Beyma TPL-150 air motion transformer

[StigErik]

I have a pair ... but no time yet to try them out. I searched this forum, but it seems like there's not much experience with this driver yet.

AMT's are quite rare anyhow. I have tested a couple from Mundorf, I found their AMT2340 to be very good, although its not happy with crossover below 3 kHz.

I hope the Beyma can be crossed over an octave lower, so it can be matched with the 8" Seas Excel magnesium (which is great only below 1500 Hz or so)

Well... I hooked them up and measured them with my Clio (without any baffle). The response is not as smooth as one might expect, but not too bad I think. It will require a couple og LRC networks for EQ to get the response within 1 dB.

Ok, here are the measurements:

http://home.online.no/~st-e-tan/bild...q-response.gif

http://home.online.no/~st-e-tan/bild...-150_decay.gif

If anyone else would like to share experience with this driver, I would appreciate it a lot.

[Taco]

Unfortunately, I've only experience with the Mundorf 2340 and the Eton Er-4, like you I learned that the Mundorf needs to be crossed > 3 kHz (also rumors are that Mundorf abandons these tweeters from DIY as they encountered a high failure rate due to incompetence). The Er-4 is better in that regard, but has an irregular FR with high distortion below 2 kHz.

I've considered the Beyma but when the high sensitivity isn't needed the Raal 140-15D is a better option. It measures even better and you can hit XO around 1500 Hz rather easy.

I can remember another design of you where you are using the Philips RSQ8P (which I'm also using in a design) and can say that with ease of integration at low XO points the Philips is the better choice.

With regard to sound quality IMHO the Raal tops the Mundorf, Eton and Philips.

Looking at your response graphs, the xo-filter needs some work to equalize the top end response, but a lot of the irregularities come from the unbaffled measurements.

I got best results with the 8" magnesiums when using a 6th order cauer elliptic cross-over around 1300 Hz (crossed to Er-4).

[elac310]

Hi Stig,

I have made some tries with the TPL 150, crossed at 2,5-3kHz with a 6 dB slope, + a serial resistor to take away some sensitivity. Works quite fine in combination with a couple of Audax HM210Z10 which cover the mids (+ a couple of 15 inchers for the low end). I do not often listen Music very loud so I have little experience to say whether they sound stressed or not at high levels (I've fed this set up with a max. of 10 watts or so per channel and my wife would come in the listening room for me to turn the volume down before I can make a fair assesment...)

Cheers.

[Telstar]

Originally posted by Taco

With regard to sound quality IMHO the Raal tops the Mundorf, Eton and Philips.

I see that you have experience with some of the ribbons that I'm considering.

What would you recommend for a very high XO point (basically a supertweeter): it can be 6k, 10k or 14k (depending on the wideband that I will choose).

The filter MUST be a 1st order. Some equalization is possible, but I dont want to rely on that. Vertical dispersion more important than horizontal to me (i'm considering mounting horizontally).

[StigErik]

Originally posted by Taco
Unfortunately, I've only experience with the Mundorf 2340 and the Eton Er-4, like you I learned that the Mundorf needs to be crossed > 3 kHz (also rumors are that Mundorf abandons these tweeters from DIY as they encountered a high failure rate due to incompetence). The Er-4 is better in that regard, but has an irregular FR with high distortion below 2 kHz.

I've considered the Beyma but when the high sensitivity isn't needed the Raal 140-15D is a better option. It measures even better and you can hit XO around 1500 Hz rather easy.

I can remember another design of you where you are using the Philips RSQ8P (which I'm also using in a design) and can say that with ease of integration at low XO points the Philips is the better choice.

With regard to sound quality IMHO the Raal tops the Mundorf, Eton and Philips.

Looking at your response graphs, the xo-filter needs some work to equalize the top end response, but a lot of the irregularities come from the unbaffled measurements.

I got best results with the 8" magnesiums when using a 6th order cauer elliptic cross-over around 1300 Hz (crossed to Er-4).

I've worked a lot with the TPL-150 now, especially in my latest open baffle speaker, so I have some experience to share... I've also used the Mundorf 2340 and Philips RSQ8P. To my ears the Philips is nowhere in the same territory sonically as the Mundorf or Beyma AMT's. Yes - it does have a flatter frequency response, and will be easier to integrate. The two AMT's both require a lot of EQ to get good results, which may be impossible using passive XO.

I favour the Beyma over the Mundorf also, because the Beyma can be crossed over an octave lower, and also has a much larger maximum SPL - it dont sound compressed at any domestic listening level, which the Mundorf will, especially if crossed over below 3 kHz.

The Beyma can be very frustrating to work with... if you dont get the EQ or crossover right, it will bite back and display your EQ errors more than you might want... but get it right... there's nothing better IMO.

My recommended XO for the Beyma is 1300 Hz or higher - perfect match for the 8" Seas Excel magnesium!

I've never tried the RAAL ribbons, so I dont know if they are better or worse. I will see if I can find a nice project to try them as well!

[Telstar]

Originally posted by StigErik
I favour the Beyma over the Mundorf also, because the Beyma can be crossed over an octave lower, and also has a much larger maximum SPL - it dont sound compressed at any domestic listening level, which the Mundorf will, especially if crossed over below 3 kHz.

The Beyma can be very frustrating to work with... if you dont get the EQ or crossover right, it will bite back and display your EQ errors more than you might want... but get it right... there's nothing better IMO.

Hi Erik,

Where the problems ends with the beyma or mundorf ribbons? If you see my post above I want to cross it VERY high (14k most likely) and using like a supertweeter. Also, passive XO, but possible EQ above.
The Beyma is quite more expensive, but more sensitive,

About this point i think the efficiency of a tweeter gets higher when crossed very high (which nobody seem to do anyway). I wonder which would be the REAL sensitivity of i.e. the mundorf 2440 (not the 2340) when crossed above 10k.