Ähm - I just showed a measurement of DAC+power amp (!) with 123dB S/N. So it is possible and you need:
*) a DSP with digital outputs. MiniDSP SHD Studio, DDRC88D or just a nanoDIGI.
And of course - digital input! Always only do one D/A conversion if possible.
*) any modern, good DAC. I used a SMSL SU-9 for this measurements, SU-9n costs € 350,- on Amazon Europe. ES9038PRO, good implementation - these units work well! https://www.audiosciencereview.com/.../smsl-su-9n-review-balanced-stereo-dac.27300/
Just buy 3-4 of them to get your channel count.
*) Get an ultra low noise amp! I use Hypex, for this measurement a NC250MP board. Has the benefit I can tune the gain of the amp and price/performance is extremely good. You can also buy a few AHB2 (hui!) or a ready made Hypex solution.
Important is gain staging, otherwise you loose a significant amount of these dynamic dBs -> your noise floor rises.
With most power amps you are far from the dynamic range of a good DAC. And very often a gain missmatch adds. (DACs often have 4-5Vrms on sym outputs. Amps 1-2Vrms for full power. You quickly gain 6-10dB noise floor.) Therefore a simple Hypex DSP module is already significant better as most chains people listen with (esp when useing the digital input. Works great for me in combination with a RME UFX).
I need such extreme dynamic ranges for my work in technical acoustics for testing microphones. And after testing these systems for listening I really liked what I heared. Actually the best I know.
And it's simple - do everything digital and get your DAC as far to the end of the chain as possible. Digital cables, no losses, no gain missmatch, no noise at all. THEN let's talk about filters and EQs ...
*) a DSP with digital outputs. MiniDSP SHD Studio, DDRC88D or just a nanoDIGI.
And of course - digital input! Always only do one D/A conversion if possible.
*) any modern, good DAC. I used a SMSL SU-9 for this measurements, SU-9n costs € 350,- on Amazon Europe. ES9038PRO, good implementation - these units work well! https://www.audiosciencereview.com/.../smsl-su-9n-review-balanced-stereo-dac.27300/
Just buy 3-4 of them to get your channel count.
*) Get an ultra low noise amp! I use Hypex, for this measurement a NC250MP board. Has the benefit I can tune the gain of the amp and price/performance is extremely good. You can also buy a few AHB2 (hui!) or a ready made Hypex solution.
Important is gain staging, otherwise you loose a significant amount of these dynamic dBs -> your noise floor rises.
With most power amps you are far from the dynamic range of a good DAC. And very often a gain missmatch adds. (DACs often have 4-5Vrms on sym outputs. Amps 1-2Vrms for full power. You quickly gain 6-10dB noise floor.) Therefore a simple Hypex DSP module is already significant better as most chains people listen with (esp when useing the digital input. Works great for me in combination with a RME UFX).
I need such extreme dynamic ranges for my work in technical acoustics for testing microphones. And after testing these systems for listening I really liked what I heared. Actually the best I know.
And it's simple - do everything digital and get your DAC as far to the end of the chain as possible. Digital cables, no losses, no gain missmatch, no noise at all. THEN let's talk about filters and EQs ...
Definitely not easy! You need to really know what you do, know if you can trust your measurements. Know about room acoustics in theory and practise. And it needs time and quickly 50-100 measurements.
But isn't that what everyone does when installing a subwoofer? 🤓
I also heared a lot of bad sub integrations. All of the ones done only by ear (even mine) are maximum OK.
But that's not the fault of the subwoofer or the system ...
At sub frequencies the shape makes little difference acoustically, but large unspanned panels means more likliehood of the box resonating.
One can rud themselves of a very significant amount of the energy that could get the box going can be actively canceled with a push-push driver arrangement.
dave
Easily improved. Make the spacing unequal, and actually use the braces to distribute driver energy thruout the box. And way overkill compared to how much simplier things get when you empty push-push mounting
dave
Its better. Way better for a woofer since you want to push box resonances up in frequency. MDF is a bad material for subs.Nite that if you were planning on 18mm MDF, you can do better with 15mm quality plywood. And if you mount the drivers push-push you could actually get away with 15mm ply.
If you use 18mm MDF you probably need twice as much wood as you would with 15mm push-push. I showed that clearly with the push-push SDX10 i showed in an earlier post, 15mm, i’d double the top now.
dave
Plywood is a way nicer material to work with. And way more sturdy when things get wet or thrown around (PA). But in terms of acoustics and sound transmission ... look yourself:
These materials are way more similar as different.
"Impulse compensation" works very well, way less vibrations on the cabinet. Even when not done perfect (= connect the magnets) it helps to reduce vibrations significant.
These materials are way more similar as different.
"Impulse compensation" works very well, way less vibrations on the cabinet. Even when not done perfect (= connect the magnets) it helps to reduce vibrations significant.
how do you synchronize the 3-4 DACs with each other?
It creates a big jitter and unsynchronization between the bands.
SPDIF outputs transmission quality is worse than asynchronous USB, more jitter, cannot play DSDs in this case.
Hypex is ideal only for the sub.
If I listen it in full range mode for a long time, my ears get tired. 🙁
It sure loses out to my Plinius or Bryston.
There is only one undoubted advantage to the DSP, ease of use.
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Agreed 100%, but you understand I was talking structurally...
I understand how the push/push configuration all but eliminates reaction forces, and reduces energy input to the baffle(s) and the enclosure as a whole (my design has no baffle), but surely the pressure exciting the remaining enclosure panels remains unchanged and a cuboid shape remains structurally flawed (but simple to build!).
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Well I've already got 2x12" drvers with the 105. They simply do not go low enough. Also the plan is to have 2 21" subs
Hi, you must tune the system with your room if you haven't.
This is mandatory no matter which sub you have, if there is strong peaks at listening postion it will never sound right, there is no lows, no kick, mid is bloated, everything is swamped due to strong modal peaks. At least this is my experience. I've always struggled with bass in room, either there is too little or too much and it never felt right. Now tried to tune it few times with more care and finally got some sensible results at one listening position. The bass is nice and tactile and doesn't sound like bass but feels like a bass 😉 Everything improved all the way from lowest lows to midrange, finally. I'm sure it could be even better, but wanted to post to underline effects of room should not be underestimated.
I've got very much undersized sealed boxes (15" though) on mains and single additional 15" subwoofer and the system sounds now as good as ever just after getting adjustments better, after enough evening out effects of room. Before I though I'm missing lows but it wasn't the case, there was just such a strong effect from room modes that I just did not hear/feel the lows. When the frequency response balance got better, peaks and dips equalized enough, it was possible to level the system right and its sounds fine now.
In my opinion, if you are having strong peaks and dips due to room modes there is no chance to have nice bass no matter what size the sub(s) are.
This is mandatory no matter which sub you have, if there is strong peaks at listening postion it will never sound right, there is no lows, no kick, mid is bloated, everything is swamped due to strong modal peaks. At least this is my experience. I've always struggled with bass in room, either there is too little or too much and it never felt right. Now tried to tune it few times with more care and finally got some sensible results at one listening position. The bass is nice and tactile and doesn't sound like bass but feels like a bass 😉 Everything improved all the way from lowest lows to midrange, finally. I'm sure it could be even better, but wanted to post to underline effects of room should not be underestimated.
I've got very much undersized sealed boxes (15" though) on mains and single additional 15" subwoofer and the system sounds now as good as ever just after getting adjustments better, after enough evening out effects of room. Before I though I'm missing lows but it wasn't the case, there was just such a strong effect from room modes that I just did not hear/feel the lows. When the frequency response balance got better, peaks and dips equalized enough, it was possible to level the system right and its sounds fine now.
In my opinion, if you are having strong peaks and dips due to room modes there is no chance to have nice bass no matter what size the sub(s) are.
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Driver size doesn't say how low they play. A modern 12" will have more and cleaner Xmax as both of yours.
Btw - 4 12" have more membrane area as one 21". Xmax is also important ;-)
A single 21" is a more cost-effective option than 4 x 12" of similar quality, which might be relevant here. Further, most 21" drivers have have higher Xmax than most 12" drivers so despite the extra 25% effective Sd of four, Vd could still be greater with the 21".
Do you have an example of a 'modern' 12" for comparison with a typical 21"?
Do you have an example of a 'modern' 12" for comparison with a typical 21"?
True, but everything is a compromise. Pressure can cause ballooning in a woofer, but if the cube is a actually a square prism, one can keep the sides small, mount them push-push, those short sides + the holey brace maximize the force cancelation affect.
With the 10” we got away with a simplish cross-brace, the only panel at issue was the top (and that with the mains turned off, and teh woofer amp likely driven into clipping [thus producing HF normally not there]), fixable with a double thickness top or a piece of granite or marble.
With a much larger woofer one probably needs ar least a 3 x 3 matrix. It should be oriented vertically to maximize the added stiffness.
The key piece from Tappan (old, old AES)
dave
I’d happilly work towards 4 x 12, as that would allow for 2 push-push boxes. Much easier boxes to build, and 2 is much more capable of getting smooth response really low (4 is even better).
dave
Fascinating data, thank you.
Does this translate fairly well from 0.5mm thick steel to wooden panels of substantial thickness?
I could not find the original paper - what were the dimensions of the brace added in the tests?
Concept applies to all materials
The one i have is in one of the loudspeaker anthologies, all 5(?) are worth having.
dave
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Of course. I actually build with SB34NRXL75-8 but if you are price sensitive take SB34NRX-6 - about €200,-. 3 of them have the same membrane area as one 21". +-11mm coil overhang. 19Hz, Qts 0,4 - just put it in a closed box and give it a little EQ to get 20Hz. 99g membrane weight. 3" coil, huge venting holes, very low thd and low noises at Xmax.
Compared to the latest B&C 21" - 21DS115. About 600,-. +-11mm coil overhang. 30Hz, Qts 0,23Hz. You need A LOT more EQ for a closed box here. 407g, 4,5" coil. I bet cooling will be excellent, THD at high levels probably also, not sure about low levels. Noises can be higher cause they use the air actively for cooling but I don't think that would be a problem in a closed enclosure.
So you see they are pretty compareable. You have the big benefit to automaticly get a multi subwoofers with more smaller membranes.
There are chassis like SB23MFCL45 - put 4-6 of these at your front wall and get a single bass array. Makes it very easy to EQ to your listening area.
I have 6 SB29NRX75-6 for my home cinema, hidden behind the screen. Easy enough level for my use.
I´m actually very curious after this woofer and how it performs around 20Hz and lower:
https://www.diyaudio.com/community/threads/18sound-18nls4000.400646/
https://www.diyaudio.com/community/threads/18sound-18nls4000.400646/