I'm thinking about trying to use a Morel MDM 55 dome mid with a Visaton ribbon or maybe one of the Founteks or Aurum Cantus in a first order, time-aligned 3 way. (Crazy, eh?)
The Morel literature indicates that due to well controlled roll-off on both ends that it's a possible to use a first or second order xover. It seems to have high power handling capability and a very clean waterfall. Frequency range extends up to around 6k with better dispersion than typical mid/bass cones.
The Visaton ribbon has very little info on the web but I've heard some positive comments and the sensitivity seems to be a good match, around 90db, with the Morel mid dome.
Question is, will the Visaton survive a first order slope if the target frequency is about 6k or 7k?
Any advice will be appreciated,
David
The Morel literature indicates that due to well controlled roll-off on both ends that it's a possible to use a first or second order xover. It seems to have high power handling capability and a very clean waterfall. Frequency range extends up to around 6k with better dispersion than typical mid/bass cones.
The Visaton ribbon has very little info on the web but I've heard some positive comments and the sensitivity seems to be a good match, around 90db, with the Morel mid dome.
Question is, will the Visaton survive a first order slope if the target frequency is about 6k or 7k?
Any advice will be appreciated,
David
Hi David,
I am not quite sure whether the Visaton ribbons will survive this or merely produce unreasonable amounts of distortion, but you might want to repost your question in the Visaton discussion forum (in german, but they'll all rally if you're anglophone, so posting in english is perfectly OK - some Dutch folks do it all the time).
http://www.visaton.de/vb/forumdisplay.php?s=&forumid=35
You need to register, though, by clicking on "Registrierung" in the top menu bar - the rest in pretty straightforward. In case of more questions, pm me.
Since one of the admin is head of Visaton's R&D, you should get all you need there.
On a more personal note, I wouldn't bother to built a time-aligned speaker if one of the xover frequencies is 7 kHz; lambda at this frequency is some 5 cm / 2", so you'll be in hefty trouble with interference between the Morel and the Ribbon. This even more so as you opt for a first-order filter, which is providing a huge overlap between these two drivers' frequency range.
Another comment: do not use odd-order filters for non-symmetric (i.e., unlike d'Appolito) configuration as the acoustical axis will "wiggle" around xover frequency. Instead, use even-order filters. Also, using active xovers will easily enable you to i) maintain proper axis, ii) ameliorate the vertical radiation pattern, iii) xover at lower frequency (12 or even 24 dB/oct!) and/or decrease distortion and overlap, and all this while iv) keeping a time-aligned, i.e. (quasi-)transient-perfect xover design (12 dB/oct only, though).
Just my ideas.
Cheers,
BK
I am not quite sure whether the Visaton ribbons will survive this or merely produce unreasonable amounts of distortion, but you might want to repost your question in the Visaton discussion forum (in german, but they'll all rally if you're anglophone, so posting in english is perfectly OK - some Dutch folks do it all the time).
http://www.visaton.de/vb/forumdisplay.php?s=&forumid=35
You need to register, though, by clicking on "Registrierung" in the top menu bar - the rest in pretty straightforward. In case of more questions, pm me.
Since one of the admin is head of Visaton's R&D, you should get all you need there.
On a more personal note, I wouldn't bother to built a time-aligned speaker if one of the xover frequencies is 7 kHz; lambda at this frequency is some 5 cm / 2", so you'll be in hefty trouble with interference between the Morel and the Ribbon. This even more so as you opt for a first-order filter, which is providing a huge overlap between these two drivers' frequency range.
Another comment: do not use odd-order filters for non-symmetric (i.e., unlike d'Appolito) configuration as the acoustical axis will "wiggle" around xover frequency. Instead, use even-order filters. Also, using active xovers will easily enable you to i) maintain proper axis, ii) ameliorate the vertical radiation pattern, iii) xover at lower frequency (12 or even 24 dB/oct!) and/or decrease distortion and overlap, and all this while iv) keeping a time-aligned, i.e. (quasi-)transient-perfect xover design (12 dB/oct only, though).
Just my ideas.
Cheers,
BK
Chagall said:
brummkreisel said:Hi David,
The Morel is an ok mid dome but its not that great in the real world, I have a pair in my AV center channel and its been tricky to get the crossover just right but even then i really dont need them and they just do not sound as open or dynamic as the ATC soft dome, The morel can sound harsh or bright. I have them and do not recommend them, there tricky.
Chagall - I made a loudspeaker like you're suggesting back in '82 for a senior paper when graduating out of EE school. The problem with the xover at 7khz is "problematical" just as Brummkreisel suggests, but I went ahead and did the unusual thing anyway, just to see more than anything. Firstly, I tested strictly around the drivers themselves and found the Panasonic EAS400 ribbon tweeter to be absolutely stunning and breathtaking in performance, and an Audax dome midrange was used, as was an 8" Audax bextrene woofer. You have to understand that choices of anything were rather limited way back when. I had to wind my own coils, and I used mylar caps. The crossover was a 2nd order Bessel for the woofer, a 2nd order BP filter for the midrange (BW was optimized for Q and linearity), and a 1st order at ~7khz for the ribbon. You should have seen it when it got done,..held together with bailing wire and ductape,..am not kidding,...and it was all staggered too...lol. When all was said and done, the midrange was staggered some several inches behind the woofer
and I smoothed the response out with a piece of foam rubber cut like a wedge with the upper part at the bottom of the midrange unit and sloping down to the top edge of the woofer cabinet. It actually worked quite well, was rather surprised how well it turned out. The ribbon rested upon a cutout placed about 1-2 inches behind the midrange, very crude,..but hey,..I was having a blast. Basically, I wanted to use those particular drivers, so that's
why the design came out the way it did. It was doable and the crossover were filters out of a textbook. Anyway, I knew at the time it was quite the unusual approach, but the sound I got
out of them was truely fantastic. I had a few people comment on how good they sounded,..one guy even said they sounded better than a high end model he had..(no names mentioned here, wanna stay out of trouble.) Anyway, the midrange and highs had an almost electrostatic quality, very transparent at any rate. I had fun with this design and used it as a learning experience. I was time challenged in getting this done, so wasn't able to take a million measurements or anything, but my spectrum analyzer told me enough about the phasing and response to get an idea of what was going on. Overall, I had no regrets making it. BTW, the speaker is dead now, gone on to audio heaven. There were a couple of things I could have done to make it live longer, but I had my fun. I still have the ribbons too. It would not have been marketable due to obvious reasons, but the sound in my living room was all I cared about.
and I smoothed the response out with a piece of foam rubber cut like a wedge with the upper part at the bottom of the midrange unit and sloping down to the top edge of the woofer cabinet. It actually worked quite well, was rather surprised how well it turned out. The ribbon rested upon a cutout placed about 1-2 inches behind the midrange, very crude,..but hey,..I was having a blast. Basically, I wanted to use those particular drivers, so that's
why the design came out the way it did. It was doable and the crossover were filters out of a textbook. Anyway, I knew at the time it was quite the unusual approach, but the sound I got
out of them was truely fantastic. I had a few people comment on how good they sounded,..one guy even said they sounded better than a high end model he had..(no names mentioned here, wanna stay out of trouble.) Anyway, the midrange and highs had an almost electrostatic quality, very transparent at any rate. I had fun with this design and used it as a learning experience. I was time challenged in getting this done, so wasn't able to take a million measurements or anything, but my spectrum analyzer told me enough about the phasing and response to get an idea of what was going on. Overall, I had no regrets making it. BTW, the speaker is dead now, gone on to audio heaven. There were a couple of things I could have done to make it live longer, but I had my fun. I still have the ribbons too. It would not have been marketable due to obvious reasons, but the sound in my living room was all I cared about.
Thanks guys
Retro, Ice, BK
Many thanks for your thoughts on the Morel dome Visaton idea.
Not having any first-hand experience with either driver, I find your comments most illuminating.
My curriosity was peaked by the morel dome, but I'm sure the ATC driver offers far better performance, albeit at a different price point.
Was just wading through the marketing mumbo jumbo, er, I mean the "white paper" of a high-end speaker company that was extolling the virtues of 24db slopes with an in-phase response when rotated 360 degrees, combining with driver roll off to create a fourth order acoustic response. Hmm... and a wonderbar 4.5" kevlar laminate focal cone mid...
Off to explore,
David
Retro, Ice, BK
Many thanks for your thoughts on the Morel dome Visaton idea.
Not having any first-hand experience with either driver, I find your comments most illuminating.
My curriosity was peaked by the morel dome, but I'm sure the ATC driver offers far better performance, albeit at a different price point.
Was just wading through the marketing mumbo jumbo, er, I mean the "white paper" of a high-end speaker company that was extolling the virtues of 24db slopes with an in-phase response when rotated 360 degrees, combining with driver roll off to create a fourth order acoustic response. Hmm... and a wonderbar 4.5" kevlar laminate focal cone mid...
Off to explore,
David
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