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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
broadstone's avatar
broadstone OP
310 posts
 
Bifwynne, your suggestion makes a lot of sense and is a direction that I'm seriously starting to lean toward. I've enjoyed the Odysseys for many years and what seems to have happened is that when I thought my equipment was failing it was actually a gradual age related hearing loss causing my problem. I agree with you that I may have been a bit hasty looking for ways to abandon the Odysseys and will repair them even if I decide to sell them.

I'm not that well versed in current design or conversant with much of the modern technical language but am not a newcomer to the hobby. I assembled my first monaural Heathkit amp and built the "Sweet Sixteen" speaker array when I was a teenager about 50 years ago. I also turned my parents' attic into an infinite woofer baffle because high volume and big bass were the kings in those early days of hi fi. Now, detail is what good listening is about for me and this seems in many ways associated with the upper frequencies. Because my hearing begins dropping off just below 5kHz I've experienced loss in this detail and I was finally fitted with hearing aids which, btw, I only use when listening to music.

To give you all an idea of how far I had gone to resolve my problem, a couple of months ago I listened to a pair of Canalis Anima's which are fantastic and unbelievably detailed but a bit expensive to experiment with. I then purchased used Jamo Concert Eights in an attempt to duplicate the Animas and it was a close comparison but some of the high frequency harshness was still there at higher volumes. Trying to identify which speakers best suited my needs I installed a speaker switcher in order to A/B between the Odysseys and the Concert Eights. I found that for critical music listening at lower volumes the Jamos shined but for TV and DVD the Odysseys were best. After I bought hearing aids, though, I started hearing more detail from the MLs and sold the Jamos.

Anyway, until the new circuit boards arrive so I can put the ML's back in service and can work on approaches to keeping them, I'm suspending pursuit of potential fixes based on choosing alternative speakers. I'll probably be asking for more advice during this process and will report on how this goes.
bifwynne
2,206 posts
 
Broadstone -- my compliments on your sage approach. Another suggestion is contacting ML to see if they rehab their older gear.

I seem to recall reading that some ESL/planar companies refurbish their older products. I can't seem to recall the ESL companies that do this, but perhaps other folks will chime in. But I'm pretty sure Magnepan refurbishes its older planars.

Frankly, I see no reason to fix what ain't broke, especially if you're happy with its performance.

Cheers,
johnnyb53
3,510 posts
 
Here are my bitches with the most popular tweeter types:

Metal domes have resonant frequencies around 25-30 Khz. One can argue that
this is above the limits of human hearing, but the resonant spike is so strong
(sometimes 10-20 dB) that I'd think that when excited it throws off the tweeter's
ability to smoothly render the audible frequencies.

Textile domes are smoother, but are often not as fast, let alone rigid, as metal
domes, and most of them roll off quickly above 10 Khz.

Ribbon tweeters are usually very fast and linear to 30Khz or more, but must be
crossed over at 3Khz or higher, which can cause a dispersion suckout around the
crossover point unless a midrange is used or the mid/woofer is 4"
diameter or less.

On the other hand:
Ring radiators don't have a resonant spike and are reasonably linear out to
around 30Khz. It's the tweeter of choice in many Sonus Faber and other high end
speaker companies.

Now, however, there is an emerging tweeter type based on a textile dome
wherein the tip of the dome is "pinned" in place. This converts the
tweeter from a traditional dome tweeter to a ring radiator. I first saw it on
Internet-Direct speaker vendor Aperion's website in their top href=http://lghttp.12393.nexcesscdn.net/805C8C/cdndirectory/media/catalog/
product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/p/r/product-
1194.jpg>Verus line, but I see where Sonus Faber has implemented a very
similar thing in their new href=http://hifilounge.co.uk/image/cache/data/sonusfaber/Olympica%20II/fea4
5bd9-7d1b-4cca-023a-0497ef7e7864-399x325.jpg>Olympica line. Such
a tweeter would be less susceptible to overshoot and beaming, and SF claims
such a tweeter can handle a lower crossover point than for the same tweeter
without the pin.

I thought this tweeter type was a clever concept when I first saw it on the
Aperion, but the Sonus Faber version sort of validates the concept for me. The
grand-bookshelf-loudspeaker-measurements>Stereophile review
measurements show the Aperion tweeter to peak by 5 dB at 10Khz, drop 5
db by 20 Khz, and then rise 5 dB again to 30 Khz, more like a Vifa ring radiator.
Similarly, Sonus Faber claims response out to 30 Khz in its Olympica line.

That said, my current favorite tweeter is the quasi-ribbon in my new
Magneplanar 1.7s. Fast, smooth, extended, good dispersion, and nary a hint of
beaming, overshoot, noticeable dips or peaks, or ringing.
bifwynne
2,206 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.
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