Nice review @mijostyn ,
I own the MA-1's and they are my winter amps for my Vandy Treo's.
Ralph is a stand up guy and as we can see from your experience, totally committed to providing top notch service.
I bought the Atma Class D amps, and trialed them for a few months. I took them to Audioconnection and had a 'shoot out' with other amps-mainly Belles. In short, we liked them, but they had a drop off in the upper frequencies that contributed to a bit of 'lack of life' to our ears. (We did hook them up to a pair of Maggies and they did sound pretty good).
Mind you, I am an Atma lover, but the Class D amps just seemed to lack that bit of 'sparkle' that Class A or AB amps can have. I probably should have contacted Ralph, but wanted to move on.
The Class D amps did sound very, very good. Excellent bass control, and overall even sound, but they just lacked that bit of upper frequency 'sparkle'. Perhaps the word 'engaging' would be more correct. I should also mention that we were listening to Vandersteen Treo's, so YMMV.
Bob
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@Mijo I bought a pair of M60s new 23 years ago and still own them and have never once thought of making a change. Other than upgrades, they have never had a service issue. About 15 years ago I bought a second pair (used) as they were on the elongated chassis that AS used for a short time for M60s as those chassis better fit into the space I have available to me. These amps have never required a repair. Naturally, along the way, I have experienced some power tube failures, but nothing at all dramatic like you did early on. But I would like to say in my overall experience that you will find the Russian 6AS7s to be the heartier and longer lived tubes. A friend of mine with MA-1s and I, starting about seven or eight years ago, began sourcing all of our 6AS7s from ebay sellers in Russia. These are all military (I’m sure) pulls but they measure strong (using a Hickok 532) and have exhibited no tendencies to early failure and such. Last time we bought they were running about $5. per tube in lots of 25 or so. I’m tubed up for now but if the day should come when I need a new supply, ebay will be my first stop.
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@gdnrbob
I bought the Atma Class D amps, and trialed them for a few months. I took them to Audioconnection and had a ’shoot out’ with other amps-mainly Belles. In short, we liked them, but they had a drop off in the upper frequencies that contributed to a bit of ’lack of life’ to our ears. (We did hook them up to a pair of Maggies and they did sound pretty good).
Mind you, I am an Atma lover, but the Class D amps just seemed to lack that bit of ’sparkle’ that Class A orAB amps can have.
Based on prior posts here I know that you have much appreciation and admiration for Atma-Sphere products. Your comments are candid. I can imagine that the MA-1 mono blocks are splendid with your Vandersteen speakers and set a very high reference point. I can understand how you preferred them to the sibling class D amplifiers In your specific situation. It’s simply personal preference for each individual listener.
Charles
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Thank you very much for your post. Really interesting. I love Sound Lab speakers. Powering them can be challenging. My hat off to you and Ralph for pushing the cutting edge. You have a beautiful system, it must sound incredible.
Since my system has always been at the very edge of my financial capability, complete reliability has been at the forefront of my mind. This kept me out of tube amps for thirty five years… which I am sorry. Happily I have gone the Audio Research route and have had complete reliability in tubes… I have replaced two on schedule among the 40 I use after 3,000 hours.
I completely understand what you are doing and respect the collaboration going on between you and Ralph. I imagine you have a truly amazing sounding system.
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@ghdprentice , My audiophile brain is never entirely happy with the results. Improving, no question. Could be better, I think so. Lewm has suggested changing the high frequency transformers for full range ones running them in parallel with the bass transformers. I have Serbian Toriods coming and am going to try this approach. I have four new subwoofers under construction almost finished using eight 12" drivers in very unique enclosures. Ralph has suggested biamping the transformers, another consideration. I will be testing the Beta program for the new DEQX Pre 8 processor shortly. I wandered into that role accidently by making myself a PITA. The people testing are supposed to get their units at a discounts. Suites me. After all, this is a hobby. When does a stamp collector stop collecting stamps.
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Ralph is an awesome person who I met for the first time thx to my Buddy Jeff (who frequents these forums as well) at AXPONA. He is a fan of Orchard Audio and has listened to Leo's Amps and like them. A friend here in Phoenix has a pair of his Class D GaN FET's. While they don't have as much power ouput as the OA Ultra's they can drive pretty much anything you can through at them and sound fantastic doing so !
He still builds the Tubes & Transistors to please us old Geezers (I'm 53.5) but his passion is the GaN FET's of his own design. If anyone can make 'em sound like a Tube....I'll bet he can for sure !!
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Why didnt you use nos RCA tubes ? Night and and day better .
I used them in my monos from Audio valve
vacuum tubes Dot Net They had trailer trucks full ofnos military surplus
I would see if they are still around , if not Brent Jesse recordings orAndy at
vintage services if still around.
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Yes give vacuum tubes
dot net a call. They still have 9 million tubes they had tractor trailers full
they still had not gone through ,for your tube 6AS7 when I clicked on it the
page didnot work call them and bring That up to their attention ,and inquire.
and ask Ralph why not use 6SL7 tube many good amps have them and RCA was there too.I bought WW2 types these guys bought Everything theUS armed forces had for Maybe 20 cents each they still have stock not gone through yet from back in the1970s . There-pockets are full $$.
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@audioman58 , I was all over the internet and all I could find were Russian and Chinese tubes. The Winged C Svetlana tubes seemed to get the nod as the best. You have to remember, I need 40 of them to make up a set. The 6AS7s do not voice the amps. The sound is determined by the four 6SN7 voltage multipliers. There I am using Russian tubes from 1965,66 and they are the best I have heard so far of three different tubes. It seems the American NOS tubes have dried up. 6SL7 tubes will not work in these amps.
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@mijostyn - congratulations with your MA-2, sorry to hear about your troubles. I have owned MA-1 for twelve years with almost zero problems, and Ralph has given excellent support to me as well. I don't understand why OTL amps are still a minority choice. I sold my big Krell FPB600 and never looked back. But, it should be said, at the time I was more into "massive" music.
@audioman58 - I agree, these amps sound better with RCA NOS output tubes, even if "night and day" is a bit strong. I have found that there are some duds, maybe one in twenty, but given proper burn-in (72 hours), the rest works fine, with no more failures than with russkies.
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@o_holter , I warned Ralph from the beginning that I had notoriously bad luck. I was born with it. Things settled down nicely.
My understanding is that the sound of these amps is mostly due to the four voltage multipliers (6NS7s) and not the 6AS7s. But, I am new to these amps and have not explored much. I can get Svetlana Winged C tubes for $12 each directly from Russia or Ukraine.
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Yes, I know this is Ralph's opinion, and I agree up to a point. For 12 usd I would go for it. Moreover, you can support Ukraine. I paid 40 something for RCA NOS some time ago.
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Bad luck - in my case, I’ve found that less is more. I gave up on subs, and my ’effect’ speakers are no longer in use - the main speakers (designed to resemble Sound labs) do the job better alone.
Heat - a cheap fix is to mount computer fans behind the amps, to cool them down, and use a transformer plus a resistor to slow them further so you don’t hear them. It won’t help your room temperature, but the amps will probably thank you. Here in Norway we (still) have a fairly cool weather, so it is only needed in the summer or when the temperature gets above 30 degrees celsius. I am using a remote control so this system is both silent and convenient to turn on / off.
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@bigtwin Thank You!
@o_holter If you look at my system page you will see two computer fans behind each amp. Each pair has an L pad to control speed. At full tilt I can hear them above in the media room. The 12 volt power supply that runs the fans also triggers all four amps. It is controlled by a switch next to the equipment cabinet upstairs. Ralph designed a trigger system for me which works beautifully. I suspect he will make it available to others. It turns the filaments on first then 30 seconds later turns on the B+. It is totally silent on and off.
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@mijostyn - thanks, I see them now. Your system probably sounds amazing.
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@o_holter , There are still improvements to be made. The current subwoofers which I built 20 years ago have some flabbiness in them that I can hear with acoustic bass. I have just finished construction of four new subwoofers which will fix that problem. They still have to be finished which will require 4 coats of various lacquers and a lot of sanding. They are seriously over the top. I took pictures of the entire process and will publish them on Imgur when I am finished. I have a new processor coming, a DEQX Pre 8. My old one is 25 years old and showing it's age. The processor chips are way faster now which is a big advantage. Signal to noise ratios are also way better. The old girl has also lost a couple of channels which is no big deal as I only need one but still. I have two Serbian toroidal transformers in route and am going to rewire the back plate of the SLs which according to @lewm will make the SLs much more efficient. The only improvements I might make afterwards at some point are a turntable I can put a Schroder LT on and a Channel D Seta L20 which has the best signal to noise ratio of any phono stage made, 12 dB better than the one I have now which is no slouch. Ralph has suggested Bi amping the two transformers in each backplate, another possibility.
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@mijostyn - I admire such dedicated work! I have two questions. Is your room very long and narrow? Seems so, from your system info. Maybe the Sound Labs dont have the space to breathe, on the sides?
Also, I see you have a screen in the middle. In our house, a first rule is, the screen goes out. For serious music listening. We turn down the lights. Candles only.
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@o_holter The wall the SLs are on is 16 feet. The rear of the room does not have a wall. It is open to the rest of the house. If you were to imagine a wall it would be at 25 feet. I did not get full sized 845s which are 40" wide. I got 36" wide 845s which Dr West called 645-8s. They fit the room better and they have plenty of space to breath. The screen is only for theater use. The room is blacked out. I also prefer to close my eyes. My wife burns the candles. I need all the oxygen I can get.
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