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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
dragon_vibe
430 posts
 
I found that the Atma-Sphere Amplifiers sound warmer if you change out all the 6SN7 Tubes provided by Ralph.

The one Ralph gives with the amplifier are Chinese made tubes which to me sound a little bright in the upper regions. Once I swapped these out for good pair of NOS tubes everything changed.

The Noise is most likely from the Tube not the Amplifier. I had the same issue with one channel constantly buzzing, These tubes I used in other pre-amps were dead quiet but in Atma-Sphere they seems very noisy. Once i changed them out for other NOS tubes the noise was gone.

The noise is not from the Pre-amp or the amplifier but the Tubes them selfs, Some of these tubes never show signs of noise in my other pre-amps but for some reason they do in Atma-Sphere.

So the goal is to feed these babies good quality low noise tubes. Once you got the tube noise down and the system dialled in with the tonal balance the system can have a nice warm balancing sound.

Just an advise for those who want a warmer sounding OTL on Atma-Sphere. Use some of the RCA, Sylvinia, Ken-rads. The Sophia Electra used on the pre-amp softened up the system too much to my liking.

mikelavigne
2,214 posts
 

dragon_vibe,

i did not make the connection between darTZeel and Atma=sphere......you did. i said that in back to back listening sessions ’16 years ago’ i preferred the Tenor OTL’s to the Atma-sphere MA2’s.....which was my opinion back then. and at that time, many agreed with me and did acquire Tenors and loved them. and i absolutely agree that back then those Tenor OTL were unstable and did blow up tubes, which i mentioned. later that design flaw of the Tenor OTL was cleaned up and I provided a link for that information.

but we are just going to have to disagree on how we view darTZeel and the current Atma-sphere amplifiers.....which i did not bring up. but, of course, i’m referring to my current darTZeel’s, the 458 mono blocks.

we all have a right to our opinion.

that said; i’m a fan of both Ralph and Atma-sphere and do strongly recommend them and have recommended them.....and agree it’s a solidly built product well supported.....and on my short list of favorite tube amplifiers.

dragon_vibe
430 posts
 
Sorry mike I misread your post.
mikelavigne
2,214 posts
 
no worries dragon_vibe.
emailists
923 posts
 
Also don't forget using an auto former like the Speltz to pair with a wider variety of speaker impedances.  

If anyone wants to hear the Atma-sphere gear in NYC give me a shout out.  TriodePictureSound. 
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