6386=5670=2C51W=396A?

[emrr]

I stuck some 5670's in my Collins 26U once, and they seemed to work a bit, but the metering was totally off. I considered going down the path of the conversion ala Manley, but never did. Shortly after that Manley admited the 5670 wasn't so great after all.

6ES8 is a proven quantity in the Langevin Leveline compressor.

There's a Gates limiter that uses PP 6J7's for gain reduction, but in combination with a lightbulb based variable resistor bridge shunt. The bulb shunt and the entrance to the variable mu sidechain are the same spot, so there's interaction and the points are probably set so the bulbs keep the vari-mu chain from bottoming out. I haven't measured the range of the vari-mu section, but it has to be relatively small. The vari-mu section acts as an initial brake before the limiting action of the bulbs kicks in. Of course it's not much of a stretch to convert that tube position to 1612's if you wanted to do so.

 

[NewYorkDave]

[quote author="tk@halmi"]I am surprised that nobody has tried the 12AV7 for varimu duty.[/quote]

I have.

 

[CJ]

You mean the One Bottle is non linear?
Shucks!

 

[NewYorkDave]

I didn't say that. I also didn't say how well the 12AV7 performed in a vari-mu circuit.

 

[SUPERMAGOO]

look at this link I found on ebay.
is a good replacement or is it a scam?


http://cgi.ebay.com/6386-Variable-Mu-Compressor-Tube-Replacement-NOS_W0QQitemZ290281814284QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item290281814284&_trksid=p3286.c0.m14&_trkparms=72%3A1234%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A0%7C293%3A1%7C294%3A50

 

[bradb]

Fear no more gents:

http://www.jj-electronic.com/pdf/6386LGP.pdf

 

[SUPERMAGOO]

if you saw him. that good news!
he had just bought 5 2c51 Brimar for 40 bucks   

 

[thermionic]

You could find a 6386 original for $129 USD - that's pretty ironic.

Oh yeah - you can find 6BA6 for a couple of dollars each if you know where to go... This seller risks some intrepid DIY-er buying his T-bar unit and copying it for peanuts... The only downside is that you need a curve tracer to match each 6BA6 transfer curve.

 

[gary o]

Is the schematic for T bar about.......

 

[Martin B. Kantola]

Have a couple of compressors with 6K7, about 40dB of gain reduction.

Martin

 

[HadYourPhil]

Like gary o, I'd love to see a Tbar schematic or something similar. I have an old Audimax II that has a badly mismatched 6386. I've never been too fond of that box, but would love to try a better tube(s) in place of the 6386.
This forum has quite the depth of knowledge!!

 

[Kingston]

"T-bar" is just two single triodes wired into a dual triode socket. More accurately two 7-pin pentodes-wired-as-triodes into a 9-pin dual triode socket.

Schematic would be pointless. Just look at datasheets of said tubes and wire them in.

 

[HadYourPhil]

OK... Since this is a branch of electronics I have not ventured on to... Do I wire the three grids (pins 1, 2 and 6) together, or some other configuration where a grid or two are wired to the plate?

 

[HadYourPhil]

Sorry to see that no one has a clue as to how to wire a pentode as a triode. I know I don't. That's why I came here, looking for advice.
And therefore I disagree, a schematic would not be pointless.

 

[Kingston]

Don't be daft. searching "pentode as triode" and one of the first links is this thread:

http://www.groupdiy.com/index.php?topic=31788.0

Everything you need served on a platter.

 

[HadYourPhil]

Thanks, I guess. Hope you feel better...