What an OTL is, and why you should care

DonH50

Member Sponsor & WBF Technical Expert
Jun 23, 2010
3,577
26
48
Monument, CO
#41
Just a note to thank Ralph for this thread, cool stuff!

Disclaimer: I owned and/or worked on a number of tube amps through the years, including Futterman (to me sound was "ok" and reliability, well, good for a college kid working as a tech ;) ), and did build a couple of OTL amplifiers based upon a push-pull approach with feedback to get a reasonable (to me) output impedance and a servo circuit to control DC on the outputs. The latter, along with a matching preamp, was a differential circuit so complicated as all get-out. It measured and drove speakers better than any of the other ARC or CJ amps I had around but I never went further with it. Sold the prototypes, but the main feedback I got was "too SS" -- it was much cleaner than the tube amps of the day but that was not what people wanted to hear. I'd love to hear an Atma-Sphere some day.

IME tubes (non-OTL amps) on ESLs are gorgeous in the midrange but have trouble controlling the bass and get harsh in the highs as the impedance drops out of the "good" region of the output transformer. The latter is also a problem for many SS amps IME but most did better than tubes -- if they could handle the low impedance!

FWIWFM - Don
 

About us

  • What’s Best Forum is THE forum for high end audio, product reviews, advice and sharing experiences on the best of everything else. A place where audiophiles and audio companies discuss existing and new audio products, music servers, music streamers and computer audio, digital to audio convertors (DACS), turntables, phono stages, cartridges, reel to reel, speakers, headphones, tube amplifiers and solid state amplification. Founded in 2010 What's Best Forum invites intelligent and courteous people of all interests and backgrounds to describe and discuss the best of everything. From beginners to life-long hobbyists to industry professionals we enjoy learning about new things and meeting new people and participating in spirited debates.

Quick Navigation

User Menu

Steve Williams
Site Founder | Site Owner | Administrator
Ron Resnick
Site Co-Owner | Administrator
Julian (The Fixer)
Website Build | Marketing Managersing