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

[tima]

Next week. I'm trying to understand what each 6SN7 position does, I think the two nearest tube dial are the most important re sound impact. I've emailed Ralph to clarify but didn't get a response yet.

I asked that same question of Ralph in 2006:

"The 2nd and 3rd 6SN7 from the edge of the chassis with the power supply cover are the most sensitive. They are in parallel, so for best effect both should be changed."

Here is the thread on 6SN7s:

The Reference 6SN7 Thread

- Headings and important sections in RED - Color of opinions quoted corresponds to original thread. 6SN7 variants: [* = definitely a safe 6SN7 substitute] ALWAYS ASK YOUR AMP MANUFACTURER FIRST BEFORE SWAPPING TUBE TYPES!!! 6SN7GT* - First designation of the 6SN7 tube type. ‘G’ =...

www.head-fi.org

 

[Nuforce]

I asked that same question of Ralph in 2006:

"The 2nd and 3rd 6SN7 from the edge of the chassis with the power supply cover are the most sensitive. They are in parallel, so for best effect both should be changed."

Here is the thread on 6SN7s:

The Reference 6SN7 Thread

- Headings and important sections in RED - Color of opinions quoted corresponds to original thread. 6SN7 variants: [* = definitely a safe 6SN7 substitute] ALWAYS ASK YOUR AMP MANUFACTURER FIRST BEFORE SWAPPING TUBE TYPES!!! 6SN7GT* - First designation of the 6SN7 tube type. ‘G’ =...

www.head-fi.org

Ah that's great, thanks so much

 

[Phantom-Audio]

Atma-Sphere Nirvana OTL Monoblock Amplifiers ( Ralph Karsten Masterpiece OTL Amps)

A True End Game OTL Amplifier by Atma-Sphere Your chance to own a one of a kind OTL amplifier, Ralph Karsten True Master Piece with over 45 years of knowledge in the OTL Amplifier a no-compromise approach to build the very best! This...

www.whatsbestforum.com

Something you don't see for sale very often!

 

[Phantom-Audio]

The Nirvana by Atma-Sphere 120-150 watts per mono depending on tubes used.

 

[ACHiPo]

Next week. I'm trying to understand what each 6SN7 position does, I think the two nearest tube dial are the most important re sound impact. I've emailed Ralph to clarify but didn't get a response yet.

All the V1 tubes are paralleled so as to drive the top tube of the differential cascode circuit (V2) with greater ease. The biggest voltage drop is across V4 which is why you need a -GTA or -GTB (note; the Russian and Shuguang 6SN7s are marked 'GT' but are GTBs).

 

[ACHiPo]

All the V1 tubes are paralleled so as to drive the top tube of the differential cascode circuit (V2) with greater ease. The biggest voltage drop is across V4 which is why you need a -GTA or -GTB (note; the Russian and Shuguang 6SN7s are marked 'GT' but are GTBs).
View attachment 91893

nu Force,
just saw you’re getting the older chassis. There should be info in the manual online as to which position is V1, etc.

 

[Nuforce]

All the V1 tubes are paralleled so as to drive the top tube of the differential cascode circuit (V2) with greater ease. The biggest voltage drop is across V4 which is why you need a -GTA or -GTB (note; the Russian and Shuguang 6SN7s are marked 'GT' but are GTBs).
View attachment 91893

So v1a on the older rectangular units like mine is the tube on the edge where the power supply is?

So am I right in saying that positions v1a and v1b achieve the most benefit from uprated tubes?

I am going to buy a quad of psvane 181-Tii

 

[Nuforce]

Actually Tima sorry I missed your post, so it is position v1b and v1c that yield the most benefit right ?

 

[tima]

Actually Tima sorry I missed your post, so it is position v1b and v1c that yield the most benefit right ?

"The 2nd and 3rd 6SN7 from the edge of the chassis with the power supply cover are the most sensitive. They are in parallel, so for best effect both should be changed."

I don't translate the position names from prior style - just follow RKs instructions. The MA-1s I had were in the same rectangular shape as the ones you are getting. I had the Mk3.1. And fwiw, Ralph can upgrade your units to current spec without changing the chassis.

You might like my article at TAB about upgrading. Looking at the lead-in picture, count from the right. Iirc there was no restriction on the type of 6SN7 (GTA/GTB etc.) - at least I did not and had zero issues. Edit: I did not try the PSVANE tubes, but I did try the Chinese Shuguang - they were a bit on the warmish, rounding side of things. Imo the older Ken-Rad black glass, Sylvania, and RCA 6SN7s are the best.

The Audio Beat - MA-1 Mk 3.1: More Than "Another Upgrade"; Atma-Sphere MA-1 Mk 3.1 mono amps

read audio reviews, ratings, and user opinions on audio equipment before you buy an audio system

www.theaudiobeat.com

 

[Nuforce]

I don't translate the position names from prior style - just follow RKs instructions. The MA-1s I had were in the same rectangular shape as the ones you are getting. I had the Mk3.1. And fwiw, Ralph can upgrade your units to current spec without changing the chassis.

You might like my article at TAB about upgrading. Looking at the lead-in picture, count from the right. Iirc there was no restriction on the type of 6SN7 (GTA/GTB etc.) - at least I did not and had zero issues. Edit: I did not try the PSVANE tubes, but I did try the Chinese Shuguang - they were a bit on the warmish, rounding side of things. Imo the older Ken-Rad black glass, Sylvania, and RCA 6SN7s are the best.

The Audio Beat - MA-1 Mk 3.1: More Than "Another Upgrade"; Atma-Sphere MA-1 Mk 3.1 mono amps

read audio reviews, ratings, and user opinions on audio equipment before you buy an audio system

www.theaudiobeat.com

I've read your article, l love it, so well written!

I'll need to ask RK to kindly pass his conversion diagrams to my local valve engineer. He may be willing. I'm in the UK and don't relish sending these amps overseas.

 

[tima]

I'll need to ask RK to kindly pass his conversion diagrams to my local valve engineer.

I don't understand. Why do you need conversion diagrams? What are you converting?

 

[Nuforce]

I don't understand. Why do you need conversion diagrams? What are you converting?

I mean upgrading to 3.3, I assume it requires rewiring etc?

 

[tima]

I mean upgrading to 3.3, I assume it requires rewiring etc?

Best let Ralph speak to that. You can send him a PM (@Atmasphere) here or his email contact is on his Web site. Have fun with your new amps!

 

[Nuforce]

i have another question re the MA-1, how important is it to keep the speaker cables short, given the OTL design?

I have the option to run them next to my magnepans, however I worry about excessive vibration in that location.

Is short cable length very important or a nice to have?

 

[Atmasphere]

I mean upgrading to 3.3, I assume it requires rewiring etc?

Yes.

i have another question re the MA-1, how important is it to keep the speaker cables short, given the OTL design?

I have the option to run them next to my magnepans, however I worry about excessive vibration in that location.

Is short cable length very important or a nice to have?

The vibration, especially with Maggies, is a non-issue. So run the shortest cables you can- we've often had owners back the speaker terminals of the amps to nearby the speaker terminals of the Maggies and just run short 8 inch jumpers, which can work quite well. If you have Maggies properly set up, there should be plenty of room behind the speakers to set the amps up.

 

[Nuforce]

My amps have arrived!

I've left them on my rack for now.

 

[ACHiPo]

My amps have arrived!

I've left them on my rack for now.

Congratulations! They are truly special.

 

[Nuforce]

I'm slightly disappointed that the power meters don't illuminate...

What I am delighted about is bringing two Minnesota cousins together, Atma-sphere and Magnepan.

Should be a special match.

 

[tima]

My amps have arrived!

I've left them on my rack for now.

Thanks for the pictures. The amps need more air circulation. Those tubes throw off lots of heat.

 

[Nuforce]

Thanks for the pictures. The amps need more air circulation. Those tubes throw off lots of heat.

Agreed, I'm moving them to the top of my rack. I don't want them next to my speakers, too fragile with my kids around