2. amps-preamps
  3. 139816-118117

My first Tube Amplifier

I have a 40 years of audio history starting with Garrard Turntable, Fisher Intergrated(SS), ADS bookself speaker on 1978.

But I started using tube amplifier on 1999.

Since then I had been using only tube amplifier in my main system.

My last SS main amplifier was Krell KSA 150 to drive Apogee Duetta Signature speakers.


http://www.jadis-electronics.com/photos/ja500/45/3/ja500.jpg

My first tube amplifier was Jadis 500 which comprised of 4 pieces weighing 120 lb each.

B&W 801 driven by Jadis 500 gave most deep and powerful bass at my home.

But it generated too much heat so it was hard to use during summer.

It was memorable experience to use it for 4 years.

I may not go back to such monster tube amplifier again.



How about you?

What is your first tube amplifier?



I bet two cents on no one had used larger one as the first tube amplifier than mine.


128x128shkong78
bdp24's avatar
bdp24
9,899 posts
 
@unreceivedogma---OTL’s (primarily and most-famously the Futtermans) came to be considered a good choice for use with the original Quad, primarily because an OTL likes to operate into a high impedance load, and the Quad was/is nominally 16 ohms. The problem was, and remains, that most ESL’s have a wildly-varying impedance curve (the Quad from under a single ohm to maybe 50), and a curve like that creates large variations in loudspeaker frequency response unless the amp has a low output impedance. The Futterman was good in that regard; not all OTL’s are.
roberjerman
4,319 posts
 
@bdp24 : I've had Futterman OTL's  in long-term use with Quad 57's. They do sound great together, even though the impedance falls to <2 ohms at 20khz. Partly due to the Futterman's low output impedance (high feedback).
shkong78's avatar
shkong78 OP
1,485 posts
 
I heard that OTL tube amplifier has an excellent transparency to be suitable for planar speakers.

For the time being, I am happy with my Line Magnetic 508 SET amplifier with magical mid range sound.
bdp24's avatar
bdp24
9,899 posts
 

@roberjerman, Music Reference's Roger Modjeski has thoroughly investigated the Futterman, and thinks highly of it. He has confirmed the amp's low output impedance, and other superior operating characteristics. The only negative I have heard about the design is in regard to reliability, due to what I don't know.

Harvey Rosensberg (and his engineer George Kaye) made some changes to the amp when he started building them under his New York Audio Labs company name, having bought the rights to the design from Mr. Futterman shortly before the latter's passing. They too are known to be failure prone. Ralph Karsten's Atma-Sphere OTL's, on the other hand, are known to be very reliable, though they suffer from somewhat high output impedance (relative to the Futterman).

@shkong78, yes, OTL's are known for their transparency, but many planar loudspeakers have a nominal impedance lower than OTL's like to see. Magneplanars, for instance, have an impedance of 4 ohms and lower, a tough load for an OTL. Atma-Sphere's Ralph Karsten recommends using an Anti-Cable Autoformer with his amps when partnered with low-impedance speakers such as Maggies. Most contemporary ESL's also are low-impedance designs, at least at certain frequencies.

roberjerman
4,319 posts
 
@bdp24 : The inherent problem with Julius's circuit has been getting the two halves of the output stage to act in balance due to differing gain (one half acting as a cathode follower). And the circuit requires high feedback to have acceptable distortion (60db) - not a problem because of the low front-to-back propagation delay.
More to discover