Atma-Sphere MA-2 Amplifier

[Chorus]

True. Better is better.

 

[Atmasphere]

Just jumping into this thread as I'm about to purchase an atma-sphere ma-1 mk11.3

It is the version with silver case and x5 6sn7 tubes.

Ralph can you please confirm which of the x5 tubes do what please? They need replacing as all of them are cheap Chinese GT tubes.

Actually the Chinese 6SN7 isn't bad. We've had them hold up well in our amps. I wouldn't throw them out without testing them first.
We used JJ 6SN7s for a while but there are only intermittently available. NOS tubes will work fine in that amp, the only tricky bit is the tube in the corner facing the power tubes must have a -GTA or -GTB suffix (although the Chinese tube is marked as a GT, apparently its got a -GTB spec).

The tube in the corner facing the power supply on a Mk2.3 is the Constant Current Source. The next two tubes are the input (bottom) of the differential cascode voltage amplifier (which is the only voltage gain in the amp). They have the most effect on the sound and they don't have to be the same brand. The 2nd tube from the corner that faces the power tubes is the top of that voltage amplifier circuit and has the 2nd most effect on the sound. Finally the driver tube is the one in the corner facing the power tubes. It controls bias and DC Offset- when you are adjusting the amp you are adjusting parameters of this tube.

 

[Phantom-Audio]

Get the Silver Dome 6SN7 they are sweeter sounding and still retain transparency well. These Chinese ones Ralph uses in my opinion is too lean and thin sounding.

 

[gleeds]

It's been a couple years since checking out the thread. I've had my MA-2's for a few years now, and have been very happy. Sadly, my Selah Audio speakers has just blown a woofer (15yrs old I think). So I am starting to look at speakers. I am looking at used Wilson's, focal, pure audio project, jbl, klipsch ak6. Thoughts would be appreciated!

Doc, when considering new speakers it would help to know what you are looking for in terms of a sound profile. Since you had your Selah speakers for years and enjoyed them I'm thinking you're trying to build on their strengths and perhaps take advantage of some of the advancements in loudspeaker design. Feel free to start a new thread with that information with a title something like "looking for speakers in the x dollars to y dollars range" and watch the input roll in

 

[Atmasphere]

It's been a couple years since checking out the thread. I've had my MA-2's for a few years now, and have been very happy. Sadly, my Selah Audio speakers has just blown a woofer (15yrs old I think). So I am starting to look at speakers. I am looking at used Wilson's, focal, pure audio project, jbl, klipsch ak6. Thoughts would be appreciated!

FWIW about 80% of all our MA-2 production is driving Sound Labs. They like the power of the MA-2s and the speaker is very fast, full range (can shake the room) and does not suffer thermal compression as is common with speakers employing voice coils.

 

[earlinarizona]

Does the MA-2 amplifier have a switch so it goes half power, shutting down half of the tubes? This could make less heat when listening to simple low volume music. I know the MA-3 has that feature which turns off one block of tubes.

 

[Atmasphere]

The newer ones do.

 

[Gregadd]

Why bother?? The class D monoblocks "sound as good or better."

 

[Atmasphere]

Why bother?? The class D monoblocks "sound as good or better."

If you have Sound Labs, because of their impedance, you need an 800 Watt solid state amp to keep up, and they will tend to be bright. As a result over 80% of our MA-2 production is used on Sound Labs.

 

[Gregadd]

If you have Sound Labs, because of their impedance, you need an 800 Watt solid state amp to keep up, and they will tend to be bright. As a result over 80% of our MA-2 production is used on Sound Labs.

I think you suspect I was being sarcastic. Of course, if you need Class D power Merril audio has a solution.

 

[Atmasphere]

I think you suspect I was being sarcastic. Of course, if you need Class D power Merril audio has a solution.

I didn't. The issue of driving Sound Labs is a major reason for sales of the MA-2.

The issue with the Sound Lab is its about 30 Ohms in the bass and so whatever the solid state amp is rated at 8 Ohms, divide by 4 and you get the power it makes on Sound Labs. MA-2s aren't affected by Sound Labs that way; they make over 200 Watts into that load, which, if you can make it, is a good amount of power on that speaker- most of the MA-2 reports we have on that speaker say they can't clip the amps.

 

[Gregadd]

i would go for the MA- 2 for other mere obvious traditional reasons. BTW your amp was sounding great at CAF in the Classic room. I should bring some is my own music for them to play.