Yeah, sometimes I feel like that 1.5-3k range has a couple of peaky responses when listening to certain female vocals on Beyma, but then again, that's the same area most (all?) compression drivers seem to measure a tombstone up-curve, so all these need to be notched or DSP'd flatter anyway..
There is a noticeable 1,6 Khz resonance, in the TPL150 from the factory, that can be corrected with a little diy effort.
@Arez That's the main offender I've heard as well. Being the TPL150 is a pro HF driver, I can see why they didn't address it.
I prefer using lambs wool for tweeter dampening.
I prefer using lambs wool for tweeter dampening.
I just saw a 800€ a pair ETON ER 4 Air Motion Tweeter disassembled. It is made from the front plate, a cheap plastic spacer with 4 round neodym magnets, the quite untidy looking AMT folding and a sheet metal rear cover. That is all. Parts maybe worth 25€. Profits seem as high as you elsewhere only find with international drug trafficking. Sound addicts?
There seems to be nothing more overpriced for the DIYS market than AMT's beside from audiophile coils, caps, resistors damping material.
No wonder that Mumdorf is offering so many of these tweeters.
I bought a pair of AMT's a few month ago, now I understand why I got them for 30% of the retail price.
There seems to be nothing more overpriced for the DIYS market than AMT's beside from audiophile coils, caps, resistors damping material.
No wonder that Mumdorf is offering so many of these tweeters.
I bought a pair of AMT's a few month ago, now I understand why I got them for 30% of the retail price.
Enlarge the back chamber and stuff it?
I kind of like how others have made a open back plate for dipole effect.
The big Hell AMTs are on sale for $250/pair with mounting kits.
https://essspeakers.store/collections/heil-amt/products/pair-of-heil-amts-mounting-kits
https://essspeakers.store/collections/heil-amt/products/pair-of-heil-amts-mounting-kits
Funny I got my cosmetically challenged, face-plate-added pair for ~$30 (thrown in by a diyer who sold me a pair of Eve Audio cones), but I'm now eyeing a $120 pair on idlefish (China's eBay). They are relatively expensive hence fairly available "arbitraged".
As I already had the boutique AMT mated with Eve, the Adam went off with large-voicecoil pancake mystery midwoofers (supposedly ultra-rich) in recycled MTM Jamo cabs. (My first year DIY.)
I decided to try out the newer Dayton AMT HR-4 tweeters on sale for $80. Their regular model AMT pro and 3-4 had a very ubrupt falling top end after 10 - 12 k which looked like it would sound dull even just slightly off axis. The membrane color looks different on these newer models, assuming they're thinner than the older ones. Sensitivity is also a little higher. I'll keep you guys posted.
Attachments
I should have been clear that 7-10 days my time is about 60 days normal people's time. [Kind of like how my dog is 7 years old in human years but 50 years old in dog years.]
Here are some measurements. On an actual baffle, not IB. Actual baffle is 15-in wide with 1-inch roundovers. Tweeter is 5-inches from the top (top edge has no round-over) - which I think is causing a little peak at 2.7khz. Distortion measurement are at 106dB at 31.5 cm ---> 96dB at 1m.
I look forward to how @profiguy 's measurements compare.
On- and Off-axis 0-180 degrees
Horizontal measurements Normalized
Vertical measurements
Vertical measurements Normalized
Distortion
I don't know, I don't measure the voltage, I just use an SPL meter (which has a +/- 1.5dB tolerance).
For xo work I just get somewhere close to 87 dB and don't really pay attention.
For distortion measurements I do use the SPL meter to get 106dB at 31.5 cm.
For xo work I just get somewhere close to 87 dB and don't really pay attention.
For distortion measurements I do use the SPL meter to get 106dB at 31.5 cm.
Wow, that measures pretty low in HD. My quick and dirty ones are perhaps too quick and dirty by comparison.
I am using AMTPro4 in full OB speaker from 1 kHz up with open back.
Distortion measured from listening position in room at about 80 db level is next.
SPL curve is DSP corrected, specially in higher than 10 kHz range.
DSP correction is next:
Distortion measured from listening position in room at about 80 db level is next.
SPL curve is DSP corrected, specially in higher than 10 kHz range.
DSP correction is next:
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Boy, that frequency response looks like AMTPro4 will lack in that "sparkle, air" department. Can DSP truly correct that well without other penalty..?
Nearly, it have not so good "sparkle, air" department as real ribbon have, but integrity of 1 kHz and up is for me little more important.
I had also OB with real ribbon cut at 3 kHz and I had difficulties to get seamless integration with OB mids because dipole peaks and minimums.
AMTPro4 have actually different lots on market and they have different SPL response curves, deviation is big. I have seen nearly flat SPL, but my ones need DSP correction.
I had also OB with real ribbon cut at 3 kHz and I had difficulties to get seamless integration with OB mids because dipole peaks and minimums.
AMTPro4 have actually different lots on market and they have different SPL response curves, deviation is big. I have seen nearly flat SPL, but my ones need DSP correction.
These cheaper AMTs appear to have quite a large fluctuation in FR and inconsistent performance. This is frustrating, as you can't count on getting a close pair, unless you buy a few at a time to pick out the best 2 that match the closest. That also creates an unnecessary burden on retailers with returned units, further complicating things for both buyer and seller. Sometimes it makes more sense to just use a pair of large domes instead.