[knestle]

I'm using Tangent's reccomended CP-43502PM high-quality in/out jacks with a Hammond aluminum end-panel enclosure.

Do these need to be insulated from the end-panel?

Is M4 used?

 

[jnewman]

The short answer is that it's usually a pretty good idea to have the outside of the case as ground (it cuts down on electromagnetic noise), so you don't need to insulate audio jacks from the case as the mounting part is always (if not insulated) at ground. Some people get insulated jacks and then very specifically solder connectors to the case.

One thing: You then must absolutely make sure that NOTHING not grounded touches the case. You should be especially careful about the DC power jack being isolated, and metal things attached to the board need to be carefully watched as well. I've never used those jacks, but it LOOKS like M4 is a connector to the mounting ring, and whether or not you use it depends on whether or not the ring is at ground and whether or not you're grounding the case.

 

[tangent]

Quote:

Do these need to be insulated from the end-panel?

Depends. What other panel components are you using, and what amplifier are you building?

Quote:

the mounting part is always (if not insulated) at ground.

Not in a PPA or PIMETA, if we're talking about the output jack. Output ground is not the same thing as input ground in these amps, and input ground is usually tied to the case through the input jacks and the pot chassis. Tying output ground to the case as well defeats the ground channel and can cause it to become unstable.

Quote:

it LOOKS like M4 is a connector to the mounting ring

I haven't bothered to look at the datasheet, but I have tested one of these jacks, and they are not isolated. So it doesn't matter what M4 is connected to inside the jack, for the purposes of discussing isolation.

 

[knestle]

Quote:

Originally Posted by jnewman You should be especially careful about the DC power jack being isolated.

I see I should have mentioned that this a a battery powered PIMETA portable.

Quote:

and metal things attached to the board need to be carefully watched as well.

Does this include the heatsink mounting tab on D1 (20TQ040)?

Quote:

I've never used those jacks, but it LOOKS like M4 is a connector to the mounting ring, and whether or not you use it depends on whether or not the ring is at ground and whether or not you're grounding the case.

The ring is mounted directly to the end panel (I think that means it is at ground with the case). As far as the case being grounded

, does this apply to a portable?

This is my forst foray into electronics and there is a LOT I don't understand.

Thanks

Ken

 

[knestle]

I know you guys are trying to help, and I do appriciate it.
But, you're going esoteric on me. I don't need reason, only direction.

Quote:

Originally Posted by tangent Depends. What other panel components are you using, and what amplifier are you building?

IN\OUT, P2U4503 pot, power switch, and LED.

Quote:

Not in a PPA or PIMETA, if we're talking about the output jack. Output ground is not the same thing as input ground in these amps, and input ground is usually tied to the case through the input jacks and the pot chassis. Tying output ground to the case as well defeats the ground channel and can cause it to become unstable.

Input and output.

Quote:

I haven't bothered to look at the datasheet, but I have tested one of these jacks, and they are not isolated. So it doesn't matter what M4 is connected to inside the jack, for the purposes of discussing isolation.

So I don't use M4?

 

[tangent]

Quote:

this a a battery powered PIMETA portable

In that case, either the input jack or the output jack must be isolated from the case, or both.

Quote:

Does this include the heatsink mounting tab on D1

He was referring to the metal bits of panel components.

Quote:

As far as the case being grounded, does this apply to a portable?

"Ground" is an overloaded word. It doesn't mean just one thing. In a PIMETA, the important thing is that only one signal can be tied to the case. You have input ground and output ground in contention here: I'd tie input ground to the case.

Quote:

So I don't use M4?

As I said, I haven't bothered to read the datasheet, or test it myself.

But, with 60 seconds of your time, a DMM and a mini-mini cable, you could figure it out for yourself. Meanwhile, something like 20 hours of real time have gone by since you started this thread. Some questions are easier to answer for yourself.

 

[jnewman]

Quote:

Originally Posted by tangent Quote: Originally Posted by jnewman the mounting part is always (if not insulated) at ground. Not in a PPA or PIMETA, if we're talking about the output jack. Output ground is not the same thing as input ground in these amps, and input ground is usually tied to the case through the input jacks and the pot chassis. Tying output ground to the case as well defeats the ground channel and can cause it to become unstable.

Right, sorry. Grounding just the inputs is a pretty good rule.

 

[tangent]

Okay, knestle PM'd me saying he doesn't have a DMM, so I went and tested one of these jacks. The lug on the side of the jack is tied to the metal shell of the jack, always. The lug directly aft of that one is tied to the sleeve of the plug and to the shell, but only when there's something plugged into the jack.

So, the difference between these two lugs is that if you run the ground wire to the one on the back end of the jack, it's connected to the shell of the jack only when there's something plugged in. If it weren't insulated from the case, this would cause the case to be grounded only when something is plugged in, which probably isn't helpful for a heapdhone amp. It's simplest, then, to use the lug on the side, since it's connected to the sleeve of the plug when it matters, and to the case always, when not insulated from it.

 

[MisterX]

So now the question becomes what is the best way to isolate the jack from the case.
I normally use a shoulder washer like mouser part number 534-4711 but with the jack you selected it doesn't fit unless you enlarge the hole in the washer. And it's black which gives the face plate weird look.

 

[knestle]

Thank you gentlemen, both for myself and anyone else desiring to use these jacks in a metal case..

I think with this last(?) question out of the way , I can complete my project with no further difficulties (assuming my soldering abilities are sufficient (always a dangerous assumption

)).