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Amps Atma-Sphere M-60 Mono blocks OTL design

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.

ozzy

ozzy
ozzy's avatar
ozzy OP
7,652 posts
 

bigboltz,

That's Great!

Mine were also shipped but Ralph said the tubes in the unit are not so good but usable. So, I ordered some NOS from Russia and China but who knows when they will arrive?

According to the Fed Ex tracking (at this time), my amps are to arrive on Tuesday. I have a doctors appointment that day so I probably won't be able to use them until Wednesday.

ozzy

gdnrbob
4,508 posts
 
Not to sound rude, but why didn't you get some tubes from Ralph?
I only got into this recently, so I don't know much regarding tubes.
Are the Russian and Chinese tubes better? I have read about tube rolling and would like to learn more.
B
ozzy's avatar
ozzy OP
7,652 posts
 

gdnrbob,

Let’s just say it was about economics. I have other new tubes available (Tung-Sol and Sovtek) in addition to the Russian and Chinese tubes that I just ordered. So, I’m really not hurting for tubes.

But Ralph said to burn in the new tubes for about 72 hours in standby before using. I will be going crazy if I could not try out the amps until 3 days later after waiting this long! So I will use the tubes that will come with the M-60’s for the trial.

And, if the Atma-spheres become a keeper, I’ll burn in the tubes that I ordered.

I have some new driver tubes coming that I will have on Monday. They are vintage RCA 1950 (9 new).

The output tubes that I ordered from Russia are (16 new) Svetlana 1970. The Chinese tubes are (16 new) Shuguang 6NP5PJ.

However, if I don’t keep the Atma-spheres I will have a lot of tubes to sell...

P.S. As you can tell, I try to never do things half way. I remember years ago my wife wanted a gold fish bowl. I ended up with a 250 gallon saltwater reef tank!

ozzy


ozzy's avatar
ozzy OP
7,652 posts
 

gdnrbob,

In answer to your question about tube quality. I believe that tubes made before transistors took over were considered to be of the highest quality. Especially those made for the WW2 war effort branded JAN. (Joint Army Navy). These tubes were used in submarines and were made to be quiet. The materials used were purer and made to withstand stress and would last longer. Replacement tubes were still made decades later.

I'm not sure when the US stopped making tubes but Russia and China continued.

Tung-Sol is still making new tubes that are said to be of high quality but still probably not as good as the older ones.

Anyone else have some input on the different brands of tubes quality?

ozzy


atmasphere's avatar
atmasphere
12,174 posts
 
@ozzy ,

The Tung Sol name got bought out a few years ago and is now being used to mark Russian-made 6SN7s. Usually these are the same tubes as the Electro Harmonix but with a brown base. They are nothing like the old-school Tung Sols which were a nice tube.

We've had some very good comments on the Psvane, Sophia and TJ Music tubes; along the lines of 'combining the best of the NOS tubes without the weaknesses' which is a pretty strong statement. You do still have to pick them for low noise and microphonics though, but generally this is not a big deal in the amps. 
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