80-200Hz dip - can it be cured ?

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jman66

80-200Hz dip - can it be cured ?
« on: 11 May 2009, 07:28 pm »
Greetings!

Like all who have come before me, I too seek guidance with my "room". As the drawing shows, my setup and listening area fall within a sort of 3-sided "room". Behind my listening chair opens up back into the basement with the wall behind me located roughly 16' away. I'm sure the drop ceilings, closets, adjacent rooms, ceiling heights and such do wonders for the sound.

Specifically, I have a dip in the 80-200Hz range. I use EchoBusters on the sidewalls along with Eighth Nerve Seams at the wall to ceiling junction. On the front wall, I have Eighth Nerve Seams at the wall junction. Finally, Eighth Nerve Corners are placed at upper and lower corners on the front wall.

With the typical Cardas speaker placement, I get nearly a 8-10dB dip in the 80-200Hz range. Positioning the speakers closer to the sidewalls improves that to about a 5-6dB dip. There are minor peaks below 80Hz, perhaps unwise on my part but I can live with the peaks opposed to the dips. I also have a pair of EchoBuster Phase-4 towers which I don't use. When placed in the corners they add further to the 80-200Hz dip.

Should I be grateful for what I have or could things be improved upon?
Present speakers are Totem Hawks.
Thanks for any suggestions!

-jim

electricbear

Re: 80-200Hz dip - can it be cured ?
« Reply #1 on: 11 May 2009, 08:25 pm »
You could try moving your seat to see if you are just sitting in a room null. If the drop out is there no matter where you take your readings, you are stuck. Short of moving walls there is not a great deal you can do. It is easy to trim down peaks but if you have a hole there's not much you can do.

jman66

Re: 80-200Hz dip - can it be cured ?
« Reply #2 on: 11 May 2009, 09:43 pm »
I did move the SPL meter around the listening area. No major improvements in the dips.
Using long wall positioning and the listening chair backed up to the rear wall, the dips are just about gone. But, that now crops up some large peaks.
At one time I had Maggie 1.6s and the dip in that region was slightly present but not as prominent as with box speakers.

Ethan Winer

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Re: 80-200Hz dip - can it be cured ?
« Reply #3 on: 12 May 2009, 04:58 pm »
I have a dip in the 80-200Hz range.

That's a very large space which means you need a fair amount of corner bass traps. Real bass traps that are thick enough to work well down to low frequencies. There is no other answer, though careful speaker placement can help too. The worst reflections in a room like that are probably from the wall behind you, so that's another good place for traps.

--Ethan

Tyson

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Re: 80-200Hz dip - can it be cured ?
« Reply #4 on: 12 May 2009, 05:12 pm »
Those speakers are designed to be placed close to a wall (ie, no baffle step compensation).  Try placing them right up against the wall.

bpape

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Re: 80-200Hz dip - can it be cured ?
« Reply #5 on: 12 May 2009, 05:31 pm »
Agreed.  You'll get smoother bass allowing the wall to reinforce things with the Totems.

While that will help with frequency response, it won't help with decay time and any other cancellations in the room which is wehre the broadband bass control comes into play.

Bryan

jman66

Re: 80-200Hz dip - can it be cured ?
« Reply #6 on: 12 May 2009, 06:42 pm »
I appreciate the recommendations. I'll certainly give them a try.

-jim

jman66

Re: 80-200Hz dip - can it be cured ?
« Reply #7 on: 13 May 2009, 11:59 am »
Agreed.  You'll get smoother bass allowing the wall to reinforce things with the Totems.

While that will help with frequency response, it won't help with decay time and any other cancellations in the room which is wehre the broadband bass control comes into play.

Bryan

Regarding broadband bass control, where's the recommended placement & how much would be needed?
Using GIK as an example, a pair of Tri-Traps in the front wall corners, 244 or Monster Traps straddling the corner?
Issue using the Tri-Traps, electrical sockets will interfer with placement in both corners.

Also, wouldn't pushing the speakers closer to the front wall exacerbate any peaks as well as affecting the soundstage. Typically rear ported speakers need to be place away from the wall. Hey, I may have it all wrong so go easy on me...  :dunno:
Thanks.

-jim

AmpDesigner333

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Re: 80-200Hz dip - can it be cured ?
« Reply #8 on: 13 May 2009, 12:51 pm »
Agreed.  You'll get smoother bass allowing the wall to reinforce things with the Totems.

While that will help with frequency response, it won't help with decay time and any other cancellations in the room which is wehre the broadband bass control comes into play.

Bryan

Regarding broadband bass control, where's the recommended placement & how much would be needed?
Using GIK as an example, a pair of Tri-Traps in the front wall corners, 244 or Monster Traps straddling the corner?
Issue using the Tri-Traps, electrical sockets will interfer with placement in both corners.

Also, wouldn't pushing the speakers closer to the front wall exacerbate any peaks as well as affecting the soundstage. Typically rear ported speakers need to be place away from the wall. Hey, I may have it all wrong so go easy on me...  :dunno:
Thanks.

-jim

Hey, Jim.  Interesting thread.  Just wondering if it's possible for you to place the speakers on the "long side" of the room...  Hope you find the solution to this problem.

Best Regards,
Tommy

jman66

Re: 80-200Hz dip - can it be cured ?
« Reply #9 on: 13 May 2009, 01:01 pm »
Hey, Jim.  Interesting thread.  Just wondering if it's possible for you to place the speakers on the "long side" of the room...  Hope you find the solution to this problem.

Best Regards,
Tommy
Hi Tommy,

Good to hear from you...
Placing the speakers on the long wall does improve the offending range but also kicks up the peaks. The listening chair also needs to be close to or backed up right against the rear wall. Problem I have with that configuration is it's almost claustrophobic. Perhaps something that one would need to adjust to.
Realistically, I need to find a huge amount of time required to exhaust the speaker positioning basics and might just come full circle in that the room ultimately sucks!


-jim

bpape

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Re: 80-200Hz dip - can it be cured ?
« Reply #10 on: 13 May 2009, 01:21 pm »
I wouldn't put them right against the wall.  Give them a few inches certainly - maybe more.  There's a fine line between designed reinforcement and having SBIR issues. 

For placement, you can do 244's straddling and/or you can actually lay the Tri Traps on their sides along the front wall/floor junction.  This won't kill off the port output but will help with buildup and decay times in the room.

Bryan

poseidonsvoice

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Re: 80-200Hz dip - can it be cured ?
« Reply #11 on: 13 May 2009, 01:47 pm »
jman66,

If you haven't done so already, I encourage you to read the discourse that occured between myself and bmckenney. Link is here. For what its worth, the Okara II's probably have a very similar low frequency extension as your Totem's and is rear ported. I stuffed the ports with straws (of equivalent length to the port) per North Creek's advice. It cleans up the bass nicely while providing the low frequency extension (as limited as it is...in my case about 55 Hz).

Best,

Anand.

jman66

Re: 80-200Hz dip - can it be cured ?
« Reply #12 on: 18 May 2009, 04:49 pm »
I had a bit of time to revisit speaker positioning, which has helped to tame the dip.
There still exists a slight dip between 125-160Hz but it's far improved and I can live with it.

Using the Phase-4 towers in the corners behind the speakers, no matter how the reflective/absorption sides were faced, they make the dip worse dip in the 125-160Hz range. It measures better without them. With the Phase-4's placed between the sidewall and speaker, with the absorption sides facing the speaker and rear wall, the 125-160Hz range improved slightly. That's where I left them...


-jim
« Last Edit: 20 May 2009, 09:19 am by jman66 »