Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: silat on May 10, 2025, 01:50:33 pm
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Bought this record player at a estate-sale. AnyONE fiddle with one of these?
Thanks in advance.
silat~
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It also has a selenium rectifier. I have the whole record player.
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A little better view of the record player control panel and it also has a field coil speaker very small.
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without a PT/isolation transformer you can assume that it'll be a shock hazard.
it's probably in the 3W range, the tube spec sheet n B+ will get you a close guess
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Shooter : "without a PT/isolation transformer you can assume that it'll be a shock hazard.
it's probably in the 3W range, the tube spec sheet n B+ will get you a close guess"
I read where someone else said it was in the 3 watt range on another forum somewhere.
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Treat it like a vintage radio (which also doesn't have isolation or power transformers)
you could add a polarized plug to keep AC line off the chassis.
Just be sure you know what you're touching.
Are you restoring as a Record Player?
If so there is some discussion on Travler 7075 (uses a 50L6) on ARF
https://antiqueradios.com/forums/viewtopic.php?p=3671331&hilit=travler+record+player#p3671331
Might be a place for Record Player advice...
I have a pair of 25L6's that will be a guitar amp some day.
Need to figure out how to get 25v.
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Just going to take the useful parts and make a 5f1 champ in the record box which is really nice. I have some transformers that will work.
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It looks like the original designers got 25V at the heater by dropping 90ish volts through the motor of the record player.
It might be a nice cabinet, and maybe you could convert it into a guitar amp, but you might not be able to salvage much from the original electronics.
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a thread with some PP 25L6 discussion
https://el34world.com/Forum/index.php?topic=25311.0
a single ended Harmony 303 that uses 50L6. This Harmony sounds amazing
https://stillampd.com/harmony-h303
if you have the transformers you could build something like 303, just sub your 25L6 for the 50L6
Plus this preamp and rectifier tube are more in the timeframe of the 25L6
maybe better than 5F1 as A 25L6 power tube might not sound like a 5F1
And the 25L6 would need a different design than the 6v6 so not a 5F1
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Single 25L6 would not work well for guitar unless you have active pickups at best. You'll need at least one more gain stage to work with conventional pickups. Maybe graft in a dMOS gain stage or two, or add another tube or two? Combination of SS & tube gain stages?
That amp is a high risk shock hazard, whatever you do, use an isolation transformer at the very least.
--Pete
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https://www.diyaudio.com/community/threads/an-ef184-25l6-2-2w-guitar-tube-amp.369501/
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Interesting 25L6 Single Ended build
Its curious how they get 145vdc from a 60vct transformer