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.

 

[Dennis Meijer]

Hi Ralph,

I thought I'd post my questions on the forum so that others might benefit from your answers. Based on your positive impression, I have ordered a pair of Linlai 6SN7 (not Globe version as you advised) for testing in the MP-3 from RvdA. But if you have time please give me your opinion regarding three questions:

1. In the new situation regarding my own MP-1 with the update Mk.3.3 we go from 8 * to 6 * 6SN7's. I obviously try to get the 'maximum' out of the MP-1 for me. For example, I have a very good experience with Foton NOS ('50s - '60s) Russian tubes with the rectangular getter (Tashkent factory), especially the midrange is beautiful (high is also beautiful in timbre with my HEAs, but that may not apply for speakers with a 'very bright' tweeter/horn). The dynamic power (let's say subjectively an 8) and the bass reproduction (subjectively a 7.5) of the Foton is quite satisfactory, but slightly less than that of the BTB S4A (Produced by JJ), which in turn lacks a lot of timbre and both in terms of bass reproduction (crazy low end dynamics) and high tones exceed the pleasant. So I will try to make a good composition again that will last me for years. Can you tell me more about the influence of each tube in the new line stage. I still try to express myself clearly. Suppose I want to retain the beautiful midrange of the Foton but would like to hear some of the dynamics and powerful bass of the S4A. How would you insert the tubes into the MP-1?

2. In the new situation regarding the phono stage we go from 8 * to 10 * the 12AT7. Of course I know that there are few NOS that are quiet enough (which I always advise my 'customers' not to use) but I am in the fortunate position that I have more than 10 super quiet and beautiful sounding EC801S's from Telefunken and 4 EC801S's from Mullard (produced by Philips in the distant past around the corner from me). I also have 10 new ones of the 12AT7 from S4A Performance (special selection produced by JJ) in stock. In the previous situation with the 8 tubes in the phone stage I mixed 4 by 4 tubes of Mullard/Telefunken, but now I want to try the same with e.g. 4 old tubes (timbre) in the back of the 6 new S4A (dynamics + bass control) towards the front. What is your idea about this with regard to the Mk.3.3 version? In your opinion, what is the influence of the various positions in the new situation and how would you insert the tubes?

3. I have the MA-1 Mk. III. I have always understood that the 6SN7 in the back left is the Constant Current Source and that the tube to the right of that and the tube to the left in the next row is the Input. Is that right? Now I have inserted the dynamic 6SN7 from BTB S4A in all positions and I am only trying to influence the sound via the pre. Is that actually a correct approach in your opinion and what are your thoughts regarding the influence of the 5 different positions on the sound?

Since there are quite a few variables, I don't want to waste too much time on tube rolling. (for the other readers, I have tried countless new production 6SN7's and 12AT7's which unfortunately are usually disappointing, especially the Russian ones are just as good as I think Putin is a good guy ) I have already spent a lot of time on the MP-3 from RvdA (which also sounds fantastic in my set). Can you help me (us) with your enormous experience in this area so that I don't lose too much time when the MP-1 is back?

Sorry for the huge digression on this point, but I hope you still find time (given the current circumstances) to address these questions. Thank you in advance.

 

[Nuforce]

What's wrong with t

I have ordered a pair of Linlai 6SN7 (not Globe version as you advised)

Are you referring to the Elite E-6SN7??

 

[Atmasphere]

Hi Ralph,

I thought I'd post my questions on the forum so that others might benefit from your answers. Based on your positive impression, I have ordered a pair of Linlai 6SN7 (not Globe version as you advised) for testing in the MP-3 from RvdA. But if you have time please give me your opinion regarding three questions:

1. In the new situation regarding my own MA-1 [sic; he means 'MP-1'] with the update Mk.3.3 we go from 8 * to 6 * 6SN7's. I obviously try to get the 'maximum' out of the MP-1 for me. For example, I have a very good experience with Foton NOS ('50s - '60s) Russian tubes with the rectangular getter (Tashkent factory), especially the midrange is beautiful (high is also beautiful in timbre with my HEAs, but that may not apply for speakers with a 'very bright' tweeter/horn). The dynamic power (let's say subjectively an 8) and the bass reproduction (subjectively a 7.5) of the Foton is quite satisfactory, but slightly less than that of the BTB S4A (Produced by JJ), which in turn lacks a lot of timbre and both in terms of bass reproduction (crazy low end dynamics) and high tones exceed the pleasant. So I will try to make a good composition again that will last me for years. Can you tell me more about the influence of each tube in the new line stage. I still try to express myself clearly. Suppose I want to retain the beautiful midrange of the Foton but would like to hear some of the dynamics and powerful bass of the S4A. How would you insert the tubes into the MP-1?

2. In the new situation regarding the phono stage we go from 8 * to 10 * the 12AT7. Of course I know that there are few NOS that are quiet enough (which I always advise my 'customers' not to use) but I am in the fortunate position that I have more than 10 super quiet and beautiful sounding EC801S's from Telefunken and 4 EC801S's from Mullard (produced by Philips in the distant past around the corner from me). I also have 10 new ones of the 12AT7 from S4A Performance (special selection produced by JJ) in stock. In the previous situation with the 8 tubes in the phone stage I mixed 4 by 4 tubes of Mullard/Telefunken, but now I want to try the same with e.g. 4 old tubes (timbre) in the back of the 6 new S4A (dynamics + bass control) towards the front. What is your idea about this with regard to the Mk.3.3 version? In your opinion, what is the influence of the various positions in the new situation and how would you insert the tubes?

3. I have the MA-1 Mk. III. I have always understood that the 6SN7 in the back left is the Constant Current Source and that the tube to the right of that and the tube to the left in the next row is the Input. Is that right? Now I have inserted the dynamic 6SN7 from BTB S4A in all positions and I am only trying to influence the sound via the pre. Is that actually a correct approach in your opinion and what are your thoughts regarding the influence of the 5 different positions on the sound?

Since there are quite a few variables, I don't want to waste too much time on tube rolling. (for the other readers, I have tried countless new production 6SN7's and 12AT7's which unfortunately are usually disappointing, especially the Russian ones are just as good as I think Putin is a good guy ) I have already spent a lot of time on the MP-3 from RvdA (which also sounds fantastic in my set). Can you help me (us) with your enormous experience in this area so that I don't lose too much time when the MP-1 is back?

Sorry for the huge digression on this point, but I hope you still find time (given the current circumstances) to address these questions. Thank you in advance.

1) Why not put the Foton in the first location (front right hand position of each board) and use the BT8 S4As in the two succeeding sockets?

2) The three rearmost 12AT7s are 90% of the phono noise and influence the sound the most. So you put your best tubes there. They should test very high on a tube tester though! So if you have older tubes its a good idea to test them and make sure they test very strong. This is pretty easy to do with the new Chinese 12AT7s; IOW easy to find those that are low noise.

3) The Constant Current Source tube (V3) is located just behind the front tube and on the right. The rear two 6SN7s have the most effect on the sound of the amp; the one behind the front tube but on the left having the 2nd greatest effect. The front tube should have a -GTA or -GTB suffix so as to hold up with the voltage dropped across it.

I agree the older (60s?) vintage Russian tubes are pretty good. But they are tricky to find and you have to know what they look like as there are subtle differences between them and the modern Sovtek 6SN7 which IMO is a pretty terrible 6SN7. We have enough troubles with the Russian 6SN7s of recent (in the last 30 years) manufacture that we've had a warning on our website for the last 25 years to avoid using them. Typically they have troubles passing the Leakage test on a tube tester- when testing for leakage, you should get no reading at all.

 

[Dennis Meijer]

What's wrong with t

Are you referring to the Elite E-6SN7??

No, I first ordered the basic version to test. The E is quite expensive, so I'll have to think about that.

 

[Dennis Meijer]

1) Why not put the Foton in the first location (front right hand position of each board) and use the BT8 S4As in the two succeeding sockets?

2) The three rearmost 12AT7s are 90% of the phono noise and influence the sound the most. So you put your best tubes there. They should test very high on a tube tester though! So if you have older tubes its a good idea to test them and make sure they test very strong. This is pretty easy to do with the new Chinese 12AT7s; IOW easy to find those that are low noise.

3) The Constant Current Source tube (V3) is located just behind the front tube and on the right. The rear two 6SN7s have the most effect on the sound of the amp; the one behind the front tube but on the left having the 2nd greatest effect. The front tube should have a -GTA or -GTB suffix so as to hold up with the voltage dropped across it.

I agree the older (60s?) vintage Russian tubes are pretty good. But they are tricky to find and you have to know what they look like as there are subtle differences between them and the modern Sovtek 6SN7 which IMO is a pretty terrible 6SN7. We have enough troubles with the Russian 6SN7s of recent (in the last 30 years) manufacture that we've had a warning on our website for the last 25 years to avoid using them. Typically they have troubles passing the Leakage test on a tube tester- when testing for leakage, you should get no reading at all.

Thank you for your response, I will get started on it. I think I'll start in the phono stage with the super quiet 12AT7s from S4A at all positions and ignore the NOS. In the MP-1 I start with the Foton 6H8C in the first position, that was my plan anyway, with regard to the other two positions I start with the 6SN7GTs from S4A. I'm going to move around a bit in the MA-1 and try it out. To be continued.

 

[Nuforce]

No, I first ordered the basic version to test. The E is quite expensive, so I'll have to think about that.

I use the Elites in the key position on each of my MA-1, they are stunning and worth every penny. If they would fit i'd run them in the two other key positions on each amp too.

 

[Dennis Meijer]

I use the Elites in the key position on each of my MA-1, they are stunning and worth every penny. If they would fit i'd run them in the two other key positions on each amp too.

I just changed the current order to the Linlai E-series. You convinced me.

 

[DetroitVinylRob]

I use the Elites in the key position on each of my MA-1, they are stunning and worth every penny. If they would fit i'd run them in the two other key positions on each amp too.

Perhaps you could just acquire some socket riser plugs to raise up a couple of the tubes. That’s what I’m doing