From: DPierce@world.std.com (Richard D Pierce)
Subject: Re: tweaks for cheap speakers
Organization: The World Public Access UNIX, Brookline, MA
Date: Mon, 14 Dec 1992 20:46:01 GMT

In article <1992Dec14.184317.17716@bmerh85.bnr.ca> shiv@bnr.ca (Shiv Naimpally) writes:
>|> I wanted better bass response out of my el-cheapo Yamaha speakers 
>|> (model NS-4), so I pushed them back against the wall. (They had been
>|> sitting out about 8-10 inches from >|> it.)  Voila!  More bass.
>|>
>|> Now, however, I'm really noticing how "mushy" the bass is.  Was the
>|> bass always this mushy, and I just didn't notice it before?  Or is this
>|> another effect of the speakers being closer to the wall?  And most
>|> importantly, is there anything I can do to "tighten" up the bass, without
>|> losing too much of the response, that will cost very little?  (If I had 
>|> money I'd just buy some better speakers.)
>|> 	In other words, I want a free lunch.
>|> 	Any suggestions?
>
>Get an equalizer. Pick up an eq with 10-12 bands per side. You should be
>able to get one used fairly cheap. This will allow you to compensate for
>your room acoustics and should allow you to tighten the bass. You may be
>able to move the speakers back out (if you can, get some speaker stands
>with spiked feet - a fairly inexpensive tweak).

It's a common myth that an equalizer is useful in this application. The
actual utility of equalizers is actually quite limited. They are good for
correcting simple non-delay, minimum phase type response errors due to
low-order electrical and mechanical problems, and little else. A very good
equalizer is useful to someone such as myself, where I might be zeroing in
on the final stages of a crossover design, and will use an equalizer to
try out slight variations in network response before finalizing a
prototype. Otherwise, mine gathers dust.

A room which has a serious narrow-band resonance simply won't be touched
by an equalizer, no matter how sophisticated or how carefully adjusted.
The problems associated with room acoustics are often ones that manifest
themselves as excessively long reverberation times in narrow bands. No
amount of equalization is going to change the revereration or decay time
of such a resonance. As an example, I recently tried to EQ out a nasty 8
dB 250 Hz peak in a samll auditorium I was doing some audio for. The
reverb time at 250 Hz was four times surrounding bands. I had the use of a
1/3 and a 1/6 octave equalizer. Even cutting the 250 Hz bands totally in
both equalizers made no real audible difference, even the the analyzer
should about a 4 dB reduction in the peak. In fact, the resyulting system
sounded less intelligable as a result.

If your speakers sound mushy, it's possible that they are mushy, and
moving them closer to the wall simply accentuated the problem to the point
of annoyability. It's certainly possible with the speakers you're using.
Far more expensive and pretentious Yamaha speakers are known to suffer
from similar problems. No equalizer will help a design defect such as
this. In all likelyhood, no cheap fix will help either.

What to do? well, with these speakers, my choice would probably be to get
them away from the walls and tolerate the now thin bass again. My own
personaly preference is for less mush at the expense of less apparent bass.

For the amount of money a decent equalizer would cost, and for the
amount of time you'd spend on dubious "tweaks", you'd be far better
off savings towards speakers which better satisfy your listening needs.
-- 
|                Dick Pierce                |
|    Loudspeaker and Software Consulting    |
| 17 Sartelle Street   Pepperell, MA  01463 |
|       (508) 433-9183 (Voice and FAX)      |
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