metal can or glass tube 6sc7?

[lexluthier72]

Hey all,
I am building up a 5c3 out of parts. I have a single metal can 6sc7 in the spares box. That being said, which do most folks prefer, metal can or glass tube? Is there a function/sonic difference? If the metal can type is good, does anybody out there have a good spare available? Lemme know price shipped to 55406....
-Erin

[Bruce / Mission Amps]

I always prefer the glass bottle RCA, Tung-Sol 6SC7GTs over the metal ones, but, I have gone through dozens, dozens and dozens to find a small handful that are not microphonic. They all are horrible by today's standards.
So much so that I stopped using the 6SC7GTS and instead started rewiring the sockets for a generic NOS 6SL7GTs, which seemed to have nearly no microphonic problems by comparison.

[lexluthier72]

Hey Bruce,
Thanks...I am working off the schematic for the 5c3. Will I need to change my component values, or just the pinout? Do I jumper the cathodes together?
-Erin

[Bruce / Mission Amps]

Originally Posted by lexluthier72

Hey Bruce,
Thanks...I am working off the schematic for the 5c3. Will I need to change my component values, or just the pinout? Do I jumper the cathodes together?
-Erin

The pin outs or very similar but not identical, so you would remedy that first!
The parameters of the two tubes are similar enough that you can pretty much use the same supporting components.

Yes, tie lugs 6 and 3 together of both triodes of the 6SL7 so they are using the same singular cathode resistor, ....just as the 6SC7 would be operating.
Again review the pin out first though because the two tubes have different elements to different lugs.

[lexluthier72]

Bruce,
Yep, I downloaded the tube data on both tubes, and re-drew the pinout. Thanks for the info. I will post photos of this project when finished.
-Erin

[jbs5280]

Bruce, Erin,

I was searching for a replacement 6SC7 and ran across your posts. Thanks for the tip Bruce. I may take that route with a couple of the amps that require that tube, both Mascos I think. Interesting you mentioned microphonics. I have not noticed it when using any of my old tube PAs (Mascos, Strombergs, Newcombs) for acoustic guitar or electric guitar.

I would be interested to know at what point or in what situations you tend to get the microphonics with the 6SC7.

Thanks again for the exchange. It was helpful.

BTW- I'm in Centennial, CO.

jerry

[Bruce / Mission Amps]

Originally Posted by jbs5280

Bruce, Erin,

I was searching for a replacement 6SC7 and ran across your posts. Thanks for the tip Bruce. I may take that route with a couple of the amps that require that tube, both Mascos I think. Interesting you mentioned microphonics. I have not noticed it when using any of my old tube PAs (Mascos, Strombergs, Newcombs) for acoustic guitar or electric guitar.

I would be interested to know at what point or in what situations you tend to get the microphonics with the 6SC7.

Thanks again for the exchange. It was helpful.

BTW- I'm in Centennial, CO.

jerry

Hi Jerry.
What I've found over the years is that when used in the first preamp stage, the metal ones seem to be more prone to microphonics and don't sound as good either... but that is when just bought outright from any tube vendor. I've had ones that were OK of course but the glass ones seemed better overall.
Unfortunately, even the glass ones were starting to get bad too so I started switching to the NOS 6SL7GTs with the rewired socket.
Then I had less trouble finding non-microphonic ones. There are even Russian ones being made.
If you have some metal 6SC7s installed now, that are not microphonic, then I think you are fairly lucky.
Still, you can get lucky and buy some 6SC7s or 6SC7GTs that are noise free... but I have not been so lucky and have been stuck with a large handful of noisy RCA and Tung-Sol 6SC7s 6SC7GTs!
By the way, a quiet Tung-Sol 6SC7GT sounds the best to me.

[zhyla]

I bought a couple Haltron 6SC7GT tubes a while back for my bassman project. Haven't had any issues with them. The metal 6SC7 tubes I had were just terrible.

The Haltrons I seem to remember being ridiculously cheap... $8 or so if I remember right, but it took some looking to find a site that sold them.

[Bruce / Mission Amps]

Originally Posted by zhyla

I bought a couple Haltron 6SC7GT tubes a while back for my bassman project. Haven't had any issues with them. The metal 6SC7 tubes I had were just terrible.

The Haltrons I seem to remember being ridiculously cheap... $8 or so if I remember right, but it took some looking to find a site that sold them.

I'm pretty sure Haltron was just another tube vendor that re branded other's tubes.
I'd be very surprised to find out these 6SC7GTs were anything other then good old American made, RCA, Raytheon or Tung-Sol tubes.