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I have bought every single component needed for this speaker. Unfortunately I learned the hard way that it must be done by a CNC machine. Just working on the CAD drawings for this speaker for CNC. Because now I'm doing this on a CNC machine, it opens up other possibilities of what could be done. Here's a rough drawing to give you an idea of what the speaker looks like and how crazy space limited it is. I always knew this speaker would be very difficult to build, but I had no idea just how insane it is until actually doing it. In my mind it didn't seem so bad, probably doable in a weekend. But in reality, every little thing is so much more difficult because of how darn space limited I am. Simple things such as just how to rear mount the drivers became another exercise because of the 1/4'' thick wood. It took nearly a full day just to cut the frames off the drivers. The incredibly small midrange and tweeter spacing causes problems in sealing the drivers, not to mention the extreme difficulty of cutting it to shape without a CNC machine. There are other things that happens when you actually build it out or model it in a 3D software. The depth of the speaker was forcibly increased by 1'' from 6'' to 7'' for several reasons such as the two woofers cannot be mounted magnet to magnet because the magnets repel each other when placed that closely and not having enough space for the larger amp. This increases internal volume, and now 2 PR's might not be enough. Should I add a third PR and lose the inert enclosure, or convert a high excursion Tang Band woofer to be a PR, increasing the baffle size and decreasing PR "efficiency", so I have to put more thought into questions like this. Originally I aimed to have this speaker completed by about now. Unfortunately I'm looking at around late December to finish the model and have the parts cut, and another month for putting everything together and applying finishing, and another few weeks for outdoor measurements and tuning. So I'm looking at February before it's done. Believe me I want nothing more than to get this speaker done. The anticipation is killing me. I also don't want to ever setup my current mini speaker again. It is a massive wiring mess where 11 boxes (3 amps, 3 power supplies, 2 miniDSP's, 2 stereo to mono boxes, one optical cable splitter), 26 sets of cables (10 RCA, 6 banana plugs, 5 power cables, 3 optical, 2 USB) and a standalone power bar are needed to power 2 little speakers. I can't wait to cut that to just 2 speakers, 2 miniDSP's, and an optical splitter. Unfortunately I will have to set it up at least 3 more times in the next 2 months... I attended the Burning Amp last week, and I heard the LXmini from Linkwitz Labs. Sounded really spacious and big (a little too big for my taste actually), but nevertheless got me curious about dipoles. The LXmini is omnidirectional to 800Hz. Mine is omnidirectional to 400Hz. Both speakers also follow the 1/4'' wavelength crossover frequency for a lobing error free radiation pattern. I had an idea on having the option to turn the speaker into a dipole by adding another set of tweeter and midrange to the rear baffle of the speaker. The ICEpower amp for the midrange and tweeter have no problem supporting the second driver, in fact it is specifically rated to be able to handle 20W 8 ohm on one channel (2 tweeter) and 82W at 2 ohm on the other channel (2 midrange). If I feel like blowing $5000 and a whole bunch of time I'll attempt this. Only reason I'm not doing this on the current speaker is that I don't have room for the rear tweeter because the woofer amp is mounted on the top baffle. And I thought a small speaker can't get more expensive than this...... (Well, I could have used some $300+ woofers, but they would have performed worse for bass than the $140 woofers I used here) But before that I want to look at moving away from a miniDSP setup and maybe to a Intel NUC setup for DSP, inspired by BassThatHz's work on a PC based DIY DSP setup. This is why the miniDSP's weren't inside the speaker, even though there is space. One feature I feel that is very important for sound quality is the equal loudness contour to maintain tonal balance at any volume. At low volume I want a more V shaped curve, at high volumes I want the bass and especially the treble to be reduced, otherwise the speaker could sound too bright at higher volumes. I'd also get much more taps for FIR filters, and can actually do more than 2 bands for the compressor without the tedious wiring solutions right now involving combining signals back into mono for the woofers. Not to mention, it would be much cheaper than 2 miniDSP's

I only have around 1500 taps available, and I'm running on 96KHz, not because I want to, but because that's the only option on the miniDSP 2x4 HD.

A few pictures of the truncated drivers. This alone took half a day!

I spent some time trying, and had all the problems you mentioned. It is extremely sensitive to the amount of delay I apply, and the resulting FR is quite different with different delays in increments of 1ms. I got something reasonable after an hour or so of playing around. The group delay around tuning was significantly reduced, but I wouldn't call it optimal. The FR curves down a bit, probably due to some cancellation from phase differences, and I'm not sure if that reduces maximum clean output. The group delay is measured on my desk, nearfield. Not sure if that's valid for measuring group delay. I also only played with IIR filters and did not attempt to use FIR filters for the crossover or any attempt at correcting phase. A quick A/B revealed no sound quality improvements, but it might be because my new room is quite bad for bass. I haven't figured out whether I have a huge 50-80Hz null or I have 2 huge 45 and 90Hz room modes. I will investigate this further at a later time as it seems like it could be promising. Right now still focused on building the speaker. The enclosure proved far more difficult and time consuming to build than expected because of accuracy issues when squeezing every bit of space possible. Looking at options to CNC the enclosure now or make it with fibreglass.

As I am working on tuning this speaker on the DSP and making it linear phase, I was reminded of a problem that I will have horrible group delay in the bass region because of the combination of a vented enclosure and massive shelf boost to flatten the bass response. I remember for my previous speaker, group delay exceeded 2 cycles below a certain frequency, let's say 60Hz. I don't have anywhere near enough taps to brute force correct the phase shift. But what if, say I separated the <60Hz band, and I delay the >60Hz band by the equivalent delay in ms of 2 cycles at 60Hz, which is 33ms. Would doing this improve sound quality more than it hurt it?

Where do you see the PB16U driver is an underhung design? The manual says overhung.

I agree with what you say when designing without DSP signal shaping. But what if DSP shaping is used, like in SVS's case? Wouldn't a higher motor force woofer perform better for a sealed enclosure?

It's in the owner's manual. It says overhung for both. SB16U: https://system.na1.netsuite.com/core/media/media.nl?id=129769&c=3634088&h=883c60d7de9cf244fe4a&_xt=.pdf PB16U: https://system.na1.netsuite.com/core/media/media.nl?id=130247&c=3634088&h=b3bcb98d34afec35feaf&_xt=.pdf

Did you guys notice the PB16U driver has 41mm of Xmax when the SB16U's driver is only 32mm? Why is the sealed version getting the lower Xmax and lower motor force driver? The ported one should be the one getting the lower excursion driver with the port managing the excursion levels down low. It doesn't need as much motor force either since the enclosure is so much bigger. The sealed version should be getting the ported driver. It needs that extra excursion and motor force in that little sealed enclosure.

Extremely interesting impressions on your room treatment experimentations. I want to share a little discovery I recently noticed that is sort of disturbing. I moved into a new place, and the bedroom acoustics are exceptionally bad to the point of almost unlistenable. It was so ridiculous that somehow there was a huge dip near the crossover between the mid and woofer and it was better to invert the polarity on the woofer in that bedroom. It was subjectively and objectively better (the dip was gone). That made it better, but the speaker still sounded much worse compared to the old room it was in (and the old room's acoustics weren't that great). I didn't get more time to tinker with the sound to deal with the room acoustics. However, it didn't take too long (a week or two) for me to get used to the sound and find it sounding good! It didn't sound amazing, or even great, but it was a positive impression instead of a very negative impression like when I first moved in. It seems like our ears are highly adaptable, and I can't trust my own ears! I hope you have some way of comparing against a reference to reduce the effects our ears could have in adapting to a particular sound after long exposure.

With a better modelling tool, the Peerless is a noticeably more "efficient" passive radiator (1-2dB) than the Tang Band. Looks like I will just use the Peerless PR's. I tried very hard to have as small of compromises as possible with this design, but it looks like this will have to be something I have to compromise in this ultra small speaker. Good thing the limitations won't show until it gets close to the limits of the speaker. I've ordered the 4 ICEpower amps and the miniDSP's. It's coming along, slowly but surely.

So I did some playing around, and I could not find a reasonable cost driver suitable to be converted to a passive radiator. There are ~$100 drivers that could, but they're a bit too expensive to experiment with. So the option that I'm considering is just to use the Peerless 5.25'' PR for the following reasons: 1. The Peerless PR has extremely suitable PR parameters: High Cms, Qms, Mms, low Fs, and decent Vas. The Tang Band has low Cms, low Vas, decent Qms and high-ish Fs. 2. Even though it only has 6mm of Xmax while modeling shows I need up to 11mm of excursion on the PR at the deepest usable frequency, the modeling software does not account for PR losses, which I think is non-trivial. Looking at my previous speakers where I used 2 of the 4'' version of the Peerless PR, the actual PR excursion was only a little more than half of what modelling suggests (partially because I used stuffing). Note this is non scientific, just comparing with my eye and comparing it with the ruler I had in hand. I saw a video of someone that used a Tang Band 3.5'' RBM woofer (7mm Xmax!) with just one of the 4'' Peerless PR (jump to 11:20). Modelling shows one would need *4* of those PR's to keep the PR excursion below the 5mm Xmax. Yet, in the video he clearly drove the RBM woofer to the max and the lonely 4'' PR did not go flying into the room (although it was doing way more excursion than what I can drive my PR's and looks like it was doing a lot more than 5mm of excursion). 3. The 11mm excursion is only achieved with 150 watts of input power. With that much power, I expect at least 3dB of compression, which would further reduce PR excursion. That said, I do still have to watch out for transients. I'm hoping the 6mm rating is actually Xmax, and the Xmech is higher (hopefully a lot higher) Has anyone blown a passive radiator before? I'm thinking of sacrificing 2 PR's by turning it louder and louder until the PR's are physically damaged from over-excursion in order to find the limits so I can dial the compressor properly. Good idea? (Probably not ). Main concern is hoping the broken parts don't damage anything inside the speaker. The only reason I mentioned printing is because it'll be a lot easier than going to the woodshop. But realistically, I'm going to the woodshop for this. There's no fancy curves on the enclosure. I just want a good looking finish on the wood.

Houston, we have a problem. In fact, this is sort of a big problem. The Tang Band W5-1138SMF cannot be converted into a useful passive radiator. I was under the impression that the amount of mass to tune a PR for a given Sd, frequency and enclosure size is a constant when this isn't the case. The amount of mass needed is dramatically changed by the Fs of the PR. The lower the Fs, the less mass it needs. Therefore, Cms can dramatically affect the mass needed. The TB driver has a very stiff suspension, so the mass requirement for tuning is much much greater, about 4x higher than the original Mms, and there's no way the suspension can handle this much weight. The backup option is to use the Peerless 5.25'' PR. However, it only has a 6mm Xmax when I need around 11mm. Any ideas? Or am I forced to just set the limiter higher so it doesn't blow up the Peerless PR near/below tuning?

I'm not an engineer. I wish I had CAD skills to draw this up and send it to a 3D printer or something. Certainly would be much easier than working with wood! Just ordered the woofers and tweeters. Will be ordering parts slowly throughout the next week or so to soften the financial sting Next up, designing a grill for these speakers to hide the "magic" design. I look forward to seeing some shocked faces when demoing this .

Yeah it is nuts! Every component is top notch. It is essentially taking the drivers of a very high end 3 way speaker, choose the smaller diameter driver in the same family, and cramming them into this tiny box. I wasn't kidding when I said the value factor is a -1. And you guys aren't helping me with fiscal responsibility! That said, if things turn out well, it should be able to compete toe to toe against some very high end "Hi-Fi" style loudspeakers. Now that would be nuts! The main reason is because I couldn't reuse any of my previous components. Originally I thought cost wise this is not gonna be so bad because I can reuse the miniDSP, amp, and the mid and tweeters. But then the HD version of the miniDSP came out and it is priced far too high (should have replaced the 6 year old 2x4 instead of charging double the price as a higher end model), but I gotta have it for the digital input, FIR filters and impulse correction. Then I decided to use 4 of the pricey ICEpower amps to clean up the clutter and a properly designed amp, so I couldn't use the 4 amps I already bought. SME mentioned I should get the 4 ohm midrange to get more out of the amp, so I couldn't reuse the 8 ohm midrange in the previous speaker. So I thought, screw it, might as well keep the old speaker for comparison and sentimental reasons and put it in another room. The miniDSP's and the 4 ICEpower amps represent nearly half the cost of the build. Fuck it, I'm gonna get the beryllium tweeters. It's *THE* ultimate small speaker, right? I better not screw up when I cut the face plate off of these! I could make an enclosure out of aluminum, but I cannot put a nice fancy finish on it, and I want this speaker to have a very nice finish to it.

Some more updates, starting with bass: I measured my previous design to see what kind of group delay I was getting. The speaker is tuned to 47Hz, high passed at 40Hz, with ~12dB of bass boost that makes it perfectly flat to 45Hz. Unfortunately, the speaker can reach 2 - 2.5 cycles at and below tuning. This is clearly not good, at least by the textbook definition. EDIT: One complication is that the SMSL amp I used to power the woofers seem to have a built in bass boost. The model shows I need up to 12dB of boost, but I only applied 9dB on the miniDSP to achieve it. This might have made the group delay a lot worse as the results are a lot worse than what WinISD predicted. One explanation could be that there were a total of 5 filters used (4 on the miniDSP, 1 in the amp) to shape the bass response. Would using 4 filters instead of 1 in the miniDSP worsen the group delay? I used 4 when I could have just used 2 (boost and high pass) because I was anal on getting the bass to be literally ruler flat. However, if more filters cause more delays, I will reduce the number of filters. That said, my subjective opinion of the bass quality is excellent. Maybe it's because I might prefer a boomier sounding bass, because I don't like the sound of many well regarded SQ subwoofers from the likes of JL, Martin Logan or Paradigm. Because of this finding, I will continue my previous plan to boost the bass flat despite the group delay problems. The second update is on the tweeter: Originally I switched out the Scanspeak tweeters because SME pointed out that their very low 85.9dB test bench sensitivity will hold back the performance. However, after some research, it turns out that it seems every tweeter that Medley's Musings test has 4-6dB lower sensitivity than the manufacturer's rating. Scanspeak is known to have accurate, if not conservative specs even with Klippel testing. Two other tests for two different tweeters in the same tweeter family showed that Scanspeak's sensitivity rating is actually 1dB conservative. Therefore I believe the D3004/602010 tweeter I previously used does have an honest 90dB sensitivity. As for the Wavecor tweeter, I noticed the sensitivity rating is an average between 5-20KHz. However, the tweeter exhibits a rising top end, which means that the actual sensitivity is actually 1-2dB lower because of the lower 2-5KHz band. Therefore, the Wavecor tweeter is only at most 2dB more sensitive instead of 7dB that I previously thought. The Wavecor tweeter also has poorer off axis response partly due to the bigger Sd. The sound quality is also a gamble. The tweeter is also 10mm bigger, increasing CTC distance. Therefore, the Wavecor lost of its advantage in sensitivity and the disadvantages now overwhelm the advantages. The Scanspeak tweeter is back because it is smaller, better off axis dispersion, better sound quality, and having a protective grill. Because the Scan is back in the game, now the question is, should I do a true Ricci style build and upgrade to the beryllium version of the tweeter? What do you guys think? The price is $120 vs $280 for each tweeter. However, I just read a measurement of the Be tweeter and the measurements and especially the distortion data is simply outstanding. It would have no problem handling the 1500Hz crossover. The tester also mentioned that besides having less sensitivity, it measures and sounds essentially the same as the $450-$520 normal sized Scanspeak beryllium tweeter as they share the same diaphragm, just a weaker motor on the small one. The devil's advocate side of me is saying no, at ~$2500, this silly speaker is already stupid expensive and way more expensive than expected. I also want to hear the difference between the old and the new and how audible the difference between the two are when they share the same mid and tweeter, but this one will have an improved crossover, diffraction control, DSP, amp, midrange damping and construction. Link to the Scanspeak small Be tweeter measurements This is the distortion measured at 98dB at 1 meter, barely any distortion even at 1000Hz.

You mention you want to improve the seat to seat variation of >45Hz. However, in my nearfield sub experiments, even 1 feet away (which is closest distance from the nearfield sub's woofer to my ear) the FR is still very much affected by room modes. Have you ever experimented with nearfield subs in your room?

That's probably true -- if box resonance is audibly contributing, that probably won't sound good. I was initially excited by the idea of squeezing even more bass out of a small speaker. So far the driver and passive radiators are contributing to the bass. It would be cool if the box also contributed to the bass output. I am curious what the box resonance frequency for the speaker I will be building is though. Is there any way to measure that? Any behaviour that could be seen though a CSD or something? I actually researched about some pretty crazy things to do to get as much bass as possible in a small speaker. The most promising one was the use of gases less compliant than air to make the internal volume larger than it is. I remember increasing by a factor of 2 was quite achievable. In a speaker this small, I'm mostly limited by the power input as most small drivers cannot handle more than 100W of power. By reducing power requirements by a factor of 4, I could have gained 6dB more output either through the drivers able to use more of their excursion or doubling up on drivers. Unfortunately, gases leak over time, and even if the box can be completely sealed, the gas will leak through the driver cones and surround, and this idea was abandoned. So on things that I could realistically do, I will be making my own passive radiator by butchering the very high excursion Tang Band W5-1138SMF that will have at least twice the excursion than the off the shelf Peerless passive radiator. This is necessary to support the active woofers since each active driver only gets one passive radiator of the same Sd.

I just got an interesting thought: I based my enclosure design on BBC's research on cabinet thickness, and how they reached the conclusion that thinner walls are better for midrange than thicker walls because thinner walls pushes the panel resonance down to a lower frequency - about ~100Hz for a 1/4'' thickness wall. So that has me thinking: what thickness and what dimensions does the walls have to be to push the resonance down to 40-50Hz where it would be beneficial to have the box resonate and add bass output to a small speaker where every bit of bass output is needed. Are there simulations or formulas to predict box resonance?

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.

More updates: Let's get the bad news out of the way first. It looks like I won't be able to fit this on a 14'' x 6'' baffle. I will need 14.5'' x 6'' if I want to rear mount all the drivers. I am considering reducing the side wall thickness of the enclosure and midrange chamber by half to 1/8'', so I'll save 4 x 1/8'' = 1/2'' to bring the dimension back down to 14'' x 6''. The other walls will remain 1/4''. While mechanical vibrations won't be a problem due to the dual opposed design, I'm not sure of the possibly consequences of reducing the side wall thickness to 1/8'' for cabinet resonances. Now for the good news! The amplifier is getting a significant upgrade. I will be using the ICEpower 50ASX2 for the midrange and tweeter, which will provide 50W for each driver. The two woofers will be powered by the ICEpower 125ASX2, which will deliver 125W per channel to the woofers. The ICEpower amps should sound much better than most of the class D amplifiers on eBay and Alibaba. I never knew ICEpower made lower power units until now. They have integrated power supplies, the dimensions are incredibly small and they're not horribly expensive. That said, they are still more than double the price of the previous amp I was considering. However, there will be no doubts on the excellent sound quality, power output, and build quality of ICEpower amps. I'm changing the tweeter to the Wavecor TW030WA13, which seems to be an upgraded version of the TW030WA04 with a nice chambered tweeter. The driver is very good at playing low with 60% more Sd and over 3x higher Xmax than the Scanspeak tweeter. Someone mentioned using this tweeter with a 1000Hz crossover and it had no problems even with volume in the high 90dB's. The only downside is the larger physical size. Even with the flange perfectly cut, it is still 7mm larger, requiring an even lower crossover frequency.

Another update: I found a suitable tweeter to address the low sensitivity issue of the Scanspeak D3004/6020 tweeter I was originally planning on using. I will be using the Wavecor TW030WA04. This is a 1.2'' tweeter flangeless 4 Ohm tweeter. This tweeter has a sensitivity of 94dB @ 2.83V, which is 7-8dB higher than the Scanspeak. Wavecor's specs are known to be very accurate, so I believe the 94dB sensitivity is real. The 57% larger Sd also means the tweeter will likely to play a lot lower with less distortion at high volumes. Since this is flangeless, I don't have to butcher an expensive tweeter's frame to reduce size, and it will make it easier for me to get very tight CTC spacing and a much better chance of getting the 1500Hz crossover for the 1/4'' wavelength crossover to work. While a few users have commented on the excellent sound quality of this tweeter, I don't know if it'll sound as good as the Scanspeak as they are the benchmark small format tweeter. I do expect it to sound very close, and the benefit of the vastly higher sensitivity for dynamics and higher peak SPL should outweigh the slight sound quality advantage of the Scanspeak. There is a non ferro fluid version of this tweeter, and the sensitivity is 1dB higher. Should I consider it?

You're right. I mistakenly remembered that cylindrical midrange enclosures are significantly better than rectangular enclosures. I remember this from the Linkwitz LXmini, but the use of a cylindrical enclosure was for optimal diffraction instead of internal standing waves. I will stick with rectangular midrange enclosures as they can act as a brace and allow a closer midrange and tweeter placement. I might try one with non parallel walls depending on difficulty. After some thought, it doesn't seem there is a nice way to deal with the group delay problem without serious sacrifices of real world performance. The bass will be significantly boosted, there's no doubt about it for a satisfying listening experience. The use of a steep high pass slightly below tuning is necessary to prevent PR over excursion. On top of that, the compressor is going to increase the group delay as well. So either way the group delay around tuning is going to be bad. Honestly, I probably will enjoy the fat sounding ringing bass like how I enjoy my Logitech Z-5500 (it actually measures extremely well, much better than it's reputation). I don't actually like the sound of most high end subwoofers using heavy duty drivers from the likes of JL, Martin Logan, Paradigm, or DIY like the Dayton UM woofers that people say as "tight" (I unfortunately own two of these kind of subs). I much prefer the thicker sounding bass from subs like JTR or the PA style subs. But this is another (long) story. On the other hand, I found a much more suitable amplifier. 4 channels, much higher power (100W @ 0.05% THD), integrated power supply, small form factor, low price. Unfortunately, I have to buy a minimum of 10 units when I only need 2. I'm trying to figure out if there is a way around the MOQ. http://www.aliexpress.com/store/product/4CHANNEL-CLASS-D-SMPS-400W-PRO-AUDIO-AMPLIFIER-MODULE-4CH-OR2CH-OR-2-1CH-SET-EASILY/601158_460608255.html I've also updated the first post with the upgrades.

Here's the thread http://techtalk.parts-express.com/forum/tech-talk-forum/1294948-anyone-used-the-aurum-cantus-ac120 I wanna announce several improvements I plan on incorporating. First, the woofer, since this is data-BASS . I found a much better woofer for my application - the little known Wavecor WF152BD05. This is the driver I was hoping for, sacrifice Fs to tighten the suspension and drop the Vas. It has a nice low Qts of 0.29 and a lot of motor strength. The Q in a sealed 5L enclosure for a pair of them is 0.69! In a PR enclosure, it delivers around 2dB more output than the SEAS L16RNX from 40-55Hz with the same input power because the PR's actually boost output. This is very close to an ideal specially designed small subwoofer driver like the Tangband W5-1138SMF that brings around 3dB more. I've attached simulations for a comparison between the Wavecor and the SEAS L16RNX. One person mentioned that the sound quality is extremely good and comparable to a Scanspeak Revelator 15W (!), and behaves very well when pushed very hard. Looks like this is about as good of a woofer for my speaker. Bass, sound quality, non crazy price, check check check. Next, I'm going to try an internally amplified design. I'm thinking of trying my hands on some electronics and put a 4 channel amplifier and power supply right into the speaker. Both components are small enough to just fit in the speaker, and would massively declutter the need for 2 external amps and 2 power bricks for *each* speaker. http://www.parts-express.com/sure-electronics-aa-ab33182-4x100w-at-4-ohm-class-d-digital-audio-amplifier-board-sta508-(t--320-335 http://hifimediy.com/power-supplies/diy-power-supplies/SMPS300R-28V-110V Unfortunately the amp won't be as powerful, 64W vs 125W per channel (1% THD), but this is close enough to the 70W power rating on the woofers. However, even if the woofers can take the 125W, after power compression the difference is probably around 1dB. So I'll sacrifice 1dB for the massive convenience from 4 less boxes and 4 pairs less wires. One other advantage is that this amp could help to thermally protect the speaker. It has a temperature sensor that'll throttle power if it gets too hot, I believe at >80C. If it gets this hot inside the speaker, the woofer's voice coil is probably straining as well, and it would be good to limit power. While this is not the ideal amp, this is more than enough when I have no experience with DIY electronics. An ideal amp would be a really nice sounding mid powered amp like the TPA3116 for the tweeter and midrange, and a powerful amp like the TDA7498E for the woofers, but that would be too much of a challenge for a first time electronic DIY. Maybe next time. After much thought, it may not be worth chasing the 1/4'' wavelength crossover with the midrange and tweeter. So I want to try something else - an cylindrical midrange chamber. In my last speaker, the midrange chamber is essentially a cube, the least ideal enclosure shape. This time, I will use a stuffed cylindrical midrange chamber to better deal with standing waves and resonances. Because of the cylindrical shape, the midrange and tweeter cannot be in the same chamber as it will take up too much internal volume because there's no way of reclaiming the internal volume behind the tweeter like I can do with wood. This results in an increase in the distance between the mid and tweeter to a point where the crossover frequency will be infeasibly low for the tweeter. However, I do expect a noticeably cleaner midrange with this change. Man, I keep thinking this is about as good as it gets, but I keep proving myself wrong. I like it!

Been very busy lately, so I haven't been able to spend time to digest SME's suggestions and give a proper response, and won't be able to for a few more days. I also have some substantial improvements in mind, but don't have time to flesh out the details yet. But I can respond to yours quickly. Yes, I actually did look at them, specifically the AC120, and the specs are unreal. However, when I asked opinions of them, multiple people chimed in to say the woofers measure *extremely* off spec, like Qts of 0.55 instead of 0.18. 14x6x6 is already bigger than I want and at the edge of what I'd consider to be a small speaker. Increasing it further will no longer make it a small speaker and becomes dangerously close to the size of a bookshelf speaker. I'd say 80% of the fun is the challenge of keeping it small and the satisfaction of being able to claim "mine is smaller and sounds way better". Unfortunately at 14x6x6 it is already bigger than most sound docks. I absolutely want it noticeably smaller than the Sonos Play 5, by far the best sounding lifestyle speaker on the market, and be able to claim "mine is smaller and sounds way better". You built the M.A.U.L. to be the coolest kid on the block, I'm sure you'd understand where I'm coming from The value factor on this project is a solid 0, but the fun factor is 12/10. And yes, I can fit the 2 woofers, mid and tweeter on the 14x6 baffle if I machine off the frame for every driver. I'm trying extremely hard to keep the box size small! Without doing this, the dimensions would have to increase by 2'' in width and 1'' in height.