back panel shield

[59tone]

Hello to all.
I finished my Mission 5E3 kit last weekend and really am diggin’ it (got to play all day today). I did put a couple of mods in from the get-go. I added the choke and volume/tone mod and am very happy with the results. Everything is good but being a perfectionist am waiting on a couple of resistors to get some voltages dead on.

Q: This not being a gain monster and all. Do I really need to shield the back panel? Did Fender?

[Bruce / Mission Amps]

When I build the kits myself, and install into the cabinet (etc.) I usually do stick the foil tape on the back of the upper valance panel.... it is not really necessary though.
If you find that you are getting some buzz when you put your hand close to the input jacks or the 12AX7 part of the chassis... then you might find the foil helps cut that down a bit.
I'm curious what resistors, other then the 100ohms ones you asked previously about ... are off enough to need replacement.

[loudthud]

I don't remember if Fender did it, but Peavey made some amps in the 70s that used a tweed like chassis and cabinet. They used Asbestos on the inside of the upper back panel. They had compactron tubes inside the chassis mounted on PCBs with ventilation holes where the preamps tubes would have been on a Fender.

[59tone]

I'm curious what resistors, other then the 100ohms ones you asked previously about ... are off enough to need replacement.

On the 6v6 cathodes I want to bump up the 300 ohm to 330 ohms. Also I used a 33k on the preamp and PI supply (27k supplied was a little high) will use a 30K. These are in the +/- 10% range now BUT I'm picky, plus I'm learning.

[RWood]

Peavey made some amps in the 70s that used a tweed like chassis and cabinet. They used Asbestos on the inside of the upper back panel. They had compactron tubes inside the chassis mounted on PCBs with ventilation holes where the preamps tubes would have been on a Fender.

This this?

I didn't notice the abestos, though - yikes. Btw, those compactrons are hard enough to find, but in this amp only the short bottles will fit, otherwise the back panel doesn't close. Which rules out most of the remaining 6C10s.
Sorry for the hijack!

RWood

[Bruce / Mission Amps]

OK...I would not go over 360 ohms on the cathodes of the 6V6s.
The preamp node dropping resistor can go as high 39K if you like lower B+ on the 12AY7.
The Carbon Film resistors are all 5% and I rarely find them more then 2-3% off, so there is very very little difference in tonal effect between any given two 5% CF resistors.

[59tone]

The Carbon Film resistors are all 5% and I rarely find them more then 2-3% off, so there is very very little difference in tonal effect between any given two 5% CF resistors.

Even in the power supply the type of resistors has an effect on tone? I think I ordered metal oxide for the 30k and wire wound ceramic for the 300 ohm. Bummer, I'll have to shop around some more.

[riz]

59tone, read this: http://www.geofex.com/article_folder...carboncomp.htm

[loudthud]

This this?

I didn't notice the abestos, though - yikes. Btw, those compactrons are hard enough to find, but in this amp only the short bottles will fit, otherwise the back panel doesn't close. Which rules out most of the remaining 6C10s.
Sorry for the hijack!

RWood

I have two of those amps. One with a missing OT and one with an arc'd 6L6 socket. I plan to just convert them to 12AX7s someday...

[59tone]

59tone, read this: http://www.geofex.com/article_folder...carboncomp.htm

Interesting, thanks