B&W 804s + Atma-Sphere M60 MkIII.2

I am setting a second audio room where I got B&W 804s. I just heard Atma-Sphere M60 with a Mervil VSM, the soundwas excellent. The details and sound stage is fantastic. I don't have a chance to try it with my B&W 804s that's why I would like to ask you whether the matching system between 804s and MA60 would work out? I mean in term of power and ease of driving 804s?! I know 804s requires some serious power. I tried it with Denon POA-A1HDCI for home media room and was just ok! besides it sounds very good with Mcintosh MC402 which is no wonder!
I like the sound of Atma-Sphere M60 MkIII.2 and always wanted to have an OTL amp but the question relies on low impedance ability of these amp?! 804s nominal impedance is 8ohm but it goes down to 3.5ohm for lower mid range frequency. I also thought to associate a Velodyne sub for getting more bass.

I would appreciate your feedback.


Never heard the Atma-Sphere, nor know much about it. I can say, though, my 804S driven by my McIntosh MC275 sounds great. It's rated at 75W per channel, and some claim these versions deliver closer to 90W, but clearly not a lot of power. At the time I bought this amp, I also tried these speakers with an MC252 Mc SS amp, and preferred the tubes - to me the added Watts weren't key. Larger B&W indeed need a lot of power. I think the 804S are a great match with tubes. BTW, my pre is also tubed.

Atma-Sphere might chime in here. If they don't, go ahead and post the question to them.

Re sub, I run two Rythmik subs and I'm very pleased with the setup. Setup is tricky, but I learnt a lot in the process. If you go down that road let me know and I can share more on the way I approached it.

Let us know how it goes.
Call Ralph at Atmasphere. He has heard his amps on most speakers out there and will give you the straight poop. One of the real good guys in this field.
Swampwalker, thanks, I called Atmasphere and Ralph was not available. I talked to someone there and he said B&W804+MA-60 would be a good match but he was not so sure! I need to drop an e-mail to Ralph himself to find out about it.

Lewinskhil01, thanks for sharing your experience. I had 804D and 804S(!) driven by Mc402 which was excellent in term of details and sound-staging! However I felt B&w804D was a little bit bright, especially with AQ-SKY cables! I thought to incorporate some Tube Pre-amp to the loop. I added a MC2300 which resolved the problem, the brightness was gone. Finally I sold my 804D and for Tannoy Canterbury. The Canterbury has too much forwarding sound which becomes kinf o tiring after a while, I am not really proud of this last choice! I have to say B&W are excellent speakers for their comparative price range.
This 804s setup is for a second audio room (vacation house) and I am using my McIntosh Mx-135 as pre-amp. It is an excellent preamp-processor with a wonderful MM phono that I used it with a SUT for MC cartridges. I don't want to go crazy on spending too much money for this second set-up, my wife wouldn't allow that!?! I Heard Mc275 at dealer driving Martin-logan and Sonus Faber speakers. I was very pleased with its sound, it has a lot authority and details. Besides when I heard ATMA MA-60, I was so overwhelmed, perhaps there is something magic about OTL amps. Of course it was not a same setup and it is not an objective comparison! I try to find out more about ATMA MA-60 and matching issues with B&W804s. Otherwise I will go with McIntosh MC275, which is also kind of my wife’s favorite stylish amp! In the mean time I use my Denon POA-A1HDCI.
Lewinskih01, Regarding Subwoofer, I was planning to get one of those Velodyne EQ-Max10”. I read too much about one sub vs. two subs! Obviously, two subs resolving is more obvious. Besides there is a lot of challenges of incorporating 2 subs, placement, added distortion etc... I don’t know how much improvements I can get with 2 subs instead of one sub!? 20%, 30% of improvement or more?! Have you done this experience with just one sub? It seems placing subwoofer in the middle would be a good compromise!?

I think Atma amps are outstanding, from what I read. Zero feedback, OTL, fully balanced. BUT...your MX135 is not fully balanced, I believe, despite having XLR connectors. Make sure you tell Ralph about this.

Buying a used 275 is certainly an option if you want to minimize expenses. Mine is a mk.IV and I have no desire to upgrade to newer ones - besides, I really dislike the green leds under the small tubes the new 275 has.

Subs: big deal! But you have to be willing to invest time in setting them up. 1 sub vs 2, don't know how to quantify the improvement but it's definitely a lot more than 30% in my case. I'm not running stereo subs playing both the same frequencies and same settings. Google Earl Geddes approach for setting up multiple subs. It made a huge difference for me.
I chose Rythmiks for having a reputation of very clean sound, not overly expensive, and have very many variables you can set up in the plate amp. BTW, my two 12" Rythmiks replaced a single REL Storm III. Nice sub, but didn't have the flexibility I wanted. BTW, my Rythmiks are DIY boxes, quite heavy and heavily braced. Each sub weights 100 lbs, for a 56 liter box.
Experimenting with placement of subs is crucial in Geddes approach. Each sub has pa different setting for crossover, slope, volume, phase (a critical feature), and amplifying/damping a certain frequency/bandwidth.
I use a measuremnt mic, an outboard USB card for the mic, and REW software. These are absolutely needed for setup. I wish I could post graphs here. With only the 804 playing you see the lowest frequencies missing as you would expect, plus the room interaction at the lower frequencies. Add one tunned sub and the lowest frequencies are boosted, but I still get huge peaks and valleys in response. Add the second tunned sub (tunned t work with the other sub) and the response gets smoothed significantly.

One of my subs ended up right in between my speakers, while the other one is tugged in a corner.

Sorry I get long winded. I did enjoy learning through this setup process!
Lewinskih01- you make a good point, although many people report excellent results running them single-ended either w a conventional RCA termination (w shorting pin in the XLR jack) or w an XLR-terminated (aka pseudo-balanced) connection.
Not to get too far off point, but can you tell us whether you are running stereo subs or dual mono subs. If the latter, do you think that the same "rules" apply to stereo subs.
Lewinskih01, you are right on real balanced connection, that’s another parameter I’ve been considering. Let’s see what Ralph is going to suggest.
For subs, your comments sound very professional and I am sure you spent a lot of time on setting the subs. I wish I had your skills and patience. I came across this article which is very interesting. I changed my mind on Subwoofer size. I guess it’s better to move toward a 12” sub. I am not really obsessed with a lot of bass in the music. I do love attending live music performances and the thing I noticed is that the bass in live music does not shake the salon, classical music to Jazz/Blues and even semi-metal group like OM! A good compromise on bass and the whole setting is the key! Besides finding a good subwoofer especially built for music is another challenge, because most subs are made for HT!


Besides finding a good matching amp, my plan is to get one good sub and perhaps later on move toward a second sub. Rythmik subs looks nice and well-built. There is not too much reviews on those subs, I was wondering how do you compare Rel Storm vs. Rythmik subs? I mean uniquely for music usage.

The link didn't go through?!

Per the B&W web site the impedance goes down to 3 ohms. Power wise the M60 sounds like it would be fine. However, the 3 ohm impedance could be a problem. The way around this would be a Zero auto former (anti cables.com) which is placed between the speaker and amp and allows the amp to "see" a higher impedance with easily selectable choices of 2x, 3x and 4x the speakers impedance. So, as an example, if you choose the 3x option the M60 would see a speaker impedance of 9-24 ohms which on paper sounds about perfect but you can easily switch between the options and see which sounds best. It come with a 60 day in home trial so there's lots of time to find out which works best for you. Another benefit, the M60 will put out 80 watts/ch at 16 ohms up from the 60 watts/ch at 8 ohms.

It may sound strange to have an OTL amp only to have but a transformer between the amp and speaker but the Zero autoformer is not like the transformer in a traditional tube amp which has both primary and secondary winding. The Zero only has primary and just enough windings to do the impedance adjustment so it much more transparent than the typical output transformer
BTW, the Zero is not just for OTL's. Virtually all tube amps will sound better into a higher impedance. For instance, the MC275 mentioned by Lewinski above, IMHO, would benefit from the Zero by not having to play into the impedances below 6 ohms with lower distortion, better bass etc. Some of the biggest users of the Zero's are Magnepan owners with their 4 ohm impedance driving them with tube amps.

Check out anticables.com. Hope this helps.
BTW, my own setup has an Atmasphere S30 driving the 16 ohm Zu Superfly's.
It asked Ralph (@atma-shere) about this issue and he responded even though his busy schedule, he is in RMAF show. That’s very impressive and shows how dedicated he is toward the customers.
Franck thanks for your suggestion. It is very interesting that even Ralph mentioned the same alternative of using Zero Auto T. I looked at several reviews too and it seems it is a valuable solution to resolve mismatch impedance issues between Tube-Amps and Speakers. There is some compromises but bottom line if one cares about OTL, that’s the solution to move toward! The other alternative is to change speakers! I was wondering with your speakers having 16ohm input impedance, you wouldn’t really need any Zero Auto T. Based on your experience, does this solution makes any changes (good or bad!) on matronymics and details?

Right now I'm running stereo subs, but's only because I have not come around to building the Y connectors to have them both sum-up L&R signals. This is the recommended approach per Earl Geddes, which I'm following with good results.

I really don't want to come across as a specialist, as I'm learning along the way. But if stereo subs sound this good and it's a "deficiency" per Geddes' recipe...I think it should sound even better with dual mono.

Some people on these forums believe we can perceive directionality below 80 Hz. I tend to believe in people like Floyd Toole (author of Sound Reproduction) who say otherwise and I can see they really know their stuff. So if we can't perceive directionality, Geddes approach makes full sense to me as it addresses the interaction with the room, which clearly is the biggest deal under 150 Hz.

Hope this helps!

Indeed, I have always heard very good things about customer service from Atmasphere. That is great. Seems is up to you which amp to go with. BTW, I've been very well behaved in not steering you towards the MC275 as I'm quite intrigued about the differences between your Tannoys and your 804S with the 275. Should you go with the 275, please let us know and I'll be bugging you down the road.

One caveat to Frank's suggestion with the Zero: the 275 has an output transformer that apparently does a similar thing to the Zero, and has 16, 8 and 4 ohm taps. In fact, an audio buddy drives his CLS planars with his 275 with no issues whatsoever.

About REL vs Rythmik. Such a difficult question to answer well. The REL is great, but I had only one so the comparison is not fair. It also has a 10" driver vs two 12" drivers in a much larger sealed enclosure each one. For the price of one REL I got two Rythmik kits and built the enclosures pretty stiff and at the ideal size. Bass is much better with the Rythmiks, but maybe with two RELs I would have gotten the same response. Yet the RELs don't have as much setup flexibility as the Rythmiks. Rythmiks are also servo-controlled, and indeed the bass sounds very controlled.

As of now I'm partial to the Rythmiks + spending a fair amount of time setting them up.

I don't use a Zero with the S30 and the 16 ohm Zu's as the Zu's impedance appears ideal for the S30. However there is a body of thought that it might sound better still thru a Zero at 2x looking at an impedance of 32 ohms. I'm happy with my situation as it is.

The Zero is really intended for your kind of situation where you enjoy your existing speakers but the 3 ohm impedance is not ideal for the amps you would like to pair it with. With the Zero you are adding wire and a passive device between the amp and speaker but in situations where it's needed the positives appear to far outweigh the negative.

Regarding changing your speaker, thats a whole other ball game. If you enjoy the B&W's keep them and find an amp that does what your looking for with them.


Wasn't trying to steer anybody anywhere. Just trying to answer a technical question of the OP regarding using an OTL with a speaker with a significant impedance dip.
As an aside, it's great that you and your buddy are getting great results with the MC275 driving speakers with low impedance dips. It's a testimony to the excellence of the output transformer and power supply. Even though the output transformer has multiple taps the amp is still "seeing" the impedance dip of the speaker. The question is, would it sound better still with the Zero in place?

Good luck making your choices.
Lewinskih01, I’ve never had this impression that you were steering me toward MC275. It is a wonderful amp and no wonder it has been around for more than a half century! Contrary to that, I appreciate your sharing experience and as always I would like to learn more on audio setting stuff, it is kind of endless passion to improve sound quality and enjoy more from the music. By next week, I plan to ask MC dealer if I could have a MC275 for a week or so for a test drive!
The comparison was not really between Tannoy Canterbury vs. 804D. They are on different leagues and price ranges. I meant regarding price tag of T. Canterbury, I was anticipating to get more sonic features, like placement/precision and better distinguishing of instruments in orchestra, more depth behind speakers, more imaging on two sides of speakers rather than in front. I bought it as used locally and placed them per se professionally with some help. Of course tastes are different when it comes to listing preferences.

Francks, As for Zero T. on amps, there is this Graff Gm100 amp which functions as hybrid OTL! It seems they use kind of zero T. for accommodating low impedance speakers. A friend of mine (back in EU) has this one and she is very happy with it. I am not sure if Graff audio is in business any more.

As my wife complains, changing audio gears and never totally been satisfied with our choices is more than a passion, it is an addiction! I would add, it is a positive addiction…

Thx, Lewinskih01. I am interested because my Ref 3A Supremas have passive subs and I have always wondered if I should drive the sub cabinets with a stereo or mono signal, downstream from an active crossover/bass management device.

I wasn't aware the Supremas had passive subs. There is still an argument for adding independent subs: a) the more bass sources in the room, the flatter the bass response (again, per Earl Geddes); b) the optimal bass drive placement is not necessarily the best speaker placement.

BTW, what do you drive your Supremas with? I've been toying with the idea of Grand Veenas with my MC275. Upgrading speakers is not really my next step, but when I day-dream I think about speakers. My speakers are the components that have been with me the longest.
Michel, and Franks,

I apologize as it seems my post was not clearly written. I was not insinuating Franks was steering Michel in any direction whatsoever. Didn't mean to.

The comment about steering someone and being well behaved was a way of making fun of myself, as I was being objective in answering questions, but down deep I was also interested in having comments from someone who could compare the sound differences between a Canterbury and an 804. I know they are in different leagues, but I understand their sound signature is different and I would benefit from some input. Logistics make it impossible for me to audition a Canterbury. Along the lines of the post above, testimony of my sporadic day-dreaming with speakers.

Maybe I should stick to speaking about the subs? :-)
Lewinskih, We all have different tastes on judging quality of speakers. The major factor is based on our taste on what type of music we are usually listening. Most of the time I listen to Jazz, blues and orchestral /classic opera and chamber music. This doesn’t exclude my love for classic rock. So my comments are based on these kind of music and I don’t consider myself as an expert on audiophiles’ topics!
Regarding Canterburry speaker, it is an excellent speaker for chamber music, Jazz and somehow the blues. For example, when Pierre Fournier plays cello on solo, it is just marvelous! However, when it comes to big orchestra, you could not properly follow the instruments, there is kind of congestion on music. The violins and altos don’t sound really good at all, besides you could clearly hear the drums! This is maybe because of its nature of forwardness of music. For Operas, when sopranos and tenors walk away from each other and change their position on the scene, for example, one goes on right corner and the other on back left, you still hear them like they are almost next to each other! Generally speaking, it has a 3d imaging but it is kind of narrow one compared to B&Ws and isn’t present toward back of the speakers! As for classic rock specially the live version, you feel the fatigues on hearing after 5-10 minutes. A few days ago, I tried AC/DC lp, it was loud with a lot of bass, but you could not too much enjoy the flow of music and instruments, the bass is THE dominant sound which covers higher frequencies. It is obvious because the 15” woofer is in charge of delivering different range of frequencies. It is not a fast and very dynamic speaker.
Tannoy used to have some dealers in USA. When I talked to a representative back in EU, he was saying their distributor in US didn’t do a good job for selling/marketing the brand. Therefore they decided to enforce their present in Asia and EU. 18 months ago, I heard Westminster in a dealer in Bay Area and really liked the sound but not for $35k! This one was definitely out of my budget. Once I found a local sale of Canterbury with interesting price! I bought it and ask a local expert to tune it to my room. I used MC402 and VTL MB-450 II as amps. I found MC402 is better because of its deep bass and fast dynamic compared to VTL 450. VTL+ Canterbury sound had too much warmness, based on my taste.
As for 804, maybe it is not a real full-range speaker, but it is an excellent speaker when it comes to be versatile on different type of music. Sound-stage and details on mid-high frequencies is fantastic. Its only default is not having enough bass! I think a proper setup of subs+804 could provide almost as much as sound quality as the very expensive speakers. This procedure needs a lot of patient and acoustic measurements, especially when it comes on positioning two subs knowing different position combination in the room. For example in last CAS’13 I auditioned a setup of Zu acoustic + Sub (total ~10k) that has better sounding ( all my friends saying the same) than the Von Schemikert VR-11SE (~140k)!? Of course all comes to proper setup. That’s why I am seeking this path toward 804s+sub! Perhaps first with one sub and after that I will move toward a second one. The Velodyne Subs have very positive reviews but the issue I found with them is that you don’t have too much freedom to setup the EQ! their big DD version could be set up with computer connection but they are too way expensive (2x~3k)! I am looking to some B&W subs because of their experience on Audio music rather HT setup. The price wise also they are much affordable, especially some used ones. I have some budget limitation setup by my wife, which makes sense because as a second audio room, we are not going to use all the time.

"I wasn't aware the Supremas had passive subs."
Yep, two 8" isobarik loaded in each lower cabinet. You can very their crossover to the Royal Master monitors w a jumper, 50 or 60 hz, IIRC. I've been driving the monitors w VAC Ren 30/30 or Doshi-modified Lectron JH-50 and using a variety of ss amps on the sub, crossing over actively w NHT X-1.
Michel, thanks for the insight. I still would love tho hear the Tannoys, but it's sounding like it might not be my cup of tea.

Swampwalker, interesting input! Somebody posted the Grand Veenas as becoming distorted at high SPLs, attributed to their direct connection between the amp and mids driver. What he meant by "high SPL", I don't know. Do you find this to be an issue with your speakers?