investigating the russian 6S6B-V tube

[moamps]

I am always surprised with the quality of Mr. Heyne's soldering and wiring. This time he surprised me even more as he missed the optimal place to solder the AC701 grid wire. So that no one is misunderstood, the picture I attached is the property of Mr. Heyne.
Happy New Year to all!

 

[Tubetec]

Yeah no reason for the grid wire to loop back in that manner ,
the grid exiting at the top of the envelope like in the AC701k saves some incidental capacitance compared to the Russian stem press type

and thanks Bremosound for posting those rare docs , a Russian tube data post in the documents section might be a good plan .
I can imagine risks had to be taken to smuggle the Russian tube data across check point Charlie back in the old days ,

 

[GeorgeToledo]

Hello,

If you read carefully, that’s not what he actually wrote. The tube in the "prototype“ wasn’t the 6s6b. However, when it returned for final evaluation, the tube was changed, and he didn’t know what it was. So a confirmed non confirmation.

I do find it an odd coincidence that since, many of the large stockpiles have been bought up…


Anyway, having been interested, I visually compared the two in pictures, and I couldn’t see any differences. Also, the Beez Neez mics owner is convinced that’s what it is. He also uses them in his 49.

Here’s pics if anyone is interested, attributed to Klaus Heyne

View attachment 102209View attachment 102210View attachment 102211

And someone who is looking at the print on the side doesn’t necessarily understand it means 6S6B, because that’s not what’s actually printed on it. It would be easy to mistakenly think it’s something different if one isn’t familiar with the common translation.

 

[Tubetec]

Different alphabet makes it complicated to read Russian ,
When I visited Russia in the mid 90's we were given phonetically translated subway names ,so at least the locals could give us directions .

 

[bremusound]

Here is another doc from 1971:

https://nvlpubs.nist.gov/nistpubs/Legacy/TN/nbstechnicalnote715.pdf
More convenient to read, and 6s6b and 6s26b are on the same page (pdf page 41, written page 29).

 

[Papa Tango Charly]

The 6S6B-V looks really like the picture of
Klaus Heyne's teardown and analysis of a preproduction prototype?
Specialy the one on the left side.
Best Merry

 

[tomas.borgstrom]

I have a contact in eastern Europe who has located some 6s6b. The quantity is still unclear. PM me if you are interested. The price will be around 10-15€ + shipping.

 

[Khron]

Per piece?

 

[kingkorg]

I have a contact in eastern Europe who has located some 6s6b. The quantity is still unclear. PM me if you are interested. The price will be around 10-15€ + shipping.

You are kidding, right?

 

[RuudNL]

I suppose the price is a joke?

 

[dmp]

If it becomes a common belief that the 6s6b is being used in the m49v, the price may increase slightly. Perhaps that has happened already... (/s)
If the critics here know of a cheaper source by all means post it to help out the desperate buyers

I would guess with patience a bunch will start showing up on ebay, like the 6n1p

 

[dmp]

I am always surprised with the quality of Mr. Heyne's soldering and wiring. This time he surprised me even more as he missed the optimal place to solder the AC701 grid wire.

I see what you mean as the shorter connection would have been to the R5 / C4 / C5 node, right next to the top of the tube.
HOWEVER, for the purposes of a A / B comparison with the temporary install of the AC701, I think he did it correctly. The factory installed tube attached at the 'G' on the pcb and he attached the ac701 the same way. For a permanent install, the shorter connection would be preferable but the trace back across the pcb to 'G' would probably also be cut. Would you want that floating?

On another note - it is a quite shocking to see this is the PCB quality Neumann is using for the reissue. No teflon turrets to isolate the high impedance sections. But I don't mean this as a criticism, rather observing the experts. Evidently it isn't necessary.

 

[kingkorg]

If it becomes a common belief that the 6s6b is being used in the m49v, the price may increase slightly. Perhaps that has happened already... (/s)
If the critics here know of a cheaper source by all means post it to help out the desperate buyers

I would guess with patience a bunch will start showing up on ebay, like the 6n1p

Bunch were available already all over eBay, but now that's over. Sharing alternative sources who still sell 6s6b for 3€ would be shooting myself in the foot, as hoarders are obviously on a shopping spree. The very reason i was hesitant sharing my findings on 6s26b-k. There are many more models great for mic builds. Fortunately i'm not one of those who need Neumann to start using a tube for me to know it's a good one.

Sorry for this cocky reply, i'm all about sharing, but this is becoming insane.

 

[kingkorg]

No teflon turrets to isolate the high impedance sections. But I don't mean this as a criticism, rather observing the experts. Evidently it isn't necessary.

Not necessary, but good practice. It's questionable how these will age and perform over time.

 

[kingkorg]

If I were the one who had paid for them, I’d be happy to!

(and I’m usually on the opposite coast these days)

Even if you opened these I bet Sennheiser took Claus' advice to remove the markings off the tube.

 

[tomas.borgstrom]

Per piece?

You are kidding, right?

I suppose the price is a joke?

Do you know a cheap source? Please share.
I used to buy these really cheap from Russia on ebay before the war but now people are buying from the Finnish site where they are 15€ each. I hope that I can sell them cheaper, perhaps even lower than 10€, but at the moment I'm just trying to find a reliable source.

Just checked on ebay. There are two listings:
- 4 pcs for 16$ +shipping from Ukraine, decent price, maybe I'll go ahead and order from that source.
- 4 pcs for 70$ +shipping from Azerbaijan

 

[RuudNL]

About a month ago I bought 25 for $5/pc...

 

[Papa Tango Charly]

Me 2 best

 

[tomas.borgstrom]

About a month ago I bought 25 for $5/pc...

ebay?

It seems as some have sources that they want to keep for themselves. In my opinion you should not bother going after other DIYers with sources that aren't as cheap. If I build a tube microphone the total cost is somewhere between 500€ and 2000€ depending on the hardware and capsule. With that in mind I don't care if the tube is 5€ or 15€.

 

[aazaa]

If we consider the quality of the tube, 5€ and even 15€ are dumping prices.