Neumann M49V tube mistery...

[OneRoomStudio]

They really copy everything you post here too

No, I haven't disappeared. I had only changed my alias, but kept the account.

After many tests I can now report that it doesn't matter which triode you use. I have not been able to detect any differences between the various 6S6Bs. The design used by Neumann has a higher internal insulation resistance, which is better in principle. But practically it doesn't matter. These tubes produce very little noise and are all mechanically insensitive. But other Soviet triodes also proved to be suitable replacements. One even better than the 6S6B or the 6S3B. There will therefore be enough replacements for defective AC701s over the next 50 years.

I’m curious which on you thought was even better! Also, have you had the chance to try other triodes, such as the EC71?

 

[k brown]

They really copy everything you post here too

No, I haven't disappeared. I had only changed my alias, but kept the account.

After many tests I can now report that it doesn't matter which triode you use. I have not been able to detect any differences between the various 6S6Bs. The design used by Neumann has a higher internal insulation resistance, which is better in principle. But practically it doesn't matter. These tubes produce very little noise and are all mechanically insensitive. But other Soviet triodes also proved to be suitable replacements. One even better than the 6S6B or the 6S3B. There will therefore be enough replacements for defective AC701s over the next 50 years.

I have long maintained that the tube is the very last thing responsible for the sound of the M 49 (and M 50). I found people's absolute obsession with the AC701 rather amusing.

 

[vintageaudio]

I have long maintained that the tube is the very last thing responsible for the sound of the M 49 (and M 50). I found people's absolute obsession with the AC701 rather amusing.

I have tried 6S6B and 5840, but it doesn't seem like what I want. I have found JRC AC701, and I wonder if its performance is consistent with Telefunken AC701? Or just changed the packaging? They are used for SONY CU-2, what's wrong with installing them on M49? I got a spare brand new tube, and the seller told me it's the same as Telefunken AC701, but I decided to figure it out before installing it in case of any unforeseen circumstances.

 

[Menschmeier]

I’m curious which on you thought was even better! Also, have you had the chance to try other triodes, such as the EC71?

I have not tested the EC71, but it works with a higher heating voltage. Others have been using them for years. The DC762, for example, works in a triode circuit from 1 volt, but it is 2 cm longer. The Soviet military tubes all work with 4 volts. They are the most suitable. I don't want to publish a recommendation, that would only spoil the prices. Unfortunately, this has already happened with the 6S6B. I therefore had to import mine from Russia in a complicated process.

 

[Menschmeier]

I have long maintained that the tube is the very last thing responsible for the sound of the M 49 (and M 50). I found people's absolute obsession with the AC701 rather amusing.

I agree with that. The capsule, the basket and to some extent the transformer are responsible for the sound. The circuit also plays a role. The tube, on the other hand, only plays a role in exceptional cases. With the U47/48, for example. Unfortunately, there is no suitable replacement tube for the VF14. Here I would switch to the replacement circuit from Andreas. His technician continues to build them.

 

[vintageaudio]

I agree with that. The capsule, the basket and to some extent the transformer are responsible for the sound. The circuit also plays a role. The tube, on the other hand, only plays a role in exceptional cases. With the U47/48, for example. Unfortunately, there is no suitable replacement tube for the VF14. Here I would switch to the replacement circuit from Andreas. His technician continues to build them.

I think the VF14ER manufactured by Andreas Grosser in my old U47 cannot distinguish the difference in sound from the VF14M. I am not referring to the solid-state version VF14EF. If they are still in production, I think I need a few spare ones.

 

[tomas.borgstrom]

I think the VF14ER manufactured by Andreas Grosser in my old U47 cannot distinguish the difference in sound from the VF14M. I am not referring to the solid-state version VF14EF. If they are still in production, I think I need a few spare ones.

The glass tube in Grossers substitutes sounds good but is clearly brighter och cleaner than VF14

 

[tomas.borgstrom]

I have tried 6S6B and 5840, but it doesn't seem like what I want. I have found JRC AC701, and I wonder if its performance is consistent with Telefunken AC701? Or just changed the packaging? They are used for SONY CU-2, what's wrong with installing them on M49? I got a spare brand new tube, and the seller told me it's the same as Telefunken AC701, but I decided to figure it out before installing it in case of any unforeseen circumstances.

View attachment 143708

Interesting, I only knew of the East German AC761. Is it possible that they were produced in Japan or just rebranded for the Japanese Radio Company? The Telefunken tubes that were exported to Finland 1950-1956 were marked Telestar. This was because the Soviet Union took over German owned property in Finland after WW2, and therefore the rights to the trade name Telefunken.

What can go wrong in an M49 if you make sure not to exceed 4V on the heater?

 

[LevinGuitar]

I have tried 6S6B and 5840, but it doesn't seem like what I want. I have found JRC AC701, and I wonder if its performance is consistent with Telefunken AC701? Or just changed the packaging? They are used for SONY CU-2, what's wrong with installing them on M49? I got a spare brand new tube, and the seller told me it's the same as Telefunken AC701, but I decided to figure it out before installing it in case of any unforeseen circumstances.

View attachment 143708

The AC701 and the AC761 do not have an unnesesary leads that can be cut as the tubes in your attachment do have, so definately not the same tubes.

 

[tomas.borgstrom]

The AC701 and the AC761 do not have an unnesesary leads that can be cut as the tubes in your attachment do have, so definately not the same tubes.

Well spotted!

 

[k brown]

I agree with that. The capsule, the basket and to some extent the transformer are responsible for the sound. The circuit also plays a role. The tube, on the other hand, only plays a role in exceptional cases. With the U47/48, for example. Unfortunately, there is no suitable replacement tube for the VF14. Here I would switch to the replacement circuit from Andreas. His technician continues to build them.

Actually, I'd say the transformer to a considerable extent; it produces euphonic colorations, especially in the lower octaves, producing a rather 'larger than life' sound. The circuit itself, on the other hand is quite linear. Decca at one point converted most of it's stock of M 50s to FET, and they found the mic's fundamental character was unaffected.