Red Bear MKE60

[lowell]

First off this amp sounds killer. Very akin to Hendrix's Marshall sound. And the worksmanship is fantastic and it's all handwired. Only catch is the 6H2N preamp tubes (12ax7 but with 6.3v filament). I believe the 6N3C power tubes are 5881s. So anyone know a reliable source for the 6N3C tubes? Reliable?

[01redcobra]

Did you try the tube store www.thetubestore.com - Your online source for audio vacuum tubes.or Tube depot Welcome to TubeDepot.com!? Looks like they have both or replacements for them.

[Chuck H]

Can't it be rewired to run 12ax7's? Schematic?

[lowell]

Yah but do these tubes impart a specific sound? The amp sounds really good tonally, and very unique.

[J M Fahey]

What's the actual problem?
Does it have bad tubes or you just want to drop worse tubes in it?

[drewl]

Worked on a friends with these preamp tubes, and he had found several.
I'll try and contact him to see where he got them.

[Chuck H]

They seem to be readily available for about half the cost of most 12ax7's. And people seem to like them. I was expecting hum complaints but I guess the EM shield (wired to pin 9 instead of pin 9 being one of the filament ends like a 12XX7) works pretty well. I'm not finding them from vendors that test for relative goodness (at a premium) so you should buy twice as many as you require so that a quiet, non microphonic example can be chosen for the first preamp position and the two hummy ones and one grossly microphonic one can be culled and discarded That's just the brakes IMHE. So it ends up the same cost as selected 12ax7's either way

[lowell]

He bought it online and doesn't know how old they are. Maybe I'll suggest he just do the power tubes

[J M Fahey]

FWIW they are an "improved 12AX7" and the most popular dual triode in Russia, hands down.
Abbundant, good, fresh, and cheap to boot.
Or to be more precise, they cost what they should, without the "Mojo Tax", he he.

Only problem?: "Jimi/Eric/Stevie/Leo/etc. never used them "

[Chuck H]

Only problem?: "Jimi/Eric/Stevie/Leo/etc. never used them "

Partly because such players just step up and play. Meaning, they don't have amp tech's per se', but rather a "dude" that knows how to keep an amp running and they like the guy. It's a coveted position to be a famous players amp tech. Yet the guys who get the job are often the guys that that can hang with a brain full of chemicals, have made connections socially rather than electronically and get on well with the artist. Before I get flamed... There ARE exceptions.

I'm sooo down to try some of these 6hn2 tubes. I've had such bad luck with the 12--7 tubes that I'd be happy to change over. From the description this tube may be the Rusky military equivalent to the 12--7 tubes. Which means that they are likely made to a higher standard than the Rusky 12--7 tubes. Which, as far as I can tell, are made mass pro like clothes pins (Except the defects aren't removed from the batches!?!). A new (to me) tube that has a little focus from the MFG would be a welcome improvement.

[Gtr_tech]

Sounds like a 6EU7 to me....

[Cpt. Fixit]

These russian bottles are available on ebay, I usually buy them directly from russian vendors and never had any trouble so far.
The 6N2P socket can easily be rewired for 12AX7/7025/ECC83 - but I would not recommend it, as long as the supply does not dry up.
If you happen to find a 6N2P-EV you have the longlife, low noise variety, just perfect as V1 in most applications.
The 6P3 is indeed the pin-compatible russian 5881, you can use 6L6 or 5881 in its place without rewiring.

Regards, Toby

[bob p]

About that 6N2P-EV -- didn't Sovtek use that tube as the basis for what they're now selling as the 12AX7WA?

my understanding is that the modified the heaters for the 6N2P (which are parallel only) and changed them to be configurable as either series or parallel, and sell the guts in a 12AX7 pinout and label it as the 12AX7WA. the result is that what they're selling as a 12AX7 doesn't have quite as much gain as you'd expect of a "normal" 12AX7. In that respect, I think the 6N2P-EV --> 12AX7WA is more like a 5751WA than a 12AX7.

That's what I hate about Russian tubes. Most of what we're buying aren't what they're claimed to be. The factories aren't producing a real 12AX7, they're just taking the closest tube in their inventory and calling it something other than what it really is. I hate it when that happens.

[bob p]

Can't it be rewired to run 12ax7's? Schematic?

my understanding is that that amp was originally supposed to have 6N2P-EV in it, not the tubes that the OP mentioned.

because of tube sourcing problems a lot of those Novik/Gibson amps ended up being converted to run 12AX7, just like you thought. what's ironic about this is that the amp is supposed to have 6N2P-EV in it, and they're hard to find, so if you convert it to 12AX7 and put a 12AX7WA in there, then you end up with the 6N2P-EV that was originally intended to go in the amp.

Crazy.

[Cpt. Fixit]

Bob,
I only have two 12AX7WA here, so this does not say much really, but compared side by side with 6N2P-EVs, these two perform quite different. A lot less gain and a bit(...a NOTICEABLE bit, that is) noisier.
Maybe Sovtek used part of the original tooling, but different materials. Or the substitute filament wire makes all the difference.
There is still plenty of old stock available - even the EV-variety, I'd just order a dozen or so and have a lifetime-supply for the amp. No need btw to use -EV throughout the amp, you won't notice a difference if you put in a bog standard 6N2P as the PI, for example.