About to buy MA-1 monos- how long do the tubes last and how easy are replacements to source?

[Nuforce]

Hmm I have an issue. Both amps are immediately blowing the B+ fuse (closest to iec) on full power.

I've been using 2.5a slow blow 32mm glass fuses as per the manual (for 240v region).

I must be doing something stupid, what gives !?

Image of fuse

 

[Nuforce]

I didn't know there are two types of slow blow. I had the wrong fuses!

 

[Nuforce]

guys I'd like to run these with a couple of pairs removed, as the power seems very good judging by how little the needle moves at high volume.

Do I remove pairs from the REAR, or from the FRONT?

 

[ACHiPo]

guys I'd like to run these with a couple of pairs removed, as the power seems very good judging by how little the needle moves at high volume.

Do I remove pairs from the REAR, or from the FRONT?

It doesn’t matter—just remove the same number from each side of each amp and make sure the offset zeroes.

What caused the (presumably sloblow) fuses to blow in the first place? Did you have tubes arc over?

 

[Nuforce]

It doesn’t matter—just remove the same number from each side of each amp and make sure the offset zeroes.

What caused the (presumably sloblow) fuses to blow in the first place? Did you have tubes arc over?

Only one b+ fuses went, and today on the same amp the corner voltage regulator tube died, so I think that was the issue, bad 6sn7

 

[Atmasphere]

I've been using 2.5a slow blow 32mm glass fuses as per the manual (for 240v region).

Just a FWIW: we've seen a lot of cheap fuses marked as slow blow that simply are not. So these days a good quality fuse (Littlefuse, Bussman or the like) is recommended to avoid a lot of hair pulling!

 

[Nuforce]

I see that the CCS stage is solid state in the latest MA-1.

Has anyone considered using Schiit LISST solid state 6SN7 in that position on older ma-1 models....?

They are discontinued but available from some sources.

 

[Atmasphere]

The CCS we use is a 2-stage device; most of the CCS circuits we've seen leave performance on the table on account of being a single stage.

 

[Nuforce]

Amps in their final place. So pleased with them, look and sound stunning.

I have x3 pairs of shuguang black treasure cv181-z coming tomorrow.

 

[Fishfood]

View attachment 92596

Amps in their final place. So pleased with them, look and sound stunning.

I have x3 pairs of shuguang black treasure cv181-z coming tomorrow.

So awesome! We live in a small loft so my desire for Atmosphere amps is tempered right now. Definitely on my list when we move in a couple years..

 

[Atmasphere]

View attachment 92596

Amps in their final place. So pleased with them, look and sound stunning.

I have x3 pairs of shuguang black treasure cv181-z coming tomorrow.

Tell me about the 6SN7s with the black base. Why are they in different sockets?

 

[andromedaaudio]

View attachment 92596

Amps in their final place. So pleased with them, look and sound stunning.

I have x3 pairs of shuguang black treasure cv181-z coming tomorrow.

I like the design atmasphere .
Looks like a old school solid indestructable piece of gear

 

[Nuforce]

Tell me about the 6SN7s with the black base. Why are they in different sockets?

I've corrected the tube position, black tube on right hand unit should be on the left, it's a GTB tube

 

[Atmasphere]

I've corrected the tube position, black tube on right hand unit should be on the left, it's a GTB tube

When using NOS tubes usually we recommend a GTB in the position in the corner, facing the power tubes, as seen in the right hand amp in the photo above. The Chinese 6SN7 (the ones with the maroon base) are marked as GTs but are actually GTBs. But I suspect the tube with the black base to be a better sounding tube; if it were me I'd put it in the middle location of each amp.
When you changed out the tube in the corner facing the power tubes, don't forget to check the DC Offset, since that tube controls the bias and DC Offset for the output tubes.

 

[DetroitVinylRob]

Please can someone tell me roughly how many hours I can expect from the 6as7g tubes and if replacements are easy to find?

Searching for 6as7g tubes doesn't show a lot of places that stock them, which concerns me.

Congrats! Welcome to the MA-1 club! I’ve had my Silver Editions for over a decade and still enjoy them immensely. I will be curious to here your 6SN7 impressions as time goes forward.

 

[Nuforce]

Thanks!

Unfortunately one of them has developed a fault, but my dealer has been superb, and has arranged for collection and repair, no questions asked, so just waiting for them to return with a clean bill of health

 

[DetroitVinylRob]

Thanks!

Unfortunately one of them has developed a fault, but my dealer has been superb, and has arranged for collection and repair, no questions asked, so just waiting for them to return with a clean bill of health

Sorry to hear that. So, they are going back to Ralph and company? Atma-Sphere products are pretty bulletproof you will find, so once they are right, they stay right. Most often, a tube is the only problem, if at all.

 

[Nuforce]

Sorry to hear that. So, they are going back to Ralph and company? Atma-Sphere products are pretty bulletproof you will find, so once they are right, they stay right. Most often, a tube is the only problem, if at all.

No I'm in the UK, so they are being repaired locally.

 

[microstrip]

No I'm in the UK, so they are being repaired locally.

Atmasphere circuits are extremely logical and straightforward - in the rare case of problems, a joy to diagnose and repair, particularly as they are point-to-point wired and very accessible.

 

[Atmasphere]

Thanks!

Unfortunately one of them has developed a fault, but my dealer has been superb, and has arranged for collection and repair, no questions asked, so just waiting for them to return with a clean bill of health

Since these were just shipped, more than likely you simply had a power tube fail rather than the amp itself. During the first week or two after installation is when we encounter the most problems with power tubes.

It the amp simply stopped playing, its likely the fuse by the power cord blew; this fuse can blow if a power tube arcs. Usually its a simple matter to replace the fuse and locate the arcing tube by simply knocking on the tops of the tubes.