Sovtek Mig 60

[DonP]

Did you see the power/filament/bias supply?
THREE sets of full wave bridge diodes!



That thing must be quiet as a church mouse.

D1-4 and D5-8 are 2 bridge diodes inside of a full wave circuit. I sometimes see three diodes in a row. This to handle more peak inverse voltage.

Very interesting is D9-12 - the first two tubes get DC fed to the heaters. Nice upgrade.

[Cygnus X1]

Called my amp guy and he has some 12AU7's and 12AY7's He said they are about 70% of a 12AX7 and would help lower the gain some.
He said you were right on the money Cyg.

You are a lucky man to have a good amp tech!

[xenophobe]

It is very quiet Cyg.
From the info I found these were built in an old military plant out in Siberia.Supposedly of left over military components.
The mig 60 is said to be one of the only true PTP amps they made except for the original mig 50's that had the PT's that sagged so they ended up referring to the early ones as mig 30's.
Got stronger PT's and sold them as mig 50's.

All of the Red Bear amps, the MK60, MK120, MKE60 and MKE120 were PTP but used 6n2p-ev tubes. Many amps were converted to use 12ax7's though. The 6n2p-ev tubes are really hard to come by, and they were hard to find over a decade ago, I can't imagine trying to find them now.

[straycat]

Amp guy Brad hooked me up and said try this in the position farthest from the power tubes. NOS USA GE 12AU7.

[Hellbat]

Was doing some research on Fender Blues Jr. Mods and stumbled across this page. Has some relevant info...

http://billmaudio.com/wp/?page_id=131

He recommends 12AY7 or 5751. The AT and AU are lower resistance/higher current designs and while cleaner, will actually cut high frequencies and reduce the "sparkle" you are looking for.

[straycat]

If I don't like it I can try the 12AXY7.

[Cygnus X1]

If I don't like it I can try the 12AXY7.

Let us know when you find that one!



12AY7

I have a large quantity of 12AU's from harvested organ donors.

Only a couple of AY's, from my Tweed Deluxe building days.

[straycat]

I will Cyg hell this might sound just fine who knows.
Brad has a stash of NOS tubes.

[straycat]

The 12AU7 I put in had some noise issues so tried a 12AY7 and all is fine with this tube.
Still sounds great not as much gain which is what I was hoping for.

[DonP]

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[Cygnus X1]

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