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Post by Deleted on Sept 7, 2022 16:03:02 GMT
Inspired by the thread about Oli’s visit, I thought I would plug my sub back in to my system.
Strange thing is, that when I turn my 686 off, the sub hums.
When it is powered on, it is silent. Could this be down to my speaker protection in the 686?
I have not yet tried the sub connected to just one speaker. It is connected using the +ve feeds from both, and negative from only one.
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Post by Deleted on Sept 7, 2022 16:19:28 GMT
If I disconnect the single +ve cable from the amplifier, the hum goes away.
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optical
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Post by optical on Sept 7, 2022 17:28:16 GMT
Are you using 'hi-level' connection (REL etc). If so I think the output of your 686 is bridge tied like mine and it could cause problems running it from both L&R terminals.
I would advise running just one side if using this connection.
Might be okay at low levels but could potentially damage things so I'm lead to believe.
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Post by Deleted on Sept 7, 2022 17:35:14 GMT
It is now connected to one side only.
If there is any doubt, I will take it out.
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Post by Deleted on Sept 7, 2022 17:40:14 GMT
I think my 686 was built in “Balanced” rather than “Bridged” configuration.
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Post by firebottle on Sept 7, 2022 18:01:05 GMT
Balanced refers to the input wiring, bridged configuration is the output configuration, totally different.
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Post by Deleted on Sept 7, 2022 19:16:28 GMT
Reading the Gaurdian 686 documentation, the boards need power to work, and are grounded through the power supplies.
It would appear that a ground loop is created when the Guardian 686 are powered down.
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Post by peterthebutcher on Sept 11, 2022 8:44:13 GMT
When I had my Rel connected to the PS S300 amp, it hummed when amp was switched off, as Rels instruction was NOT to connect the black wire. Since then I have bought the PS M700 mono's and another sub, and the dealer wired them both up but connected the black earth wire to the ground plug, then high level... No more hum
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Post by Deleted on Sept 11, 2022 11:18:18 GMT
Inspired by the post above, I did some reading to edumacate myself this morning.
My amp is a BTL (Bridge Tied Load) so to connect a sub I should use the two speaker +ve terminals, and a common ground on the chassis, or add another subwoofer for 5he other channel.
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Post by antonio on Oct 24, 2022 6:50:47 GMT
Rather than start a new thread, thought I'd just continue with this one since I have a hum coming from my REL sub. I have disconnected it from the amp and is still there. I don't get any hum from any other components except for my Quad's which will be going back when a slot is available at OTA.
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Post by Deleted on Oct 24, 2022 8:43:10 GMT
How is it normally connected Dave?
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Post by antonio on Oct 24, 2022 9:26:09 GMT
A neutrik connector on the rear of the sub with a three conductor wire, one wire to the left and right plus speaker terminals, one wire to either of the negative terminals on the amplifier.
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Post by Deleted on Oct 24, 2022 10:30:19 GMT
Sounds like you have the same issue with the amplifier not having a common ground.
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