My open baffle dipole with Beyma TPL-150

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Which one Mundorf? I had a couple of Kitharas for several weeks at home and I'd never seen any other looking similar.
Similar to these running open backed and nude.
.
http://www.mundorf.com/english/speakerschassis/Air-Motion-Transformer.pdf

BTW
this is my latest:

P3120007_bearb.jpg



beautiful Mundorf AMT 2510c.
Seems - on request - they are available as "nude" for dipole horns as well (with considerable cost saving due to missing front plate)
:)


Michael

:)
Michael
 

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I think the only similarity is that ALL are AMTs (Mundorf, ESS, etc.) with a pleated diaphragm, but if you have a close look to a Kithara you'll be rapidly convinced that this beast is unique !...

At least it is half an ESS !...:))

Unique yes - beast possibly - but nothing I'd think would have any sonic advantages.
Looks a little bit as if they agreed to pay half the tax for building half a Heil.
;)
Fortunately the patent expired - maybe those Swiss missed it ...
:D

Michael
 
Hello Stig,

at first - thank you very much for sharing all this very inspiring findings here on-line !

The `new´ solution you are exploring now is close to something I am mentally pregnant with for many years now. It is so elegant and simple. The only `downside´ for a DIY addict is that there isn´t too much to build and develop myself any more :eek:.

What held me back trying something like this till now. But may be not for too long any more ...

Have you done 0-90° measurement on the RD´s? And - even more important in my view, because sometimes I need to listen loud - did you took a look at the distortion behaviour of the modules? What do you think is the loudest they can stand if used down to 180 HZ in a pure dipol configuration? I heard/read that the big BG RD´s should have mechanical problems in the most important mid tone area. But I could not find any valued data about that claim.

Greets Fabian
 
Hello StigErik,

You finally went to line-source! I remember I posted a long time ago about it. I am very curious on what your thoughts are and how it compared to your previous setup.

Is the high end as transparent and fluid as the beyma ribbon?

How does the sound stage of the line-source compare to the multi-way?

Do single musical elements like the voice get "tall" because of the line-source?

etc, etc..

Thanks!
 
Why is that crazy? Anyway its crazy good. :)
.


I guess there is sort of homogeneity in presentation of full range speakers that is hard to achieve with *any* multi way system - no matter how well EQed and how good impulse response may have looked like.

Great to hear it turned out so well, Stig Erik and thanks for sharing your impressions.


Michael
 
Why is that crazy? Anyway its crazy good. :)

It is crazy because not so log ago it was unthinkable that such device would ever exist. Even much larger ESL panels have to be crossed higher. That relatively tiny BG (tiny area, 75inches is way too big in my book for a domestic speaker) can actually generate almost 100dBSPL at 150Hz is, well, crazy !
Yes, crazy good :D
 
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Joined 2008
Hello Stig,

at first - thank you very much for sharing all this very inspiring findings here on-line !

The `new´ solution you are exploring now is close to something I am mentally pregnant with for many years now. It is so elegant and simple. The only `downside´ for a DIY addict is that there isn´t too much to build and develop myself any more :eek:.

What held me back trying something like this till now. But may be not for too long any more ...

Have you done 0-90° measurement on the RD´s? And - even more important in my view, because sometimes I need to listen loud - did you took a look at the distortion behaviour of the modules? What do you think is the loudest they can stand if used down to 180 HZ in a pure dipol configuration? I heard/read that the big BG RD´s should have mechanical problems in the most important mid tone area. But I could not find any valued data about that claim.

Greets Fabian
Something has held me back from trying the RD-75 ribbons for a long time - they are expensive and have fairly low sensitivity, but the main factor was the top-end roll off I think. I believed it need a super-tweeter, but in fact it doesn't. You can EQ it, but its really not required. I do have an EQ at 20 kHz to lift the response, but the difference when I turn that EQ off is almost zero.

I have not as yet done proper off-axis measurements. Will do that later. From just listening I can tell that there are no big nasties in the off-axis response, but at high frequencies the front and rear lobe is much smaller than at lower frequencies. This is because of the width of the driver; its not going to have a good figure-8 pattern above 2-3 kHz or so.

I did have a slight "buzz" in one of my ribbons, it has more or less disappeared now... of some reason. This "buzz" was a mechanical thing with the ribbon, possibly caused by the ribbon touching the magnet. It was easiest to provoke with soprano singers... around 4-600 Hz I guess.

Have not measured distortion, but it sure sounds very very clean, even at 200 Hz. Much cleaner that the four 8" Seas Excel I used in my 4-way dipoles!

I don't think the ribbon can play very loud at 200 Hz, but its enough for me, and I like to play up to 95 dB on average (that's 105-110 dB peak). I can do some measuring here as well!
 
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Joined 2008
Hello StigErik,

You finally went to line-source! I remember I posted a long time ago about it. I am very curious on what your thoughts are and how it compared to your previous setup.

How does the sound stage of the line-source compare to the multi-way?

etc, etc..

Thanks!
It was a surprise for me as well to discover how amazingly good this B&G RD-75 driver really is! :)

Line-source or not - I'm not sure if that's the main explanation for its performance. I think its more due to low distortion, low coloration, and the lack of crossover points in the midrange.

Compared to my old system its cleaner, less coloration. Better resolution, and better imaging - both more stable pin-pointing, but also deeper and wider soundstage with more spaciousness. The dynamics are different, I think the ribbon is more "correct", while the old dipoles could offer some more "punch". But I think that this "punch" is wrong - it's transient distortion in my opinion.

One thing that I never actually solved with the old 4-way dipoles was the mid-bass. It was a bit "fat". I think the main reason for this is distortion. Nude 8" drivers will have a rising frequency response that augments the higher order distortion products, which is not a good idea. I actually found that my 21" Beyma woofers in H-baffles were far better up to 200 Hz than the nude 8" Seas Excels.


Is the high end as transparent and fluid as the beyma ribbon?

It is better, no doubt.

Do single musical elements like the voice get "tall" because of the line-source?

No, but then I cant hear height either... When I move my head up and down the ribbon, the sound remains firmly in front of me.
 
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Joined 2008
I guess there is sort of homogeneity in presentation of full range speakers that is hard to achieve with *any* multi way system - no matter how well EQed and how good impulse response may have looked like.

Great to hear it turned out so well, Stig Erik and thanks for sharing your impressions.

Michael
Well yes..... but what are our best choices for a nearly fullrange driver? I've heard some of the paper-cone wideband drivers out there... You can EQ to hell and back, and it still sounds like shite to me. Large electrostatics can sound quite good though, but they are not without problems either. And then we have large ribbons. The only non-DIY ribbon I know that can do 150 to 20 kHz is the B&G RD-75.

It really turned out well! And its suspended in a swing... thanks to you Michael for that great great idea! :)
 
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