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Suggestions for Speaker Placement & Sub Crossover
#272955 09/22/09 03:02 AM
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Rob H Offline OP
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This may come across disjointed and not too clear, but here goes...

I recently posted in the Gallery that I had changed the orientation of my speakers in relationship to my room. I am still not quite satisfied with the sound and am looking for suggestions as to how I might improve it. Sound is somewhat thin, with slightly boomy bass (from the sub). Also, not a lot of "punch" (for lack of a better term) in the midrange.

My system is a 2.1 setup, comprised of M22v2's and a HSU STF-2 subwoofer. I own both a Harman Kardon 3490 stereo receiver and an Onkyo A-9555 integrated amplifier. I alternate between both power sources. The HK has a subwoofer output (RCA jack), but no crossover. A full range signal goes to the sub. To try and achieve proper integration between the speakers and sub, I set the sub's crossover at 60 Hz; which is the M22's lowest frequency at -3dB. The Onkyo has no subwoofer output, so I must use the subs high level (speaker) inputs. Since the Onkyo can run speakers A+B, I connect the sub to speaker B terminals and set the sub's crossover the same as with the Harman Kardon (60 Hz).

Lastly, my room is large...especially large for bookshelf speakers...and this could be the main problem. The room is 12 x 24, with a 7.5 foot ceiling. Also, one half of one of the 24' length walls opens up into another larger room.

Currently the speakers are on the 12' wall firing down the long dimension. Speakers are approximately 7' feet apart. My setup is in a basement and unfortunately no portion of the basement (other than two small bedrooms) has sections smaller than the one I am using.

Hopefully the above info makes sense and gives you a feel for my listening space. Even in my large room, the M22's have great potential, I just think they could be a lot better. I'm hoping some of you may have suggestions for things that I could try.

Thanks in advance.

Rob



Last edited by Rob H; 09/22/09 03:23 AM.
Re: Suggestions for Speaker Placement & Sub Crossover
Rob H #272959 09/22/09 03:37 AM
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Rob, looking at your pictures, one suggestion is to have the distances from the M22 mid-woofer cones to the three nearest room surfaces(floor, front wall, side wall)as unequal as possible. The distances are hard to judge from the pictures, but possibly moving the M22s back to just a few inches from the wall behind could be tried.

As to sub boominess, is it simply a bit too loud in relation to the M22s or have you calibrated its level with the help of an SPL meter? Again, trying the M22s closer to the wall behind should also increase their bass in relation to the sub.


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Enjoy the music, not the equipment.


Re: Suggestions for Speaker Placement & Sub Crossover
Rob H #272960 09/22/09 03:43 AM
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Here are a few things to consider :

1. You mention that you are alternating between two amplifiers. Just wanted to check that you are disconnecting one amp from the speakers and sub when using the other... the switched off amp can interfere with the sound in some cases.

2. With M22s I would take the crossover frequency up to 80 or 100 Hz. In a large room I would lean towards 100 Hz.

3. Your description of the sound (thin and boomy) is a classic "room interaction" problem. Sub placement can make a big difference - have you done a sub crawl ? If you haven't, the idea is that you place the sub in your listening position then crawl around the room looking for the spot where the bass sounds the most smooth and clear - then put the sub there.

The location of your listening position relative to the room walls can also make a difference. If your speakers are at the walls and you're at the midpoint between the walls then you're probably going to get relatively weak LF response.

There are all kinds of other room issues you can play with but get the sub placement right first. You can also tweak the sound a bit by playing with the M22 distance from the back wall; too close gives boomy bass, too far away can give weaker bass. If you raise the crossover frequency then M22 placement won't make as much difference as sub placement.

4. Thin and boomy also sometimes describes main speakers wired out of phase, but that doesn't happen so much these days now that everything is colour coded. Worth a quick check anyways.

Anyways, that's a start. Good luck...

EDIT - there are pictures ? D'oh !!

(thanks JohnK ;))

Last edited by bridgman; 09/22/09 03:52 AM.

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Re: Suggestions for Speaker Placement & Sub Crossover
JohnK #272961 09/22/09 03:46 AM
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Thanks, John. I'll try moving the speakers closer to the back wall. Any thoughts on the sub's crossover setting? Is my reasoning correct about setting it at 60 Hz?

Re: Suggestions for Speaker Placement & Sub Crossover
bridgman #272962 09/22/09 03:54 AM
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Bridgman wrote:

"You mention that you are alternating between two amplifiers. Just wanted to check that you are disconnecting one amp from the speakers and sub when using the other... the switched off amp can interfere with the sound in some cases. "

Thanks for the feedback. Much appreciated. BTW, amps are disconnected and used one at a time.

Regarding raising the subs crossover, will that be a problem since the sub's crossover does not limit frequency to the speakers...just limits what frequencies the sub will receive. The speakers would still get a full range signal even with the sub's crossover set at 80Hz.

Last edited by Rob H; 09/22/09 03:56 AM.
Re: Suggestions for Speaker Placement & Sub Crossover
Rob H #272965 09/22/09 04:14 AM
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>>Regarding raising the subs crossover, will that be a problem since the sub's crossover does not limit frequency to the speakers...just limits what frequencies the sub will receive.

Doesn't the STF-2 have speaker-level inputs and outputs with a passive high pass between input and output ? I seem to remember them having two sets of 4 posts for speaker wire...

In case it helps, I went through some of the same "this way / that way" furniture re-arranging and realized the problem with speakers on the long wall had nothing to do with placement and everything to do with a reflective back wall right behind my ears which totally killed stereo imaging. Once I put an absorbent (and ugly) wall hanging on the back wall the sound quality improved significantly.


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Re: Suggestions for Speaker Placement & Sub Crossover
bridgman #272971 09/22/09 05:00 AM
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John, a few years ago some of the Hsu subs had a separate fixed high-pass filter on the speaker level outputs which could be connected to the mains. The present models have just a straight-through full range connection to the mains(if used instead of a direct connection of the mains to the amplifier).

Since the M22s are therefore having to run full range, a 60Hz sub low pass(if the settings on the Hsu control are accurate, which they may not be)probably is reasonable in trying to get a good blend without receiver bass management being available.


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Enjoy the music, not the equipment.


Re: Suggestions for Speaker Placement & Sub Crossover
JohnK #273009 09/22/09 10:08 PM
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Good to know ;\)

Looks like they replaced the built-in speaker-level high pass filter with an optional line-level filter box that goes between pre-out and amp-in :

http://www.hsuresearch.com/products/high-pass-filter.html

Seems like a nice idea - switchable frequencies and 12 db/octave instead of the 6db/octave in most of the passive filters.


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