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<50Hz bass for stereo

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#1
I've set-up an old pair of wide-baffle 3-way book-shelf speakers in our 12' x 16' room as a nice listening nook for when our son, and his friends, take over our main lounge where the main system is set-up. I've set-up some tuned bass traps in the front corners and super-chunks in one rear corner, and after a bit of tweaking locations as well as use of DSP, have got good bass performance. The real remaining issue is a 8 dB dip centered at 40Hz (35-50Hz, Q~2). This dip correlates exactly to the cancellation from the back wall reflection. It probably not practical to address via room treatment and, with the main system involving multiple subs, I'm keen to keep this system system. Is it correct to guess that there is little benefit in solving the issue for most 2-channel music? But if I do attempt to solve it has to be with subs as room treatment won't address . Is this right?

Bass Response.JPG
 

DonH56

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#2
40 Hz is right near the fundamental (lowest frequency bass string) of a guitar and well above the lowest fundamental note on a piano (27 Hz). I would not want a dip there. With multiple subs you should be able to eliminate it if you have some flexibility in placement. Endless articles on that; look at the Harman site and Amir's articles here on ASR.

FWIWFM - Don
 

Krunok

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#3
40 Hz is right near the fundamental (lowest frequency bass string) of a guitar and well above the lowest fundamental note on a piano (27 Hz). I would not want a dip there. With multiple subs you should be able to eliminate it if you have some flexibility in placement. Endless articles on that; look at the Harman site and Amir's articles here on ASR.

FWIWFM - Don
Yet another example is bass (not guitar but double bass) which goes down to C1 (33Hz) so If you listen to jazz you may be hearing this dip.
 
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#4
40 Hz is right near the fundamental (lowest frequency bass string) of a guitar and well above the lowest fundamental note on a piano (27 Hz). I would not want a dip there. With multiple subs you should be able to eliminate it if you have some flexibility in placement. Endless articles on that; look at the Harman site and Amir's articles here on ASR.

FWIWFM - Don
Thanks. I e had a look at some of the articles and use the multi-sub technique in the main system. It’s not clear to me, however, that this multi-sub solution necessarily solves this specific issue which is related to the cancelation off the back wall. A sub at the front wall or sidewalk would, I think, have the same issue. I guess that the right thing is to high pass the main speakers and have a sub on the back wall?
 

DonH56

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#5
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#6
40 Hz is right near the fundamental (lowest frequency bass string) of a guitar and well above the lowest fundamental note on a piano (27 Hz). I would not want a dip there. With multiple subs you should be able to eliminate it if you have some flexibility in placement. Endless articles on that; look at the Harman site and Amir's articles here on ASR.

FWIWFM - Don
Note that A piano does not produce a high spl at 27hz, for the lowest note 2nd and 3rd harmonic (of 27Hz) have a higher spl and that’s what you hear.
 

DonH56

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#7
Note that A piano does not produce a high spl at 27hz, for the lowest note 2nd and 3rd harmonic (of 27Hz) have a higher spl and that’s what you hear.
I am aware of that thank you. And that low A is not used all that often either; also, the big 16' Bosendorfers go deeper, and the new S&S actually goes to ~16 Hz (!), but chances are none of them are all that loud relatively speaking. Although the 54 Hz second harmonic is pretty close to the 40 Hz dip he showed. I was actually more concerned with string bass, bass guitars, and other things like drums and such with LF pressure waves. I assume you feel the dip is not an issue then?

There are actually quite a few instruments that have content to 40 Hz and below but if the dip is inaudible it does not matter. Instruments playing together produce very low frequency beat tones and, as I am used to listening for them for tuning when playing, I may be more sensitized to listening for them in reproduction as well. Speaking only for myself, I had a pretty severe dip in my system due to room modes at 30 Hz and getting rid of it helped on some music (and was unnoticeable on other music).

Anyway, the OP asked, I responded to him with my thoughts, which may not match those of yours or any others. - Don
 
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#8
I am aware of that thank you. And that low A is not used all that often either; also, the big 16' Bosendorfers go deeper, and the new S&S actually goes to ~16 Hz (!), but chances are none of them are all that loud relatively speaking. Although the 54 Hz second harmonic is pretty close to the 40 Hz dip he showed. I was actually more concerned with string bass, bass guitars, and other things like drums and such with LF pressure waves. I assume you feel the dip is not an issue then?

There are actually quite a few instruments that have content to 40 Hz and below but if the dip is inaudible it does not matter. Instruments playing together produce very low frequency beat tones and, as I am used to listening for them for tuning when playing, I may be more sensitized to listening for them in reproduction as well. Speaking only for myself, I had a pretty severe dip in my system due to room modes at 30 Hz and getting rid of it helped on some music (and was unnoticeable on other music).

Anyway, the OP asked, I responded to him with my thoughts, which may not match those of yours or any others. - Don
I was not clear. I think this dip is audible and I would add 1 or 2 subs to remove it.
I would put the speakers in another room and listen to some music to hear if yes or not it is audible. Installing subs and matching all speakers is not hard but takes some time.
 
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#9
Hmmm. I'd let the kids listen to the old system, dip and all and keep them the heck away from my main system.
 
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#11
I have 3 satellite - sub setups. But have single subs due to space and placement limits for 2 of the systems and inability to obtain a second sub for the 3rd one (NHT Xd). To mitigate this though I use Anthem ARC for the 2 systems which IMO improves things considerably.
 
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