Axiom Home Page Forums General Discussion Stereo sibilance

I would definitely try the felt if I were having a similar problem to yours. Alan has recently mentioned that the M60s have great off-axis response, which means the tweeters send quite a bit of information out toward the side walls. This helps contribute to the perception of a wider soundstage. In your case, since your room is decidedly 'live' with all its hard surfaces, the off-axis response is probably what's causing the sibilance and ear fatigue.

In addition to trying the felt, or instead for that matter, I'd try to soften the room a bit, especially on the walls to either side of your listening position.

Has anybody ever had a problem with either sibilance or had a desire to add resistors to either an M3, M40 or M50? Any of you M3 M40 or M50 oweners wish to respond?

I've got the M50s. I've never noticed a problem with sibilance, but I really don't listen at high volumes. The M50s tend to be more forgiving (from what I've heard) of poorly mastered things than the 22/60/80s.

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.

In reply to:

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I’d recommend the SPL meter to anyone wanting to diagnose their system

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Sounds like another shill for Radio Shack!




Just kidding of course Alex (was a joke in reponse to some name calling that took place a week or so back). You are correct though, the RS SPL meter is a must to get your system running optimally. Anyone who is prepared to spend $1000+ for a speaker setup should be able to budget $40 for one of these - it's crucial.

Hi Alex:
I appreciate your report! I have a few questions, though:

Are you saying that you used both the pads and the resistors together? Did you try them individually and, if so, what were the results?

Did you notice a loss of detail in the highs, or was it just a matter of reducing the sibilance you were hearing and leaving the detail intact?

How did you attach the felt? Is it something that was easily removed?

Hi Mark,

> Are you saying that you used both the pads and the resistors together? Did you try them individually and, if so, what were the results?
> Did you notice a loss of detail in the highs, or was it just a matter of reducing the sibilance you were hearing and leaving the detail intact?
> How did you attach the felt? Is it something that was easily removed?

Yes, I use them both at the same time. I tried the resistors at first to tone down the highs and added the wool felt later to remove the sibilance which was still there. I didn’t experiment with having just the felt since I was pleased with the results, but I might remove them later to see how it sounds. The felt is very easy to attach/remove: I used double-sided (removable) 3M scotch tape.

I don’t think there is a loss of detail with the felt. I actually feel that the grills reduce some detail, so I don’t have them on (although they do help a bit in reducing sibilance if on).

You can experiment with the shape of the cut-out on the felt, as the article on the Sound and Vision forum describes (see link on my previous post). I did not do this and the round opening I used might be sub-optimal. I was just curious to see if it would help—it did.

I bought the SPL meter that day so I used the test CD to proceed with the frequency response. It was a very useful experience and changing the placement had a big impact (positive) on the sound. Have a look at the Audioholics link from the Rives website about placement. It talks about subwoofer placement but the same applies for speakers.
The frequency scan I got with the new placement was pretty flat up to 10 KHz, so that’s why I did not want to mess with removing the resistors—the response above the crossover (~2 KHz) was at the right level.

Were the measurements with the meter done on axis or from your sweet spot? If your highs are flat out to 10,000 khz I can't see how you listen to your speakers.They would be way to bright.To solve my problem with brightness and sibilence I use a DBX 10/20 equalizer to lower high frequency response at 4,000 khz and 8000khz by 2 db's.The DBX is computerised and gives me a flat response from 31hz to 15,000khz at my listening spot.If I leave my m80's at flat they are impossible to listen to because of excessive brightness.

> Were the measurements with the meter done on axis or from your sweet spot?

The SPL meter was placed on a tripod at the listening position, as advised in the Rives test CD booklet. The attenuation I get from the 1.5 Ohm resistors and the wool felt around the tweeters, along with proper placement (to remove low frequency room modes), is enough to give a reasonably flat response throughout the frequency range of the M60’s. I used the response chart as a guideline. More importantly, I like how the system sounds.


>If your highs are flat out to 10,000 khz I can't see how you listen to your speakers. They would be way too bright.
>If I leave my m80's at flat they are impossible to listen to because of excessive brightness.

Are you saying that a flat frequency response is a bad thing? The terms ‘flat frequency response’ and ‘flat setting on the EQ’ are not to be confused. I think what you’re describing is that in order to get a flat frequency response you needed to bump down the highs by a few dB (using your EQ), and if you left the EQ at ‘flat’, your system was bright.

Personally, I’m not a big fan of electronic equalizers and prefer tweaking the sound in other ways, as I described.

I wanted to relay my personal experience on how I improved the sound of my system in the given listening environment, hoping that someone might benefit from it as I did reading various posts on this forum. If without ever having heard my system you can’t comprehend how I could possibly stand to listen to it, that is your prerogative.

The DBX 10/20 is computerised and is used to get a flat response using a mike and white noise at my listening position.The actual equalizing is not done manually but is done by a micro computer.The flat response is not on the equalizer but at my listening position.I bought the DBX to flatten two room nodes in the bass region but there are always trade offs.The flat response in the treble area makes the speakers difficult to listen to.I then reduce the flat treble response manually by two db's.I was always under the impression that studio monitors used for recording purposes are flat in the treble area off axis,but home speakers have some roll off in the high frequency response to make them listenable.I am not questioning your right to choose your listening preferences.I myself prefer the Axiom M80's even though many people consider them to bright.