Bad setup, bad room, or sensitive ears? Subs are just never from the "same cloth"!

diggo

New Member
Aug 4, 2011
2
0
0
#41
Welcome to the WBF. Great (first) post. I would add that even in a well treated room moving the subs a few inches may result in noticeable change in sound/performance. Else I agree with you.
Yes. The only honest and fair way to compare subs (and such nebulous concepts as "fast" vs "slow" etc) is in a very large space (eg an open field) when the influence of the room is minimised. Regarding positioning in a treated room, moving the subs by small amounts can indeed change the response, but at least the cause of such changes can be more easily determined if the room has been effectively treated. I suppose I was saying "the optimal position cannot be easily verified in the absence of effective treatment which derives optimal mitigation of detrimental influences"

All true. Plus, room treatments for low frequency problems aren't cheap by any means.
It does need to be said that such treatments are often cheaper than the speakers/amplifiers and associated electronics. I never cease to be amazed at audiophiles who listen to $100,000 systems in rooms containing only token gestures of room treatment. And they scratch their chins and muse "Maybe if I buy XYZ DAC, or XYX Room/Speaker EQ I'll get better 'resolution' and 'speed' in the bass", all while their rooms are ringing like giant gongs with HUGE modal peaks and nulls and diabolical SBIR problems.

It's not expensive to add superchunks to all corners for useful velocity absorption. And for serious listeners with a reasonable budget, compound baffle absorbers for pressure absorption are affordable. Not cheap, but affordable for anyone investing serious money in their system. One good thing about CBAs is they are easily retrofitted and can easily travel to new abodes.

The problem audiophiles have with room treatment can essentially be boiled down to "it doesnt seem to DO anything", unlike (say) a really expensive room/speaker EQ with beautiful glowing lights and gleaming facade. There's no pay-off in showing their latest purchase off to their friends...and (aside from the inital setup) there's nothing to obsessively and endlessly tweak.

Sean
 
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twelti

WBF Technical Expert (Subwoofers In Rooms)
Apr 29, 2011
38
0
0
#42
It does need to be said that such treatments are often cheaper than the speakers/amplifiers and associated electronics. Sean
Yes, when you are talking about a high end audio system, the cost of room treatment starts to look not as expensive by comparison. Doens't mean it's cheap though. On the other hand, moving subs around and/or optimizing level/delay etc. really can be cheap. Room treatment still might be needed though, for example if improper wall construciton is used. We used to have a room with double layers of GWB on the interior. That room was terrible. I was actually sad when they fixed it, since it was usefull as a demo room for modal problems!
 

DonH50

Member Sponsor & WBF Technical Expert
Jun 23, 2010
3,707
91
225
Monument, CO
#43
My room treatments ran around $3500 in DIY kit form (had to put the bags over the 703 and assemble the frames; a compromise between complete home-made and pre-built). My total system is probably around $20k, so <20% for treatment seems a good deal. Plus, my room is heavily overdamped (a lot of you probably wouldn't like it but it works for me -- dipoles in a smallish room can be a pain). This is on top of the ~$10k extra paid to build the room when we finished our basement a few years ago (floating walls and ceiling and its own HVAC unit to isolate from the house -- ain't perfect, but ain't bad).
 

twelti

WBF Technical Expert (Subwoofers In Rooms)
Apr 29, 2011
38
0
0
#44
My room treatments ran around $3500 in DIY kit form (had to put the bags over the 703 and assemble the frames; a compromise between complete home-made and pre-built). My total system is probably around $20k, so <20% for treatment seems a good deal. Plus, my room is heavily overdamped (a lot of you probably wouldn't like it but it works for me -- dipoles in a smallish room can be a pain). This is on top of the ~$10k extra paid to build the room when we finished our basement a few years ago (floating walls and ceiling and its own HVAC unit to isolate from the house -- ain't perfect, but ain't bad).
If you built your own space, I assume you only have a single layer of sheetrock on the inside (?). Metal studs? I would think that if you design you own room , and it has a reasonable amount of absorption in it (furniture etc.) then you wouldn't need much additional LF absorption. How thick are you panels, and how much of the walls do they cover? Are they primarily for the mid/hi frequencies (for the dipoles)?
 

DonH50

Member Sponsor & WBF Technical Expert
Jun 23, 2010
3,707
91
225
Monument, CO
#45
Concrete floor (basement), double-wall floor and ceiling (two sheets of 5/8" sheetrock, staggered joints), all suspended using Kinetics IsoMax clips, and 6" of mineral wall in the walls and ceiling (actually, a bit more in the ceiling). All sealed with acoustic caulk (at least as much as possible; I also sealed the back of the outlets and such). Heavy (solid exterior door) and the window wells also float. I have mostly 4" panels on walls and ceiling with a couple of 6" on the back wall and 10" total in the two front corners (no place for corner traps in the rear, alas). Room is roughly 13'3" x 17'7" x 8'5" and not that much furniture so it was very, very bright plus had some fairly closely-spaced room modes. My speakers are all Magnepans (except the subs) so the panels are doing double duty as mid/hi and bass('ish) absorbers. I have somewhat of a studio (recording) background so the fact that it is pretty dead does not bother me too much, and of course the imaging is great. Ideally I would replace some of the panels with diffusers, but that would either cost much more or require a lot more time for me to build. Someday... The only other thing I would do differently is to fully float the ceiling instead of suspending from the joists; heavy footfalls will still come through from the kitchen above (sob). However, when all is said and done, I can crank the system without bothering people upstairs or even my son in his bedroom on the other side of the front wall. And, very little sound comes through from anywhere else in the house. Virtually the only transmitted noise are those footfalls from the kitchen above, something I should have foreseen, but it would have required a lot more structural work to fully isolate the ceiling. Fortunately they are only rarely an issue.

I'll repeat what I (you, and many others) have said before, that room isolation and compensation (treatment) are not the same thing. Isolation is a lot more work, but well worth it. It does drive me nuts (OK, it's a short drive :) ) when I see folk who have actually worked hard at isolation but forgot to deal with the HVAC system... I used a small mini-split type unit so the room has its own HVAC, plus a (code-required) ventilation fan to the outside.
 

Sammy T

Well-Known Member
Aug 30, 2012
199
5
93
#46
My buddy has a subwoofer, never liked it. One night while listening to some music with some wine, something happened. The little light came on in my head , I took off the grill covering his subwoofer. What a difference It made. I remember seeing an ad for Velodine Subs with no cover grill.
 
Jul 25, 2012
2,542
13
150
NY
#47
My buddy has a subwoofer, never liked it. One night while listening to some music with some wine, something happened. The little light came on in my head , I took off the grill covering his subwoofer. What a difference It made. I remember seeing an ad for Velodine Subs with no cover grill.

When a subwoofer does not sound well integrated with the main speakers, it is due to a combination of some or all these factors:

1--the crossover point it too high and you have too much overlap between the mains and subs
2--the crossover point is too low and the mains don't extend low enough to meet the subs and you have a frequency gap
3--the crossover slope is too steep and you have have a gap between the mains and the subwoofer because the mains "roll-off" does not complement the "roll-on" of the sub.
4--the crossover slope is to shallow and you have to much overlap between the main woofer and subwoofer
5--the sub volume is too loud relative to the main speakers
6--the sub volume is too soft relative to the main speakers

With a good subwoofer, none of these are insurmountable problems.
It just takes a little time a patience and definitely the exclusion of alcohol.

I sincerely doubt a cloth grill would impact the sonic signature of a subwoofer. Tweeter yes, subwoofer no.
 
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FrantzM

Member Sponsor & WBF Founding Member
Apr 20, 2010
6,464
5
255
#48
When a subwoofer does not sound well integrated with the main speakers, it is due to a combination of some or all these factors:

1--the crossover point it too high and you have too much overlap between the mains and subs
2--the crossover point is too low and the mains don't extend low enough to meet the subs and you have a frequency gap
3--the crossover slope is too steep and you have have a gap between the mains and the subwoofer because the mains "roll-off" does not complement the "roll-on" of the sub.
4--the crossover slope is to shallow and you have to much overlap between the main woofer and subwoofer
5--the sub volume is too loud relative to the main speakers
6--the sub volume is too soft relative to the main speakers

With a good subwoofer, none of these are insurmountable problems.
It just takes a little time a patience and definitely the exclusion of alcohol.

I sincerely doubt a cloth grill would impact the sonic signature of a subwoofer. Tweeter yes, subwoofer no.
Mostly agree with you ... Allow me to edit your last statement some: "Tweeter maybe, subwoofer NO!!"
 

terryj

New Member
Jul 5, 2010
512
0
0
bathurst NSW
#49
Mostly agree with you ... Allow me to edit your last statement some: "Tweeter maybe, subwoofer NO!!"
Never found the grill to affect the tweeter Frantz? I know you said maybe which means sometimes, anyway I never have grills so (for me) it stays a yes for the tweeter too. For the sub no, unless it was rattling which kinda means yes but in a different way! Prob does not need to be an 'obvious rattle', low level buzz that cannot be consciously determined as such if you follow.

To the very good list above I have to add correct timing (delays). Dunno why that is such a big thing for me and hardly ever mentioned by others, I suspect it has to do with the dsp applied to the system (which entails delays) so a final check for me is that all signals arrive at the same time.

Most likely it never comes up in other systems. Man, it bugs me no end if that step is not done so I add that point with an 'if needed'.
 
Jul 25, 2012
2,542
13
150
NY
#50
Mostly agree with you ... Allow me to edit your last statement some: "Tweeter maybe, subwoofer NO!!"
I'll go along with that!
 

kach22i

WBF Founding Member
Apr 21, 2010
1,303
108
225
Ann Arbor, Michigan
www.kachadoorian.com
#51
UPDATE: March 2020

Read the Sound Doctor's (Barry Ober) paper, and watch a few Dennis Foley videos on room acoustics and subs.

http://soundoctor.com/whitepapers/subs.htm

In essence, recordings on LP's deep bass is mono otherwise the needle would jump out of the grooves, and on CD's deep bass is mono because that's the way it is recorded and mixed. The exception is a few Techno-Rave tracks where the bass is supposed to swirl around the nightclub/dance floor (or so Barry says).

The author's of these documents neglect to mention Reel to Reel (Master Tapes) as I suppose they might disrupt their argument.

So bass is mono in the recording, it's directional because of room interfaces, and less directional as you free yourself of adjacent room surfaces.

Subwoofer-Center-tRTtr.png

I set up my room like the above diagram (unknown original source), and it works, it's the only thing that has ever worked for me.

Lots of reading also lead me to believe the lesser of evils is using Low Line Level IC's inputs from a dual output preamp verses speaker wires to High Level Inputs.

Barry Ober says use a real crossover after the preamp and don't get upset about putting more stuff in your signal chain, if you only knew how much that signal has gone though in the recording process it would not be so precious to you.

Sorry, I got it to work to my satisfaction without another box and more wires.
 

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