thermally coupled electrolytis

[nashkato]

i know this from transistors , but why on input coupling caps ?
or is this a gnd shield ?

 

[Khron]

Looks more like shielding rather than thermal coupling, to me. Or just mechanical reinforcing..?

 

[Newmarket]

i know this from transistors , but why on input coupling caps ?
or is this a gnd shield ?

I'd guess a 0V shield ? What piece of kit is it ?

 

[rock soderstrom]

i know this from transistors , but why on input coupling caps ?
or is this a gnd shield ?

Interesting question, I have also seen this with broadcasting equipment.

Looks more like shielding rather than thermal coupling, to me

Maybe actually RF shielding?

 

[nashkato]

What piece of kit is it

I have also seen this with broadcasting equipment

its a pr&e rmx broadcastmixer i just bought

 

[user 133392]

It's shielding. Electrolytics and films both act as antennas.

Is that an AMX or B-series PR&E?

 

[Tubetec]

Maybe as the caps are opposite ways round relative to 0v , the outermost foils in the caps isnt connected together and so leads to unbalance at very high frequencies .

I think in the modern age with RF garbage floating around everywhere these kinds of steps the broadcast industry developed are a good idea in a music gear .

 

[nashkato]

Is that an AMX or B-series PR&E?

It's a RMX ( Radiomix )

 

[JohnRoberts]

+1 vote for shielding...

JR

 

[PermO]

If you zoom in on the pic you can clearly see these are soldered to the board and not just sitting there.

Sheilding.

 

[Tubetec]

The Marantz line I used sell years ago used copper sheilded op amps , was it HDAM I think they used call it .

 

[user 133392]

I should add that it's electrostatic shielding, not magnetic.

PR&E consoles are built like tanks.

 

[Newmarket]

If you zoom in on the pic you can clearly see these are soldered to the board and not just sitting there.

Sheilding.

Yes.Although you'd want them tied to some voltage to avoid "floating metal".

 

[AngryAudio]

I designed that console. Everyone who guessed shielding got it right. Here's the idea: Electrolytics have large conductive surfaces rolled up inside. It does indeed provide some electrostatic attenuation (not electromagnetic since copper is not permeable), but its main purpose is to control parasitic capacitance to the surrounding circuitry to maintain high CMRR at higher (above the audio band) frequencies. If you need to change caps and you can't find any that fit into the shield, you can remove it without any concern for deterioration. I hope you enjoy the Radiomixer. It does my heart good to see so many of these still in service.

 

[gyraf]

Angry: Details, please!!!

/Jakob E.

 

[rock soderstrom]

I designed that console.

Yeah, some background infos would be nice.

 

[AngryAudio]

Sorry about that. I started my reply and hit send prior to finishing it.

 

[JohnRoberts]

Welcome, it is always good to hear (straight) from the horse's mouth so to speak.

JR

 

[AngryAudio]

I suppose I should also mention that PR&E consoles were designed for broadcast, so some of the circuitry will be a bit different from the usual pro audio stuff. Mostly subtle differences, but some will be real head scratchers. Though usually our consoles were installed in nice clean studios, sometimes they would be installed in high RF fields. We guaranteed our products would be free from RFI in any environment. So while that copper shield might not do much to attenuate RF directly, the improved CMRR at AM frequencies helped. To this day, PR&E consoles are considered by many to be the gold standard in broadcast boards. Also, Deane Jensen was our audio circuitry design consultant so some of his ideas are found in those consoles including the use of JE-990 discrete op-amps in summing amps and the generous use of Jensen transformers in some designs (not Radiomixer though, that is a solid-state preamp design).

 

[nashkato]

(not Radiomixer though, that is a solid-state preamp design).

i'd like to add that the micpre uses a MAT02 .

looking forward to power it up . was in use at a local radiostation until a short time ago , so i don't expect big problems.

but man , that PS ... that really needs some muscle.