Tenor OTL 75wi vs 175s

Hi Atmasphere,
Thanks for the suggestion. By weak tubes, are you indicating at the driver tubes or the output tubes ?

Secondly, do you have any recommendation on what kind of speaker cables should be used between a typical speaker and an OTL for a good match ? I currently use a 3 meter biwiring set of Auditorium23 speaker cables. Do you think shortening the speaker cable to less than 2 meters can actually improve the amp's response ?

I also owned a pair of Tenor 75WI around the same time that Mike owned his. I actually spoke with him prior to buying mine. They were "magical" but didn't really work well with my speakers either. Mine ran out of gas just as yours do. I was concerned that they really limited the speakers that paired well with them but boy, when they were playing the right type of music in the ranges they excelled in, they were really something and they were damn pretty to look at with all those tubes glowing. I moved on to a Boulder 1060 and ultimately paired that with an Aesthetix Janus which suits my needs better. I do miss those Tenors, but like Mike, mine had some problems that were repaired under warranty. I didn't want to have to deal with long-term reliability issues and the replacement tube sets would have also been expensive.

My Tannoys are not exactly a bad match. For at least 75% of the music I listen, I do not have the trouble in getting the desired SPLs. Only with stuff like Michael Jackson where you really would like to crank it up and swing, you kind feel shortchanged for the SPLs. These well recorded pop numbers have great punch and dynamics with lots of instruments playing simultaneously at various SPLs, so to resolve all that at high DBs is not always easy. Good SS amps can do it well (like my FM Acoustics F10 does), high powered push-pull tube amps also do it well (may be not nearly as good as SS) but SET and OTLs would only do it with the best matched speakers. I am thinking of getting an Avant Garde when I have a bigger room to play music. My heart though skips a beat whenever I see/hear a nicely driven pair of Tannoy Canterburry.

Pani, based on your post above I think the problem is you just don't have enough power.

So you might want to consider a more efficient loudspeaker or a more powerful amplifier. The problem is that you have heard what OTLs do and you are not going to be satisfied by a solid state amp, which might have plenty of power but really just won't have the finesse.

There are larger OTLs available.

plan B: get a set of speakers that are more efficient. I use the Classic Audio Loudspeakers mode T-3.4, which are about 98 db and 16 ohms (both the efficiency and the impedance are a boon!). With our M-60 OTLs I have to put on earplugs to actually be able to clip the amps as they can make 110db at the listening chair. My room is 17' x 21' 21'. I play all sorts of stuff including electronic music with plenty of thump- my speakers go down to 20Hz and I can literally shake my house with them. They are very satisfying, very detailed and very smooth, image beautifully and I've no complaints.

The only thing is they are not cheap. I think if you do the math and you are happy with your speakers that a more powerful OTL will be less expensive and will very likely sound even better.