John Curl's Blowtorch preamplifier part II - Page 3429 - diyAudio
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Old 6th February 2013, 02:13 AM   #34281
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Kgrlee,
Just out of curiosity what type of plastic did you use for the suspension? TAD uses the beryllium itself but to try and get down to 2.5Khz I feel will not be practical for that much excursion.
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Old 6th February 2013, 02:24 AM   #34282
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Quote:
Originally Posted by john curl View Post
At this time, both Jack Bybee and I will be watching MAIGRET on independent TV, in our separate residences..
It was our studio whitch did the sound post production for Maigret (Editig and mixing). All digital.
We first used a lot of 4track virtual machines (Akai DD1000) working in sync. Not designed at all for that kind of work. We had designed a computer based program to drive the machines in midi with ATARI's computers. That surprised a lot Akai, so they came from Japan to visit us and few time later asked us to help them to design a new more powerful machine with can be used for movie work. We realized with them the DD1500, a fantastic 16 tracks virtual recording, editing and mixing machine, with DSP etc...
Those machines had survived at all the computer progress for more than 15 years, incredible !!! We had a lot of them, working in dispatch from a nodal to reach an unlimited number of tracks in each room, including the mixing studio.
One sympatical detail: As the line inputs where feed in permanence in first-in first out memories, it was possible to edit sounds that occurred one second BEFORE the record button was fired. The machines was able to synchronize in slave with all existing equipments at this time, audio (SMPTE), cinema (Biphase) or video and can be used as a digital master clock too.
Click the image to open in full size.

To come back to this super tweeter question, i would like to add some precision. I use a JBL driver up to 16Khz. All my attempts to add a tweeter gave bad results. Of course, the tweeter was time aligned. But the tweeter i was using was not going so high in frequency. So i wonder if the phase problems induced by the filters was not adding more prejudice than benefit. May-be, trying to cut the tweeter at 16Khz with a super tweeter up to 50Khz would give better results ?

About Plasma tweeters, i had experience and measurements with IONOVAC. Very bad : they just produced some kind of modulated pink noise.
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Last edited by Esperado; 6th February 2013 at 02:44 AM.
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Old 6th February 2013, 02:50 AM   #34283
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A small correction, Jack Bybee's Bentley was only certified at 202.9 MPH at the Bonnieville Salt Flats driven by Jack, himself, rather that 205 MPH that I first presumed. '-)
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Old 6th February 2013, 03:03 AM   #34284
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Christophe,
I have no experience with the plasma tweeter and don't intend to even look in that direction, I'll leave that to others to play with........

As to your upper frequency response I don't know if you are using a 2", 1 1/2" or 1" driver for your top end. I would take a look at the Brush Wellman beryllium replacement diaphragms and see if the decrease in mass wouldn't help lift the top end. I know I have read articles that have said lowering the mass has no effect but I don't believe that. And the resonance modes are moved higher in the band. The only problem is that the diaphragms are so expensive, but we are after the best sound not the cheapest sound we can get. You and I both know that live sound reinforcement is very different than playback and the requirements are very much different. If size was not an object I would build an ultimate horn system, but alas I just don't think I want to bring any of my double 18" waveguides into the house. I have 8 units that I need to finish but I will sell those to someone doing PA work. I used four of these cabinets to replace 16 of the cabinets that John's friend John Meyers built back in the day.
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Old 6th February 2013, 03:05 AM   #34285
jcx is offline jcx  United States
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accuton® Carefully selected loudspeaker drivers. | Drivers

the actual product datasheet fr plots only show to 20 kHz

directivity may be a problem with 20mm dia dome - as with anything that high


electrostatic headphones may your best bet for listening tests

even if they acheived a mostly planar wavefront it still wouldn't be "realisitic" for any musical instrument''s 20+ kHz acoustic radiation pattern reaching your ear either

Last edited by jcx; 6th February 2013 at 03:20 AM.
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Old 6th February 2013, 03:30 AM   #34286
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Originally Posted by Kindhornman View Post
As to your upper frequency response I don't know if you are using a 2", 1 1/2" or 1" driver for your top end.
To go flat up to 16Kh, it is a 1", of course, used from 750Hz. I will not change the membrane for no price, as it was paired and selected at the time and a lot of work with the filter for it.
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Old 6th February 2013, 05:41 AM   #34287
fas42 is offline fas42  Australia
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You and I both know that live sound reinforcement is very different than playback and the requirements are very much different.
There are plenty of gentlemen here, , who have the experience to answer ... why? What intrinsically is so different from, say, reproducing the vocals of a singer on stage to an audience, getting the tonality right, from doing the same thing, for the same singer, in someone's lounge. Yes, the SPLs will be quite different, but ... if I lowered the PA volume to match the highest volume the domestic system could cleanly reproduce, by sound metre at 1 metre, shouldn't they sound the same? Okay, FR for the stage setup may have been manipulated to account for the auditorium acoustics, but let's say the response is adjusted to match the domestic system ...

Is there any theoretical reason why those 2 sound sources won't reasonably match, to a casual listener?

Frank
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Old 6th February 2013, 07:31 AM   #34288
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Originally Posted by john curl View Post
A small correction, Jack Bybee's Bentley was only certified at 202.9 MPH at the Bonnieville Salt Flats driven by Jack, himself, rather that 205 MPH that I first presumed. '-)
He MUST be a great driver. I wonder if James May, Jeremy Clarkson and Richard Hammond have already contacted him
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Old 6th February 2013, 08:25 AM   #34289
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Some of the smaller AMT (i.e. mundorf) claim ~50khz extension, and even higher claims the smaller raal ribbon.
I remember in my research to look also as other drives of this type.
Besides, there is a new seas fabric dome which shows a very nice hf beyond 30k. A bit inefficient but maybe fits your bill.
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Old 6th February 2013, 09:20 AM   #34290
SY is offline SY  United States
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He MUST be a great driver.
He taught Richard Feynman how to drive.
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