Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Apexelectric on June 04, 2017, 09:36:58 am
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I've got a friend that wants me to build him a new amp. He is currently playing a Fender Hor Rod Deluxe and wants to up grade. Overall, he is pleased with the amp but just wants something more refined. He plays strats almost exclusively but occasionally uses a ES-335. He is a blues player and is rather talented so I'd like to get this one right for him the first time around. I've kicked around a AB763 design with 6L6's but I don't need the Vibrato effect or the two channel options. We definitely are looking at something as loud, maybe a little louder than the Hot Rod. He likes the drive option as well as the master volume on the Fender he's using. Reverb is also a must with possible addition of a dwell control. Debating over a 1 x 12 or a 2 x 10. He seems to like a little darker sound that he can get out of the ceramic speakers in the Hot Rod.
Ultimately I'm looking for a base design that I can tune without having to do a lot of re-engineering. I've got no problems with modifying the chassis and making a turret board to fit the design. Just looking for the path of least resistance on the circuit design.
Ideas?
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Look at Hoffman's single channel AB763 with reverb. Easy to add dwell control. It also has vibrato but that's very easy to eliminate. A Celestion speaker may just make your friend happy with his current amp.
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Wouldn't there be noticable tonal change in the elimination of the vibrato circuit and its associated tube other than just the effect being gone? Was considering that direction but wanted to add another switchable gain stage as well.
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Wouldn't there be noticable tonal change in the elimination of the vibrato circuit and its associated tube other than just the effect being gone?
No change in tone. Replace the mid pot with a 100KA pot, call it RAW, and you may not even need an additional gain stage.
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Is it just a matter of getting rid of the components in the schematic I circled? Would I need to add a resistor in place of the Intensity pot?
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Just delete the stuff you circled then connect the wiper of the bias pot directly to the junction of R47 and R48.
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Thanks, Sluckey. I'll give it a try.
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There's a current thread about a Hoffman DR build. Even has some sound clips. Worth a read.
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Not being him, it's hard to know what your friend wants. But you wrote that he likes the drive feature of the Blues Deluxe. The BD preamp could be implemented if you're starting with a Hoffman single channel AB764 kit but not using the vibrato. The increase in parts count is probably less than the deleted vibrato, though I didn't actually count components. There is the added complication of two relays though. (Could be a single 4P2T relay.)
Don't bother trying to copy the BD relay driver circuit. It is truly ridiculous. Who controls relays with opamps? :l2: If this is something that interests you then I can help sort out the relays and how to actuate them.
I'd prefer that someone other than me created the layout. I can do it, and come up with a good design at the end of the day, but it takes me a really long time to get there.
EDIT: What a dope I am sometimes. You wrote that your friend is using a Hot Rod Deluxe, not a Blues Deluxe. Oh Well...
(http://misguidedmonkey.net/lychee/uploads/big/159f174f53d5320ca60c80c285847a49.png)
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The world is full of AB763s. Why bother to make another one? Maybe take a look at Mark Fowler's Rocket Reverb over on ampgarage.com .
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I think the kit was suggested as a starting point since it includes all the major pieces. So yeah, he definitely should look at Mark Fowler's Rocket Reverb, possibly as a direction to go with the kit.
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Thanks guys, just looking for a direction on a starting platform design not a kit. The AB763 was just an idea on a starting design but it has things I don't want and is missing things I do want so I thought there might be a better starting platform out there that I might be missing. I'll check out the Rocket Reverb
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I suggested AB763 because you mentioned it in the original post. There are plenty of other designs out there that may appeal to you. Maybe something in the Dumble family. Take a look over at the Amp Garage. Lot's of info about Dumbles.
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The world is full of AB763s. Why bother to make another one? Maybe take a look at Mark Fowler's Rocket Reverb over on ampgarage.com .
schematic available?,
--pete
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Look at Hoffman's single channel AB763 with reverb. Easy to add dwell control. It also has vibrato but that's very easy to eliminate. A Celestion speaker may just make your friend happy with his current amp.
Sorry to Hijack, but it seems like a good opportunity for a question regarding the AB763 circuit
I haven't studied Hoffman's Single Channel AB763, I know that you provided the original schematics drawings, I am assuming that it is very similar to your TDR, correct. Aside from the Tremolo, what difference are there between the two circuits?
I am considering the board size and layout and don't want to re-create the wheel. I'm not that good at wheels yet.
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schematic available?,
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Aside from the Tremolo, what difference are there between the two circuits?
None
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schematic available?,
gracias dr.
viva texico!
--pete