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Old 1st October 2012, 08:01 PM   #1
TP143 is offline TP143  United States
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Default Protection Relay

I am looking to add a speaker protection relay to my LM4780 parallel kit. I have found many available on ebay but few elsewhere on the web. Does anyone have a recommendation?

Thanks
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Old 1st October 2012, 08:30 PM   #2
sreten is offline sreten  United Kingdom
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Hi,

One of the advantages of chip amps is the comprehensive protection,
so I can't really see used properly why a relay would ever be needed.

Proper use of the chips mute function fully emulates relay operation.

rgds, sreten.
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Last edited by sreten; 1st October 2012 at 08:33 PM.
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Old 2nd October 2012, 02:50 AM   #3
Minion is offline Minion  Canada
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I have had speaker frying from LM3886 a couple of times , once when I put the wrong gain set resistor so it was configured as unity gain and oscilated like crazy and caused by speaker to smoke a bit , It also happened once when i miswired the PSU to the amp so there was no -v which caused a huge DC offset which caused my speaker to heat up a bit ......
When it is configured correctly there is little chance it will fry yer speaker ......
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Old 4th October 2012, 01:04 PM   #4
frank1 is offline frank1  United Kingdom
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Quote:
Originally Posted by sreten View Post
Hi,

One of the advantages of chip amps is the comprehensive protection,
so I can't really see used properly why a relay would ever be needed.
Because the protection doesn't work when these things fail.
They are more than capable of destroying a loudspeaker, just like any other amp.

Frank
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Old 4th October 2012, 07:11 PM   #5
TP143 is offline TP143  United States
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Does anyone have any experience with the cheap ebay relays? I have read that a relay can negatively influence the amps sound but I wasn't sure if this was limited to certain designs.
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Old 4th October 2012, 07:56 PM   #6
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by TP143 View Post
Does anyone have any experience with the cheap ebay relays? I have read that a relay can negatively influence the amps sound but I wasn't sure if this was limited to certain designs.
No experience of Ebay but relays can give problems. A subtle problem is distorted sound at low volume that mysteriously corrects itself when the amp is turned up. Cause... contact degradation, and the higher current at loud volume then finds a path through the contamination and all OK again... until the next time. Having had this happen to me I went down the solid state route. I don't think I'd go back to mechanical now.

Very long thread on this that finally gets round to SS relays, you'd have to read it all,
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