OK, I was running late to get to Jim's house to help him set up his Majestic panels, and, I forgot my camera. But, I got it all wrong. his old panels (2006) are not U-1PX, they are M-1PX panels. Don't know how I got that wrong, but I did.
The Majestics are indiscribable. I've never heard such large staging and such increadable detail. If the M-1PX are even 80% of the Majestic, I will be very saticfied.
As I saw it, the M-1PX use the same interface as the Majestic so I don't think there will be any change in my approach. I will be talking to a friend that has 8 KLH 9 panels with interfaces as well as a stack of ML and Acoustats. So I might be able to talk him out of an interface or two. He "WAS" an ESL fan for many years but has moved to horns......just the opposite of what I am doing.
Anyone hear the M-1PX? Jim powered them down two days ago just to work on them so I could not hear them again. I heard them a year ago and I still remember being blown away by the sound.
The Majestics are indiscribable. I've never heard such large staging and such increadable detail. If the M-1PX are even 80% of the Majestic, I will be very saticfied.
As I saw it, the M-1PX use the same interface as the Majestic so I don't think there will be any change in my approach. I will be talking to a friend that has 8 KLH 9 panels with interfaces as well as a stack of ML and Acoustats. So I might be able to talk him out of an interface or two. He "WAS" an ESL fan for many years but has moved to horns......just the opposite of what I am doing.
Anyone hear the M-1PX? Jim powered them down two days ago just to work on them so I could not hear them again. I heard them a year ago and I still remember being blown away by the sound.
Hi Jer, I might have a lead on a pair of Acoustat interfaces and will know more tonight. My GM70 SET amp runs 850volts B+ and I am comfortable, nut leary, of working around high v.
Do you have a link that might explain direct drive amps and how they work. Or better yet, a schematic that I can look at?
I like the idea of a large toroidal trannies. They seem to be very effective for the ESL and cost less then conventional trannies.
Hi Bentoronto, I will be looking into that. Need to find a schematic to check out.
Hi djn,
in Heidelberg/Germany there is a man, who had a small production line of ESL's
He is still selling a brochure for a DIY direct-drive high voltage tube-amp:
>EURO 13.-: CONSTRUCTION-MANUAL. Containing more than 20 pages with the diagram and parts
>list and very important constructional details for the tube-amplifier and
>associated circuits. Special emphasis is laid on the efforts to be taken for
>security of the user, without which the amplifier should NOT be used.
>It´s plate-voltage is 1.800 Volts !
>ATTENTION! This manual at present is only available in german language
If you are interested I can send you his address.
Reg.
Frank
in Heidelberg/Germany there is a man, who had a small production line of ESL's
He is still selling a brochure for a DIY direct-drive high voltage tube-amp:
>EURO 13.-: CONSTRUCTION-MANUAL. Containing more than 20 pages with the diagram and parts
>list and very important constructional details for the tube-amplifier and
>associated circuits. Special emphasis is laid on the efforts to be taken for
>security of the user, without which the amplifier should NOT be used.
>It´s plate-voltage is 1.800 Volts !
>ATTENTION! This manual at present is only available in german language
If you are interested I can send you his address.
Reg.
Frank
Here is a few things (but not all) on dirrect drive amps.
Audio Related Articles and this old thread
http://www.diyaudio.com/forums/plan...age-type-transistors-directly-drive-esls.html.jer
Audio Related Articles and this old thread
http://www.diyaudio.com/forums/plan...age-type-transistors-directly-drive-esls.html.jer
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Hi Frank. I would like his address. I do have one question. Is this type of amp the same as what I've always known as an OTL amp?
Although I love tubes,they are very expensive these days and a good source is very hard to come by.
I searched high and low for data on the 8068 and found a little few bits and pieces.
From what I gathered it looks like a typical horz. sweep tube and a PL509 or PL519 would probably work.
I also have David hermeyers design in my archives which uses opamps to drive the 813 tubes.
It is a simpler circuit that uses opamps to replace all of the transistor circuitery.
The 6146 could also be used and seems to be still available,but as you know prices just keep going up.
I still have one out of a pair of 833A's that one lost its vacuum and these would make an excelent amplifier and could be found for as little as $35 a piece some 5 or 10 years ago,but try to price one now.
I can post a picture of it if you like as it is a beutiful big triode tube with big .5" diameter connector caps and all.
My goal at one piont was to get eight of these and run them SRPP fasion on a (you guessed it) 5kv to 7 kv supply using MOT's to supply the current.
Danger? Ha ,you know what it entales!
The designs in the old thread are based upon Neil mckean's design and is the current design that I have been pursuing.
That thread was started right at the same time I got my dumb a$# in some trouble and wasn't able to continue with my research until now.
I have circuit maker files dating back to 1998 using the same technique in my early days of learning amplifier design and is very similar to the Nelson Pass designs aswell only at a much much higher voltage. jer
I searched high and low for data on the 8068 and found a little few bits and pieces.
From what I gathered it looks like a typical horz. sweep tube and a PL509 or PL519 would probably work.
I also have David hermeyers design in my archives which uses opamps to drive the 813 tubes.
It is a simpler circuit that uses opamps to replace all of the transistor circuitery.
The 6146 could also be used and seems to be still available,but as you know prices just keep going up.
I still have one out of a pair of 833A's that one lost its vacuum and these would make an excelent amplifier and could be found for as little as $35 a piece some 5 or 10 years ago,but try to price one now.
I can post a picture of it if you like as it is a beutiful big triode tube with big .5" diameter connector caps and all.
My goal at one piont was to get eight of these and run them SRPP fasion on a (you guessed it) 5kv to 7 kv supply using MOT's to supply the current.
Danger? Ha ,you know what it entales!
The designs in the old thread are based upon Neil mckean's design and is the current design that I have been pursuing.
That thread was started right at the same time I got my dumb a$# in some trouble and wasn't able to continue with my research until now.
I have circuit maker files dating back to 1998 using the same technique in my early days of learning amplifier design and is very similar to the Nelson Pass designs aswell only at a much much higher voltage. jer
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Hi,
I´d like to dampen the emphsis about directdrive a bit and hint You to a more neutral sight of matters.
Supplying the panel via a premium amplifier and a first class transformer yields measurable and sonic results which most directdrive amps still try to even come close to. Distortion values, bandwidth and dynamics of a transformer are just a few parameters to name, which hardly any(!) DD-amp is on par with. Who would seriously call an amplifier true HiFi -let alone Highend- which doesn´t even reach 10kHz or fullpower bandwidth? As a typical audio amp most DD-amps would rather be considered as lowFi-class. And feeding the most revealing and sensitive speaker principle should than result in superior sonics? Well, belief is everything I guess (sarcasm mode off
)
Basically You need to divide into two voltage classes. One may need up to 2.5kV of supply voltage and possibly increased current capabilities to drive efficient panels (hybrid panels, sheet metal stators, non-segmented panels). The second class with at least 4-5kV could drive less efficient panels (fullrange, wire stators). In any case, calculating the current demand for sufficient bandwidth (min. 20kHz) You quickly realize enourmous power demands even if the amp runs in class-B, which required tight feedback, which in turn required ridicoulously high openloop gains, which in turn made it difficult to reach sufficient bandwidth, which ......... oooh I think I´ll still stick to a nice SE-Triode and a good tranny and enjoy listening
Of course You could construct a DD-amp after a fashion that is considered as good audio design, but this would consume several hundreds of idle Wattage.
jauu
Calvin
I´d like to dampen the emphsis about directdrive a bit and hint You to a more neutral sight of matters.
Supplying the panel via a premium amplifier and a first class transformer yields measurable and sonic results which most directdrive amps still try to even come close to. Distortion values, bandwidth and dynamics of a transformer are just a few parameters to name, which hardly any(!) DD-amp is on par with. Who would seriously call an amplifier true HiFi -let alone Highend- which doesn´t even reach 10kHz or fullpower bandwidth? As a typical audio amp most DD-amps would rather be considered as lowFi-class. And feeding the most revealing and sensitive speaker principle should than result in superior sonics? Well, belief is everything I guess (sarcasm mode off
) Basically You need to divide into two voltage classes. One may need up to 2.5kV of supply voltage and possibly increased current capabilities to drive efficient panels (hybrid panels, sheet metal stators, non-segmented panels). The second class with at least 4-5kV could drive less efficient panels (fullrange, wire stators). In any case, calculating the current demand for sufficient bandwidth (min. 20kHz) You quickly realize enourmous power demands even if the amp runs in class-B, which required tight feedback, which in turn required ridicoulously high openloop gains, which in turn made it difficult to reach sufficient bandwidth, which ......... oooh I think I´ll still stick to a nice SE-Triode and a good tranny and enjoy listening
Of course You could construct a DD-amp after a fashion that is considered as good audio design, but this would consume several hundreds of idle Wattage.
jauu
Calvin
Dear Calvin,
if one applies 5...10kV PP to ESL panel, i.e. full power @ frequency above 5kHz,
not to mentioned 20kHz, it will be the very last moment of such panel lifespan.
Let's calculate @ 1200pF, 3500V RMS, 20000Hz
Reactive power 1800 kVA, current level 0.5 A.
That's how ozone generator works
22ppm, 3 hrs is LD50.I've been getting 30g/hour at power level six times smaller.
This can be reasonably easy constructed using high voltage lateral FETs, not to mentioning RF tubes.
I doubt, though, that sheer DIY enthusiasm will compensate the knowledge needed to do so, not to mention danger of high DC voltage present.
For sure transformer output stage is much easier to implement Home Page of Arto Kolinummi, Audio.
And a LOT safer.
In reality voltage level @ the upper range is rather small,
which you have indirectly confirmed by mentioning SE stage.
The latter usually provide below 100W, even with obscene generator tube used...
Alex
P.S. What about idle wattage of SE amplifier at, as mentioned, 100 W output?
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Please read http://www.diyaudio.com/forums/cerp...ruct-cube-louver-acoustat-15.html#post2197145
in regard to my previous post.
Sincirely,
Alex
in regard to my previous post.
Sincirely,
Alex
Hi,
energy and level content of typcal music signals drop with frequency, thats true. It is the one reason why You can get away with amps similar to the Strickland/Acoustat style, which seems to be the grandfather of nearly all commercially available DD-amps. Still though I´m quite sure that no one would regard an lowvoltage HiFi-amp with specs like those DD-amps offer as a good and true highend amp. To say it another words..... Though not impossible, its not at all an easy task to construct a HV-amp, that comes close to the performance of a good tranny, neither measurementwise nor acoustically.
jauu
Calvin
energy and level content of typcal music signals drop with frequency, thats true. It is the one reason why You can get away with amps similar to the Strickland/Acoustat style, which seems to be the grandfather of nearly all commercially available DD-amps. Still though I´m quite sure that no one would regard an lowvoltage HiFi-amp with specs like those DD-amps offer as a good and true highend amp. To say it another words..... Though not impossible, its not at all an easy task to construct a HV-amp, that comes close to the performance of a good tranny, neither measurementwise nor acoustically.
jauu
Calvin
Hi Calvin,
What do you think about the innox direct drive in this respect?
regards, martin-jan
We did an A-B at a gathering of the Toronto hi-fi enthusiasts a few decades ago. I don't think anybody thought the transformer drive was as good as the direct drive sound quality. Having lived with direct, home-brew transformers, and Dayton-Wright transformers (they come in an 80 lb box) long-term, absolutely no comparison to my ears although nobody could swear the are no "pitfalls of measurement" in making such comparisons.
The irregular distortions introduced by a 100:1 matching transformer (which obviously has no corrective feedback around it) is orders of magnitude out of range of a home-brew HV Sanders amp. I just don't know what Calvin must be thinking?
I always say, a great amp from 1965 would be a perfect match for today's best speakers (OK, maybe today's best amp might be a tiny bit nicer, but you get the idea).
Correct me please, but isn't there an interesting and feasible compromise using a medium-high-voltage output (like a tube amp or special HV FET) and a slight-step-up transformer?
The irregular distortions introduced by a 100:1 matching transformer (which obviously has no corrective feedback around it) is orders of magnitude out of range of a home-brew HV Sanders amp. I just don't know what Calvin must be thinking?
I always say, a great amp from 1965 would be a perfect match for today's best speakers (OK, maybe today's best amp might be a tiny bit nicer, but you get the idea).
Correct me please, but isn't there an interesting and feasible compromise using a medium-high-voltage output (like a tube amp or special HV FET) and a slight-step-up transformer?
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Building one right now, see this thread:
http://www.diyaudio.com/forums/tubes-valves/164904-dedicated-esl-amp-please-comment.html
Kenneth
Hi,
@MJ
I don´t know the schematics of the innox, but what one can conclude from the infos on the website it will probabely work with a Schmitt or a SRPP-like structure in the output circuit. The idle current is quite low, so it is a class AB-design which needs to rely on serious feedback. I assume it is a redesign of the Strickland-amp.
The innox is an HV-amp somehow in between. On one hand its anode voltage is too low to drive medium- to large-sized wire stator panels, on the other hand its current capability will be too low to drive non segmented medium- to large-sized metal sheet stator panels to the full (have a look at the bandwidth screen shots). Its rather an amp for smaller panels with lower voltage and current demands. The output tubes (something like PL519) used are specced for lower continous anode voltages. As a result tube life will be shortened (Innox talks of ~500hours?). Hopefully the µController will provide for all necessary safety functions.
@Ben
"...a few decades ago"...come on Ben, tell us some news for a change ;-)
I think that the results of a single listening test decades ago are rather questionable today. At least a few things have changed and improved meanwhile *lol*
Well, the end result depends very much on the driving amplifier, the audio-tranny and the panel itself. As we all know, ESLs are no easy load and many amplifiers experience audible problems driving a panel properly.
The quality of the transformer is probabely the most important parameter regarding distortions. Just one decade ago, it was quite common to find low to lowest quality transformers with insufficient bandwidth and high distortion values. Reasons were cost and lowered drive demands for the amps.
No doubt that a reasonably constructed HV-amp could perform better than that.
But companies started using better transformers that allow for much higher bandwidth and greatly reduced distortion values.
With my panel-tranny-combination such low THD-values could be measured even at highest SPL-levels, that any HV-amp would have difficulties reaching similar SPL-values in first place let alone perform on such low distortion level.
Going directdrive dos not necessarily mean an improvement, neither measurement- nor acoustically wise. Getting rid of one problem-point (the transformer) introduces new problems which are not easier but rather more difficult to solve. Uhh ooh just one last remark....the HV-amps typically need output coupling caps! Aren´t coupling caps regarded as bad as trannies? *lol*
jauu
Calvin
@MJ
I don´t know the schematics of the innox, but what one can conclude from the infos on the website it will probabely work with a Schmitt or a SRPP-like structure in the output circuit. The idle current is quite low, so it is a class AB-design which needs to rely on serious feedback. I assume it is a redesign of the Strickland-amp.
The innox is an HV-amp somehow in between. On one hand its anode voltage is too low to drive medium- to large-sized wire stator panels, on the other hand its current capability will be too low to drive non segmented medium- to large-sized metal sheet stator panels to the full (have a look at the bandwidth screen shots). Its rather an amp for smaller panels with lower voltage and current demands. The output tubes (something like PL519) used are specced for lower continous anode voltages. As a result tube life will be shortened (Innox talks of ~500hours?). Hopefully the µController will provide for all necessary safety functions.
@Ben
"...a few decades ago"...come on Ben, tell us some news for a change ;-)
I think that the results of a single listening test decades ago are rather questionable today. At least a few things have changed and improved meanwhile *lol*
Well, the end result depends very much on the driving amplifier, the audio-tranny and the panel itself. As we all know, ESLs are no easy load and many amplifiers experience audible problems driving a panel properly.
The quality of the transformer is probabely the most important parameter regarding distortions. Just one decade ago, it was quite common to find low to lowest quality transformers with insufficient bandwidth and high distortion values. Reasons were cost and lowered drive demands for the amps.
No doubt that a reasonably constructed HV-amp could perform better than that.
But companies started using better transformers that allow for much higher bandwidth and greatly reduced distortion values.
With my panel-tranny-combination such low THD-values could be measured even at highest SPL-levels, that any HV-amp would have difficulties reaching similar SPL-values in first place let alone perform on such low distortion level.
Going directdrive dos not necessarily mean an improvement, neither measurement- nor acoustically wise. Getting rid of one problem-point (the transformer) introduces new problems which are not easier but rather more difficult to solve. Uhh ooh just one last remark....the HV-amps typically need output coupling caps! Aren´t coupling caps regarded as bad as trannies? *lol*
jauu
Calvin
Well, this has been a tough decision for me, but after doing a lot of thinking, I am going to pass on my friends Sound Lab panels. I have read up enough to know that building the interfaces is within reason, but I started looking at all the amps I've built and realized that none of them would work so I'd have to build amps as well. Basically that means a total change in direction for my whole system. The cost, time, and energy is just too much for me to handle at the moment. I want to say thanks to all of you that have chimed in to help out. Your assistance is much appreciated. I am going to stick with the high eff horns for the time being as all my support gear is design for them. Cheers and thanks again.
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