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Speaker Height - improved bass response.

I recently replaced integrated amps and ended up disastisfied with the results. Whether this is because I expected more or was just used to the sound I don't know. However, I was prepared to replace equipment again to get the sound I was looking for. I tried a variety of speaker cables, and a few interconnects although I don't have a bunch on hand. I don't really buy into expensive power cords but I did wire a dedictated circuit with Cooper Isolated ground recepticles (I think these rival some "audiophile" expensive outlets, really well made, copper, really exceptional contact with plug, $12 per)

Then, came the economic meltdown creating some pressure on me not to just throw money at the situation but to look at some alternative, lower-cost solutions. I started investigating tweaks and wanted to share one that has really improved my listening experience.

Speaker height - although I have spent time and energy measuring distance from walls and creating an appropriate listening triangle, I did not spend as much energy adjusting the height of my speakers. This is partly because my stands are good quality, metal and made to be about 22 or 24 inches high. Even though I have had good advice from Roy Johnson of Green Mountain about floor reflections impacting bass. I just didn't make the connection. At the current height, my ear level was at about the middle of the speaker between the woofer and tweeter. A number of articles I have researched indicate ear level should be at tweeter height and typically speakers are mounted too high. I looked online at stands and was hard pressed to find stands with height options.

So, in my frustration at not being able to buy new stuff, I went out and got a metal saw blade for my chop saw, took my stands apart and cut six inches off of them. This put my ear right at tweeter level or slightly above. After painting them and putting them back together, I set up my system and was amazed to find that not only was the soundstage improved, more defined and clear but my bass response had improved dramatically. I actually had to turn my subwoofer level down quite a bit and adjust the crossover frequency as the low ranges of bass in the speakers was brought out (50 to 100 hz) where there had been kind of a suck-out before.

So my experience indicates that there is standing wave interaction with speakers depending on height and that adjusting height, not just for ear level but for bass response is a low-cost and useful exercise.

I am wondering if anyone has more technical insight into this or has had similar experiences.

thanks.
drewh1
drewh1 OP
115 posts
 
Shadorne,

I have only been involved in Audiogon for about a year but have appreciated your input on many of the technical threads, especially your practical approach to expensive "tweaks". With some engineering background (more in digital technology) and also as a retired professional musician, I am generally very skeptical about audio tweaks that don't seem to make sense from a physics perspective. Anyway, thanks for your input.

I can see the sense in the idea of an infinite baffle for speakers and feel this would be an ideal solution with the green mountains. I am wondering if the baffle, rather than being a complete soffit, could be a large standalone baffle that surrounds the speaker to the floor and then 2 or 3 feet in all other directions. The speaker would be flush with the baffle. I am envisioning a plywood construction with solid foam insulation (1 or 2 inch) to absorb vibration.

I rent and cannot make permanent mods. So I am thinking of alternatives. This would take the place of numerous and complicated corner and wall sound absorbing materials.

What do think?

Drew.
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shadorne
7,477 posts
 
I am wondering if the baffle, rather than being a complete soffit, could be a large standalone baffle that surrounds the speaker to the floor and then 2 or 3 feet in all other directions.

You can build half walls or 3/4 walls and they will still improve things (the arger the wall the more ideal), however, you have to kill all the rear energy. Green Mountains use solid cabinets - so that is already a good start but you really want to enclose the speakers soffits with acoustic damping and then heavily brace your construction to make the wall solid and ensure it does act as a "sound board". In practice this means plenty of MDF and it means filling empty spaces (cavities) with wadding. The John Sayers website I linked to explains what is involved - I would not recommend it in a rental as you are talking significant expense and time.

Genelec sell soffit mount kits for their 8050A monitors - you can look up these too - but again it is not something suited to a rental property.

FWIW: Improvements from soffit mounting are definitely audible (why else would studios go to so much trouble) however it will not be night and day. 5 - 10% improvement max...
mwiii
2 posts
 
Shadorne,

First I will say that correct speaker height is essential.

Now I will add that I think you unknowingly resolved an issue with your stands. I suspect that they were not mass loaded and your reducing their height by 6" provided for a stiffer connection to the floor, one that sucked up less of your sound. If you can, try adding sand or BBs to your speaker stands and see if what results.

Do you use blu-tac under your speakers to secure them to your stands?
drewh1 OP
115 posts
 
Mwii,

I have always had the stands filled with sand. I also, according to the suggestion of Roy Johnson of GMA, use blue-tak to secure the speakers to the stands.

I had assumed that it had to do with wave cancellation but you're right, s.hortening the stands would cause them to be stiffer. GMA's are made of epoxy-concrete and are pretty impervious to cabinet resonance.
theaudiotweak
2,801 posts
 
The late Peter Garland Snell has patents from the early 70's on the shape and design of baffles and their relationship to loading to room surfaces. Some may look to the United States Patent Office for guidance, number 3,964,571 issued June 22nd 1976 for these always contemporary disclosures. Mr Snell's designs also lend themselves to the acoustical design and enhancement of one's listening room. This is only possible if your mind is not filled with convoluted foam. Tom
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