurement, analysis, simulation, and processing into a single system with all the flexibility you'd come to expect from software that runs on a PC.

 

Of course, my "solution" is unrealistic for most people unless/until I can make such software available.  I believe most people who are buying the Motu A16 and related products for custom audio processing are also using a PC and are using software such as JRiver DSP and/or some other kind of FIR convolver program to do the processing.  I believe you can use REW to help you design the filters, or you can use something more powerful like Accourate if you have FIR capability.  I don't have any first hand experience with any of these other options, but I know people like 3ll3d00d here uses Accourate with JRiver DSP (correct me if I'm wrong) and is very satisfied with the results.  You might try sending him a private message if you want to go this route.  Other than that, I think Motu provides some kind of software for their units, but I don't know if it's free with the product or whether it runs on Windows or just Mac.  And I think the software is geared more toward a mixer's workflow than a configurable DSP system.

 

Good luck!

[3ll3d00d]

There are a few options for generating/designing FIR filters

 

I do use acourate generated filters in jriver, there is a cutdown version that runs on opendrc hardware

some others (like mojave) use audiolense

rephase is a free option, this one is a largely manual filter designer

I came across http://aplaudio.com/conc2/products/tda-eq/ recently, no idea if it's any good

 

I have a motu now (the 1248) as well as the PSU on my RME died. The motu mixer app is served by the hardware via a built in web server so is accessible via any device on the network (assuming you have a network cable plugged into it of course).

 

I don't think there are many options outside of a PC or a minidsp for running arbitrary FIR filters though. You can get devices like a DEQX but they're 1) expensive, and 2) often limited to a preselected set of steep crossover slopes.

 

Does the OpenDRC have the same issues as the 10x10? It's a different hardware platform after all.

[SME]

I don't know how the noise floor of the 10x10HD compares to the OpenDRC-AN, but I did find the noise floor of the OpenDRC-AN to be excessively high for me to use with high sensitivity speakers.  I'm surprised that the MiniDSP stuff is so widely recommended as I have had a variety of issues with the products, but I guess it makes sense given the lack of affordable alternatives.

[Ricci]

I don't know how the noise floor of the 10x10HD compares to the OpenDRC-AN, but I did find the noise floor of the OpenDRC-AN to be excessively high for me to use with high sensitivity speakers.  I'm surprised that the MiniDSP stuff is so widely recommended as I have had a variety of issues with the products, but I guess it makes sense given the lack of affordable alternatives.

 

I agree. They seem to work for a lot of people but the 2 units I tried a few years back I had a number of issues with. They just weren't for me. 

[lukeamdman]

I don't know how the noise floor of the 10x10HD compares to the OpenDRC-AN, but I did find the noise floor of the OpenDRC-AN to be excessively high for me to use with high sensitivity speakers.  I'm surprised that the MiniDSP stuff is so widely recommended as I have had a variety of issues with the products, but I guess it makes sense given the lack of affordable alternatives.

 

 

I agree. They seem to work for a lot of people but the 2 units I tried a few years back I had a number of issues with. They just weren't for me. 

 

I think they're popular because they're low cost and are one of the only DSPs on the market that let you set PEQ and XO below 20hz without extra workarounds.  They also have a frequency response that's pretty much flat to DC.

 

As you've pointed out there are definitely some downsides though.  The unbalanced 2x4 lacks voltage headroom, and my balanced 2x4 did have some pretty nasty "thump" when powering on and off.  Even that balanced 2x4 would benefit from more voltage headroom.  

 

My first 10x10 board was actually missing components on the PCB.  The noise floor was even higher and there was some really high frequency noise (above 20khz) that kept the amps signal lights lit up constantly.  They did send me a new board, and my only issue with the 10x10 now is the noise floor when trying to full active with high efficiency mains.  

 

I've seen the capability and flexibility of using the Motu/JRiver combination from mojave and it's really impressive, but I don't want to rely on running absolutely everything through JRiver.

[3ll3d00d]

I've seen the capability and flexibility of using the Motu/JRiver combination from mojave and it's really impressive, but I don't want to rely on running absolutely everything through JRiver.

 

I would say your choices, for video playback, are;

 

jriver as the source

or

normal consumer equipment as the source + some opendrc model OR a PC running as a custom audio processor fed by an appropriate set of pro audio interfaces 

[SME]

Better late than never right?  I finally added a picture/design of my DNA-360 passive circuit:

 

 

I also added a plot of my current 1/6th octave-smoothed steady crossover / frequency response at the MLP.  (Follow the link.  I'm not posting it here because I'll probably delete that image when I update it.)

 

Admittedly, 1/6th octave smoothed response plots don't tell you a whole lot about what's going on.  I purposely optimized the EQ for a smooth power response that's flat through the mid-range, and I think this sounds better that way.  With my last speakers I used a software algorithm to optimize response across multiple seats and ended up with an MLP 1/6th octave steady response that's +/- 2 dB of the target curve.  However, the 1/6th octave plot failed to reveal the fact that the power response was very unbalanced with a big spike around 3 kHz that colored the sound considerably.  This was a problem with the speaker that I could not correct without redesigning the crossovers.  I'm not certain, but I wouldn't be surprised if better acoustic treatment has the effect of reducing the tilt required to keep power response flat.  We'll see.

 

Until I update my measurement program to be able to run the sweeps directly from my Motu A16, I am only relying on single point measurements and doing the EQ by hand.  OTOH, my new real-time DSP software let's me hear changes I make to the filters very quickly.  I can switch between DSP configurations in a split second, which allows me to hear even subtle changes without audio memory coming into play.

 

For this last configuration, I tried something new.  I created an array of shelf-filters at 1/3rd octave intervals.  Then I made minor adjustments to the filters while listening to various music selections.  I also had my measurement mic plugged in and off to the side.  Using the RTA in REW, I could see which frequencies were involved when I heard tonal imbalance.  Then I could tweak one or more of the bands, usually by no more than 0.25-0.5 dB or so at a time, to try to make it sound nicer.  I mostly concentrated my adjustments above 4 kHz and between the 125-1000 Hz range.  The curve I posted is the response I landed on, doing this entirely by ear without taking measurements.  I don't have a picture here (the spec/decay plots take up a lot of my image storage here), but the decay/spectrograms indicate a very smooth and even decay from 100-5500 Hz or so and a linear reduction in decay energy with increasing log-frequency above 5500 Hz.

 

I do think it sounds very good, even though I am still making minor adjustments.  The treble and top-octave roll-off has proven to be very hard to get right.  Even though I started out with things basically flat out to 15 kHz, more careful listening has led me to slope it down more and earlier.  My old speakers sounded better with the response closer to flat.  They had horns, but I think they narrowed a lot more at the top than these.  With the exception of the 17 kHz break-up, the SEOS maintains wide dispersion all the way up to the top.

[SME]

Oh yeah, I should mention that my SP2-12000 is ordered.  I can't believe I'm finally going to update my subs.  I'm so excited!

 

For behind the sofa, I'm still looking at doing the dual-10", except with the TD10X instead of TD10S woofers.  While the TD10X is a tad less sensitivity in the region above tune, it is more efficient overall.  Conveniently, SpeakerPower just introduced their SP4-2800 rack amp with 4 x 700 W that I can use to power these things.  These ought to be handle to handle 4 x 1200 W, but SpeakerPower doesn't have an amp for that yet.  And anyway, I should still have an absurb amount of mid-bass headroom with four D.O. pairs running along with the monstrous (TBA) front-wall subs I'll be building and the mains speakers.  If what I have planned works out, I'll have 11 independent mid-bass sources playing together.

[SME]

I ordered 8 Acoustic Elegance TD10X drivers to use in dual-opposed pairs for mid-bass units behind the sofa.

 

I also ordered a SpeakerPower SP4-2800 amp to power them, but unfortunately, they had to delay the product and they cancelled my order.  Now I need to choose different amps.  The obvious alternative is to just buy 4 SpeakerPower SP1-700 plate amps.  However, I wanted to avoid plate amps for a variety of reasons.

 

I'm considering other brands of rack amps, but I'm not too thrilled about having to deal with fan noise and am not too keen on doing any fan mods.  Still, the QSC PLD 4.3 catches my eye, offering a fairly similar continuous power spec but with higher burst capability, for what it's worth.  The price is not bad, and it comes with a whole lot of DSP capability I'm not going to use.  I am a bit concerned about bus pumping being that it's designed to allow for bridging and I intend to run all 4 channels separately.  Also, I'm planning to go ported (30-45 Hz tune) for these cabinets now and not bothering with ULF, so this may not be a big issue.  Still, I really don't want to deal with the fan noise.

 

Bummer.  Does anyone have any suggestions?  I also looked at some amps by Crown and others, but finding an amp with 4 channels and a good amount of power in a 2U is hard.  The Crown amps cost more money than I want to spend.  I may just give in and buy the plate amps as they are cheap at least.

[SME]

IT'S DONE.  All my MiniDSP equipment has been removed and the filters migrated to custom DSP.  I also got to get rid of a lot of extra cables.  Now I have room for sub amps, and I have the two subs and two MBMs are running directly off of Motu outputs.

 

I've been eager to accomplish this work for a long time.  As part of the work, I re-did my gain structure again.  It's not really optimized yet, but I have more headroom than I had before.  The sub gain knobs are way lower than they used to be, so hopefully the very slight noise I could hear is gone.  And now I don't have to endure any more thumps from the 2x4 or be paranoid about the OpenDRC-ANs powering up in a weird state.  I also now have the ability to matrix process with independent filters between each main and each of the subs.  The simplest realization of this capability is to implement a different set of sub delays for each main speaker they we're crossing to.  This allows delays to be optimized for all the speakers in the system instead of just one like the center channel.  It'll likely be a while before I play with that capability though because I want to get back into the shop to finish my center channel.

 

The filters transitioned very well, with a few exceptions.  The MiniDSP 2x4 has less numerical precision and this alters the filters, somewhat, in the bass frequencies.  I had some notes on the changes I had to make for the 2x4 vs. simulations, so I was able to use the original filters, but the FIR filter was computed from the response after applying the modified biquads.  So there were minor changes.  The bigger issue was the sub delay.  Each DSP unit added some unknown (and possibly even configuration-dependent) latency, and since the subs were processed different from the center+surrounds, which were process different from the front left and right, I had to re-do all the delays.  I got the speaker delays fixed, but the sub delay is always tricky.  I'll need to do more measurements tomorrow to find a good value.  Grr.  It always bums me out when I fire things up and the bass sounds a lot worse than it used to.  Sub distance is so crucial, ya know?

 

Oh, and it looks like I may be able to get the SP4-2800 from SpeakerPower after all, but it'll be a little while before I know for sure.  I'm not in a big rush.  I will soon have have a huge backlog of speakers and subs to build.

[SME]

I added this GIF animation to the first post.  It depicts the parts and assembly sequence for the front left, right, and center speakers:

 

 

I plan to augment the bracing under the woofer with 1" dowel, once everything else is glued together.  I'll probably retrofit the other front speakers with dowels as well as they seem to very effective to stiffening where it's needed most.

 

The pieces fit together very snug, and the assembly is structurally very solid even without glue.  But the glue makes it permanent and helps tighten up the seams and seal the air gaps.  It'll take a week or so to complete all the gluing steps.  In the meantime, I'll work on designing and building the horn box with slanted face.

 

It looks like the SP4-2800 from SpeakerPower is delayed for the time being, but I am hoping they will finish very soon.  As I don't have the drivers for that build yet, I'm not going to worry.  I have plenty of other projects ahead of me as well.

[SME]

The center bass box is fully glued.  It's sitting in the shop, waiting to be sanded.

 

I have been working on the design for the horn box with a 10 degree slanted face.  I expect to get to work on it very soon and expect it to go together pretty quickly.  At the same time, it occurred to me I needed a more detailed plan for my front stage.  I gave more serious thought to things like how deep to make the shelf above the TV, which in turn impacts how far back the TV will sit to form a flush boundary with the speaker face.  All of this in turn affects the design for whatever acoustic treatments and/or baffles are to be used.  I'm not going to commit to any particular acoustic treatment until I can do more measurements, but I did want to settle on a depth and run through different acoustic treatment scenarios using that depth.

 

Another important design consideration is that I plan to add a drop-down screen that drops just barely in front of my TV.  I figured I'd research projectors some more.  I really like the looks of the Epson LS10k, and it is one of few that has a short enough throw ratio for my needs.  Sadly, I probably won't benefit as much from it's high contrast and black level performance because I can't really black out much of my living room.  While I feel guilty for buying an expensive project that lacks all the fancy UHD stuff that actually matters vs. 4k, I also kind of hope I can get the LS10k for a better price after CEDIA.  In any case, I'm looking at using a 90 inch wide A.T. screen with a 2.31ish aspect ratio.  As much as I'd like to do 16:9 at that width, the wife and I are both concerned about viewing height discomfort.  The screen can't go lower than the A/V racks. which are 24" high.  We sit at 9 feet or less.  Ergonomics matter a lot to both of us.

 

Other than that, my SP2-12k amp looks like it's about to ship.  My TD10X drivers will also ship soon.  Too bad the amp isn't meant for the TD10X, but I'm hopeful I don't have to wait too much longer to order the SP4-2800.  Meanwhile, the "front of the house subs" are still in the works, and I still can't share any details.  Soon.

[SME]

A preview of things to come:

 

 

I've been distracted lately by some family stuff.  I also blew out my router bit trying to do the SEOS cutout for my center channel horn.  I decided that the cutout template was too flimsy and was being deflected by the router bit, causing inefficient cutting and excessive heat build-up.  That's what I get for trying to conserve material.  It was a pain to clamp too, so I'll make a new one with a lot more extra wood.

 

I also snapped a picture (not the best) of my current living room with the prototype front left and right speakers:

 

 

It's pretty rough looking so far, but I have an ambitious vision of what I want the end result to look like.  I'm thankful my wife is so patient.  The ugly jute covered acoustic panels next to the front left/right speakers have been there for far too long.  They are at uneven height because the subwoofers are different heights.  The big pieces of foam on top of the subs were added after I set up the new front left and right speakers to control reflections there.  The old Hsu speakers didn't need it because they were placed further out into the room.

 

The things sitting on top of the horns are polystyrene diffusers.  Measurements show they don't really interact with the direct sound from the speakers, but they do help diffuse some secondary and tertiary reflections.  They used to be installed over the top halves of the absorber panels, but they did cause acoustic problems in that location with the SEOS horns.

 

Now that I have a replacement bit and a few supplies I was missing, I'm hoping to have a center channel up and running as soon as next weekend.  That will be a big milestone for the room makeover.  Then, depending on which new drivers I get first, I'll start building my subs or my MBMs, or if I don't receive either, I will probably work on rebuilding the left and right speaker horns with slanted faces and giving all the speaker cabinets a proper finish.

 

I'm tentatively planning to add another layer of 1/2" plywood to just the front face of each front speaker so that it's flush with the trim on the TD12M woofers, and I think I want to upgrade from binding posts to Speakon connectors.  I'm also about to start experimenting with Keda wood dyes to see if I can dye the baltic birch veneer a charcoal color.  I hope I can bring out a lot more contrast in the wood grain by doing that.

[lowerFE]

I read through this thread with awe and jealousy!

 

Unbelievable setup and execution! Top notch driver and amplifier selections and that custom DSP! I can't imagine how amazing your audio experience will be when finished. I wish i could do this for my home, but unfortunately I will have to get rid of my current HT setup in a couple of months and I don't know when I can have a HT again. 

 

How are you planning to setup the nearfield subs? I currently have a nearfield ported UM15 behind my couch. Whlle it is pretty awesome for movies, I find it distracting for music because it sounded a bit muddy and it felt unnatural to feel the couch vibrate with the music but not my chest or my clothes.