@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.
Atma-Sphere MA 2s for Dummies (by a dummy)
After a 9 month wait (covid) I finally received my MA 2s. Because these amps were going to be located in the shop under the loudspeakers I asked (demanded?) for trigger inputs. Ralph Karstens agreed to do this and did not charge me an extra cent for it. More on this later. Ralph warned me up front that the 6AS7 driver tubes were going to be problematic for a while and he was not kidding. I got the amp with 40 Chinese 6AS7s and rapidly started blowing tubes. The trigger on one amp did not work. Ralph warrantees the tubes and immediately sent me new ones. With the amps I also ordered a full set of tubes to have on hand and Ralph promised the Russian versions which most people think are better. Ralph felt the bad trigger was due to one of two relay boards. He was game to let me change it out and sent me two new ones just in case. I installed it and both triggers have worked perfectly since. The reason it was two relay boards and not one is because the first trigger lights the filaments immediately and the timed 2nd relay turns on the B+ 30 seconds later. When I had the amp apart I took a picture of the construct which I encourage you to see on my system page. These amps are totally hand wired, point to point and are an electronic work of art. The board that failed was at the bottom between the inputs right in the center. Tubes may fail but not these amps they are rugged and will last eons.
The amps were running fine for over a week and I was busy adjusting to them when the Russian tubes arrived. I pulled all the Chinese tubes and installed the Russian ones. As per Ralph's instructions I let the tubes run on filaments only for 6 hours and was going to play them lightly for several days before rocking out. I put on Analog Productions 45 RPM copy of Waltz for Debby and was floored by the sound. The Sound Labs were more energetic with the MA 2s, a lot more energetic. About midway through the second side there was a pop in the right channel and I knew I had lost a tube. I went downstairs climbed a ladder and looked over the face plate to see that one tube all the way in the back was dark. This was VERY unusual. When these tubes blow they burn out their fuse links only and the filaments continue to run. To find the bad tube you have to pull each tube and inspect the fuse links which are hard to see. This one tube had really torched itself. The inside of the tube had a large black ring and the getter had turned white. I installed a new, broken in tube and returned to Walt for Debby. In 10 seconds there was a very loud sizzle then pop and the amp went dead. Now I was really worried. You can blow 3 or 4 tubes at least and the amp will keep running. Something bad had happened. The post mortem exam revealed 3 bad 6AS7s and the two 6NS7 driver tubes had blown. This hardly ever happens. I sent Ralph a picture of the black tube and he was amazed. He knows these amps backwards and forwards. This was a rare event. We hypothesized that the black tube had somehow weakened the driver tubes and they failed the next time they were run taking out three more weak 6AS7s. I did not have any extra 6NS7s so the system was down for a few days. The moral of the story is the Russian tubes are no more reliable than the Chinese tubes. The problem with 6AS7s is that the element is supported only at the top of the tube. At the bottom it is just hanging in the vacuum. If you drop one just right the entire element goes crooked ripping the connections at the bottom. They ship poorly. About one in twenty are "wonky" when you get them another two will blow their fuse links indicating a short within the element.
Ralph assured me that the amps were ok and sent me 10 more 6AS7s and a full set of 12 NOS Russian 6NS7s that were obviously better constructed than the new JJ tubes the amp came with. I kept JJs in the driver positions and put four NOS tubes in the voltage multiplier sockets of each amp. These are the tubes that "voice" the amp. Since then I have blown one tube in the left amp and that is it. The amps have been trouble free since. One night I had an old musician friend over, a real rocker and we spent two hours at 95 dB and I did not lose one link. Ralph knows his amps and his support is second to none.
80% of MA 2s are being used on Sound Lab speakers for good reason. The impedance of ESLs increases as you go down in frequency from 1 ohm at 20 kHz to 30 ohms at 20 Hz. Normal amps lose power into an impedance that high where you need it most. The MA 2s do not. They put out 220 watts regardless of impedance. The result is that first you have to turn the brilliance control of the SLs all the way up and turn the bass control all the way down. Measuring this revealed a very flat curve from 120 Hz to 10kHz with a slight downward slope to 20 kHz which was down 4 dB. This is great for louder listening. I cross to subwoofers at 120 Hz currently. The increase in the power of percussion produces frisson. The buzz in bass strings is more evident. Little details are more obvious. I should also mention that the amps are dead quiet. The midrange, as others have noted, is in a class by itself. I cannot find adequate words to describe it. The high frequencies are as good as any class A amp I have heard. I can not comment on the bass below 120 Hz. Others with SLs have not liked it and they have switched to SS amps. I personally think this is a characteristic of the SLs which do not like making low bass. The SS amps have so little power down there they are not exposing this problem. From about 100 Hz up the SLs are brilliant. As a one way driver the cohesiveness of the music produced by SLs is a trait absent in multiway speakers. You have to hear it to understand it. For certain the MA 2s and SL speakers were made for each other.
I forgot to mention, MA 2s get very HOT.
I should also mention that to please SS fans Atma-Spere is now making a class D amp that reportedly sounds like a tube amp. He is using a proprietary circuit, no modules. The amps have large linear power supplies and produce power like most class A amps. The price is also very reasonable. There is a review pending.
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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. |
@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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@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. |
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. |
@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. |
@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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@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. |
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 $$. |
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 !! |
@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. |
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. |
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 |
@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. |
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 |
