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What's your OTL tube amp experience and suggestion?

Are OTL amps in general much less reliable due to their nature, or due to the implementation quality, or both?

Perhaps this has been discussed a zillion times in the past.   Perhaps, however, makers have now improve on past experience?  So it could be worth re-visiting.

My past encounters with OTL tube amps are among the most negative: Wonderful (but never great) sound during the brief period that they work.  Otherwise, major fire hazard.  Overheating, red hot plates, sparks, consistently toasted fuses, burning smell, you name it.  My past OTL amps are like crying babies on an changing table - don't you ever walk away from an arm's distance.   The used market seem to reflect such as well --- way more 'as-is for parts' or 'totally refurbished' units than reliable 'used' units that rarely need service.

Beg your pardon if it's just my poor judgement that keep getting the lemons.   What's your experience, and tips to keep OTL amps up and running happily?


bsimpson

Showing 2 responses by rusty_jefferson

rusty_jefferson
8 posts
 
To answer the original questions, there can be reliably and potentially safety issues with OTL amplifiers, especially early designs.  The best implementation I've seen are the Berning ZOTL amps.  They are safe, and reliable.  Most won't require retubing for years, or decades. They have autobias, and protection circuits, plus very low output impedance,  making them very versatile in matching them to a wide variety of speakers.

As well as the models available on his website, or licensed by LTA, David has a collection of small, lower power models available he doesn't promote on the website that includes  300b SET and PP, 6b4 SET and PP, 845 SET, etc. All the models I've heard (and owned) sound outstanding. 
rusty_jefferson
8 posts
 
@atmasphere

Just to be clear, I'm not Trolling you, or your company, just answering the question in the thread title, "What's your OTL tube amp experience and suggestion".

By stating you made the first reliable OTLs does indicate that some or all of your predecessors were in fact, not reliable. And by safe, I didn't just mean not catching on fire, but rather safe and reliable in our systems.  The Berning ZOTL amps have no chance of passing DC, no popping noises, and extremely long tube life, again, on the order of many years to decades of daily use. If your amplifiers are capable of similar safety and reliability, I apologize for not knowing so.

And if some think ZOTLs aren't really OTL amplifiers because they don't meet some engineering criteria that fits their needs, well, I don't know what to say about that. I don't think anybody has ever sued Berning for false advertising.  Here's a nice discussion from the Berning website, including pros and cons of different OTL implementations, for those interested. http://davidberning.com/products/qz
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