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Tweeter type and brightness

I presently own Martin Logan Odysseys that I purchased new in 2005. I've enjoyed them very much but I'm having to replace the power supply board in one of them as I did in the other one about 5 yrs ago and I'm thinking that it may be time to look into speakers using more recent technology.

I auditioned several new sets at Sound Advice including the Monitor Audio silver 2, 6, 8 and 10 plus a small pair of ML's. I thought all of them were very good. Additionally, I bought a pair of Jamo Concert Eights several months ago that were fantastic for my type music which is mostly solo guitar. I regret selling them but at least I learned how good quality bookshelf speakers can be.

Anyway, I've read in several posts that metal dome tweeters have a tendency toward exaggerated or tinny brightness which can be very uncomfortable for me because of a hearing issue that I have. I want to avoid this and am asking for advice regarding this experience of others and what tweeter construction, if any, is generally best to avoid what I call screechiness.

I've been told that the technologies that best avoid this are ribbon tweeters or domes of some softer material than the various metals used in many of them. In one of the forums here on Audiogon this subject was discussed in some detail and at least several participants seemed to minimize the relationship between tweeter design and this problem. They suggested that more likely potential causes would be such things as room acoustics, interconnect quality, rake, crossover problems, etc.

I agree that each of these considerations could lend to the issue but I'm looking for a good starting point to at least minimize the contribution of the speaker design to this problem.

I've heard the gold series Monitor Audio speakers which do incorporate ribbons and they seem to work perfectly with my music but they, like the larger new ESL's are substantially outside my current budget limits. I'm currently using some borrowed temporary speakers while I'm waiting for the new circuit board so I can sell my Odysseys. In the meantime I would appreciate any advice I could use to help with an approach to selecting a speaker best suited to my needs. My upstream equipment includes Shanling solid state CD player, CAL DAC and Rogue Audio Sphinx 100W hybrid amp.
128x128broadstone
bifwynne
2,069 posts
 
Johnnyb53, I think the resonant point of beryllium dome tweeters is somewhat further out than most other metal domes tweets. My fronts are Paradigm Signature 8s (v3), which as I mentioned above use beryllium tweeters. My speakers are very fast and detailed, but not bright and harsh.

That's not to say that I didn't have configuration issues relating to amp/speaker compatibility. But I think I wrestled that bad boy down by using the 4 ohm taps on my new amp and moving the speakers around a little.

Interestingly, I think the reason the use of the 4 ohm taps calmed the S8s down had more to do with an impedance hump at the 2.2K Hz X-over point. I don't think tweeter ringing was at issue at all.

In fact, speaker impedance in the "power" range (say 30 Hz through 700 Hz) was 4 ohms. So ... using the amp's higher output impedance tap (8 ohms -- about 1 ohm)) flavored (for lack of a better term) the acoustic presentation by reducing output voltage in the power range by almost a full db and increased the output voltage by almost a full db in the upper midrange/low treble spectrum. The 2 db difference had the effect of brightening the acoustic presentation, which I found fatiguing.

So, by using the 4 ohm tap (output impedance about .55 ohms), output voltage regulation was tighter (about +/- .4 db) reducing the coloration by over 1 db. Ergo the speakers sound very sweet.

I'm not familiar with ring radiator tweeters. Thanks for the link. I'll check it out.

Cheers,
astrallite
15 posts
 
I think woofer type is more likely to result in brightness than tweeter type, very few of us in the audio hobby can hear above 20KHz anyway which is where the breakup mode is for most tweeters.
broadstone's avatar
broadstone OP
277 posts
 
As it turns out, it may have nothing or very little to do with tweeter design or construction material at all, in my case. Recently, I bought a pair of Monitor Audio S8's and had a tweeter failure in one (open circuit). It took me an hour or so to pin down the reason that the sound was unbalanced and sounded so generally bad.

Because it will be at least 3 weeks to get the tweeter replacement, and even though there is a significant loss of quality, I decided to remove the tweeter from the other speaker because listening with one tweeter out was very fatiguing and annoying. The resulting sound quality was, of course, bad, having lost detail and timbre.

Now, the rest of the news; even in the absence of tweeters, the sounds that caused me discomfort because of what I call shrillness, were pretty much still there so the tweeters, in my case at least, are not the culprits. To test this I used the CD "jazz at the Pawnshop" which has a pretty good range of frequencies and sharp volume rises. With no tweeters, this music lost its personality but retained harshness in those areas that bothered me with the tweeters in place. So.....where do I go from here? BTW, the upstream equipment is Shanling Digital CD player, CAL Sigma DAC and Rogue Audio 100 WPC hybrid amp.
mapman's avatar
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mapman
15,679 posts
 
Broad,

Clipping could be another factor that affects all sound, not just high frequencies.

Also noise resulting from power source, nearby EM fields, etc.

Do you know if your setup might be clipping, even subtly/slightly when the problem occurs?

Once clipping and avoidable sources of noise are out of the equation, sound quality of good quality gear should be fairly optimal. THen it comes down more to personal preferences regarding the "flavor" of sound, which often no two people will ever agree upon exactly.
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mapman
15,679 posts
 
..and also lets not forget the potential issue with jitter in digital audio specifically.

Noise/jitter/clipping....minimize those three and be in a good position to judge all the rest.
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