I just purchased a used OTL Atma-Sphere M-60 mono blocks that I have sent to Atma-Sphere to be upgraded to the current model 3.3 and I also added the option of a higher quality power supply and V caps.
I have sold my old trusted Eggleston Andra 2’s speakers and have built some monitors using Aurum Cantus ribbons (102db) and Aurum Cantus midwoofers (90db) that are both rated as 8 ohm nominal. I have a DEQX Premate and will be crossing over to (2) JL Audio F-113 subs at 80hz.
Currently I am using a solid state high power stereo amp (Pass Labs) that I used with the Andra 2’s.
The Atma-Sphere M-60 is rated at 60 watts class A and is said to work better with higher impedance loads.
It will probably be a few weeks until I get the M-60 and was hoping someone could provide opinions of what to expect.
I listen to late 60 early 70’s classic rock music mostly. Sometimes loud.
@charles1dad , I think you might misunderstand. People hang on to their equipment, sometimes for life **regardless of the equipment**. To say that it "never goes one way" as you did earlier must be seen by a reasonable person as incorrect. That's all.
I was simply illustrating from personal experience that this is so.
The most common theme I hear when people actually tell me why they sell our gear (the second most common theme being they bought speakers our amps won't drive) is that they are downsizing or simplifying their setup (although its unclear what the latter means; if simplifying the signal path, the only amps I know of that have a simpler signal path are the First Watt DIY amps which have a single output transistor as the sole aspect of the signal path). As tube amps go we only have one gain stage which is about as simple as it can get.
I am not disputing that you have very loyal and long term customers at all. I'm merely stating that given the nature of some audiophiles there is always some degree of movement between various choices of components including amplifiers. Tube to solid state, Class A/AB to class D, single chassis to mono blocks and back and forth it goes. Some former OTL owners are now SET owners and certainly the converse is also true.
When I first got started decades ago it took me a while to get used to the fact that people would sell our amps and look for something else.
Over the years though the one thing that has really shown itself over and over again is how successful the initial setup of the amplifier installation actually was. If that was right (meaning: the right speaker load, short speaker cables, a competent preamp and front end to drive it) we found that owners tended to hang on to their gear. I don't know if owning it for decades until death counts, but if it does then the above quote is false.
This is why we developed our update and warranty reactivation policy, so owners of older gear could keep it current.
Understood. yet people move between OTL and SET with traffic flow and preference moving in both directions. No doubt you have customers who formerly owned SET. SET builders can cite former OTL users as their current customers . These things never move in only one direction.
^^ Rear right and rear left are the input tubes, in parallel.
They are part of a single gain stage called a differential cascode, common in solid state circuits but unusual in tubes- when we first started using this topology we were the first to do that in a tube amplifier.
The middle tube is the top of said cascode circuit.
Therefore the two bottom tubes in the cascode circuit are the most important in the amp for sonics, followed by the top tube in the cascode (rear middle position).
The front tube has no gain and is the driver for the output tubes. It controls the Bias and DC Offset. It should be a -GTA or -GTB if using NOS types.
I believe a more compelling and "competitive" comparison would be the
Line Magnetic 805ia. This is a very highly praised 805 tube SET with 45
watt output. Of course with these types of comparisons, final choice
has much to do with plain old taste. Both of these fine amplifiers will
have their passionate and loyal advocates.
The speakers used are going to play an enormous role in the results! In this case, the Line Magnetic is at a bit of a disadvantage due to power, not just because its only 45 watts. The problem is that if you really want to know what the two amps can really do, the LM should not be run past about 20% of full power for its best results (otherwise the higher ordered harmonics tend to show up in its output). That's about 10 watts. Ozzy's speakers seem to be about 90 db or so; that really isn't going to allow the LM to strut its stuff without a lot of distortion unless you keep the volume down.
We have a lot of feedback from our customers on this sort of comparison.
I picked up a couple used Sophie 6SN7 tubes. I think Ralph suggested that the center back would be the best placement. A few moments of listening and they do sound more lively than my previous NOS RCA's.
So, I also just bought another 2 more (used on line) Sophie's. I think Ralph said to place them in position 1 and 3. Is that the opposite back corners?
Can someone explain the tube numbering scheme on the M-60's 6SN7 tubes.
Starting with the front, then left back, middle , then right back.
I think an M-60 to the Linear Tube Audio ZOTL 40 comparison would be very interesting. David Bernings OTL design and Atma-spheres OTL. Two very fine amps with similar design concept.....or maybe not so similar? I know they are both OTL but after that they may not be similar at all. I've heard the ZOTL 40 and it took my breath away. Would love to hear the M-60, even if it it out of my price range, as I'm sure it would also.
Ozzy, I believe a more compelling and "competitive" comparison would be the Line Magnetic 805ia. This is a very highly praised 805 tube SET with 45 watt output. Of course with these types of comparisons, final choice has much to do with plain old taste. Both of these fine amplifiers will have their passionate and loyal advocates. Charles
OK: you asked. A lot has to do with the speaker of course, but the feedback we have from customers is that if the two amps are on a speaker that is friendly to both that essentially it is as you surmise.
But we get that a lot and not just with comparison to the Primaluna. That such is so is not surprising on two fronts; the most obvious being that obviously the positive comments are coming from customers that set the amps up right. The other is the overall design features of the amp; M-60 has full power to 2 Hz and can play bass quite well, owing to only one stage of gain and a direct-coupled output. With so little to go wrong its obviously very fast and more transparent without brightness. Triode operation. Fully differential. And so on (no single feature, but the combination of all of them makes for what the amp is). manufacturer caveat: we make the M-60 amplifier.
Can you share your comparison? Ralph, I know you are the owner of Atmasphere but I would really like to hear your opinion. And Is there an on line comparison?
I am only asking because I really do love the M-60’s amps. But, the Prima Luna gets more press coverage and is only single ended.
I think it would be very interesting for a head to head comparison sound quality wise. I did hear the Prima Luna at a Dealers showroom a few years back and I was not impressed. At the time I was using Pass Labs amp and the Eggleston Andra 2 speakers and the dealer was using Sonus Faber speakers with the Prima Luna.
My bet would be on the Atmasphere stomping the Prima Luna.
@ozzy , make sure that 6SN7 that sits in the front by itself is a -GTA or -GTB. That particular position has more voltage on it and the older GT style tubes will have a shorter life in that position. FWIW the Russian and Chinese tubes marked 'GT' seem to be OK in that position.
Yes, I do have (2) JL Audio F-113 subwoofers. With the DEQX I am crossing over at 100hz. And yes, this combo far exceeds my Egglestons. I sold them.
Well my 72 hour abstinence is complete! I just turned back on the Atma-Sphere M-60's with the NOS 1970's era Russian 6H13C output tubes and the RCA 1950's era 6SN7GT driver tubes.
Wow, not bad. I own a pair of Zu Omen Bookshelves. They have a similar range, and I like their simplicity (crossover-less). I find it amazing that such a small enclosure can still reproduce such low frequencies.
Will you be adding subwoofers? Looking at the DEQX and its' capabilities, I would imagine that your DIY speakers and a pair of subs could possibly out perform your Egglestons. Perhaps you could build those, too? Bob
The rated FR is 37 to 4000hz. But that is probably with a ported design and to me would be very subjective anyway. I would say reasonable / usable low end and a non ported design would be about 50-60hz.
Thanks for your info. The Grand Prix amp stands that I am using have little pads that go between the acrylic 3/4" shelf and the carbon fiber stand. They are available in different "squishy" pads for different weight loads. I did try Stillpoints Ultra SS under my Pass labs amp and I did not like the sound with them with my Grand Prix amp stand.
o_holter,
Thanks for your post. My DIY speakers have a very flat 8 ohm load and a high sensitivity rating. Couple that with the high crossover setting , I think they are easy to drive.
First off I am getting older and my Eggleston Andra 2 speakers were 215lbs each. Moving them around the room is no fun. I always wanted to try tube amps but I knew that my Andra’s required a fairly hefty amp to drive them properly.
Once I got the DEQX Premate with its built in subwoofer crossover, my brain juices started to flow. BTW, I also retired 2 years ago so I now have extra tinkering time available.
Anyway, I wanted to make a very easy to drive stand mounted speakers to use with my JL Audio subs. I made a prototype with some drivers I bought on EBay. They actually sounded pretty good but the cabinets still looked very DIY (I own a jig saw and a circular saw and haven’t changed the blade in 30 years)!
I then found on Parts Express some really nice Hi Gloss cabinets with the internal volume and size I was looking for. So keeping with Parts Express, they sell the Aurum Cantus G1 ribbon tweeters that can handle 100 watts rms. (I have always loved the sound of ribbon tweeters). I then thought keeping within that family line was the top of the line Arum Cantus 6.5 mid woofer. It had the specs that I was looking for. Well, the 6.5 mid woofer really turned out to be a 7" size and the High Gloss cabinets were a pain to cut. The front baffles are 1 1/2" thick !
But I did it, and they look great. I stuffed them with " acousta stuff". I wanted to be able to experiment with different crossover settings so I built an external crossover box. Well as I started trying more and larger caps and inductors that box became too small and I made a larger one with spikes! ( BTW, I ended up with all Mundorf silver, Gold, Oil caps).
Anyway, it has been a fun challenging project that I am really proud of. I have listened to many systems and I think I have a winning combination! Total cost about $2600.
It is certainly possible to overdo the DEQX calibrations/corrections, resulting in unnatural sound. But as my dealer advised me (Nyal Mellor of AcousticFrontiers.com, who is wonderful), corrections should be applied conservatively. Especially with respect to the natural upper treble rolloff that most speaker/room combinations tend to have at the listening position.
My Daedalus speakers are rightly known for having a very natural sonic character, and that was only improved as a result my use of the DEQX. Most notably in the case of recordings having sound quality that is mediocre or worse, especially in terms of harshness or excessive brightness in the treble region. As I said in one of my posts in the DEQX thread:
Perhaps most notable among the differences that I and my wife perceived were on some recordings having overly bright string sound, including some string quartets as well as symphonic recordings. Those became much more enjoyable with the filters engaged. Not because the sound was dulled down, but because there seemed to be increased detail and improved definition in the upper midrange and lower treble, as opposed to a more homogenized presentation of those notes, which in turn resulted in the brightness being less objectionable.
I can say also, in the case of my HDP-5 and as Ozzy and numerous others in the DEQX thread have attested to in the case of other models, that with the corrections bypassed the unit is amazingly transparent. Even when an analog source is being used (via unbalanced connections, at least; I haven’t used its balanced analog interfaces), and is therefore processed through the unit’s A/D and D/A converters. I can’t say that there is zero effect on the signal, but it is remarkably small, and easily outweighed by the benefits the processing provides.
@almarg , et al. Considering how much you are doing to the original signal (when processing through the DEQX), do you think you are altering it to something 'unnatural'? Bob
I don’t recall anyone reporting having used a DEQX with a time coherent speaker (e.g. Vandersteen, Thiel, Green Mountain Audio).
BTW, time coherence implies phase coherence, but phase coherence does not necessarily imply time coherence. Many speakers are phase coherent without being time coherent. See the post dated 7-15-2014 by Roy Johnson of Green Mountain Audio in this thread:
As you've probably seen in the past, though, John Atkinson’s measurements that are presented in conjunction with most speaker reviews in Stereophile sometimes provide impulse response graphs (and associated commentary), and usually provide step response graphs, which can also provide insight into time domain performance.
Presumably the time alignments provided by DEQX would not provide a benefit in the case of a speaker that is inherently time coherent, such as your Treo. But of course the frequency response and room corrections it provides would presumably still be applicable. As well as preamp functionality that is provided by some models, and A/D and D/A converter functionality.
Thanks ozzy and Al! I have been reading and rereading the manual, as well as the thread Al linked to.It is a lot of information, and I am not the most technidally proficient person. So, sorry if I repeat something that has already been answered.
Has anyone used the DEQX on phase aligned speakers like Vandersteens? As a Treo owner, I would be curious to see what a phase aligned speaker would show on a graph. I think I saw a mention on the long thread Almarg linked to, but I can't find it again. Bob
+1 to Charles’ comment. Great job, Ozzy. Between developing the DIY speakers, becoming proficient with the DEQX, and integrating both of them with subs and two very different amps, you’ve certainly dealt with a multitude of challenges.
And Bob, +1 to all of Ozzy’s comments about DEQX. Regarding the graphs, btw, when you go through my posts in the sections of the DEQX thread I referred to you’ll find links I provided to graphs of the speaker and room measurements I took, and the resulting calibrations. As well as descriptions of the necessary measures I took to minimize the effects of room reflections on the speaker measurements, which as will generally be the case included (among other things) moving the speakers from their normal positions. That can be a challenge if the speakers are large and heavy, of course, and for one reason or another it will probably have to be done more than once.
Thanks!. I finally received my 1970's new Russian output tubes. With these tubes and my newer 1950's RCA driver tubes, I think I can finally be ready for the final voyage.
But, Ralph says for tube longevity to put these new tubes on standby for 72 hours before using them. That means no music until Tuesday night! Yikes!
gdnrbob,
Yes, I have done probably a dozen or more calibrations. But I guarantee no matter how many times you read the manual the first time you try it you will be going back and forth through the instructions mumbling words that you won't be proud of.
I still have a problem interpreting the impulse response graph and the corrections settings. But most everything else I could help you with. Al is also very knowledgeable about the DEQX and its settings.
So, Ozzy, you managed to do the calibrations without help from DEQX? I am reading the manual. It is pretty detailed, but seems doable.(I still haven't finished reading it completely). My biggest concern is interpreting the graphs. Not so much the deviations of frequency but time and phase lag. Maybe it becomes clearer when using it. Bob
Hello Ozzy, Well, that says quite a lot. Purity is immensely desirable yet hard to achieve, it goes hand in hand with naturalness. This is the mark of genuinely top tier components IMHO. Congratulations 😊 Charles
Ozzy, I'm glad that the acquisition of the Atma-Sphere power amplifiers worked out well for you, it's apparent that you're very pleased with their sound. What is their most noticeable contribution to your system? Charles
In my experience, amp / speaker / room matching is the way to go with OTL amps. I can get my MA-1s to sound okay with 8 ohm speakers but I chose speakers that have been developed for OTL (Audiokinesis) and have not looked back. It is only then, that you fully hear what the amps are capable of.
I can’t really comment about DEQX support. ( I hope I don’t have to find out). In actuality the DEQX is more complicated than the on line info shows. But, many of us are now mastering all the quirks and can help you. I must say the finished calibration does not sound in any way digital or with the negatives I have experienced with previous room correction devices. (The current one that comes to mind is the DSPeaker). The DEQX is the real thing!
bugredmachine,
Now that I’m getting more time with my Atma-Spheres I am so impressed that I can’t imagine anything sounding better!
The heat in my audio room will increase about 4 degrees, IF I have the amps on all day.(12+ hours). This amount is probably not much more than when I used the Pass Labs the same amount of time.
I must add that Ralph at Atma-Sphere is a A+ dealer and will provide help when needed. Highly recommended!
Geez Ozzy, I moved from the east side to the west side a few years ago and I just caught wind of this thread where you are making changes once again. I'm taking delivery of a pair of older Atma's that Ralph did years ago to try my hand at OTL's as well. I bought them last week and they are being shipped now from the west coast. Not thrilled with the expected heat in the room but excited about the potential for another step up in "magical sound".
Thanks Al/Ozzy. Since were still encased in snow here in the NE, GardenerBob hasn't been doing much gardening. So, after a sunny Friday afternoon, I have been aquainting myself with the DEQX. I still have to go through the Agon thread, but it really is interesting. (Perhaps next winters' project). @ozzy , I probably will buy used, too. Has DEQX been okay with non original owners, in terms of support?
It sounds like ozzy has gotten the amps to work in his system.
I have some tips:
The most important tubes for the sonics are the ones at the input of the amp. The precise location varies depending on when the amps were built (the M-60 has been in production in various forms since 1991). NOS 6SN7s get rolled into the amps quite often; the input tubes can be GTs. This means you can use Ken-Rad (of the NOS tubes they get the best marks from our customers), the Sylvania metal-base 'chrome domes' or the RCA Red Base (and its variant, the CBS Zalytron). But our customers have indicated that the Sophia, Psvane and TJMusic tubes seem to have all the best properties of the NOS tubes but without the weaknesses!
Keep the speaker cables as short as possible and the speaker connections as tight as possible- but don't tighten them so hard that you strip the threads or you will really regret it! Tight connections do sound better.
Ozzy sounds like he's running the amps on platforms. To test the efficacy of the platform, place isolation devices (squishies) beneath the amp and audition. If better, the platform isn't doing its job. If worse, then apply some sort of point system (Tip-toes, Stillpoints, etc.) to get the most out of the platform.
Damping rings can be applied to the 6SN7s but not the power tubes.
Power cords make a difference and the difference is measurable and audible. We've had excellent luck with the Purist Audio power cables and there are many more.
Fuses can made a difference too, but the most important fuse is the one by the power cord, and that one is the speaker protection fuse. If a tube arcs and does its worst, that fuse is going to blow, so if you have a $30 fuse in there it can get old pretty fast.
Of course in that regard, our experience is that the Russian 6H13s (the Russian version of the 6AS7G) hold up a lot better than the Chinese tubes. Set up on the right speaker we've seen them last many years.
Never apply contact enhancers to the input connections or the tube sockets other than a light spray contact cleaner. Radio Shack sold a spray contact cleaner that was quite acceptable and you can also use the red and black DeOxit in a spray can. Anything stronger than that is asking for trouble.
almarg's earlier post that he references to above is what got me interested in the DEQX units. It is quite the animal. The one I have is the Premate+. I bought it used. It is a preamp, it analyzes your speakers + subwoofers, your room, and you can make corrections based on the graphs and charts produced. It also has a variable crossover for subwoofers including delay and gain adjustments.
But, there is a stiff learning curve because it is a complex unit and the instructions are complete but in a confusing order. I have finally developed my own easy to follow notes that allows me to take measurements quicker. But it still can take 2-3 hours.
I use their top of the line HDP-5 model, which serves as my preamp as well as providing speaker and room calibrations/corrections. (And yes, to answer your question those can be switched off or on at the touch of a button on either the remote or the front panel).
My own experiences getting it dialed in, which at my slow and methodical pace extended over about 6 months, are reported in the above mentioned thread in posts between 5-16-2015 and 12-2-2015.
Thanks for posting your impressions. Your experience mirrors mine and is significantly better worded. I have no doubt that as things 'burn in', you will notice even more details. As I have said before, I was completely amazed with how musical Ralph's amps are. I think having two different amps is a nice way to keep things fresh. Bob
Well, at this point here’s an update of my opinion of the
Atma-Sphere M-60’s compared to my Pass Labs X350.5.
First off, the cu V-Caps have maybe 40 hours on them. I
recall reading somewhere that these caps take the longest of all caps to break
in. Somewhere between 250-500 hours! Ralph from Atma-Sphere indicated 140 hours
is probably all they need. Also, I am still using the older mismatch tubes that
came with the used M-60’s. In addition, some of my favorite tweaks did not
apply well with the M-60’s. One of them that surprised me was the Synergistic
Research carbon XOT’s. The XOT’s placed at the speaker cable ends had provided
a nice sharpening of the image. But now with the Atma-Sphere amps the sound was
limited in the frequency extremes. I think they must have had a conflict with
the M-60’s 4 ohm output impedance. So, I ended up selling them!
So, with all that being mentioned, I am getting some very
nice sound quality even at this early point in the break in process. There is a
very wide and deep soundstage. There is a smoothness that is hard to describe.
It is not a veiling of upper frequencies for I have noticed so many chimes,
bells and every king of tingling sounds imaginable in familiar recordings that
I did not notice before. No, it is a smoothness that makes it easy to listen to
music for long intervals. The vocals are pure and true and to me very lifelike.
And although I am crossing over the lower bass at 100 Hz to (2) JL Audio F-113
subs the bass notes are taking on a more definitive tone. That is, you can
follow the walking of the bass lines better, very enjoyable. Evidently the bass
notes do not just reside in just the lower range.
I originally thought that playing music as loud as before
(compared to my high power SS amp) might be a problem. Yeah, I’m an old time
rocker (64 years old). And, I have been known to crank it up to, “feel the
music”. All you air guitar rockers know what I mean… With the M-60’s, I can still
play the music quite loud with my DIY speakers and external crossover’s. So, I
did a good job matching the driver components to mesh well with the
Atma-Sphere’s. But, the weird thing is, I find myself listening at lower sound levels
more than before and I don’t know why.
Both of the amps (Pass Labs & Atma-Sphere) have their
sonic qualities. I do however believe that my Pass Labs amp has more dynamic’s
and will play significantly louder, especially with lower impedance speakers
like my old Eggleston Andra 2’s. The Pass Labs also has more slam and startle
factor, and they do have similar warmth as the Atma-Spheres
The Atma-Sphere M-60’s have a purer tone and I think
reveal a little more detail. I have many audio recordings that I recorded through
the decades of live performances from TV/Cable/Satellite broadcasts (the
Tonight Show, Jay Leno, Grammy award shows and such) that with the M-60’s I now
detect distortion. Distortion that I never knew were in those
TV/Cable/Satellite recordings with the Pass Labs amp.
At this moment, my preference is the Atma-Sphere M-60’s over
the Pass Labs for its higher sonic purity. And I love those dimly lit tubes!
But, we audiophiles are a fickle bunch that changes minds often. If I change speakers
or if I long for more slam and loudness the Pass Labs will be sitting on the
sidelines. I don’t intend to sell either product at this time.
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