100W plexi...so um....are they supposed to be noisy?

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beasleybodyshop
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Re: 100W plexi...so um....are they supposed to be noisy?

Post by beasleybodyshop »

Roe wrote:
Structo wrote:...

As for the hum, 60Hz is usually related to the heater circuit and the 120Hz is usually a power supply problem.
in these amps the hum is also related to the transformers. Specifically, the PT hums and the OT pickups up this hum even when the amp amp is on standby
Yeah i do hear some transformer hum - not much i can do about it though, the chassis im using is all set up for a 67/68' plexi. Apparently the 69' chassis are slightly different, moving the transformers further apart and causing less hum. oh well. lol.
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Roe
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Re: 100W plexi...so um....are they supposed to be noisy?

Post by Roe »

beasleybodyshop wrote:
Roe wrote:
Structo wrote:...

As for the hum, 60Hz is usually related to the heater circuit and the 120Hz is usually a power supply problem.
in these amps the hum is also related to the transformers. Specifically, the PT hums and the OT pickups up this hum even when the amp amp is on standby
Yeah i do hear some transformer hum - not much i can do about it though, the chassis im using is all set up for a 67/68' plexi. Apparently the 69' chassis are slightly different, moving the transformers further apart and causing less hum. oh well. lol.
rotating the OT 90 degrees helps
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beasleybodyshop
Posts: 1089
Joined: Tue Jul 02, 2013 12:51 am
Location: East Texas (Yee Yee!)

Re: 100W plexi...so um....are they supposed to be noisy?

Post by beasleybodyshop »

Roe wrote:
beasleybodyshop wrote:
Roe wrote: in these amps the hum is also related to the transformers. Specifically, the PT hums and the OT pickups up this hum even when the amp amp is on standby
Yeah i do hear some transformer hum - not much i can do about it though, the chassis im using is all set up for a 67/68' plexi. Apparently the 69' chassis are slightly different, moving the transformers further apart and causing less hum. oh well. lol.
rotating the OT 90 degrees helps
Thanks. Will give it a try.
"It's like what Lenin said... you look for the person who will benefit, and, uh, uh..."
beasleybodyshop
Posts: 1089
Joined: Tue Jul 02, 2013 12:51 am
Location: East Texas (Yee Yee!)

Re: 100W plexi...so um....are they supposed to be noisy?

Post by beasleybodyshop »

Amp is done! Man it sounds like a Plexi for sure. I found a late 70s JMP headcab for it - I replaced all the busted up corners and spruced up the dirty tolex. She looks as good as she sounds now!
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