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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.
broadstone
erik_squires
17,576 posts
 
You may already know in this context pistonic means the first breakup mode is above 20K and that many soft domes break up at 8K or so and go into controlled Kaotic motion. This goes back 30+ years when Celestion campaigned their pistonic tweeter which was one of the first. Best, JohnnyR

@audioconnection

Right, so pistonic means pistonic within the used band. Can you point me towards any modern, reasonable quality soft dome that does not behave this way??

Best,

E

audioconnection
1,271 posts
 
Hey Eric, I’m no speaker engineer/designer but have read several articles over the years about this common knowledge but not seen any measurements since the Celestion campaign mentioned earlier. Do remember reading something on Genelec’s web site about the difference between soft and hard domes is that soft domes first break up at less then 10 k. Bad thing about age is the gray matter don’t work like it used to.  Best, JohnnyR
erik_squires
17,576 posts
 
Hey @audioconnection

I’m not familiar with tweeter breakup 30 years ago.

In looking for evidence of it in cone drivers like a midrange or woofer you usually see it as a sudden peak. I just checked a random $12 driver from Peerless and I did not see this.


The closest thing I’ve seen to break up modes in modern tweeters is in metal tweeters, not soft dome. I don’t pretend to know everything either, but darned if I’ve seen this over the past few years of looking.  If you happen to run into this again, I'd be happy to read up on it.

Best,

E
erik_squires
17,576 posts
 
I also took a look at a couple of soft dome’s at Zaph audio. The lack of a FR peak as well as the lack of distortion in the audio band and relatively clean waterfall plots of these cheap tweets does not show me any evidence they are anything but pistonic.

I look forward to being more educated on the subject with specific examples in the future.
roberttdid
534 posts
 
Don't always blame the tweeter. That harshness is in most cases, just excessive volume, at least in good quality speakers, and not distortion/breakup.

If the speaker has wide dispersion at high frequencies and your room is untreated or poorly treated, the total energy reaching your ear at high frequencies may be excessive, especially late arrival.  Room treatment will be your friend (or a different speaker).
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