budget vs expensive tweeters

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#81
yes, but I have read about dome tweeters doing the exact same thing; of course; it would depend on if there were any signals high enough in frequency to stimulate or "excite" the break up peak...not even 6 AM here in the middle of the US yet, still waking up, more coffee required to fully engage my brain ha ha ha...
 
#82
Metal-Dome Tweeters

Advances in German metallurgy (at Elac and MB) resulted in thin profile titanium and aluminum domes in the mid-Eighties, with drivers from several vendors in Germany, Norway, and France now available. This type of driver can offer very transparent sound, rivaling the best electrostatics if correctly designed.

The downside is the lack of self-damping, with aluminum coming a little ahead of titanium in being better behaved in the ultrasonic region. At the present, all metal-dome drivers have significant ultrasonic peaks, ranging in magnitude from 3 dB (excellent) to 12 dB (not so good).

There’s controversy about the significance of this ultrasonic peak, since the engineers of Philips and Sony have gone to great lengths to ensure that none of our wonderful new "Perfect Sound Forever" recordings ever have any musical information above 20kHz. Not withstanding limitations of the signal source, power amplifiers (and CD players) can generate spurious ultrasonic signals, especially at or beyond clipping. These ultrasonic signals can excite the metal-dome resonance, causing IM distortion to fold down into the audible region.

Strengths are: Uniform piston action right up to the HF resonance, providing sound of very high resolution, transparency, and immediacy if correctly designed. Dispersion is typically excellent, since the metal domes have flatter profiles than soft-domes.

Weaknesses are: Potential for (dare I say it) "metallic" coloration caused by the HF peak intermodulating with the inband sound. Some early designs have restricted power-handling. If overloaded, breakup distortion can be extremely harsh.

here is one description of what I was getting at

from here:

The Art of Speaker Design, Part II
 
#85
They are NOT necessarily talking about clipping here. This is about ultrasonic frequencies causing intermodulation distortion down into the audible band. I have read about this several times elsewhere. You have valid points; has anyone actually measured this IM and it's effects? Probably; I don't know for sure. All else being equal; I avoid drivers with really bad break up peaks; it doesn't matter if it is a woofer, midrange, fullrange or tweeter. It would be interesting if someone reading this here has knowledge of real measurements and published papers that address this "ultrasonic IMD"...
 
#89
Yes, BUT, if the high frequency peak causes IM; the dome material can ring or modulate at frequencies that we DO hear. This is the whole point; I would like to see some measurements as would you and others. Think; sum and difference frequencies, etc. I, myself, have very poor hearing above 15 KHz. I have a horn tweeter that has a really high peak above 25 KHz. On some recorded material; this tweeter sounds harsh or grainy. Perhaps this due to this exact IM I have read about!?? These same recordings sound perfectly normal on other tweeters I own.
 
#90
Zvu, I read the link you given just above. Was it an impedance notch (// to the tweeter) or a spl notch (in serie with the signal).


When you said resonance peak of the dome that improved dramaticaly h3 on the whole tweeter band, you meant the 26k hz resonance of the dome I assume , not the impedance resonance peak in the low ?


Very interessant discovry indeed 🙂 . I used narrow notch (serie) in the 2k to 5 khz, cause the recess I believe to like in my room but maybe the result ws more about a H3 reducing...
 
#91
... while if I understood the link given, it talks about H3 reduced below the spl peak that is notched... not above (while we are not bats, I ask myself if it works also above, I assume it doesn't logicaly)


So anyone, please, having heard both the SB26CDC (aluminium+ceramic coated) and one of the Peereless corundum ?


Here the cheap and cool SB26 STAC is still breaking in before the speakers given back to his owner, I assume fabric surrounds needs a 100 of hours to get his definitive sounding character ?!
 
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#92
diyiggy said:
... while if I understood the link given, it talks about H3 reduced below the spl peak that is notched... not above (while we are not bats, I ask myself if it works also above, I assume it doesn't logicaly)


So anyone, please, having heard both the SB26CDC (aluminium+ceramic coated) and one of the Peereless corundum ?
Click to expand...

I have heard both of them in my home briefly in an active XO setup and found both to be excellent, with an edge to the peerless da25tx. It may be the best dome tweeter I've had direct experience with, better to my ears than the SB29RD or SD, CSS LD22, and Hivi RT1.3WE that I was trying out in the same session, better than the Seas 27TBFC/G. Those are all tweeters I think highly of by the way, it's just that back to back I preferred the da25tx.

There have been several excellent designs using the SB26 hard dome tweeters and the Peerless conundrum tweeters. These have been toured at the various DIY audio meets in the last couple of years to generally excellent reception. I heard many designs with both at last year's Meniscus get together, and all sounded very good indeed. The fact that Jon Marsh considers the da25tx one of the better tweeters available at any price carries a lot of water with me as well.

People are of course free to use whatever criteria they want to evaluate; but personally I would put a lot more weight on the excellent measured performance and abundance of real world experiences with these tweeters than in speculation about potential ultrasonic issues from those who have neither heard or measured them, or indeed in Lynn Olson's general musings about hard domes circa 2001. YMMV.

BTW I have heard a few designs using the sb26stac as well and they sounded quite good, I've not had the chance to play with them personally yet. By all accounts, they should be one of the best budget tweeters available.
 
#93
Thank you for the testimonial. I think I pull the trigger on the 25TX, trying a circa 87 dB 3k to 3.5 K hz 12 db slope with a 3" mid. for casual domestic use...


I wish not to try a first order, cause it's too much touchy without experience, despite sims (at least fr my limited experience).


Cool thread, really show you can go right with not too much monney and a little sweat and nice shared information.


Thanks guys.
 
#94
morbo said:
I have heard both of them in my home briefly in an active XO setup and found both to be excellent, with an edge to the peerless da25tx. It may be the best dome tweeter I've had direct experience with, better to my ears than the SB29RD or SD, CSS LD22, and Hivi RT1.3WE that I was trying out in the same session, better than the Seas 27TBFC/G. Those are all tweeters I think highly of by the way, it's just that back to back I preferred the da25tx.

There have been several excellent designs using the SB26 hard dome tweeters and the Peerless conundrum tweeters. These have been toured at the various DIY audio meets in the last couple of years to generally excellent reception. I heard many designs with both at last year's Meniscus get together, and all sounded very good indeed. The fact that Jon Marsh considers the da25tx one of the better tweeters available at any price carries a lot of water with me as well.

**********

Good to know for sure. The IM from an ultrasonic break up mode getting down into the band of interest IS REAL. That doesn't mean it will always happen obviously. I have had thoughts of these same tweeters myself for other projects and am glad to finally get your type of feedback. In general though; I DO try to avoid drivers with nasty break up modes; all else being equal.

*********


People are of course free to use whatever criteria they want to evaluate; but personally I would put a lot more weight on the excellent measured performance and abundance of real world experiences with these tweeters than in speculation about potential ultrasonic issues from those who have neither heard or measured them, or indeed in Lynn Olson's general musings about hard domes circa 2001. YMMV.

BTW I have heard a few designs using the sb26stac as well and they sounded quite good, I've not had the chance to play with them personally yet. By all accounts, they should be one of the best budget tweeters available.
Click to expand...
 
#97
Thanks ScotG, if it's good enough for Mr Marh it's ok for me.

Did you noted the worying bump between 3/4 k hz from Evil Twin measurement ? ask myself if it's not the set up? Seems also there in the SB29 measured as well in the next page !

Howver not sur I understand why a larger dome helps for a higher frequency XO. the larger the worse when diameter of the dome increase for off axis and even on axis for a tweeter ? More Sd = less exursion at iso spl?, which is needed for a first order ? I also read in a US diy forum they found the1.1/4 32TX a little topy/hot ... for what it worths 🙄

My understanding is for a first order you have to XO much higer to match the - f3 targeted?This may needs perhaps a higher spl/2.83V tweeter to match the mid .

Anyway either the Peereless and the SB26cdc match the cool price spirit of the thread and the 90 bucks 3" SS 10F/8424G00 (8 ohms) I find very neutral and good q/pfor the price as well - default being the short spl capacity at Xmax- I plan with for a first run. horn intended after, for the story, but perhaps bad idea for a 3" without tweeter from an E. Gedles 's input.

Not sure btw the idea of first order is quite good, I'm not Dunlavy. It seems hard to acheive easily.

News from the SB26STAC : seems even better after 50 hours : less thin sound and smoother than out of the box, The XO is not optimised for it as it is a swap for a speaker refurbishing. I just can imagine how good in a diy from scratch with the good XO 🙂.
 
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#98
diyiggy said:
More Sd = less exursion at iso spl?, which is needed for a first order ?
Click to expand...

:yes:

-the larger driver also has a bit more linear excursion.

Note that more directive drivers can sometimes be described as sounding a bit "bright" on-axis. (..though I don't think that's the case here.) I'd think it was more likely to be a poor implementation with driver and baffle. The ultra-sonic break-up is another possibility leading to higher-order harmonics lower in freq., but a simple filter can resolve that problem.
 
#100
ScottG said:
:yes:

-the larger driver also has a bit more linear excursion.

Note that more directive drivers can sometimes be described as sounding a bit "bright" on-axis. (..though I don't think that's the case here.) I'd think it was more likely to be a poor implementation with driver and baffle. The ultra-sonic break-up is another possibility leading to higher-order harmonics lower in freq., but a simple filter can resolve that problem.
Click to expand...


Another technique is to use a felt circle around the tweeter. One of my old favorite yet inexpensive tweeters was the DTi-01 (or something like) that by Audax. It was Titanium dome with the "radially compliant surround"...(I'll see if I can find any old data sheets)...Anyway; it had a really nice sound quality but was a little too "splashy" in the highest octave on-axis. I experimented and finally decided only HALF of a felt tweeter ring sounded best. No ring; too much "splash"; full circle ring; too "dull". I placed the half ring (semi-circle) at the top half of the tweeter mounting face; this sounded best to me over all other configurations...cheap, easy and very effective for sure...

Good to see others have heard those tweeters you were most interested in first hand!
 
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