Differences between tweeter designs?

[March Audio]

Yes the AMT23 is quite bad (or good, depending on your room) / narrow in vertical dispersion.
See how for the AMT23 the dispersion given is for 5 and 15 degrees and for the dome tweeters the dispersion is given for 30 and 60 degrees.
And you can't look at the 15 degree dispersion and add two of them to guess for the 30 degree dispersion as usually the 30 degree dispersion will be far worse than adding twice the 15 degree number.
Similarly you can't guess the 15 degree dispersion from the 30 degree dispersion number of the domes as the 15 degree dispersion of the domes will be much better than half the 30 degree dispersion.
So in my guess the AMT23 will be at least 4 times as narrow vertically than the already "bad" measuring domes in this respect you listed below.

So in other words you don't know that it's bad, just inferred it from a lack of information.

Well some measurements will come soon but I can certainly tell you that it doesn't suffer a noticeable difference when you stand up from sitting down. If it beamed it would be noticeable.

 

[March Audio]

I've found my tweeter!
The BlieSMa T34A-4
http://www.bliesma.de/product.html
http://hificompass.com/en/speakers/measurements/bliesma/bliesma-t34a-4
http://www.audioxpress.com/article/test-bench-the-t34a-4-tweeter-from-bliesma
http://www.troelsgravesen.dk/BlieSMa_T34A-4.htm

I was looking in a very different direction, using an ATC or Volt middome and crossing this over at 3 to 3.5kHz to the tweeter, perhaps Mundorf AMT21.
But then I was a bit hesitant about crossing over around 3 to 3.5kHz. I was thinking why am I hesitant about this.. Is it past speaker experience? I've had a bad experience around this region with the K+H O300 and to some degree several other speakers, it is the presence / harshness region. And speakers that cross lower haven't sounded harsh to me in this region. Also when looking at reviews of quality speakers which use a very low distortion ATC dome but again cross at ~3kHz they seem to give a magnifying glass to the mids but are particularly hard on songs and are not particularly good at giving a whole picture of the music. In contrast, for instance the Amphion speakers get rave reviews at how great they are at giving the whole picture and fantastic holographic soundstage and these cross over at 1.6kHz (with a waveguide and measurements still show a distortion bump around the crossover due to the tweeter being stressed). And these don't even measure as good as an ATC for instance. How can this be, while the crossover is smack in the middle of the midrange and there are so many testaments all over the internet on how not to cross over in the mids as this is where our ears are most sensitive.
And then it occured to me.. The equal loudness curve, doesn't this have a little dip in the middle?
I looked it up and it sure does!
View attachment 16010

And just look at that..
How can you get a more clear picture of where to cross over?
You cross over at ~1300-1400Hz!
And certainly not at 3-3.5kHz where the ear is ~6 to 9dB more sensitive.
And this is not just because of crossover slight off-axis phasing and ringing. There are many other things to consider around the crossover. Mid/woofer dropoff, change of diffraction due to different location of the drivers, shift in harmonic and non linear distortion signatures from the different drivers, even the effect on the ear/pinna of the different vertical placement of the drivers which is more sensitive in higher frequencies. All of these are ~6-9dB less audible when placing the crossover this low. And you get the most sensitive and important region of about 2-5kHz handled by a single driver. Coincidentally you also get easy near coaxial vertical phase behavior as discussed earlier in this thread
Perhaps an alternative could have been a mid driver handling 400Hz to 5-6kHz or so, but it feels less natural to me to cross over to a supertweeter at 5-6kHz or higher (hard to get a good in phase angle at the crossover due to the very small distance required to the mid driver) and I'm not sure if there is a mid driver that can do the ~400-6000Hz range well enough with room to spare around the crossover points.

Anyhow, this is how I found the BlieSMa driver. It's clear a 1" tweeter is not up to the task of this low a crossover even in a waveguide (compression driver in a horn is a different story but not suitable for my nearfield use) and the BlieSMa is the only one that can do it this well. Lucky I didn't want to design this speaker a year ago as there would have been no good tweeter yet for the task, the BlieSMa was only released this year
Btw, there is a beryllium version as well, the T34B-4, but I don't see any benefits other than for bats and a slightly enhanced sensitivity (and it does slightly worse in fact for the third harmonic around the crossover).

Now looking for a great woofer to go with the BlieSMa. Perhaps a Seas W18EX001 would be a natural match.. Could add a true sub later as well.

The Morel mid I use can cross at 5 kHz, but they have to be small, 2 inches is about the limit.

 

[March Audio]

I've found my tweeter!
The BlieSMa T34A-4
http://www.bliesma.de/product.html
http://hificompass.com/en/speakers/measurements/bliesma/bliesma-t34a-4
http://www.audioxpress.com/article/test-bench-the-t34a-4-tweeter-from-bliesma
http://www.troelsgravesen.dk/BlieSMa_T34A-4.htm

I was looking in a very different direction, using an ATC or Volt middome and crossing this over at 3 to 3.5kHz to the tweeter, perhaps Mundorf AMT21.
But then I was a bit hesitant about crossing over around 3 to 3.5kHz. I was thinking why am I hesitant about this.. Is it past speaker experience? I've had a bad experience around this region with the K+H O300 and to some degree several other speakers, it is the presence / harshness region. And speakers that cross lower haven't sounded harsh to me in this region. Also when looking at reviews of quality speakers which use a very low distortion ATC dome but again cross at ~3kHz they seem to give a magnifying glass to the mids but are particularly hard on songs and are not particularly good at giving a whole picture of the music. In contrast, for instance the Amphion speakers get rave reviews at how great they are at giving the whole picture and fantastic holographic soundstage and these cross over at 1.6kHz (with a waveguide and measurements still show a distortion bump around the crossover due to the tweeter being stressed). And these don't even measure as good as an ATC for instance. How can this be, while the crossover is smack in the middle of the midrange and there are so many testaments all over the internet on how not to cross over in the mids as this is where our ears are most sensitive.
And then it occured to me.. The equal loudness curve, doesn't this have a little dip in the middle?
I looked it up and it sure does!
View attachment 16010

And just look at that..
How can you get a more clear picture of where to cross over?
You cross over at ~1300-1400Hz!
And certainly not at 3-3.5kHz where the ear is ~6 to 9dB more sensitive.
And this is not just because of crossover slight off-axis phasing and ringing. There are many other things to consider around the crossover. Mid/woofer dropoff, change of diffraction due to different location of the drivers, shift in harmonic and non linear distortion signatures from the different drivers, even the effect on the ear/pinna of the different vertical placement of the drivers which is more sensitive in higher frequencies. All of these are ~6-9dB less audible when placing the crossover this low. And you get the most sensitive and important region of about 2-5kHz handled by a single driver. Coincidentally you also get easy near coaxial vertical phase behavior as discussed earlier in this thread
Perhaps an alternative could have been a mid driver handling 400Hz to 5-6kHz or so, but it feels less natural to me to cross over to a supertweeter at 5-6kHz or higher (hard to get a good in phase angle at the crossover due to the very small distance required to the mid driver) and I'm not sure if there is a mid driver that can do the ~400-6000Hz range well enough with room to spare around the crossover points.

Anyhow, this is how I found the BlieSMa driver. It's clear a 1" tweeter is not up to the task of this low a crossover even in a waveguide (compression driver in a horn is a different story but not suitable for my nearfield use) and the BlieSMa is the only one that can do it this well. Lucky I didn't want to design this speaker a year ago as there would have been no good tweeter yet for the task, the BlieSMa was only released this year
Btw, there is a beryllium version as well, the T34B-4, but I don't see any benefits other than for bats and a slightly enhanced sensitivity (and it does slightly worse in fact for the third harmonic around the crossover).

Now looking for a great woofer to go with the BlieSMa. Perhaps a Seas W18EX001 would be a natural match.. Could add a true sub later as well.

It's got good 3mm travel for low frequency xo. Take a look at the sb acoustics woofers, I found the specs of many of the usual Scandinavian suspects unimpressive.

Mw19

 

[JustIntonation]

So in other words you don't know that it's bad, just inferred it from a lack of information.

Well some measurements will come soon but I can certainly tell you that it doesn't suffer a noticeable difference when you stand up from sitting down. If it beamed it would be noticeable.

I inferred it from much information regarding off-axis behavior of tweeters
But still curious about the measurements!

What the AMT does do is have a good horizontal dispersion. Perhaps with a fairly large listening distance and in your room with partly diffuse sidewall reflections this makes up somewhat for the narrow vertical dispersion?
Btw, if I were listening in an average room I'd probably prefer a very narrow vertical dispersion of the tweeter. Ceiling and floor reflections are usually pretty bad for treble quality. (but my room won't have any floor or ceiling reflections in the treble to start with and I'll be listening nearfield so then treble vertical dispersion becomes an issue, already well known from for instance ADAM nearfields and they use tiny AMTs which still give a very narrow vertical window)

And thanks for the woofer suggestion!

 

[March Audio]

But you said you can't infer . BTW I do have diffusion on my ceiling.

 

[March Audio]

OK, I tried a very quick and dirty measurement of the vertical dispersion. Its pretty crude by any standard so dont take it too seriously, but I wasnt about to haul it into the garden . So on axis at 1m, about 15deg, 30deg and 45 deg.

What is interesting, and its seen in the manufacturers data, is that between 10 and 20kHz the amplitude drops, but doesnt keep on dropping with increasing frequency unlike all the domes I have seen.

I have a pair of B&W CM5 S2 here and will try the same measurement for comparison when I get a chance

 

[andreasmaaan]

I've found my tweeter!
The BlieSMa T34A-4

Good choice IMO. Only slight quibble would be with off-axis response, which is a little erratic in the 2-5KHz region, so be conscious of that when designing the crossover. Averaging measurements across e.g. a +/- 15° listening window will produce better results than simply equalising for a flat on-axis response. I'm sure you're on top of this already anyway

 

[JustIntonation]

Good choice IMO. Only slight quibble would be with off-axis response, which is a little erratic in the 2-5KHz region, so be conscious of that when designing the crossover. Averaging measurements across e.g. a +/- 15° listening window will produce better results than simply equalising for a flat on-axis response. I'm sure you're on top of this already anyway

Thanks! And yes I saw the off-axis response at the lower end (I belief it's shown best at the voice coil test bench), but it only truly shows itself starting somewhere between 15 to 30 degrees, I won't be moving that far off-axis and won't get any off-axis reflections either.
edit: I now think these are baffle diffraction effects of the measurements of both Voice Coil and Troels Gravesen (both are different) these effects are not visible in other measurements.

 

[JustIntonation]

OK, I tried a very quick and dirty measurement of the vertical dispersion. Its pretty crude by any standard so dont take it too seriously, but I wasnt about to haul it into the garden . So on axis at 1m, about 15deg, 30deg and 45 deg.

What is interesting, and its seen in the manufacturers data, is that between 10 and 20kHz the amplitude drops, but doesnt keep on dropping with increasing frequency unlike all the domes I have seen.

I have a pair of B&W CM5 S2 here and will try the same measurement for comparison when I get a chance

View attachment 16039

View attachment 16047

Cool
But I think that it doesn't drop so much and doesn't keep dropping because of reflections. The direct sound seems to me must continue dropping?

 

[March Audio]

Cool
But I think that it doesn't drop so much and doesn't keep dropping because of reflections. The direct sound seems to me must continue dropping?

Certainly a possibility, but you can also see it in the manufacturers graph.

I will measure the B&Ws when I get a chance and see what they do.

 

[March Audio]

The B&Ws arent anywhere near as flat as my own on axis, +-3dB as shown here between 6kHz and 20kHz, but the vertical dispersion is better, in fact way better than some of those examples in the earlier post. Follows the sort of curve you might expect, so I dont think reflections are entirely the answer to the AMT flat response.

on axis AMT v B&W +-1dB, +-3dB

AMT & BW 45 deg. However, if the B&W did not have that 3.5dB hump at 10kHz it wouldnt look so impressive off axis.

The bliesma looks good

I will try the horizontal of the AMT when I get a chance, we know this is much better, but how much better than the domes?

 

[JustIntonation]

Just a little update..
Have found my mid-woofer The SB Acoustics SB17NBAC35-4.
For some time I thought it would be the Seas W18EX001 but the more I read about drivers and the more I thought about what matters most I came to a different conclusion.
The W18EX has its main cone breakup right in the middle of the most sensitive zone for our ears if you look at the equal loudness curve. And it's a nasty cone breakup as well giving a 15dB peak which rings like crazy at just under 5kHz. And if the tweeter is crossed steep at 1.3kHz then most of the 3rd harmonic distortion can be supressed before it falls on this peak but not all, and the fifth harmonic distortion at just under 1kHz will be reduced only less than 3dB so it is very much amplified by this peak. And on top of that the ear is about 6dB more sensitive at that point (than at the fundamental frequency of 1kHz) so in reality it may well be somewhat audible especially given that it will also ring in time. I like that the W18EX has great linear behavior / CSD and fairly low distortion, but the very worst place to have a big ringing peak is between 2 and 6kHz and its the very region I want to keep as clean as possible as I've had issues with this region with previous otherwise very good speakers.
The SB17NBAC35-4 (and the SB17NAC35-4) is an aluminum 6" driver, but as I think the only aluminum driver of this size it does not produce its main breakup peak in the sensitive region but instead manages to shift it all the way to 9-10kHz! There is cone breakup starting above 4kHz but it is very mild and mostly non ringing untill it is at about 10kHz where it does ring though even then not as bad as for instance the W18EX. And around 10kHz the ear is a whopping 15-20dB less sensitive (for low level sounds like harmonic distortion) than between 2-5kHz. Further reading showed my reasoning to be correct in that people have commented when listening to this driver full range during measurement tests that it doesn't even sound like a metal driver. So you get the benefits of an aluminum cone without the main drawback. Furthermore the CSD looks fine and distortion is very low and t/s parameters look fine. Added benefit is that this driver costs 4 times less than the W18EX Oh and it can be crossed higher than the W18EX, 1400Hz which was my original plan is perfectly fine with the SB17NBAC35-4 and gives a nice range above this for the crossover to be perfect and when crossed at 1400Hz the off-axis radiation pattern still perfectly fits a direct radiating dome tweeter! (no waveguide needed at all for off-axis radiation pattern matching)

As for the tweeter.. with a bit more knowledge I think I can now see that the BlieSMa T34A-4 has mild cone breakup starting already at 14kHz. This is part of the reason for its very wide dispersion above this. The very round dome profile should start dropping off at 14kHz on-axis and it looks flat on-axis because this is where the breakup rise is starting. Designed this way of course, but there is no perfect piston motion above 14kHz anymore.
For the beryllium version T34B-4 the cone breakup doesn't start till above 19kHz. So perhaps it is the better choice even though it costs 100Euro more per tweeter..

So SB17NBAC35-4 + T34B-4
Only need to find a good bass woofer now (closed box), thinking about ~160Hz crossover. Any tips welcome!

 

[JustIntonation]

No decision on the bass-woofer yet. Ordered 4 past editions of Hobby Hifi with a lot of woofer measurements in them that should help, will get them somewhere next week. Though so far the ScanSpeak 26w/4867t00 looks great.

As for the amp. I don't think I'll be going for the Hypex Fusion amp.
The DAC in it had me doubting a little bit already. It has -102dB THD+N at -1dBfs, not really that great. And no mention of jitter or linearity etc or anything else. And the signal path goes from an asynchronous reclocker to DSP to DAC.
On top of that, this DAC has to work really hard/well at low levels. If I were to go for the FA253 if the bass-woofer needs 250W then the mid-woofer also gets 250W which means it needs quite a bit of attenuation. So the DAC would be used quite a lot of dB down. And it wouldn't be easy to add a stepped attenuator or something like that and would void warranty.
And the final straw is the following.. They are to be used with one FA253 amp per speaker. And the amps are linked digitally through a cable. However, this does not sync the clocks in each plate amp. The clocks can drift relative to eachother. And I also saw mention that with at least earlier Hypex plate amps that there seems to be a delay introduced for the slave and that people are commenting that when using the digital input on the master and linking it to the slave that imaging is affected which is solved by using the analogue inputs of the plate amps..
All in all I don't have full trust that it is all done perfect enough on the digital side..
So I think I'll be getting (maybe partly building) a multichannel DAC, do the crossover filtering and driver EQ corrections on the computer, and get a few Anaview AMS amps. Certainly won't loose quality over the Hypex Fusion amp this way and could possibly gain some (at least on the digital / DAC side). edit: though perhaps getting a seperate Hypex DLCP could be an option too as it has 6 channels running from a single clock.. hmm.

Oh and btw, I'm selling my Anedio D2 DAC. Won't have any use for a stereo DAC anymore. If anybody is interested send me a pm.

 

[andreasmaaan]

Thanks @JustIntonation. Keep the updates coming

 

[lamode]

I just registered after stumbling upon this thread. Seems that we have some similar ideas. (Enjoyed the Aruna Sairam link too)

No decision on the bass-woofer yet.

Did you make a decision re the woofer?

As for the amp. I don't think I'll be going for the Hypex Fusion amp.

I share all your concerns, though they are only unverfied concerns at this stage. Need to dig a little deeper.

 

[JustIntonation]

I just registered after stumbling upon this thread. Seems that we have some similar ideas. (Enjoyed the Aruna Sairam link too)



Did you make a decision re the woofer?



I share all your concerns, though they are only unverfied concerns at this stage. Need to dig a little deeper.

Yes I've dug deeper and made the decisions. More talk on this forum spread out over several threads, a bit of a mess sorry
Woofer is Seas L26ROY XM001-04 and amp Hypex FA123. (and BlieSMa T34B-4 tweeter,SB Acoustics SB17NBAC35-4 mid)
Had a few delays. Will finally be building the final cabinets this month. (4cm thick walls, closed with about 10cm radius roundover)

 

[Newk Yuler]

This is suppose to be a drop-in EMIT-R replacement for late Arnie Nudell era Infinity and Genesis Technologies speakers in the 1990s. I believe Genesis Tech still uses them in their speakers. I'll let you do the research instead of elaborating further. I have long had a huge appreciation for EMIT tweeters. Especially when I had a young man's hearing. The price is right for you, too.

https://www.ebay.com/itm/161675153684

Just realized this thread has long teeth.

 

[maty]

Tannoy has two new concentric / coaxial studio monitors. Biamp with only class AB -> tweeter without cheap class D.

https://www.tannoy.com/Categories/T...io-Monitoring/GOLD-7/p/P0CMZ#googtrans(en|en)

https://www.tannoy.com/Categories/T...io-Monitoring/GOLD-8/p/P0C2C#googtrans(en|en)


Gold 7

Cleared to see the front-firing bass port!

• Premium 300 Watt bi-amped nearfield studio reference monitor for accurate sound reproduction with outstanding definition
• Ultra precise and neutral soundstage delivers non-fatiguing sound for extended listening sessions
• Legendary Tannoy Dual Concentric driver technology provides class-leading phase coherence and point-source imaging
• Front-firing bass port design allows for near-wall placement and ensures optimal low frequency performance
• Next generation 6.5” Dual Concentric driver secures unrivalled musical articulation and outstanding dynamic
• 1" titanium tweeter with Tulip waveguide produces detailed stereo image with widened “sweet spot”
• Class-AB system with transducer-matched LF and HF bi-amplification for accurate dynamics
• Continually-active XLR and TRS phone jack inputs let you connect up to 2 audio sources
• Dedicated input trim, bass and treble controls let you optimize the audio for your listening conditions
• Selectable automatic standby mode conserves energy...

Resiced, optimized..

 

[Norway]

I am looking into adding a tweeter on my Altec system. Any suggestions where to look? The 1505/288 have very high sensitivity so the unit must(for the integration) be in the 100 db+! Mundorf AMT 29 CM 2.1 is a possible candidate, but how will this integrate? Planing on crossover(active) point in the 8-10 kHz region. RAAL 140 is another candidate.