Thunder T-1 Twin amp speaker impedence

powdog

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Hi all. I have a Thunder T-1 twin amp that is missing its speakers. Any idea what impedence the original speakers were? Secondary impedence of the output transformer? Thanks for the help!
 

matsickma

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I owned one years ago but the speakers were shot. I ended up modifying the amp by replacing the 2-10's with a single vintage 15. My memory says I installed a 8 Ohm 15 inch speaker so the 10's would have been 4 Ohm in series or 16 in parallel.
I'm sure that doesn't help much as it is based on memory.
I will check around to see if I have a record of the mod. It would be in an old ebay write-up.
M
 

matsickma

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I found a picture on ebay and the speaker shows the speakers wired in parallel.

I sent the seller, The Blackrider, a message asking for speaker info. Years ago I bought a few Bigsbys from him si maybe he will help.

M
 

powdog

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Yea, I already asked that guy and he’s acting like it’s a National secret.

I did find a site that says the OT secondary was 8 ohms for the 12” speaker and 4 ohms for the 2x10”. Don’t know why someone would make something like that up.
 

matsickma

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Come to think of it... I think their is a schematic floating around out there that shows both speaker options.
M
 

powdog

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Did that schematic ever surface? I’ve never found a definitive answer to the 2x10” speaker impedence.

cheers.
 

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I suspect it's a four ohm load. I've never seen a Guild amp with two speakers with anything other than a couple of 8 ohms in parallel.
 
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