Amplifier Pairing with Coherent 15s

Hello all,

About to finalize an order for a pair of Coherent 15s (yay!) and now I'm starting to look at possibilities for amplification for them. Since they are very efficient (I believe 106db efficiency), they can work well with flea amps+, so there's a wide range of possibilities.

I have a few criteria though: I would prefer an integrated amplifier vs separates/mono blocks, both for cost and space reasons, so something like AirTight is out (plus, a bit too expensive anyway). Looking around the $10k range at the higher end.

I don't listen to things super loud, and tend to prefer tube amplification. Music tends to lean majority Jazz, with some other things throw in here and there, but Jazz is the most important genre to get right.

Frank (from Coherent) recommended a couple -

Tektron Two 2A3/50S-i
Mastersound Compact 300B

Some others I've looked into:

Tektron Two 211-i
LTA ZOTL Ultralinear Integrated

I do have a few concerns with hand-crafted, more 'custom' made amps, especially by manufacturers overseas (I'm in the US) - mainly inability to demo them and ease of service/warranty. They also tend to be more difficult to sell in the case of deciding to go a different route, though this is of a lesser concern.

Anyone have any experience with any of these, have any other suggestions to explore, or any other comments?



@alexberger Thanks! Yeah, they will only sound better as they break in more. They were finished in early December, but because of holiday travel, Frank held onto them and started breaking them in over the holidays before sending them to me in mid-January. Gave him plenty of time to tweak them if needed too.

I've probably listened about 20 hours in the past 10 days or so since getting back from my long work trip and they keep getting better!

The 300b amp looks interesting! It's possible at some point I may pick up a 300b amp just to compare and contrast, but not anything I want to think about right now. Need to recover after a very expensive year in 2023!

Hi @mmcgill829 

With model 18 2a3 has enough power if you listening room is not huge. 

300b amplifier is not better vs 2a3 but more chalanging to make it sound good. Because 300b is much more difficult to drive. If you don't need extra power 2a3 is better solution. 

Great to hear these have met your expectations! When I was speaking to Frank (this was like 2 years ago) he seemed to have a great understanding design and of the sound he was after. He was also quite familiar with the Verity line, which I am too. Seems like a speaker I'll go out of my way hear soon.

Anyone able to compare the Coherent to the Devore O/96 in a similar room? Impressions?

Hi @bjesien ,

I heard both at Montreal audio show. But in different rooms.

I will not comment Devore. I think it was a bad match with amplifier. I liked Coherent model 18 a lot. I think this room was one of the best.

These speakers are so different in therm of sensitivity. Coherent with 300b integrated SET filled out 500 square feet room easily. Devore 0/96 were underpowered with another 300b SET in a small hotel room.

From what I've seen, The o/96 is 10ohm and 96db (though, seems like they test closer to 91db, at least from Stereophile review), so they aren't as efficient as they're made out to be. I looked at the O/96 as an option around the same price point, but I just am not a fan of that type of speaker - they are similar to Audio Note and both are 'inspired' by Snell. I feel like they might need a push-pull or parallel 300b to really sing, but I know there are folks out there using SET with the O/96 and are happy. Diff'rent strokes!

I believe the room with the Coherent 18 was 'best of show' in the Montreal show you are referring to, @alexberger?