Neumann M49V tube mistery...

[klausheyne]

From what I've read, they can't produce more than 25 pcs./month.
(Especially because "there are only three people on this planet who can assemble a M49V". Well,I doubt that...)

Don't use my copyrighted photos without attribution!

 

[kingkorg]

You posted a picture that has my copyright (as is clearly stated in my review) Have the courtesy and honor the copyright and not post it without attribution

I'm ready to pay anyone not to post anything ever atributed to you.

 

[vintagelove]

You posted a picture that has my copyright (as is clearly stated in my review) Have the courtesy and honor the copyright and not post it without attribution

No problem.

 

[soapfoot]

From what I've read, they can't produce more than 25 pcs./month.
(Especially because "there are only three people on this planet who can assemble a M49V". Well,I doubt that...)

In fairness, I believe the photo you've critiqued is of a pre-production prototype, and wasn't ever intended for public sale.

I make my living as a musician, and certainly wouldn't want someone to document and then publicly adjudicate my performances "in the woodshed." That's where I work stuff out, pay attention to the big picture, and leave the finer details to be refined later

 

[klausheyne]

No problem.

Thank you very much.

 

[vintagelove]

In fairness, I believe the photo you've critiqued is of a pre-production prototype, and wasn't ever intended for public sale.

I make my living as a musician, and certainly wouldn't want someone to document and then publicly adjudicate my performances "in the woodshed." That's where I work stuff out, pay attention to the big picture, and leave the finer details to be refined later

Disregard

 

[soapfoot]

I don’t think that’s the prototype, as KH stated he could read the lettering on the tube in the prototype.

I think he stated that he could just barely make it out despite a removal attempt, and that he'd signed an NDA with Neumann to not reveal technical details that they didn't approve (presumably any choice of photograph would've taken this legal obligation into account)

He also said the production models used a film-and-foil coupling capacitor at his recommendation. The photographed specimen on the site appears to have a Vishay MKP type, so I assumed the photographic evidence must be of the prototype.

I could be mistaken, however.

It must also be said that part of Mr. Heyne's evaluation included substituting an AC701k for comparison, and we don't know whether these photos were taken before or after this substitution and restoration to original spec (rework is always a bit trickier to get tidy than starting fresh)

 

[TLRT]

There are hundreds maybe thousands of ac701 out there(I know big stocks but they dont let me to test it before purchaseI thought they ask the collectors for a limited run of tubes or go towards the fetron direction. For me s6sb always sounded worse and it generated lot of heat compared to ac701. 6s31br characteristic is totally different and most of them become noisy soon. Anyway they wont produce many mics and they will be expensive (and probably already pre-ordered)

 

[vintagelove]

I think he stated that he could just barely make it out despite a removal attempt, and that he'd signed an NDA with Neumann to not reveal technical details that they didn't approve (presumably any choice of photograph would've taken this legal obligation into account)

He also said the production models used a film-and-foil coupling capacitor at his recommendation. The photographed specimen on the site appears to have a Vishay MKP type, so I assumed the photographic evidence must be of the prototype.

I could be mistaken, however.

It must also be said that part of Mr. Heyne's evaluation included substituting an AC701k for comparison, and we don't know whether these photos were taken before or after this substitution and restoration to original spec (rework is always a bit trickier to get tidy than starting fresh)

My fault, I think you’re correct, I glanced at the review and it said the one marked 3304 or something was the prototype.

 

[kingkorg]

Mr. Heyne is clearly invested in this mic. If not for direct financial benefit than clearly for the reputation. This is the only reason he was so quick on the trigger to make this review. As we know anything he touches turns into gold, and so did this mic. Sennheiser!!! went for his suggestion to add those switches, and now even those otherwise "inferior" russian tubes suddenly became as amazing as the ac701. I believe Sennheiser!!! went for this (and the NDA) in order to hopefully stop his potential ranting on how this new mic is inferior to the vintage ones. And here comes his attempt to moderate things on this forum in the same exact fashion he does in his own forum. Pathetic!

 

[vintagelove]

There are hundreds maybe thousands of ac701 out there(I know big stocks but they dont let me to test it before purchaseI thought they ask the collectors for a limited run of tubes or go towards the fetron direction. For me s6sb always sounded worse and it generated lot of heat compared to ac701. 6s31br characteristic is totally different and most of them become noisy soon. Anyway they wont produce many mics and they will be expensive (and probably already pre-ordered)

Hello, how did you test the 6s6b and in what? Thanks

 

[kingkorg]

There are hundreds maybe thousands of ac701 out there(I know big stocks but they dont let me to test it before purchaseI thought they ask the collectors for a limited run of tubes or go towards the fetron direction. For me s6sb always sounded worse and it generated lot of heat compared to ac701. 6s31br characteristic is totally different and most of them become noisy soon. Anyway they wont produce many mics and they will be expensive (and probably already pre-ordered)

There are many more (some potentially better performing) tubes coming from the same place other than 6s6b-v

 

[Murdock]

What I don't understand, and maybe Mr. Heyne can explain it to me, why he wired the grid connection from the AC701 all they way down to the PCB pad and not directly to the insulated standoff right next to it?


Photo:© Klaus Heyne, 2022

 

[kingkorg]

What I don't understand, and maybe Mr. Heyne can explain it to me, why he wired the grid connection from the AC701 all they way down to the PCB pad and not directly to the insulated standoff right next to it?


Photo:© Klaus Heyne, 2022

It's part of the magic we're not supposed to discuss. And yes, of course, this adds to noise, inductance, and microphonics.

 

[Murdock]

Also this is the way Neumann delivered it...
Insulated standoff connects to the PCB...
Only explanation I have is that they did it that way to accomodate AC701 retrofits. One would than remove that link.

Photo:© Klaus Heyne, 2022

 

[TLRT]

Hello, how did you test the 6s6b and in what? Thanks

Did standard noise and curve tests did some test circuits and comparison with ac701's(sold around 50pcs ac701 at that time without any complaints) we have hundreds of 6s6b but honestly I didn't deal with them too much time.

 

[TLRT]

Also this is the way Neumann delivered it...
Insulated standoff connects to the PCB...
Only explanation I have is that they did it that way to accomodate AC701 retrofits. One would than remove that link.

Photo:© Klaus Heyne, 2022

Based on the pinout this is definitely 6s6b. I can run a query in roetester database for similar tubes.

 

[GeorgeToledo]

In fairness, I believe the photo you've critiqued is of a pre-production prototype, and wasn't ever intended for public sale.

I make my living as a musician, and certainly wouldn't want someone to document and then publicly adjudicate my performances "in the woodshed." That's where I work stuff out, pay attention to the big picture, and leave the finer details to be refined later

They gave it to someone to base a review on!

 

[GeorgeToledo]

What I don't understand, and maybe Mr. Heyne can explain it to me, why he wired the grid connection from the AC701 all they way down to the PCB pad and not directly to the insulated standoff right next to it?


Photo:© Klaus Heyne, 2022

Yeah, at first late look I was puzzled about that, and then finally thinking the same thing last night.

 

[mrbutterskin]

I think it's a very high chance that the tube is indeed a 6S6B(-v)
There's a few things we know:
1. It's a USSR tube
2. It has the electrode structure of a 6S6B
3. Many of us here have had positive results using the 6S6B in place of an AC701
4. In the M49c circuit at the specified current and plate voltage, the plate resistance and gm of the 6S6B is roughly equal to the AC701.

It's definitely not a 6S7B. Similar structure, but the plate size of a 6S7B is larger.
All russian subminiature triodes would have the designation of 6SxB, where x is whatever series number. Out of the existing common types the 6 is the only one that makes sense. Maybe there are less common types that Neumann found a cache of but this just seems unlikely to me. I'd love to be proven wrong but for now, all things point to 6S6B.