General Technical Question RE: RCA input on amplifier

[beerguy]

Hello all hope this is not too out of bounds, just looking for a quick answer/opinion. I am fighting (unsuccessfully) to eliminate a ground loop and on an amp that I have never noticed one on before. I tried all the logical basic stuff. When trying to isolate the issue I brought the amp down to a point with no input, but with RCA's plugged into the amp, nothing plugged into the source end. I had a loop. I shut it down, removed them, and it was gone. I started looking at the rca inputs in it and became curious about on of the female receptacles. One has been replaced and although I have never noticed a loop like I did recently, I started testing continuity and resistance. This is a modular input that goes to a board BTW. So come to find out, the left RCA input shield/outside has no continuity with the shield on the right, or the case of the amp. Of course the pin on both inputs work, as the amp works, but could this be causing this problem? I have never had a loop in this room before. 2020 construction, and all on the same circuit. My thought is to replace the inputs, but wanted to see if this is a logical move.

TIA to anyone that knows the answer!

[babadono]

RCA input jacks are unbalanced input connections. Yes the shield needs to go to the chassis on the left input just like the right. If it has always been like this you have been lucky. Or perhaps a solder joint has cracked or opened in some other fashion. Could even be lifted foil on the circuit board. What amp is it?

Everything you wanted (or didn't) to know about grounding:

https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

[henry4841]

6 hours ago, babadono said:

RCA input jacks are unbalanced input connections. Yes the shield needs to go to the chassis on the left input just like the right. If it has always been like this you have been lucky.

Correct. Fix the known problem now, RCA inputs, and chances are really good that is the only problem. 

[beerguy]

Hey folks, thanks for the input. it's a pretty obscure amp, a Alcheminst Kraken ADP8 About 20 years old. Really nice though, 55 watts of British Class A with an independent power supply. I did just recently reconfigure my rack and recabled everything. I am guessing whatever type of repair that was done to the RCA input module finally failed.

 

Thanks so much folks, I am going to order some nice inputs and panel mount them with jumpers to the board. Appreciate the quick responses!

[beerguy]

Ok, I am back to ask one last question. I need this exact part, but would prefer it to be prettier. Gold or brass plated. I have looked on and off all day and cannot find one anywhere. Does anyone have any pointers for me? Thanks again team

 

https://www.ebay.com/itm/196078285185?hash=item2da72d3181:g:9soAAOSwFxplem7j&amdata=enc%3AAQAIAAABECQJUJg5z7HtlUKBiHnaFOnox%2FBaMWuyFBGIAzTG0iQOnfJzymOFEnII%2FFaeAkJpL9JpjeSYBLV%2BB8xQis9ZuIbtAX0Wq7eI8ulQlS3zRR4Bx%2B43mwP961Pfx7mWyGdVdK%2BIdBUiFYUWUXyDSvZ9ZB2F%2FiWQuQ%2BjAMnqKjMFaS73Y92LW1vO4EIeJ7YXh2tLyl0tjK6aLSPqqq9T9Fzkvl33MNtIaJ45ueW4QrJ4e72Sm52K7nPKBszvRpuJ1omJJs0nzUkg5QeicXC2NmKWAi4NC%2Ff5AGW9YrJ%2F2pkv4dJLxplkPDF1SXuBZmE1Zb%2FfqXGbcqnxtL9fYsfdMDwyUqzrth8l0oSB20KIIbCTllg9|tkp%3ABFBM1Pz2-JBj

[OO1]

1 hour ago, beerguy said:

  Gold  

 https://www.ebay.com/itm/234694162211?hash=item36a4dcb723:g:O7cAAOSwqMpjILE6&amdata=enc%3AAQAIAAABEB43oowYWUf9351%2B9Og2Bjhlk9Qj5Eq4%2F%2FjaRfDr%2FLiDP1bsKhrZgHpHiWWp275YN79DUBJ%2BYUsuWihYm8iDSnnRKjXDGXjKS4sD6%2Fb%2FT6nCsg192f%2FUflB6iLUpBI5LjrFBUfLPPI4iqveBxVJw73mTC7ojxziby1FX4an%2B1npp3xx%2F9rFYQy7e7BT6wTxN1QuNeoFd7o5qSTop2Qh4V2Y8pDmGIDAqjYuDTA%2B3rWc7cZfeGPpLQG4qnkFwbp%2BrExPO1pOKBW4g0zB2NY1P4VBX3tmWsDulnJIPHqx%2ByKVs5PkctIQ410t%2Bymb6DVNcZSGi%2B%2F4G8G4KU4DLaR7MQSujiADRa10bG1BSQagZsaXB|tkp%3ABk9SR4y7zKSRYw

[beerguy]

Ahh, close, but that is horizontal... I suppose I could jumper off of the pins though

[babadono]

is this close enough?

https://www.mouser.com/ProductDetail/Switchcraft/PJRAS1X2S02AUX?qs=mcPJWgAPNrf54bk5GcnDZQ%3D%3D&mgh=1&gad_source=1&gclid=EAIaIQobChMIjL-_i4-hgwMVXi-tBh0AIwGHEAQYBiABEgJGXPD_BwE

 

Personally I would get rid of the PCB mount type. Get a standard panel mount type and add an inch of wire. It is the force transferred on the connector down to the PCB that breaks connections and cracks traces on circuit boards

  

On the right the standard PCB mount jacks have been replaced with standard panel mount type. This is the main in and out connections. On the left are the PCB type that is the tape monitor loop connection which I left as is because I don't use.

 

WHY DONT THIS CHEEZEBALL APP ALLOW ME TO ATTACH PICTURES

[babadono]

Here they are:

 

[Marvel]

@babadono   Are those Jensens on the XLRs?

[babadono]

Yes Sir

[Marvel]

Nice! I plan on getting a couple (I'll start with two) to build a couple of mic splitters. . Would love eight, but... those are pricey.

[babadono]

Jensen is now owned by Radial Engineering out of Canada...not making any predictions but I would  procure what you want/need ASAP.

@Marvel you saw this comment/observation?

[Marvel]

Thanks for the info. I wouldn't want to make a prediction either way.

[OO1]

Jensen is owned by Radial since 2014  , just sayin  

[babadono]

20 hours ago, OO1 said:

Jensen is owned by Radial since 2014  , just sayin  

Correct. But things are changing...many IsoMax models are unobtanium...I suspect certain transformers will go by the wayside also....just my opinion/belief. But I am an idiot.

[OO1]

16 hours ago, babadono said:

Correct. But things are changing...many IsoMax models are unobtanium. 

 supply issues  affect all brands these days  , nothing anyone can do about it 

[Marvel]

On 1/2/2024 at 1:31 AM, babadono said:

 But I am an idiot.

Can't help you with that. 🤣

 

Radial makes similar products, so I could see them phasing out similar products. Radial hasn't made transformers, I don't think. They've been using Jensens in theirprodu ts and have a lot bigger portfolio of products. Perhaps the transformer prices will actually end up less expensive.