Recommended Speaker List for Atma-Sphere OTL Amplifiers.

OK, I am not sure how many times this has been disscused but the information is found all over the forum. I would possible love to compile a list here.

I personally own the Classic Audio Loudspeakers T1.5

I am now looking to build a second room with the M60 Mono Blocks and MP-3 Pre-amp.

Would love fellow audiogon memebers posting any feedback with speakers they have used with these Amazing OTL sounding Amplifiers.
Note on these amps, although I've never heard these amps I think I saw one as a prop in a Frankenstein movie…possibly one of the most retro designs out there…cool. Also Atmasphere the person posts smart stuff here frequently.
I played a pair of Zu Union speakers with my MA-1's/MP-3, the results were incredible. They came close to my Vandy Treo's.
I don't have the M-60's but wonder if a pair of Zero's would allow you to use them with the Treo's?
In any case, Ralph makes a heck of an amp/preamp.
I use M60s and an MP-3 in my system first with Audiokinesis Jazz Modules and now Quad ESL 57s. I’m getting a pair of Spendor 1/2E speakers to use with them as well.

Dealer disclaimer.

I've been designing speakers with Ralph's smaller amps (S-30 and M-60) very much in mind for years, but my speakers tend to be bigger than average (though usually not "T-1.5 big").  I do horn speakers that hopefully don't sound like horns, well at least not in the negative ways that the word "horn" can bring to mind.   

In a fairly compact speaker, you might consider High Emotion Audio and Omega Loudspeakers. 

At what they do well the Quad 57s are just magnificent.  If you decide to do a stacked pair, contact me for a tweak suggestion.

Best of luck in your quest,



I have the S-30 and Raidho C1.1s. An excellent match.

I did consider your speakers. Ralph always speaks highly about you. The issue with me was I was looking for something more exotic. I am still searching and planning to fly into the USA to have a a listen to a few speakers and may visit you if you dont mind.

I have had a number of people listen to my Jazz Modules. One in particular who is pretty well known in the audio world mentioned that they sounded better than the German and other exotic horns he has heard. If you do visit Duke and hear his speakers I'm pretty sure you'll drop that exotic requirement. I only sold my Jazz Modules because my bi-amped ESL 57 set up with multiple woofers in a "swarm" array (ala Duke) gave me the benefit of what the ESL 57 does best without the bass limitations and resonance issues of those speakers.

Thank you very much, Clio09. I don’t mind my Jazz Modules being replaced by Quad 57s + swarm! Very nice combination.

Dragon, thank you for having considered my speakers.

Cosmetically they certainly are not exotic, nor do they use any particularly exotic technology in the drivers, aside from optional Beryllium diaphragms for the compression drivers. I now have access to a master woodworker who has built T-7s for John Wolff, so I can offer excellent cabinetry on a custom basis, but he is not cheap.

Speaking of which, have you considered the T-7? Field coil motor, wizzerless fullrange cone, beautiful tonal qualities, and magnificent cabinetry.

I don’t know whether this would be "exotic", perhaps merely "unorthodox", but some of my models deliberately approximate the acoustic effects of being in a significantly larger room, which imo has psychoacoustic benefits.

If you are serious about hearing what I do, I would like to put you in touch with a colleague of mine who a) has more of my designs on hand than I do; b) has a much better audition set-up than I do; and c) has contributed ideas which have significantly improved my designs.  I spoke with him just a few minutes ago and he'd enjoy it very much.   


I have the M60s and MP3 and use Vandersteen Quatros. Sounds incredible with no zeros needed.
I use a pair of John Wolf's T3.3 Classic Audio Loudspeakers  with the field coil option with my Novacron's. 
The Atma-Spheres are amazingly transparent with a huge sound stage. I would go with speakers capable of producing a huge sound stage and ones that are transparent. 

I have used the M60's and the MP-3 with the older model Wilson Benesch Curves. Great sound. There is a pair of Audiogon right now.

At the risk of stating the obvious, they should have a high, relatively flat impedence curve for the most part, although as others noted, they are reported to mate well with Quads.  Also Soundlabs and Magnapans, IIRC.  I have used them successfully with Merlins, Hornings, and now with a DIY pair of open baffles with field coil mid/tweet and conventional mid/low bass units.  From personal experience, if you have the room, they are fantastic with the Classic Audio speakers, being able to reproduce live SPL rock music in a very large room with the M60s..  If you want to get an opinion about how they mate with a particular speaker, you should ping Ralph (Atmasphere screen name), if he doesn't show up here on his own.  You will get an honest opinion with, IMO, no marketing hype. 
I am well aware of the smaller inconvenience of owning OTL gear but in my honest opinion for this level of quality in enjoyment I am more then willing to compromise. Once the match of the speaker and amplifier is complete all you experience is pure magical bliss!

The T1.5 Classic Audio Loudspeakers are excellent and magical theirs nothing like it. Its just flows with music in a emotional way that sparks your deepest feelings so easily, I feel like I'm transported somewhere else. 

The speakers are full field coil. These are a keeper I would never part with them. Mines are paired with the New Atma-Sphere Amplifiers "Nirvana". A Super Regulated OTL Amps LOL The best Atma has developed till date I guess.

The OTL amps have been a revelation. I was more in to SET and certain push pull class A design but never experience this form of lucid feeling from a sound system.

Its going to be hard to find a speaker that can perform like a Classic Audio Field coil but in a smaller and less expensive package and designed for smaller rooms.

I have been considering smaller horn speakers or Single wider-band drivers too. Just not settle down yet and need to go out and listen to some of the manufactures that are based in the EU.

My ultimate goal was to build a smaller system with another set of Atma-sphere gears this time with the MP-3/MA60. Once you go OTL you cant go back :-)  Everything else just sounds slower and less transparent. I cant seem to enjoy my previous gear (for second system) and thus had to sell some of them off.

Good suggestions here, thank you all.

I remember Ralph telling me he used Bud Fried's loudspeakers when he developed his amplifier, and I'm not sure there's a better match for either.  The series crossovers and true transmission line couples magically with the OTL.  Even after a couple of attempts at revival, sad to say the brand has faded into the vapor.

For what it's worth, though still owning several other speakers, including several Frieds, after hearing the Quad ESL57, which Bud brought to the USA, I've stopped thinking about loudspeakers.  No other brings as much reality
Dragon-vibe.....can you expand on your statement....I know very little about OTL

"I am well aware of the smaller inconvenience of owning OTL gear "
 I hope Ralph (atmasphere) responds. If not, you can always PM him.
I own a pair of MA-1's and have found them to be the most remarkable amps providing unmatched sonics as well as reliable, trouble free performance.
Go to his website, he has some good pages on his design.
As far as OTL inconvenience, there were earlier designs (Futterman, I believe), that were known to be problematic. Ralph's design improves upon this and makes his amps essentially bullet proof.
With my Atma-Sphere M-60 Mk 3.3 I ended up making my own DIY speakers. I stayed with 8ohm hi sensitivity drivers. The cabinets were purchased from Parts Express and are High Gloss, they look very nice.

I used Aurum Cantus G1 Ribbons and ScanSpeak drivers. My DIY external crossover boxes were made using Mundorf SGO classic caps, Path Audio resistors and Janzen inductors and the speakers were wired internally with Cerious Technologies Graphene Extreme wire.

Recently, I thought that I should upgrade my amps and then speakers. I don't know why just had the itch I guess.

So, in the last few weeks I have heard Magnapan 3.7i's with Rogue Audio amps, (very disappointing IMHO) Focal Kantra 2's with Nagra $80,000 amps and today the Goldenear Reference speakers with some $$$ French amps.

To my ears, none of these amps/speakers combinations sounded as good as my Atma-Sphere M-60 3.3 with my DIY speakers.

Bigger and more expensive is not always better...

I agree with the praise for OTL, and Atma-Sphere. I own a pair of MA-1s and have not looked back. I tried with different speakers, and even if 8 ohm speakers sounded OK, the full benefit of the amps was evident only when I got Audiokinesis Dream Maker speakers (16 ohm). Very much recommended, if you have room for them.
How does Tannoy & atmasphere match up?  Especially in the bass department......
full range or electrostatic speakers are excellect for tube OTL
my Fall project may be a set of the Monobloc kits to run the Vandersteen Treo at the condo for coastal winter heat !!!!!

Proac3.8 or any other proac before they switched to a 4 ohm load,which they recently did, why I don’t know, but the earlier proactive speakers are madgic with the atma spheres!

The Eminent Technology LFT-8b is very well suited for the M60 in all regards save one, that of sensitivity/efficiency. The LFT is rather insensitive/inefficient (rated at 83-4 dB), so in a large room at high listening levels the M60 may not provide enough power to the speaker. But planars are known to sound louder than equivalently-rated dynamics.

In all other regards the LFT-8b is an excellent match for the M60. It presents an almost purely resistive 8 ohm load to the amp, the midrange/tweeter panel itself an 11 ohm load. Put a solid state amp on the dynamic woofer (180Hz down), the M60 on the m/t panel, and live happily ever after! Ralph Karsten says he has M60 owners successfully using the amp with the LFT-8b.

Contact Emerald Physics (sold direct) o see who has their 2.8s in your area

Very easy load   

2.8s received an Absolute Sound award

MSRP $9998, but they run specials,


I have their KCIIs with upgrades similar to their Pro model. One of the very best speakers I've owned, including Genesis Vs, Accoustat 2 + 2s, Nearfield Pipedreams, Magnepan 3.5Rs, Usher 6371s...

KCIIs < $2500     
I think that the impedance curve is more important than the sensitivity. The DeVore 0/96s are a superb match and this comment is based on hours of actual listening experience. A friend and myself built a pair of M60s and have never heard a better amp on the DeVores. We compared the M60s to VAC, Audio Note and Mastersound. 
Vandersteen 5 series, Quatro series, Treo's with Sub 3s  have an easy impedance for most any tube or OTL design.
The unique 100  HZ high pass unloads the heavy lifting for the main amp and allows the speakers internal solid state amp to take care of the bass frequencies, in room compensation adjustments takes out your room / placement issues dramatically improving transparency and clarity of the whole system.
 Vandersteen dealer
..and to pile on a bit, the Vandersteen way preserves the transfer function of the main amplifier, which is part of the point of this thread....

How does Tannoy & atmasphere match up? Especially in the bass department......
Very well is the short answer.