Which brand of 45 tubes do you use?

clio09,  Thanks for your detailed description of the subject OTLs.

The OTL amp(s) will be used to power just our towers which play down to 120 Hz. The speakers have powered woofers. Do you think the "better low frequencies" of the M60 fall below that range? I personally don't like overblown bass. Good definition matters. If the recording has lots of bass, so be it. If not, a system shouldn't add or overemphasize what's there.

My understanding is that the Music Reference OTL-1 is no longer available and that few were made.

Thanks for your comments.

I also use amps designed for 2A3 tubes. I have a few NOS, Shuguang and EMLs. In those amps in my system I prefer the EML 2A3s, mostly because they are the most transparent and balanced.

For my 45 amps I have several NOS and Sophia Electric. I'm trying to decided whether or not I should try EMLs. They are kind of expensive. I agree that good NOS 45 tubes are very close in SQ based on the small selection I have. I have no complaints about the NOS 45 tubes other than availability and reliability. They sound great to me. My overall preferred amp/tube combo in my system is my 45 tube mono amps using NOS 45s. 

@jmolsberg  I will give Andy at vintage tube services a call. Thanks for the contact. I guess a google search will find him?

@gwalt  Thanks, I will check out the recent posting under chakster.

Larry,   Now that you mention it, It's very possible that some of (or maybe all) the NOS tubes I bought aren't but just tested within new specs. They came in factory boxes with what appears to be period correct wrapping. I was told they were NOS. Who knows. Doesn't really matter, they sound great.

The EML 2A3 tubes I have are solid plates. I never tried the Mesh plate type. Did you prefer one over the other?

Larry,  Thanks for sharing your thoughts. I like a wide open soundstage, "phasey" not so much. I don't know if you can answer this but even a hunch will help. Is the "phasey" sound characteristic of mesh plate EML tubes or could something else be at play? 

I am looking into trying OTL amps as well. I have never heard our new speakers powered by OTLs. Could be a nice pairing.

audition_audio, I might be interested in adding another pair of NOS 45s to my stash. Can you share or PM contact info for your company? Thanks.

Larry,  I believe I understand your description of  "phasey". My 45 amps are a simple SET using one 45 tube (1.5 watts) and silver hybrid transformers. Our speakers are very dynamic so the mesh plate EML might be a nice match

The only OTL amps I've owned were Joule Electra. The mid-range and upper mid-range was wonderful, bass not so much. I got them from a friend so I don't know their history but they turned out to be noisy, finicky and hot so they didn't last long in my room. I am interested in trying contemporary OTLs. 

The Joule Electra OTLs were very nice sounding amps but too finicky for the showroom. Maybe the set we had needed repair. The biasing system was not consistent. I never experienced loud pops from faulty tube sockets but had read about it. The contact between the pins and sockets were, in most cases, very loose.

Yes, the Atmasphere OTL S-30 is on the top of my list to try. Our speakers have powered woofers. The main towers have a sensitivity of 105 dB and the high pass is 120 Hz. They are a very easy load for most amps. As long as the S-30 is quiet enough it should work well.

I have read about the Berning amps but have never heard them. I had a chance to speak with David Berning at the CAF 2018 show. Very interesting design but beyond my price point. I prefer to not demo our speakers with amps that cost more than three times their cost. I wouldn't mind trying them though.