OTL Asylum

RE: Reference 3A NEFES

68.104.11.135

ltman

In Reply to: RE: Reference 3A NEFES posted by MP on March 15, 2024 at 12:45:38

ZEROS are transformers at the speakers?
Kind of defeats much of the point of an OTL?

Follow Ups:

Not exactly. - Ralph 08:00:13 03/20/24 (1)
Usually the output transformer is the bandwidth limit of any tube amp, save for perhaps some tuning on the bottom end to reduce the possibility of saturation.

The ZEROs convert from 16 Ohms down to 4,3 or 2 Ohms so have a really low turns ratio. Owing to it being an autoformer (since it does not have to block DC) rather than a transformer, there isn't any interwinding capacitance. So its bandwidth is a lot higher than that of the OTLs themselves.

In the case of lower impedances, the amps aren't showing off their best stuff! You get more power, lower distortion and less heat (since more power developed by the output section is dissipated in the load rather than in the output section itself) with no down side.

This kind of amplifier would not be possible if DC were present at the output and the amp not already fairly low output impedance!
- RE: Not exactly. - ltman 13:49:04 03/21/24 (0)
  re: lower impedances
  
  That's pretty much why I bought Ref3A DeCapoI speakers. Match made in heaven with the OTL.
  
  I could have gone with horns, but I cannot tolerate any ear-bleeding highs. Which is also why I am still very much into analog sources: Music Hall TT,
  Sony TC-458 Open Reel Tape deck, and Dynaco FM-3 tuner.
  
  Just finished doing a minor restore of the reel to reel and it sounds great and works amazingly well after 50 years from date of manufacture.
  
  I do expect Reel to Reel will be the _next big thing_ in Audio.

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