I’ll post my success in softening the highs of the M60’s using wool felt pads, 1.5 Ohm resistors, and improving the overall frequency response using the Rives audio test CD2 with the analog Radio Shack SPL meter.
Wool Felt:
Bought it for around $1 at the local fabric store. I cut out a circular torus with outer diameter the size of the tweeter bracket (covering the mounting screws), and inner diameter the hole of the tweeter opening. I attached it using double-sided scotch tape.
I doubted that it would make an audible difference so I was really surprised that it was not a subtle one. It did tone down the sibilance and was very noticeable with the ‘ssss’ not having as much of an edge to them as before. I went back and forth removing and putting it back on and the effect was very reproducible. So the wool felt and the 1.5 Ohm resistors stayed (no grills).
SPL meter:
http://www.rivesaudio.com/software/softframes.html
What a great deal! I bought the Rives audio test CD2 (mention Audioholics and you’ll get a 10% discount: so $21 incl. shipping) and Radio Shack analog SPL meter ($40) mainly out of curiosity. It turned out it’s a really nice tool to find problems and help you to improve the sound. For a good sounding system, it’s important to remove any large peaks in the bass response (20-160 Hz). I had an 8 dB hump in the frequency response around 80 Hz, which was due to a room mode. The spacing of the speakers did not affect the peak, but the distance from the back wall did. I originally had them 13” from the rear wall, and had to move them to 24” to bring the hump down to the same level as the other (lower bass) frequencies. I experimented with the placement while playing the 80 Hz tone. So at 2’ from the rear wall, the 80 Hz boominess went away. I did a full scan and there were a few dips throughout the frequency spectrum (dips are not that much of a concern, unlike peaks) but overall the response was now flat within +- 3 dB or so. The difference was dramatic. The midrange cleared up and became more pronounced. Before I always felt that the midrange sounded a bit recessed, but it was due to the peak in the bass response.
The combination of the resistors, wool felt, and room placement (to remove a hump in the lower bass) produced a great result. I’m now much happier with the sound and I’d recommend the SPL meter to anyone wanting to diagnose their system.
