OTL amplifiers

[Neil McCauley]

Hello colleague members.

Shown here below is the unedited text I received as an unsolicited email today. On the face of it, it might be something of interest to some of you. Not my sort of thing though. Before poking fun at the unusual grammatical style, I realised that I cannot read or write any foreign language whatsoever!

Regards

Howard

PS:

If through ignorance and/or stupidity I have placed this thread in an inappropriate scetion, then please accept my apologies.


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Dear Audiophiles,

OTL (“Output Transformerless”) tube amplifiers are existing for as long as 40 yrs., and they were always highly appreciated by the serious audiophiles searching for the ultimate sound reproduction. But, with all adoration, OTLs hardly tamed temper (impedance sensitivity, operation reliability) limited their possession to the very few audio enthusiasts.

The goal of VDN’s engineers was to reach this gem design by meeting the highest possible requirements of the modern fastidious audio community. The REX-100 mono integrated tube OTL amplifier is designed with the sole purpose to reflect the harmonic structure of the real life music, hence enabling the listener to experience his feelings completely immersing its essence…

It is our believeing that our OTL approaches the unparalleled sound to the electrostats, as well as to electrodynamic loudspeakers additionally enabling the precisely defined bass reproduction…

The VDN team”

(the link for the large compressed photos/.RAR file: http://www.usaupload.net/d/xsryvwh91m7)

** tech.data of this particular product is here: http://www.vdn-otl.com/page2.html

Suggested Retail Price: 11,000.00 EUR/pr.
Direct purchasing price for end users from UK (while no official Importer exists): - 25% !

Damir/VDN
www.vdn-otl.com

[Spectral Morn]

I once tried a set of mono OTL amps from Atmosphere. Very nice sound but the amount of heat generated made them totally unsuitable for my living room, turned it into a sauna. I have also heard that otls can be very unreliable (not the Atmosphere amps by the way), but in general. They can also be very hard on the output valves.

Cetainly if I had a bigger room the Atmosphers might have been a contender as the sound was very pure and immediate, with out being spot lit.

Regards D S D L---- Neil :)

[John]

Nice but very expensive

[Billericay Dickie]

All hail Julius Futterman!! :youtheman: See link below:

http://en.wikipedia.org/wiki/Julius_Futterman

[Ali Tait]

I heard one of the Transcendent Sound kits quit some time ago and it was excellent.HUGE sound stage!

[tfarney]

Is it OTL that are supposed to sound more "Tubey," or the other way around?

Tim

[purite audio]

OTL's are speedy,dynamic can sound a little strident in the mids and highs, ,mind you I have very limited experience of them.

[Primalsea]

Horses for courses like most things. I've heard they do some stuff very well but you wont be rocking like fuk as they are incapable of delivering large currents into bass drivers. However an OTL that puts a high voltage signal direct to a stat panel would be something. Usually you have a output transfomer to reduce voltage and increase current to drive a cone driver. On electrostatics you have a input transformer to increase voltage to drive the panels. I would hazard a guess that getting rid of both transformers wouldn't be subtle.

[tfarney]

OTL's are speedy,dynamic can sound a little strident in the mids and highs, ,mind you I have very limited experience of them.

Ahhh...the other way around, then.

Tim

[anthonyTD]

Horses for courses like most things. I've heard they do some stuff very well but you wont be rocking like fuk as they are incapable of delivering large currents into bass drivers. However an OTL that puts a high voltage signal direct to a stat panel would be something. Usually you have a output transfomer to reduce voltage and increase current to drive a cone driver. On electrostatics you have a input transformer to increase voltage to drive the panels. I would hazard a guess that getting rid of both transformers wouldn't be subtle.
hi paul,
you make a good point there, however, the main reason that most OTL amplifiers have the reputation of being un-reliable is due to the fact that they are! valves are high impedence devices, compared to solid state, therefore, you cannot get a low enough output impedence to drive a loudspeaker direct unless you use the lowest impedence valves,[all too often these are types that were not designed for audio] in multiples of parrells, and even then you have to run them very hard, hence the heat, so, even though the sound from running valves in this paticular way can be dynamically involving, the main reason for this is i suspect due to their lack of ability to reproduce real bass, therefore making the mid and top frequencies in paticular types of music more pronounced.
hope this makes sense.
anthony...

[Marco]

Tim,

If you want "tubey" then some 300B SETs, biased the right way in the circuit would be the ones, or some vintage Quads, although others may have a different opinion on this. I suspect though that this is not quite what you would want if going down the tube amp route ;)

'Tubeyness' is certainly not what I'm looking for in a tube amp!

Marco.

P.S Did you see Steve's reply about my audio supports in the other thread?

[Neil McCauley]

Horses for courses like most things. I've heard they do some stuff very well but you wont be rocking like fuk as they are incapable of delivering large currents into bass drivers. However an OTL that puts a high voltage signal direct to a stat panel would be something. Usually you have a output transfomer to reduce voltage and increase current to drive a cone driver. On electrostatics you have a input transformer to increase voltage to drive the panels. I would hazard a guess that getting rid of both transformers wouldn't be subtle.

Harold Beveridge, designer of arguably the finest loudspeaker system ever built (general consensus with Ricardo, Helmut Brinkmann and many others, inc me) used OTL amps to drive the electrostatic elements.

http://beveridge-audio.com/white_paper.html

These speakers, using his amps had to be heard to be believed. Nothing, and I mean nothing today and in recent years comes really close. The Levinson HQD system, the Infinity IRS (full) system did and, err, that’s about it. The Steinway/Lyngdorf system I heard recently had much of that elusive Beveridge magic but – truth be told – today I'm selling mere toys (albeit good ones) in comparison. I have no technical basis for arguing the merits of OTL design, reliability and application.

All I can tell you is that in the context of his overall design, that of using OTL technology to drive the electrostatic elements of an 8' high vertical horn with 15" woofers, everything else was an also-ran. And if that's what OTL can do, then that just fine by me!

[anthonyTD]

Harold Beveridge, designer of arguably the finest loudspeaker system ever built (general consensus with Ricardo, Helmut Brinkmann and many others, inc me) used OTL amps to drive the electrostatic elements.

http://beveridge-audio.com/white_paper.html

These speakers, using his amps had to be heard to be believed. Nothing, and I mean nothing today and in recent years comes really close. The Levinson HQD system, the Infinity IRS (full) system did and, err, that’s about it. The Steinway/Lyngdorf system I heard recently had much of that elusive Beveridge magic but – truth be told – today I'm selling mere toys (albeit good ones) in comparison. I have no technical basis for arguing the merits of OTL design, reliability and application.

All I can tell you is that in the context of his overall design, that of using OTL technology to drive the electrostatic elements of an 8' high vertical horn with 15" woofers, everything else was an also-ran. And if that's what OTL can do, then that just fine by me!

hi harold,
when an OTL amp is designed to drive an electrostatic panel direct, ie, no transformers in the signal path, there is no reason why it shouldnt sound good, which is why i commented on what paul had to say, but as you have just stated, to get the low end frequency,,, well, thats a diffrent story.
anthony,TD...

[DSJR]

I had an un-regulated Croft OTL for a few months. it sounded absolutely wonderful in the finest, most delicate "crystal glass" kind of way.

Unfortunately, it kept blowing line rail fuses with no warning and on different speakers too, causing me to keep a multimeter alongside. One Saturday with visitors round I forgot to check the voltages every half an hour and was repaid with a firework display inside. I got rid soon after and went to AVI. Their products sounded really good to me and in the years I owned them, never put a foot wrong for me.

[tfarney]

If you want "tubey"....

I don't. I was just trying to remember what I had read somewhere. It was probably SET, not OTL. Crossed acronyms.


P.S Did you see Steve's reply about my audio supports in the other thread?

Yes. Thanks.

Tim

[Primalsea]

hi paul,
you make a good point there, however, the main reason that most OTL amplifiers have the reputation of being un-reliable is due to the fact that they are! valves are high impedence devices, compared to solid state, therefore, you cannot get a low enough output impedence to drive a loudspeaker direct unless you use the lowest impedence valves,[all too often these are types that were not designed for audio] in multiples of parrells, and even then you have to run them very hard, hence the heat, so, even though the sound from running valves in this paticular way can be dynamically involving, the main reason for this is i suspect due to their lack of ability to reproduce real bass, therefore making the mid and top frequencies in paticular types of music more pronounced.
hope this makes sense.
anthony...

Yep, makes sense to me.

On another note, I often wonder if some people don't tailor their system properly and as a result it only does certain music well. After speaking to some people at shows it seems that they let their hifi dictate their choice of music that they listen to, not the other way round.

It seems to me that SET or OTL would be one of the set ups where this happens. Where a OTL designed to put out high voltage (which makes it pretty much a normal valve amp without output transfomrers) into stat panels would be unbeatable for highs and mid. Maybe for bass too if you had huge panels.

[Will]

Just a point of interest for me anyway is Volker Bohlmeier and his Eienstein OTL Amps because he funded the best re-mastering of Muddy Waters Folk Singer and I think his Amps played some part in the project.:cool:

[tfarney]

Just a point of interest for me anyway is Volker Bohlmeier and his Eienstein OTL Amps because he funded the best re-mastering of Muddy Waters Folk Singer and I think his Amps played some part in the project.:cool:

If he funded the best re-mastering of Muddy Waters Folk Singer and he's recommended by someone who has a young Johnny Cash as an avatar well, that's good enough for me.

Tim

[anthonyTD]

Yep, makes sense to me.

On another note, I often wonder if some people don't tailor their system properly and as a result it only does certain music well. After speaking to some people at shows it seems that they let their hifi dictate their choice of music that they listen to, not the other way round.

It seems to me that SET or OTL would be one of the set ups where this happens. Where a OTL designed to put out high voltage (which makes it pretty much a normal valve amp without output transfomrers) into stat panels would be unbeatable for highs and mid. Maybe for bass too if you had huge panels.

hi paul,
totaly agree, the whole reason most of us got into "hi fi" was to be able to re-produce the music we liked as well as posible, unfortunetly as you so rightly pointed out some people end up with a hi fi system that only sounds good on certain types of music, which is in my view as much use to a real broad minded music lover as a choclate fire guard! therefore, and i will choose my words carefully here,,,a "recorded music reproduction system" should as a whole be able to play all types of recorded music well, ie it should be capable of following faithfully the footprint of the original recording.:)
anthony,TD...

[Clive]

It's also possible that people will select equipment that plays their favourite music really well. I've found there are precious few systems that do everything really well. I'd like to think that my system does most things well but I know where it truly excels and this happens to be the type of music that moves me most - that's no coincidence.

[anthonyTD]

It's also possible that people will select equipment that plays their favourite music really well. I've found there are precious few systems that do everything really well. I'd like to think that my system does most things well but I know where it truly excels and this happens to be the type of music that moves me most - that's no coincidence.

hi clive,
again i agree, we all know from experience that it is posible to further tune a good system to get the absolute best out of the type of music you are more likely to listen to most...
anthony...

[Clive]

hi clive,
again i agree, we all know from experience that it is posible to further tune a good system to get the absolute best out of the type of music you are more likely to listen to most...
anthony...
I suppose I should add that this does take a certain degree of enlightenment (grasshopper) :)

For many people this takes years of search and swapping kit before the realisation sets in.

[John]

Yes could not agree more and it took me a few years!!!