50 Hz peak in very small room

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Atexanathome

Re: 50 Hz peak in very small room
« Reply #20 on: 31 Mar 2012, 02:43 am »
I would prefer the diamond layout.  While it is not symmetric to the length and width, it is at least putting the speakers symmetric left to right with regard to the side walls so their gain and reflections will be pretty much the same and we don't run into issues with the image 'pulling' to one side as frequency shifts into and out of the boundary related phase reinforcements and cancellations.

This all assumes that we can't tweak normal seating position and speaker positions.  Sometimes, one can deliberately generate a counteracting null from the wall behind the speakers that will help to offset the peak from the room width.

Bryan

I'll trying moving the chair back in 6" increments. At 18" back the chair back is against the trap.

I noticed before that small changes have a big effect. The exact center of the room gives the smoothest resonse, though the 20 Hz level drops quite a bit. I listen to a lot of organ muusic, so some bumping up of the low bass is not all bad.

 The Josephs are not the best for near-field use. Too bad, they were great in my old, larger, room.I think I might need to go with 1-meter listening distance and coax speakers. I thought about GR Research Super-V's for near field. It would look strange, like the world's biggest pair of headphones.

I can drop the traps about 8" before they cover an outlet I need.

doug s.

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Re: 50 Hz peak in very small room
« Reply #21 on: 31 Mar 2012, 06:23 am »
I have a pair of Velodyne HGS-10 subs and an XM-9 crossover. I'm trying to avoid using them if possible. I was trying to simplify the system and get away from the complexity I had with a combined HT/music system.

then simply try the relocation suggestions. 

if you do wanna try your subs, (i definitely would, w/the issues you are having), while i normally believe using an active x-over w/subs is best, as it frees your main amps/speakers from seeing the lowest frequencies, in your case i would simply run the subs w/their own low-pass filters set to ~70hz, and run your speakers full-range.  two reasons - 1st, your speakers' woofers are already crossed over low - 125hz - and using the marchand won't really improve their performance much.  2nd, you want low end from multiple locations in your room, to help smooth out the response.  the only "added complexity" would be connecting the subs to your preamp, and plugging them in to 120vac wall outlets.

doug s.

doug s.

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Re: 50 Hz peak in very small room
« Reply #22 on: 31 Mar 2012, 06:41 am »
look at the measured frequency response plot of your speakers, according to s'phile.  large peak - ~5db - right about 40-50hz.  mebbe it would be beneficial to use your xm9m w/your subs, set at 50hz, and w/the damping pot turned down...   :scratch:



doug s.

bpape

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Re: 50 Hz peak in very small room
« Reply #23 on: 31 Mar 2012, 12:06 pm »
Well there you go. Always good to look at the speaker data too.....

Nice catch Doug.

Bryan

doug s.

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Re: 50 Hz peak in very small room
« Reply #24 on: 31 Mar 2012, 06:00 pm »
I'll trying moving the chair back in 6" increments. At 18" back the chair back is against the trap.

I noticed before that small changes have a big effect. The exact center of the room gives the smoothest resonse, though the 20 Hz level drops quite a bit. I listen to a lot of organ muusic, so some bumping up of the low bass is not all bad.

 The Josephs are not the best for near-field use. Too bad, they were great in my old, larger, room.I think I might need to go with 1-meter listening distance and coax speakers. I thought about GR Research Super-V's for near field. It would look strange, like the world's biggest pair of headphones.

I can drop the traps about 8" before they cover an outlet I need.

if you are wanting to try different speakers, i'd suggest getting in touch with a/c vendor aj in fla, and querying him about his sam1 speakers.  at retail $1300, they might be yust the ticket for you.  they are a monitor, w/built-in powered 8" woofer and passive kef coax driver.  search a/c; they have gotten raves from all who have heard them.

one big a/c thread; (i understand that aj is doing some updates to the speaker, so a new one might be even better?):
http://www.audiocircle.com/index.php?topic=97955.0

website:
http://soundfieldaudio.net/

doug s.

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Re: 50 Hz peak in very small room
« Reply #25 on: 31 Mar 2012, 06:09 pm »
one last comment - first things i would try, would be re-arranging the system per my earlier suggestions.  like bryan, i also believe that the diamond set-up has the best chance of success in a small room, because the walls adjacent to the speakers have less interaction at the diagonal, and you have more space behind you at the listening position.  (we may disagree as to whether or not it would be best to have a symmetrical vs a-symmetrical layout, but it's easy enough to try either way.)  but, simple cocking of the system per my first suggestion is obviously a lot easier to try, than setting up a diamond layout, which would inwolve completely re-arranging your room.

and, it would also be easy to try using your subs.  looking for different speakers would be a last resort, if you can't get what you already have to work for you...

keep us posted w/your findings.

doug s.

bummrush

Re: 50 Hz peak in very small room
« Reply #26 on: 31 Mar 2012, 06:35 pm »
I hope all works for you . But im sticking with those speaks are way to big for that space.

doug s.

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Re: 50 Hz peak in very small room
« Reply #27 on: 1 Apr 2012, 08:29 am »
I hope all works for you . But im sticking with those speaks are way to big for that space.
it's not that the size of the speakers themselves are too big - it's the size of their bass bump at 50hz that is too big...

doug s.

JohnR

Re: 50 Hz peak in very small room
« Reply #28 on: 1 Apr 2012, 10:20 am »
I didn't read the whole thread... sorry... but has plugging the ports been tried/suggested?

jimdgoulding

Re: 50 Hz peak in very small room
« Reply #29 on: 1 Apr 2012, 10:34 am »
Doug, win, lose, or draw . .
What an effort by you :thumb: :beer: :notworthy:
, sincerely!

Atexanathome

Re: 50 Hz peak in very small room
« Reply #30 on: 1 Apr 2012, 12:37 pm »
one last comment - first things i would try, would be re-arranging the system per my earlier suggestions.  like bryan, i also believe that the diamond set-up has the best chance of success in a small room, because the walls adjacent to the speakers have less interaction at the diagonal, and you have more space behind you at the listening position.  (we may disagree as to whether or not it would be best to have a symmetrical vs a-symmetrical layout, but it's easy enough to try either way.)  but, simple cocking of the system per my first suggestion is obviously a lot easier to try, than setting up a diamond layout, which would inwolve completely re-arranging your room.

and, it would also be easy to try using your subs.  looking for different speakers would be a last resort, if you can't get what you already have to work for you...

keep us posted w/your findings.

doug s.

Hello Doug,

Thanks for the suggestions. I'd been thinking about trying the subs with crossover, but I only have 60, 80, and 100 Hz modules at the moment. Rotating everything was also considered, but I was too lazy to move the 60 lb amps, the Equitech, the LP cabinet, etc. I guess I'll have to get with it, maybe after turkey season is over.

I have to use the closet door and keep it clear because my guns are in there. At least the Omnimic  makes it easy to get  curves, and I'm sure they are more accurate than the RS meter.

I'll try these suggestions before going with all dipole speakers. These speakers were great in my old great room. it was over 23' long, with a cathedral ceiling, and it was part of an L-shaped space that included the dining/kitchen area.

The space was actually a little too big for the speakers;I used the subs for HT work, and I blew 4 plate amps and a driver over a seven year period. Respons with the Josephs alone was good, no 50Hz peak to speak of, and they were down -3dB at 31.5Hz, -6 dB at 25 Hz, and -10 dB at 20 Hz. I did have a big suckout at the listening position at around 60 Hz. I guess the room always has the last word, eh?

Thanks,
Jon Davis

doug s.

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Re: 50 Hz peak in very small room
« Reply #31 on: 1 Apr 2012, 07:18 pm »
I didn't read the whole thread... sorry... but has plugging the ports been tried/suggested?

might be worth a try; according to s'phile, the port also has a peak at ~50hz.

doug s.

doug s.

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Re: 50 Hz peak in very small room
« Reply #32 on: 1 Apr 2012, 07:22 pm »
jon d., doing the 1st asymmetrical layout won't take much re-arranging; that is certainly worth a shot at minimum.  and using the marchand w/a 60hz module will also be worth trying, as it will certainly lower any peak at 50hz...

good luck,

doug s.,
awaiting some fresh wild turkey meat.   :green:

mjosef

Re: 50 Hz peak in very small room
« Reply #33 on: 1 Apr 2012, 09:24 pm »
The Marchand also has a trimmer pot which allows +/- 4dB at the crossover frequency.  :thumb:

doug s.

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Re: 50 Hz peak in very small room
« Reply #34 on: 1 Apr 2012, 09:38 pm »
The Marchand also has a trimmer pot which allows +/- 4dB at the crossover frequency.  :thumb:

yup; that's why i said earlier:
"mebbe it would be beneficial to use your xm9m w/your subs, set at 50hz, and w/the damping pot turned down..."  8)

it would likely still help even w/a 60hz x-over point...

doug s.

Atexanathome

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« Reply #35 on: 6 Apr 2012, 07:42 pm »
might be worth a try; according to s'phile, the port also has a peak at ~50hz.

doug s.

I tried the subs, in an asymmetric arrangement, and there is definitely a difference. I'm sensitive to noise, and the HGS-10's make a low growling noise whenver they're on. It wasn't audible in my old room, but it's almost a problem here.

The good news is that the response is significantly better, as shown below. I see +/- 6 dB from 20 Hz to 15 kHz and +/- 3 dB from 165 Hz to 14 kHz, which is as high as I can hear.
The 20 -30 Hz region is always a problem because of all the LF noise from the kaolin plants in the area. I see a background of -55 dB in this region all the time.

I still see a peak at around 140 Hz, but maybe I can tweak the seating position a little more. I need to do some more listening tests, but the curve does look smoother.

Thanks for all the suggestions. I may not get to turkey hunt again until I can get rid of this kidney stone that put me in the hospital yesterday.

By the way, anyone who calls himself an audiophile needs an Omnimic. It's the best accessory I've ever purchased, and I've purchased a lot!









doug s.

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Re: 50 Hz peak in very small room
« Reply #36 on: 7 Apr 2012, 01:23 am »
cool, glad it is coming together for you.  curious - are the rm33's asymmetrical, or yust the subs?  rm33's run full range, or w/marchand?  still have a decent soundstage?  try the diamond layout yet?

sorry to hear about the kidney stone - i have fortunately never had the pleasure, but a buddy of mine has been thru that, and he said the pain is excruciating.   :o  hope it passes soon!   :wink:

doug s.

Atexanathome

Re: 50 Hz peak in very small room
« Reply #37 on: 7 Apr 2012, 03:18 am »
cool, glad it is coming together for you.  curious - are the rm33's asymmetrical, or yust the subs?  rm33's run full range, or w/marchand?  still have a decent soundstage?  try the diamond layout yet?

sorry to hear about the kidney stone - i have fortunately never had the pleasure, but a buddy of mine has been thru that, and he said the pain is excruciating.   :o  hope it passes soon!   :wink:

doug s.

I left the mains in place, but I put one sub inboard and behind, and the other is outboard and even with the front of the right speaker. I'm using the 60Hz crossover at 24 dB/octave. I've got the highs dropped down about 10 dB and the low outputs dropped 4 dB, but that will change when I start using my Odyssey Stratos monos again. I've been playing with a newly refurbished Dynaco ST-150, so the gain will probably be different.

Soundstage seems strangely moved forward. I'm not moving the mains until the crisis passes and my body improves;those things weigh close to 90 lb with the feet on. 

No one has commented on the decay curves; are they good, bad or ugly?

doug s.

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Re: 50 Hz peak in very small room
« Reply #38 on: 7 Apr 2012, 04:57 am »
not surprising that yust adding the subs, and having them in different locations, would offer improvements.  did you try w/o the marchand, letting the rm33's run full range?  even tho they have a bass bump, it would be curious to know what effect there would be, w/four different bass sources loading the room.

i am not sure exactly what those decay curves are indicating, so it is hard for me to comment...   :scratch:

doug s.