Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Hoffman Turret and Eyelet Boards => Topic started by: EL34 on July 31, 2014, 10:57:20 am
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The layout Diagram, Schematic and BOM and other build information can be found on the library page here
http://el34world.com/schematics.htm (http://el34world.com/schematics.htm)
Layout and Schematic
http://el34world.com/Hoffman/files/Hoffman_StoutReverb.pdf (http://el34world.com/Hoffman/files/Hoffman_StoutReverb.pdf)
BOM - Parts list
http://el34world.com/Hoffman/files/Hoffman_StoutReverb_BOM.pdf (http://el34world.com/Hoffman/files/Hoffman_StoutReverb_BOM.pdf)
Hoffman Board install instructions (http://el34world.com/Hoffman/instructions.htm)
Hoffman Turret Boards are on this page
http://hoffmanamps.com/MyStore/catalog/TurretBoard.htm (http://hoffmanamps.com/MyStore/catalog/TurretBoard.htm)
Hoffman amps Public parts list page is here
http://hoffmanamps.com/MyStore/catalog/PartsListIndex.htm (http://hoffmanamps.com/MyStore/catalog/PartsListIndex.htm)
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Newbie here with questions.
I'm thinking of building this project but I have a couple of questions.
1. there doesn't seem to be a chassis in the BOM. Will it fit into the Stout chassis (with a couple of extra holes) or is there another box that would work? I'd prefer to not have to punch all those holes myself.
2. Actually interested in doing the project with a gain pot and a switch or relay for the gain stage so that's probably a few extra holes in the chassis.
I was going to ask if the reverb tank fit into the chassis somewhere but reading in the forum it seems that it is usually stuffed away somewhere else in the amp box.
3. Is there a good reason to use a tube rectifier in the power supply? Tubes in the audio circuits I can understand but wouldn't solid state be better for the rectifiers? More reliable and more power efficient?
4. Are power transformers available with multiple primary windings for 100, 120, and 240V? I'd like to be able to take this thing out of the country. Also since mains power in Japan are 100V RMS I will probably need to re-calculate everything because B+ from a transformer designed for 120V will be lower than expected.
5. Does anybody care about power line frequency? In Japan power line frequency is 50 Hz in Tokyo and 60 Hz in Osaka. (Or is that the other way around?) Anyway it's probably the only country in the world with two separate grids running at two different frequencies. :BangHead:
Many thanks,
Hank C.
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1. there doesn't seem to be a chassis in the BOM. Will it fit into the Stout chassis (with a couple of extra holes) or is there another box that would work? I'd prefer to not have to punch all those holes myself.
No, the stout chassis are too small
reverb tanks are almost 17 inches long
Use a princeton reverb chassis, I stock those
I built mine in a princeton reverb chassis
3. Is there a good reason to use a tube rectifier in the power supply? Tubes in the audio circuits I can understand but wouldn't solid state be better for the rectifiers? More reliable and more power efficient?
You can do that any way you want
4. Are power transformers available with multiple primary windings for 100, 120, and 240V? I'd like to be able to take this thing out of the country. Also since mains power in Japan are 100V RMS I will probably need to re-calculate everything because B+ from a transformer designed for 120V will be lower than expected.
Look at the 18 watt tranny set specs.
The link is next to the transformers in my catalog
The 18 Watt PT has multiple taps
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Mr. Hoffman,
Thanks for the prompt response. This pretty much makes up my mind about which amp to build.
I need to do a few things first. I think I'll make a signal generator so I will have a test source before building the amp.
Winter is a time for preparation. I'll probably send you my order early in the Spring.
Best regards,
Hank Cohen
P.S. I love the choice of Slim Pickens for your avatar. :worthy1:
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Thanks