Looking for isolated, high quality 1/8" jack.

[bg4533]

I am building a Pimeta and have changed my mind from building an acrylic case to using a Hammond 1455 with metal ends.

I am now planning on using an Elpac WM080 with a isolated DC jack. I plan on having RCA and a 1/8" input and a 1/8" output. Does anyone know of a nice isolated 1/8" jack?

I was originally looking at the high quality jack Tangent recommends, but it doesn't seem it is isolated. Link

Thanks,
Brian


edit:
From looking at the PDF on that webpage it appears this jack is isolated. Due to the construction of a 3.5mm plug I don't see how this could be so. Can someone please verify if it is isolated.

 

[drewd]

The data sheet PDF shows how it's insulated. The sleeve of the plug does not touch the metal of the jack. You'll see that there is an insulator that runs around the inside of the jack and the ground contact is made by a spring that is insulated from the rest of the case. There is a fourth contact that grounds the actual body of the jack.

But it looks like there could be a hitch if the plug pushes too far into the jack and the metal flange part of the plug touches the threads of the jack.

But I haven't actually used this jack, so I can't say for a fact that it will or won't work.

-Drew

 

[bg4533]

Quote:

Originally Posted by drewd But it looks like there could be a hitch if the plug pushes too far into the jack and the metal flange part of the plug touches the threads of the jack.

That is what I was thinking. Thanks for the response.

 

[GainHead]

I think these are the nicest 3.5mm jacks available from Mouser or Digikey: http://www.mouser.com/catalog/specsheets/0417189.pdf

By the way, the contacts are gold-plated too.

 

[bg4533]

I really like the look of the CUI jack I originally posted. I am thinking about getting them and trying them out. If they don't work how bad would it be to put a piece of electrical tape or heatshrink tubing over the metal flange? I will only be using one pair of headphones with this Pimeta.

 

[tangent]

Quote:

Can someone please verify if it is isolated.

I just ran a continuity test on one with a mini-to-mini cable plugged in, and it is definitely not isolated.

Quote:

how bad would it be to put a piece of electrical tape or heatshrink tubing over the metal flange?

I tried such hackery years ago when I was first getting into DIY, and it almost always failed in some way, usually due to the threads or nut cutting through the insulation. Not to mention that it usually looks ugly.

The only way I was ever able to get something that works is to modify some plastic shoulder washers with 1/4" holes in them. I believe they came from cheap insulated RCA jacks. It was a lot of work because I had to thin them out enough that I could get the nut on the bushing.

 

[jonesy]

I've just been through all of this, and the best I can come up with is to use the Neutrik locking 1/4 inch jack socket-if there's space- and use an adaptor. It's totally isolated and has gold contacts. Needs a 24mm hole though.....

 

[robzy]

Sorry to thread-hijack, but what are the advantages of an insulated socket?

 

[bg4533]

Quote:

Originally Posted by robzy Sorry to thread-hijack, but what are the advantages of an insulated socket?

I don't know the full details of it, but the Pimeta uses an opamp and buffer on the ground channel of the amp. Without an isolated jack the ground of the output gets tied to the metal case. This can defeat the purpose of the opamp and buffer on the ground channel. With a plastic case an isolated jack is not needed.

 

[tangent]

Quote:

what are the advantages of an insulated socket?

A non-isolated output jack ties the ground connection to the jack case. When used in a metal case, the jack ties the case to output ground. If you have something else tied to the case, that ties output ground to that other thing.

This is a problem in a PIMETA or PPA because output ground is not equal to input ground. Tying them together through the case will usually cause instability. Even if the amp doesn't fail, you're disabling one of the most significant features of these amps by tying IG to OG. Since you usually want IG tied to the case for shielding reasons, OG needs to be isolated from the case.