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Driver choice for a shallow subwoofer

ai1

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Hello Everybody,
I am writing to the forum for the first time, although I am following it for quite a moment already. I am trying to catch up with an old hobby, but if considering that it was really another time and another place, I might be seen as a newbie here. So, from the beginning, I would like to excuse myself if asking stupid questions which were probably discussed many times. Anyway, here we go:

I would like to build 2 shallow subwoofers to accompany John K.’s great Nao Note II RS speakers (essentially, to experiment with room modes) and, possibly, using them in other projects (music). What I have in mind is something in the spirit of Inkognito's excellently executed by Sigberg Audio. I know, cheating is not good, but with strong size and look constraints, the choice naturally goes in that direction. So, the subwoofer will be down-firing ~40L closed box with minidsp pwr doing amplification and correction. I am stuck with the driver choice constrained by
  • geography (Europe),
  • budget (<300EUR),
  • enclosure internal depth (14-16cm).
I do not listen loud, so high max SPL is not really expected, but getting ~100db at 30Hz would be nice, along with a reasonable level of THD. The price of Scan-Speak revelators being way above my constraint, right now, the contenders are (in alphabetic order)
  • SB Acoustics SB34SWPL76-4
  • Scan-Speak 32W/4878T00
  • SEAS XM001-04 L26ROY
I believe that L26ROY has a reputation of small distortion, I have not found distortion measurements for SB34SWPL76 or Scan-Speak 32W/4878T00.
In any case, I would be happy to get an educated second opinion, I am open to all suggestions.
 

Moonhead

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SB acoustics is engineering know how from scan speak, so you cant go wrong with
any driver from Sinar Baja as it is high vfm.
 

headshake

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Chrise36

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At 40l no 10" or 12" will play flat down to the fs. You might consider an isobaric arrangement or smaller 8" or DSP.
 
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ai1

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Thank you for comments!

At 40l no 10" or 12" will play flat down to the fs. You might consider an isobaric arrangement or smaller 8" or DSP.

Of course! All considered drivers have max SPL 98-100db at 25Hz. The idea is that miniDSP PWR-125 with 450W max output will take care of 8-10db of FR decrease at 25Hz w.r.t. 60Hz (not taking into account room gain). I just wonder in what excursion and what THD it will result.
 

Chrise36

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For 100db with low distortion i feel you need more drivers or high excursion ones.
 

kipman725

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Thank you, have not seen this one, it has slightly higher max SPL (3db), yet it is 160mm deep, this is really the limit, it will touch the bottom...

you will also need some extra space for the pole vent
 
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ai1

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For 100db with low distortion i feel you need more drivers or high excursion ones.
Well, should I say "reasonable distrortion" at 100db and "quite reasonable distortion" at, say, 87-90db? Will I get any advantage using, say, Dayton audio Ultimax 10-22? What would be a better choice of the driver?
 
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ai1

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I have modelled 2 PIONEER 300S4 in 36.8 litre box will give 109 db max spl at 30hz (800watt continuous) or about 100db for 100 watts for both drivers in one box
This would be an extraordinary price/perf ratio. Yet, I have not seen any measurement of those woofers, and it looks like that they are aimed at car/portable applications. As I said, max SPL is not really an objective, getting small THD at 80-90db would be one.
 

Chrise36

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This would be an extraordinary price/perf ratio. Yet, I have not seen any measurement of those woofers, and it looks like that they are aimed at car/portable applications. As I said, max SPL is not really an objective, getting small THD at 80-90db would be one.
Yes car subs are made for small boxes thd is not a concern at ultra low frequencies the real problem is to have flat frequency response because the room will cause uneven frequency response and you need as many woofers as possible for this. Using EQ will raise the distortion but many drivers can have the same output with lower distortion. So the best is to have drivers in the right box and as many as possible.
 

Wolf

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The UM10 is nice and takes EQ well should you boost it.
 
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ai1

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The UM10 is nice and takes EQ well should you boost it.
I have not found measurements for UM10, but there is a Voicewcoil review for Um12 here:
https://www.yumpu.com/en/document/r...icecoil-review-by-vance-dickason-dayton-audio
I do not know how the distortion measurements in Fig. 11 may be interpreted (free air, 94dB et 1m), but they looks less impressive than similar measurements of L26ROY
https://audioxpress.com/article/test-bench-the-l26roy-10-subwoofer-from-seas
It may be worth mentionning that the price of both drivers is essentially the same here in Europe.

Well, it looks like I will just have to try one of each and see;-)
 

Chrise36

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I have not found measurements for UM10, but there is a Voicewcoil review for Um12 here:
https://www.yumpu.com/en/document/r...icecoil-review-by-vance-dickason-dayton-audio
I do not know how the distortion measurements in Fig. 11 may be interpreted (free air, 94dB et 1m), but they looks less impressive than similar measurements of L26ROY
https://audioxpress.com/article/test-bench-the-l26roy-10-subwoofer-from-seas
It may be worth mentionning that the price of both drivers is essentially the same here in Europe.

Well, it looks like I will just have to try one of each and see;-)

While it is has been recognized for years that human hearing is not very sensitive to low bass frequencies, which must be reproduced with much more power and intensity in order to be heard, what these results show is that our detection threshold for noise (made up of harmonically related and non-harmonically related test tones) is practically non-existent at low frequencies. (The noise test tones are noise in the sense that they are not musically related to tones commonly found in musical instruments.) In fact, the noise tones at 20 Hz and 40 Hz had to be increased to levels louder than the music itself before we even noticed them. Put another way, our ability to hear the test frequency noise tones at frequencies of 40 Hz and below is extremely crude. Indeed, the results show we are virtually deaf to these distortions at those frequencies. Even in the mid-bass at 280 Hz and lower, the noise can be around -14 dB (20% distortion), about half as loud as the music itself, before we hear it.
https://www.axiomaudio.com/blog/distortion
 
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