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?

 

128x128mmcgill829

@mmcgill829 No worries. Have fun. I have owned several (many?) SET amps and while I appreciate their simplicity and beauty they just didn't do it for me, sound wise. Personally, I find 23a and 45 tubes too "polite" for my taste. 300bs are better but I heard phenomenal midrange but fall off in the upper and lower ranges. Not one 300b amp but several, over the years. Again, that's just me. YMMV.

My favorite pairing with my Coherent 8s and Omega single drivers was the vintage McIntosh MC225 amp, a 2-stage PP design. That amp drove my HE speakers closest to full-range. My second choice would have to be the lowly Decware Zen Triode amp, preferably the mono version. To my ears these amps bested any classic SET or DHT amp I tried. But whatever sounds best to you is best.

@br3098 I suppose what I meant was that I was after more 'standard' SET options - 45, 2a3, 300b - and that's not really what Decware seems to do or specialize in.

I'm sure they are fine amps - I've read wonderful things from the owners!

 

@mmcgill829 have fun with your new Aric separates. Good choice, enjoy.

I'm a little confused re: your comment about Decware and tube choices. They offer several different amps and amp designs. Some of them use tubes that are less known. I believe that these were specifically selected by Decware to be low cost and highly available. The two Decware products I have owned were highly rollable; able to use variety of power, preamp and voltage regulator tubes.

@br3098 Thanks for the info!

I did look into Decware when I was looking around, but it seems they use a fair amount of off the beaten path tube choices, which I thought could be a bit more difficult when it came to sourcing alternates/replacements to roll.

I did end up going with Aric audio, and picked up his Super 2a3 SET, and Super 6SN7 linestage. I was surprised to be able to get separates within my budget, and I've been very happy with them so far. Have two sets of 2A3 options (other than the pair that came with it) to do some testing with now to see which I prefer.

With the 18s, this 2a3 amp produces plenty of power to fill a room (even a larger sized room) at not even halfway up the volume knob.

There are many great amps that will drive your Coherent speakers well. I had a pair of Coherent 8s for years and finally settled on an EL-34 amp and 4P1L preamp by Raul Tarta. Made in CT (as I recall). I know, you prefer an integrated solution but these are great, unsung products and a great value. Made in the USA. Simple Pleasure Tube Amps

I'm surprised that no one has mentioned Decware. Steve Deckert is a legend in the (mostly off Audiogon) audio community and he offers several integrated amps, of different configurations. FYI I believe that all of the Decware amps use a passive preamp section. But they are very well made, sound great and seem to retain phenomenal resale value.

Yeah, I believe the dealer Frank shares a room with deals with Allnic so they get paired together a lot. The M-2500 is a bit overkill for these speakers, I think.

But really, if you are in the market for over 100db efficient speakers, it's usually because you want to run low-power SET. 😅

I double checked.

On Montreal show last year Allnic Audio M-2500 monoblock power amplifiers derived Coherent model18 speakers.

Hi @mmcgill829 ,

Yes. To my taste this room was the best on this show.

I liked this Coherent Model 18 room sound 2 years ago with the Allnic Audio T-1500 integrated 300B SET. A year ago Model 18 was drived by Allnic Audio monoblocs. It still sounded good, but I liked the more warmish sound with the Allnic Audio T-1500.

 

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?

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.

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 @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. 

@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 ,

My congratulations.

In any case new speakers need a long break in to sound their best. I liked model 18 at Montreal audio fest a lot. It is very interesting to listen these speakers at home. In any case I don’t have a budget for new speakers. So I will stay with my old Altecs 604E. I just finished my DIY 300B SET project. I have a good first impression from this amplifier. After 50 hours the sounds is changing all the time. I am watching when break in will be finished.

https://photos.app.goo.gl/isJsvYM3x7hDaput9

 

@bjesien Just wanted to chime back in here since you asked - I have some notes on my thoughts on the speakers on my system page.

Just a very quick summary though: I love the speakers, and the combo with the Aric 2a3 and linestage is wonderful.

@bjesien Not quite. I ended up asking for them to be held until early January to ship as it was getting into a time crunch before I was out of town for the holidays. I was supposed to receive them last week (they've been in the shipping process for a bit now), but the winter weather that swept across the US last week delayed it for some days. They're currently in a warehouse about 30 minutes from me waiting on last mile delivery appointment - should get that call on Monday.

A bit down to the wire - I go out of town on business for three weeks this upcoming Wednesday - though no fault of Frank. The weather threw a wrench in delivery.

I'll likely get them and get them set up the night before I leave for some weeks, so it will likely be after I get back before I can really enjoy them. The good news is, I received my amplifier and pre-amplifier from Aric earlier last week and have them set up. So, the speakers are the final piece to the puzzle now. The anticipation is killing me!!

@toro3 I certainly hope so! Definitely will be a big step up from what I am using now, but it was just temporary anyway. :)

I also was checking on Coherents on the used market - but only saw stuff pop up very rarely - mainly 12s from what I saw - and mostly due to people stepping up the line. A great sign! I've been dealing with Frank directly and he's been a joy to work with.

Coherent 18 + Aric Audio Super 6SN7 Linestage + Super 2A3 SET = pretty sure this is going to expedite your journey to Nirvana. I was waiting for some Coherent’s to pop up on the used market, but it seems like owners rarely let go of them which seems like a testament to how they sound. I’ve been eyeing that Super 6SN7, too. Regardless, stellar selections, sir.

As a follow up to this since its been a few months...

I actually decided on going with the Coherent 18 speakers instead of the 15s, and I put a deposit down on a pre-amp and amplifier combo the other day and decided to go with Aric Audio.

Preamp - Super 6SN7 Linestage
Amplifier - Super 2A3 SET

This set pretty much tops out my budget, but after speaking with another Coherent 18 owner who loves them, talking with Aric, and looking into reviews, they seem like a great choice.

Other than that, a major selling point for me is that they are made in the US. I'm not really a 'made in US' only buyer (clearly, given the Coherents are Canadian), but for tube amplifiers, I prefer for peace of mind when it comes to potential future repairs. I've read many horror stories about amplifiers made overseas and trying to get service done being not only a huge hassle, but expensive with shipping and long down time.

Going the separates route will also give me greater flexibility with amp experimentation in the future, should I want to try out different SET amplifiers, since it's often easier to come across stereo/mono amps versus integrated with SET.

The LTA ultra linear (20 watts) and Audio Research I50 would both be excellent choices. I have the LTA preamp and it is magical. I’ve heard the newish AR I50 and it was spectacular. 
 

 

Hi @bjesien ,

I put a number of videos from the Montreal audio show on YouTube.

Just search: "Montréal Audiofest Coherent Audio", "THE EIGHTEEN Coherent Audio - Allnic Audio - Kuzma - Montreal Audio 2023"

It can give you some idea about how it sounds.

I almost bought them too but I just didn’t have the gonads to buy them without listening. Not knowing anything about the driver and the fact that every designer says they have the best bass…

let us know your impressions please.

@alexberger I was originally looking at both the 18 and the 15 models, but the 18 was outside of my price range a bit. I ended up getting a good deal on the 18 that made it work with my budget nicely, so decided to go that way after all. just made more sense to go for the top of the line since the price was right.

Either way, I would have been happy getting the 15 as well. If you have a smaller room, the 15 is likely a better match, I'd think, but chat with Frank @ Coherent and he can help you pick the best size for your room. He's very friendly and helpful, though expect somewhat longer response times (which is to be expected - he's busy making speakers!)

@mmcgill829 

 

Yes, being an audio gear reviewer or working in a high end store would be a real advantage.

@ghdprentice : OP, I hope things work out. I am sure you are aware that matching / purchasing unheard is a really difficult way to get an optimal system, one in close alinement to your preferences. If you look at how well a system fits your values as on a ten point scale plus or minus… with zero being perfect, one would probably only return or trade if it is really bad… out at 8 - 10 at either extreme. Meaning you’re likely to randomly fall in the huge area of ok, but not really that close to perfect. It’s hard enough when you intimately know the sound of each component to match them. Anyway, that has been my experience.

Yeah, I know. It does not help when much of this stuff is made to order or made overseas and US-based dealers often do not feel comfortable sending demo models in the mail (which is fair). I've been leaning toward the amplifiers that Frank @ Coherent recommended since he's tried a lot with the speakers and thinks that those options are the best at the moment. He mentioned that he used Triode Labs amps for some time, but feels that the Tektrons and Mastersound amps are overall better.

However, the Tektrons he uses are mono blocks that they no longer make (at least not on their website). They have an integrated version of it now instead (which I listed in my original post).

The only way to truly know if something will work perfectly is to demo it at home with the rest of my gear, so it's a bit like shooting blindfolded. Bummer that I'm not an audio gear reviewer who can get demo gear 😛

OP,

I hope things work out. I am sure you are aware that matching / purchasing unheard is a really difficult way to get an optimal system, one in close alinement to your preferences. If you look at how well a system fits your values as on a ten point scale plus or minus… with zero being perfect, one would probably only return or trade if it is really bad… out at 8 - 10 at either extreme. Meaning you’re likely to randomly fall in the huge area of ok, but not really that close to perfect. It’s hard enough when you intimately know the sound of each component to match them. Anyway, that has been my experience.

@ghdprentice :

Road trip. Sometimes it is well worth doing a really long drive… or even a weekend trip. Schedule listening sessions in advance. Explain what you are looking for in advance.
 

I made it a habit of visiting audio stores all over the country when on business trips as well. Even when not in the market. So, next time an upgrade cycle started I had had a good idea where I wanted to go.

Yeah, though many of the amps I am looking at are built to order (like the Triode Labs and Tektron mostly) and the Coherent speakers are the same. So while something may sound great in a shop with certain speakers and gear, it may not have good synergy with the gear I have at home. I've run into this issue a few times with purchases and wound up either having to return them or re-sell since it just didn't work out once I got it home, so I only really find in-home demos relevant for the most part. 

@alexberger :

I heard Coherent 18 in Montreal show. They sound very easy and dynamic. In term of dynamics they more similar to old Altecs or Tannoy Silver and Gold from 50x-60x than to modern Tannoys.

Coherent 15 should work well with  Aric Audio Super 300B, Allnic Audio T-1500 300B stereo, Coincident Frankenstein 300b monoblocs amplifier.

You don't need any of pentode push-pull amplifiers for these speakers. These amplifiers are more powerful but much less transparent and refined.

Good to know. I've heard both modern Tannoy Prestige speakers and vintage ones and the older ones tend to sound better to me anyway.

I heard Coherent 18 in Montreal show. They sound very easy and dynamic. In term of dynamics they more similar to old Altecs or Tannoy Silver and Gold from 50x-60x than to modern Tannoys. 

Coherent 15 should work well with  Aric Audio Super 300B, Allnic Audio T-1500 300B stereo, Coincident Frankenstein 300b monoblocs amplifier.

You don't need any of pentode push-pull amplifiers for these speakers. These amplifiers are more powerful but much less transparent and refined.

Road trip. Sometimes it is well worth doing a really long drive… or even a weekend trip. Schedule listening sessions in advance. Explain what you are looking for in advance. 
 

I made it a habit of visiting audio stores all over the country when on business trips as well. Even when not in the market. So, next time an upgrade cycle started I had had a good idea where I wanted to go. 

Probably the most annoying thing is that I don't have anywhere nearby to really demo any of these things, and many of the dealers have a 'no return' policy, so makes this especially difficult!

I hear ya, and in this instance I’d try to buy used at a good price (and from a reputable seller) so if it doesn’t work out you can likely turn around and sell it for little/no loss.  Example would be this AH Qualiton X200…


https://www.usaudiomart.com/details/649972223-audio-hungary-qualiton-x200-integrated-amplifier-spare-tubes-included-kt170-and-kt120/

Just a thought FWIW. 

@nordicnorm :I love them! I replaced my Martin Logan Spires with them. Prior to that, I thought nothing could out-perform the Spires (in that price range). I was very wrong.

That's great to hear! I've talked with a couple owners of the 15s and they said they outperformed speakers they paid quite a bit more for, and I've heard basically the same about the 12s and he used to make some smaller bookshelf sized ones as well.

I'm very much looking forward to them, and Frank has been wonderful to work with - very patient and helpful!

I love them! I replaced my Martin Logan Spires with them. Prior to that, I thought nothing could out-perform the Spires (in that price range). I was very wrong.

Probably the most annoying thing is that I don't have anywhere nearby to really demo any of these things, and many of the dealers have a 'no return' policy, so makes this especially difficult!

@soix :Very helpful stuff. Given that I’d look at the Audio Hungary Qualiton X200 or VAC is also worth a good look. If you can entertain a SET amp the Allnic T-1500 Mk2 could be a really nice amp given what you’re looking for.  Hope this helps, and best of luck.

Thanks! I'll check them out. I looked into Audio Hungary a while back and there seemed to be some grumblings about availability of warranty service in the US, so I didn't look into them much more at that time. Worth another look though! 

I did have some VAC things recommended to me when I was initially looking at Turnberry/Kensingtons as an upgrade, so will have to take a look at those again.

@nordicnorm :

I am powering my 12’s with a Coincident Dynamo 34SE MKIII amp that puts out a whopping 8 watts. Which is more than enough power for the 12s to sing.

The Coincident is being fed by a Don Sachs 6SN7 linestage.

Good to know! The 15s are even more efficient, so the little fleas will probably do well!

How are you liking your 12s?

I am powering my 12’s with a Coincident Dynamo 34SE MKIII amp that puts out a whopping 8 watts. Which is more than enough power for the 12s to sing.

The Coincident is being fed by a Don Sachs 6SN7 linestage.

 

Oh, another I have been looking at is the Triode Lab 2A3 EVO, but know next to nothing about them.

I have to second the recommendation for the Audio Research I-50. It is an amazing, musical, natural sounding integrated amp. I recently auditioned a Luxman, Pass, and the Audio Research integrated. The Luxman had great knobs and flashy faceplate ($10K), the Pass had great power and excellent rhythm and pace ($10k), but the Audio research caused ne to instantly close my eyes and be completely emursed in the music ($6K)… what a deal!

Wide and deep soundstage, wonderful midrange and vocals, not overly harsh on the top end, full bass without being too sloppy. Overall, I lean toward liking the slightly more lush/musical tube amps I’ve had in the past vs the hybrids/solid states.

Very helpful stuff. Given that I’d look at the Audio Hungary Qualiton X200 or VAC is also worth a good look. If you can entertain a SET amp the Allnic T-1500 Mk2 could be a really nice amp given what you’re looking for.  Hope this helps, and best of luck.

@bjesien :

Leben CS600 with KT66 would be great. the little 300 is great too but I liked it more for guitar and vocals than thumping bass type of music. I've owned the Mastersound 300BPSE, great amps. There's a compact 300B for sale on Audiomart from a well known speaker maker.

 

Have you heard the Coherents? I got close to ordering the 12 m a few years ago but just needed to hear them and couldn't. Please post some results.

I'll check that one out. I'm not really a thumping bass music person, so that's not a big concern, but I do wonder how versatile the tiny watt amps are. I'd imagine with speakers of this sensitivity, it should be fine for most things though.

I haven't heard the Coherents myself, so I am taking a bit of a leap of faith. However, I've chatted with a few current owners who listen to similar music and have had a similar 'journey' with gear as me and they can't say enough good things about them. I currently use Tannoy speakers (though not any of the Prestige line) so the Coherents are fairly similar in concept at least. I got to hear some Kensingtons when I was considering a few options, and they were good, but they felt a bit too big for me (and the Turnberrys felt a little too small in person, and didn't sound as good). There are some other small 'boutique' speakers I was interested in like Daedalus, but couldn't get a chance to hear them (and the models I was interested in were beyond my budget anyway). Not sure what the lead time will be on these, but I'll circle back once I get them and sit with them a bit!

Leben CS600 with KT66 would be great. the little 300 is great too but I liked it more for guitar and vocals than thumping bass type of music. I've owned the Mastersound 300BPSE, great amps. There's a compact 300B for sale on Audiomart from a well known speaker maker. 

 

Have you heard the Coherents? I got close to ordering the 12 m a few years ago but just needed to hear them and couldn't. Please post some results. 

@soix : What type of sound characteristics are you after with the new amp?

Wide and deep soundstage, wonderful midrange and vocals, not overly harsh on the top end, full bass without being too sloppy. Overall, I lean toward liking the slightly more lush/musical tube amps I've had in the past vs the hybrids/solid states.

@yogiboy :This Audio-Research should fit the bill! Audio Research I/50 Integrated Amplifier (overtureav.com)

Thanks for the suggestion! I've looked at their amps before, but from what I've read, when tubes are replaced it has to be done by a technician, which I do not like the idea of. I don't want to have to send it off for extended periods of time every few years (and pay) to get tubes replaced when there are plenty of other options where I can just do that myself.

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