JJ capacitor can in a combo. good or bad ?

[pietro_moog]

hi guys. i'm building a small combo, and i want to use the jj capacitor cans.
do you think there's a problem in stability placing them horizontally? can vibrations do bad things to this configuration?
the combo is a simplified Bf deluxe in a tweed cabinet, the chassis is aluminum, just to make the things clear.

thanks guys

[Chuck H]

The cap probably doesn't have a mounting plane specification. I've never seen a normal cap that did. You should be fine mounting it horizontal. Grounding is a bit of a problem with can caps though. You can't idealize the ground scheme with all the filters grounded at the same point.

[pietro_moog]

ground scheme? i usually just use aluminum chassis and my scheme is this: preamp G goes in a common point with input and pots, bias is on its own like everything, PW tubes, output, elec. cap cans, and whatever. nowadays i almost never twist ac power wires between tubes, and use CT tap to DC elevation.
the amps works fine. the only problems in noise i have them with Lar-Mar MV, but the attenuation is huge.
do i do something the wrong way?

[Chuck H]

Your not doing anything "wrong". What your doing is what's been done forever. It probably matters most WRT high gainers, but it's usually best to have filters grounded either along a buss with the circuits they decouple or to ground them at nodes corresponding to the circuits they decouple. Due to very small resistances and high gain factors, if you ground the all the filters, amp output and the PT CT on the same node, or late in line on the same area of a buss, a high gain type amp could suffer a lot of avoidable noise.

WRT more typical "vintage" type circuits any noise isn't usually bad enough to be objectionable with the scheme your using.

[pietro_moog]

cristal clear, thanks

[soundguruman]

hi guys. i'm building a small combo, and i want to use the jj capacitor cans.
do you think there's a problem in stability placing them horizontally? can vibrations do bad things to this configuration?
the combo is a simplified Bf deluxe in a tweed cabinet, the chassis is aluminum, just to make the things clear.

thanks guys

you can mount the cap in any position,
too much heat, too much ripple current, or too much voltage is what damages the cap.
On an aluminum chassis you should run ground wires to studs that are tightened or heliarc welded to the metal.
I think I would prefer heliarc over tightening.
Actually, there is a method of cutting a ground tab in the chassis metal, then using pressure type push on connectors.
A lot of aluminum is being built that way, as opposed to ground screws or welding.
Aluminum tends to oxidize the electrical connections when the oxygen gets inside the connection.
Therefore the safety ground onto an aluminum chassis requires a special treatment. Dissimilar metals corrode and oxidize much faster than like metals.

[Steve Conner]

If you can't be bothered breaking out the TIG welder, you can just use a toothed washer and tighten the ground bolt up good and tight, so the teeth will bite through the oxide layer. Always worked for me.

[Chuck H]

If you can't be bothered breaking out the TIG welder, you can just use a toothed washer and tighten the ground bolt up good and tight, so the teeth will bite through the oxide layer. Always worked for me.

That's how I do it also. I never feel good about it though. I keep expecting problems to pop up in my builds because of a failing ground. The oldest amp I still have contact with that I built on an aluminum chassis is five years. No problems yet.

[Prairie Dawg]

I've put two of them in my Traynor YGM3 GuitarMate. A lot less expensive than replacing the Mallory cans on board. They sound good and all you have to do is drill one hole for the mounting clamp.