Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Thisismyname on January 11, 2023, 03:13:25 pm
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So I originally started this project a year ago by purchasing a Pacific OT for a brownface Deluxe build.
Somewhere between then and a few months ago when I started buying parts, I misremembering that and believed I had been building a 5E3 Deluxe all along.
So the only thing that actually matters is that I just realized I have a brownface OT with a 8K primary instead of the tweed with a 12K primary.
In my limited experience regarding transformers, I'm somewhat confident this should be fine, but what effects could I expect with this mismatch?
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So if it's an 8 ohm secondary run a 4 ohm speaker to raise primary reflected impedance? Something like that. You can adjust the mismatch of the primary at the secondary, inversely if I remember correctly. Or just get the right OT.
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So the only thing that actually matters is that I just realized I have a brownface OT with a 8K primary instead of the tweed with a 12K primary.
Not a problem. Carry on. I've never seen a 5E3 OT spec'ed for 12K. Why do you say that?
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So the only thing that actually matters is that I just realized I have a brownface OT with a 8K primary instead of the tweed with a 12K primary.
Not a problem. Carry on. I've never seen a 5E3 OT spec'ed for 12K. Why do you say that?
It's what the Pacific spec sheet says.
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I'm no expert, but I've never seen a 5E3 OT with 12k CT. You may want to contact pacific to see if it is a typo. I've certainly read trheads with people using 6.6k and 8k. I hope everything works out for ya!
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Do a turns ratio test to see what it actually is.
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The Hammond 5E3 spec OT differs to the Pacific, 8k5
https://www.hammfg.com/files/parts/pdf/1750EP.pdf
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12k would suit p-p 6K6 at 10W. Maybe Leo found some 6K6 iron surplus at a great price?
The "20W" could be 10W at 50Hz and 20W at 70.7Hz same THD. (Guitar vs full-range.)
Usually speaker and tweed-color make more difference than impedance.
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There’s a thread over at TAG where the unusual transformer specs chosen by Pacific is commented on https://ampgarage.com/forum/viewtopic.php?p=435348#p435348