pbc
Hi guys,

Finally got the new house and set up 2 of the Cat 8Cs along with one of my DIY subs to try them out in the room.

I have 2 20 amp circuits on either side of the fireplace (probably will have to add a 15 amp next to one of them where I have my equipment). A panamax power conditioner plugged into the 20 amp circuit and my Funk Audio external subwoofer amp also powered into the same 20 amp circuit. Currently have all equipment and my left Cat 8C plugged into the Panamax until i add more circuits.

1. I have a 60hz hum coming from my Cat8's . I have isolated the cause,I believe, to the Funk Audio sub amp as when in remove that from the system the hum goes away.

2. When I run test tones (channel level test) to my Cat8Cs,the tone sounds distinctly different between the two Cat8s. I know due to being in different places in the room the timber can be a bit off,but the difference in sound in too much to be just this? Shouldn't they sound somewhat similar being the same speaker? One is much higher pitched than the other (a huge difference between the two)?

Any guidance would be appreciated on getting rid of the hum and on 2 as well!

Thanks!

Steve
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Mark_Seaton
Please first verify all 3 mute switches are at the IN positions using the tip of a pen. There can be some variation in how deep the switches sit vs the aluminum panel. Next run pink noise through the speaker while muting each channel to verify output from each element. The noise test from a preamp is often band limited which can reduce the tweeter and woofer output, so REW or a test disk is preferred.
Mark Seaton
Seaton Sound, Inc.
sales@seatonsound.net
773-290-8436
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calentz
It might be useful to cross-swap the outputs to see if the problem originates BEFORE the cats.
Carl
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pbc
Thanks guys, will check when I get back home.

Any advice on the ground loop?
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pbc
So as Mark thought it was that the mute buttons weren't all pressed in. Possibly from lifting and moving them. Test tones sound very similar now.

Now it's the ground loop that is left..
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pbc
Unfortunately it wasn't the external sub amp. If I unplug it and run the speakers full band I have the same hum. Man I hate ground loops.
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pbc
... And turns out it was, as usual, a ground loop in the cable line. Thankfully I had a cable TV ground isolator hanging around which fixed the issue.
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