Does OTL pre-amplifier exist?

Yu11375, thanks for the comment on the S-30.

Onhwy61 is correct- most preamps have no output transformer. But with preamps the usual limitation at the output of the preamp is often the coupling cap, rather than an output transformer. Removing this part can result in a huge increase in detail/transparency and apparent speed without edginess or brightness.

Doing this is a but tricky; there are only a handful of ways to do it. Reliability is a factor- you don't want the preamp making DC voltages that could damage a power amplifier or speakers. We patented an elegant (IMO) method of doing this some years ago. Seems to me there are a few other tube preamps that also have direct-coupled outputs but this is quite rare! I think, other than the ones we make, you can count the others on one hand with fingers left over.

Ask Ralph he often contributes to posts here and Audio Asylum. I thought that pre amps didn't have output transformers but I may be wrong. If they do I have had very few if any compatibility problems.

I believe you need a cap to block DC at either the ouput of the preamp, or the input of the amp. You don't need both, so it may be safe to remove one or the other as long as you keep this in mind when changing to other components. I'm no tech, just a tinkerer, so please, someone correct me if I am wrong. This cap will change the sound, but I suppose it's possible to prefer it with, rather than without. I removed them from my vintage amps and it did improve the sound. I now have to be careful though that any pre I use will have output caps.

Thank you all for your inputs.

Yes, it is output coupling cap.

Could you please suggest some line only preamplifiers without output coupling cap?

I like Amtasphere but I don't have turntable. Having a preamplifier with phono input is underutilizing its full capability.

Happy Listening!

Otto

I'll take a risky guess here and assume you mean direct coupled tube line stages?: Sonic Frontiers.