[IronLion]

Hi all,

I'm not sure where else to turn so I'm posting my question here in the hopes that someone more knowledgable than me can advise. The tl;dr of this post is: can I connect a subwoofer to my Job 225 amp using speaker level/high level connection? Additional context below...

I have a Job Electronics 225 stereo amp that I bought used over the summer. I absolutely love the unit, it replaced a Spectron Musician III SE MKII that ended up with a common channel-balance issue (if anyone is interested in buying it for dirt cheap, DM me) powering some SP Technology Timepiece Mini's that I've had since 2008.

I have a Gallo TR3D subwoofer that I would like to use with my setup to make it a 2.1 system, but when using the other pair of outputs on my Modwright Transporter to create a low line connection between my DAC and the Gallo sub (I use the single ended Transporter outputs to feed the Job, and the balanced outputs to feed the sub, with XLR to RCA adapters as the sub only accepts single ended inputs), I have a persistent ground loop hum that I can't eliminate. So, I'd like to try using the speaker level connection to connect the sub to see if that method eliminates the ground loop hum.

So far, emails to the previous owner of the amp, as well as to Job Electronic's service email that they list on their website, have not given me any answers, and because I don't have the manual for the amp, I don't have that to reference.

Can anybody here advise? I've had tripath amps in the past which as I understand it don't support speaker level subwoofer connections, hence my trepidation about trying this on the Job without asking around first.

[Phil A]

So if I understand the question, you're using a single mono subwoofer and connecting it via the two RCA jacks?

[TomS]

The Gallo looks like it has a set of RCA pass through outputs, so can you just connect the Modwright TP to the Gallo, then from there through RCA outputs to the Job amp? The 2 outputs on the Modwright are probably just hard wired together internally, driven from only 1 buffer/driver, so probably not going to work well to drive 2 independent devices (in parallel).

Otherwise, the Jenson IsoMax series is always your friend for ground loops.
https://www.jensen-transformers.com/product_line/iso-max-2/

[IronLion]

So if I understand the question, you're using a single mono subwoofer and connecting it via the two RCA jacks?

Correct! I only have one sub at the moment.

[IronLion]

The Gallo looks like it has a set of RCA pass through outputs, so can you just connect the Modwright TP to the Gallo, then from there through RCA outputs to the Job amp? The 2 outputs on the Modwright are probably just hard wired together internally, driven from only 1 buffer/driver, so probably not going to work well to drive 2 independent devices (in parallel).

Otherwise, the Jenson IsoMax series is always your friend for ground loops.
https://www.jensen-transformers.com/product_line/iso-max-2/

Oh interesting, I hadn't considered this approach before! There's a "signal purity" part of me that would prefer not to introduce something in between the DAC and amp, even if it's just a pass thru, but this is definitely what I'm going to try next.

Thank you!

[opnly bafld]

Oh interesting, I hadn't considered this approach before! There's a "signal purity" part of me that would prefer not to introduce something in between the DAC and amp, even if it's just a pass thru, but this is definitely what I'm going to try next.

Thank you!

Y connectors to split the RCA out or with RELs when using a common ground amplifier you connect both positive and only 1 negative wire to the subwoofer.

2 subwoofers solve the problem and are better than one.