Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TubeJunkie on January 02, 2020, 01:30:07 pm
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Okay, so I need some help reading and putting together a circuit from the schematics below. They show an Excelsior Americana amp that has tremolo on the Treble/Bass (accordion) pre-amp section only, and reverb available to both pre-amp input sections. The amp also keeps the wet reverb from the dry signal, and outputs the wet reverb through a separate power amp and speaker. This gives a wet/dry reverb rig in a single amp. What I need help with is: how/where the pre-amp output (1) connects; how/where the reverb volume pot and foot switch (2 & 3) connects to the reverb amp section (5); how/where the power-amp section connects to the pre-amp section; and, how/where the left reverb input(s) connects (6). The Reverb Input connection was pretty obvious. I've scoured the Internet, and haven't found any real detail of how this goes together. The first PDF shows the pre-amp section, and the second PDF shows the power-amp section.Thanks in advance for your help and insights.
:w2: :dontknow: :help:
https://www.vintageguitar.com/17184/excelsior-americana/
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:anyone:
Does this have everyone stumped?
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Probably most people are on break right now. Looking at your project, it's way over my head, but you might want to define your goal - is it to restore the original? There's quite a lot going on with it. Wish I could help.
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This is what i think but i might be way off so beware :)
Going with numbers on your picture:
1 (audio output) connects to 4
2 in your picture connects to nothing
3 connects to 5
6 has me stumped, no idea where the reverb tank gets its input :dontknow:
I hope someone with better schematic reading skills will chime in and confirm or point out possible mistakes i made
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Looking at these pictures:
https://reverb.com/item/530387-1969-excelsior-americana-all-tube-amplifier-2x12-reverb-trem-stereophonic (https://reverb.com/item/530387-1969-excelsior-americana-all-tube-amplifier-2x12-reverb-trem-stereophonic)
looks little like reverb tank might get its input from the speaker (red wire)
Just a guess again.
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Also found this old thread that might have same amp just under Sano name:
https://el34world.com/Forum/index.php?topic=18563.0 (https://el34world.com/Forum/index.php?topic=18563.0)
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1 connects to 4.
2 connects to nothing.
3 connects to 5.
6 connects to main speaker (or OT secondary).
Do you have this amp?
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Looking at these pictures:
looks little like reverb tank might get its input from the speaker (red wire)
Just a guess again.
That's the best set of pics I've seen so far, and pretty much confirms what I first suspected . . . but with the schematic not showing anything about an OT secondary tap/connection, then it is just a best guess. However, I did find a Guild T1RVT accordion amp that is very similar to the Excelsior, and it did show a speaker tap to the reverb input of a speaker-out wet reverb signal, but just different enough to not take it as definitive. These pics I think are pretty clear that it's coming from the main speaker OT secondary. Thanks VMS.
https://elektrotanya.com/PREVIEWS/63463243/23432455/guild/guild_thunder-t1rvt_sch.pdf_1.png
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1 connects to 4.
2 connects to nothing.
3 connects to 5.
6 connects to main speaker (or OT secondary).
Do you have this amp?
That's what I suspected, but wanted some fresh-eyes to take a look. The schematics are pretty rough, especially the pre-amp, and interpreting them has been a challenge. It's interesting that there's no indication anywhere that the reverb input comes from the OT secondary. Thanks for your insights sluckey.
No, I don't have the amp, but I'm contemplating doing a scratch build, eliminating the accordion bass section, and having the option of using the accordion treble section to boost the signal by plugging in to Bright-In and then jumpering from Normal-In to accordion Treble-In.