Its always intriguing to me how the little spikes of higher order harmonics draw immediate attention to themselves and define the overall acoustic signature of a midrange.
The cheaper metal mid domes tend to fall short of the clinical sterility typically associated with most metal dome drivers. When you remove all the enhancing 2nd order harmonics softer dome materials tend to exhibit, you're left with a rather dry presentation of music. This allows for all those little annoying peaks and other issues to come through, which can ruin the overall transparency of the driver. I think this is why we rarely see budget priced larger metal dome mids.
The only one budget metal dome mid coming to mind is the Dayton 52AN. This driver sounds irritating to my ears. It has quite a bit of junk across its "useful" passband with a breakup peak that wanders depending on listening axis. I have heard one or two sucessful implementations of this mid, but it requires ALOT of attention to make it sing. The money you save on the driver is quickly spent on crossover parts to make it behave. Such is the case with some other dome mids.
The cheap hivi DMB-A has some potential, but you have to deal with the junk in the lower mids, included the poorly dampened, high Q lower rolloff and hash in the upper mids. Once you have to pull apart a driver to mod it, trying to address some of its engineering shortcomings, its no longer a bargain driver, especially when needing to purchase an extra driver to get a decent pair.
The cheaper metal mid domes tend to fall short of the clinical sterility typically associated with most metal dome drivers. When you remove all the enhancing 2nd order harmonics softer dome materials tend to exhibit, you're left with a rather dry presentation of music. This allows for all those little annoying peaks and other issues to come through, which can ruin the overall transparency of the driver. I think this is why we rarely see budget priced larger metal dome mids.
The only one budget metal dome mid coming to mind is the Dayton 52AN. This driver sounds irritating to my ears. It has quite a bit of junk across its "useful" passband with a breakup peak that wanders depending on listening axis. I have heard one or two sucessful implementations of this mid, but it requires ALOT of attention to make it sing. The money you save on the driver is quickly spent on crossover parts to make it behave. Such is the case with some other dome mids.
The cheap hivi DMB-A has some potential, but you have to deal with the junk in the lower mids, included the poorly dampened, high Q lower rolloff and hash in the upper mids. Once you have to pull apart a driver to mod it, trying to address some of its engineering shortcomings, its no longer a bargain driver, especially when needing to purchase an extra driver to get a decent pair.
Jup, that's how the RS52 sounds. My hearing experience comes very close to what you describe here.
I crossed them pretty low so it was not very pronounced but still noticeable. As it was active I had no dampening for the (high) membrane resonance - this would be the perfect driver to give the effectiveness of such dampening a listen.
Drivers do distort, they are the weak point in any system and even the most neutral ones like Purifi or Bliesma are still distoring in a way we can hear. Our hearing can hear distortion to +80dB below the fundamental, and most drivers get distortions to 40 to 50dB below the fundamental. paper distort in another way than metal or plastic and so on. So the distortion is a big part of that "sound" of a driver, study the distortion in detail and you learn more, and after studying enough drivers and their distortion profile you will see what you like and what not from graphs. I know i can predict almost perfect if I will like a speaker partly due to that (there is more off course, di and frequency response are also major factors. But distortion is often overlooked. The high rated Bliesma T34B has a high 3th order distortion above 10K, something i often see with BE tweeters, and what is probally causing the sharp fierce tone i don't like.
@waxx That rough 10k+ sound you describe on the T34B is due to insufficient electro-mechanical dampening of the upper breakup mode. Many designers believe you can simply avoid exciting the breakup range with DSP EQ and everything is handled, but thats simply not true.
If you look at down-modulated components on most metal dome tweeters, the problem is the type of modes that are reflected back into the 5 - 10k range.
With most 25 - 28mm Ti and Al/Mg alloy HF drivers, the primary upper breakup is right around 25 - 27 kHz. That leaves a 5 - 8k audible mode in the upper mids - lower treble and usually its an aggressive radial mode that involves the entire diaphragm radius, pushing the tip 180 deg out of phase with the outer radius. Part of the solution to eliminating this problem is using a phase shield at the tip and 2/3rds down the radius.
The older Vifa D25AG35 Al/Mg dome was one of the few metal HF domes which got all this right and sounded better than almost any other tweeter of its type. I've listened to hundreds of HF domes in my lifetime and can say without hesitation the Vifa Al/Mg HF dome is one of the few metal domes that can be enjoyed without the typical long term listening fatigue associated with metal domes.
Most Ti domes are too aggressive to my ears. They have a much less dampened breakup mode due to the.dome material itself. Al/Mg gets around this due to its self dampening nature, as does Be.
So to put it simply, the only way to remove most of the junk in the 5 - 10k range of a metal dome is via a carefully placed and verified electrical LCR notch. Sometimes a phase shield is sufficient, but much harder to implement correctly. At a minimum, electrical EQ on a DSP level is needed, but isn't sufficient.
I absolutely love the T34B when used with a 27kHz LCR . Its one of the few dome tweeters that can keep up with a compression driver but doesn't have the typical CD distortion. When played loudly, all you get is music and no other distortion. The only commonly available ribbon tweeter better than this one is the Aurum Cactus G1 and some of the RAAL ribbons.
If you look at down-modulated components on most metal dome tweeters, the problem is the type of modes that are reflected back into the 5 - 10k range.
With most 25 - 28mm Ti and Al/Mg alloy HF drivers, the primary upper breakup is right around 25 - 27 kHz. That leaves a 5 - 8k audible mode in the upper mids - lower treble and usually its an aggressive radial mode that involves the entire diaphragm radius, pushing the tip 180 deg out of phase with the outer radius. Part of the solution to eliminating this problem is using a phase shield at the tip and 2/3rds down the radius.
The older Vifa D25AG35 Al/Mg dome was one of the few metal HF domes which got all this right and sounded better than almost any other tweeter of its type. I've listened to hundreds of HF domes in my lifetime and can say without hesitation the Vifa Al/Mg HF dome is one of the few metal domes that can be enjoyed without the typical long term listening fatigue associated with metal domes.
Most Ti domes are too aggressive to my ears. They have a much less dampened breakup mode due to the.dome material itself. Al/Mg gets around this due to its self dampening nature, as does Be.
So to put it simply, the only way to remove most of the junk in the 5 - 10k range of a metal dome is via a carefully placed and verified electrical LCR notch. Sometimes a phase shield is sufficient, but much harder to implement correctly. At a minimum, electrical EQ on a DSP level is needed, but isn't sufficient.
I absolutely love the T34B when used with a 27kHz LCR . Its one of the few dome tweeters that can keep up with a compression driver but doesn't have the typical CD distortion. When played loudly, all you get is music and no other distortion. The only commonly available ribbon tweeter better than this one is the Aurum Cactus G1 and some of the RAAL ribbons.
I know that, but i don't think that BE response looks good, my favorite hard dome is the AL SB26ADC because it damps the resoances well. They are also there, and in the same region, but the amplitude is way less, so also the smaller ones in our hearing range. You can find find full measurments here: https://hificompass.com/en/speakers/measurements/sbacoustics/sb-acoustics-sb26adc-c000-4
And you see it also in the distortion profile, that the distortion in the high treble is way less pronounced in that region compared to the T34B
In general, softdomes damp resonances a lot better than hard domes. But it's not that no hardome can have a good damping of resonances neighter. BE diagramp are hard to do right for me, just like TI diagrams, but AL diagrams can be done right to my taste.
And you see it also in the distortion profile, that the distortion in the high treble is way less pronounced in that region compared to the T34B
In general, softdomes damp resonances a lot better than hard domes. But it's not that no hardome can have a good damping of resonances neighter. BE diagramp are hard to do right for me, just like TI diagrams, but AL diagrams can be done right to my taste.
@waxx I can definitely concur with most hard domes. I was very skeptical about the T34B and its character, but when I gave it a thoroughź check over with music and listened for a while, it became obvious this tweeter sounded considerably different than other Be and Ti domes. It didn't have the aggressive upper octave the others had when used with the upper notch filter, especially at higher playback levels. The top end was pristine as the best available ribbons.