Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: printer2 on June 01, 2014, 01:28:18 pm
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When I started building amps I took the lead from Fender. So while these are not amps Fender made their circuits are the basis of the amps. The first is a Champ spinoff but rather than decide on going with a Blackface or a tweed tone stack I went with both. While some just use a BF tonestack and just disconnect the mid resistor from ground I decided I wanted to have the Tweed tone control when running the amp as a Tweed. When I first found out you can get three or four pole miniature toggle switches I started looking at ways to get more tone options. While the below schematic and layout uses a three pole switch I went for a four pole and also switched the cathode capacitor on the second stage. In BF it is in, in Tweed out.
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/ChampwithTweedandBFToneControls_zps5fd9e6b5.jpg)
Rough layout of the board. I was planing on adding reverb so the board had to be small enough for the added board, probably would not have laid it out like this without the reverb. Never did get around to doing the reverb yet. Was going to feed the reverb into the cathode of the second stage and take its signal after the volume control.
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/ChampwithTweedandBFToneControlsLayout_zpsee8e77b1.jpg)
Used counter top laminate as board material and home made turrets, stuff I had laying around. The filter caps were pulled out of dead equipment, transformer out of a old radio. Had to reduce the heater voltage a little using resistors at the right of the transformer.
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/AmpBuildNo227_zps1ea61caf.jpg)
My Champ.
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/AmpBuildNo226_zps34be10b1.jpg)
Needs a handle.
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/AmpBuildNo225_zps2e2c3b77.jpg)
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How about a simple P-P amp which can not decide between the Tweed tone stack or the Big Muff?
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/BigMuffTweedSimpleP-PAmp_zpsbec14aa9.jpg)
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/TweedBigMuffLayout_zpsce3d9c0b.jpg)
Heck, lets go real crazy and use another switch to change the PI between the Paraphase 5E9a Tremolux and the LTP 5G9. May get around to making it yet.
Oh wait, I did have a schematic with the switched cathode resistor of the Champ.
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/ChampTweedBF_zps4f97cd12.jpg)
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Cool ideas! Very ambitious!
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Instead of building the above amps I decided to do a 5E3 but also wanted to have the BF option.
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/5E3-PrincetonLow_zps69b0f121.jpg)
I made this one but with a SS rectifier and no 5Y3 but the 5E3 did not do much for me and the BF stack just took too much gain away. So I rewired the amp into a Tweed P-P with a parallel input triode. Ran the triodes in series with the BF tone stack in between. I left out the foot switch boost feature on the amp but kept the switch.
(http://i406.photobucket.com/albums/pp142/printer2_photo/guitar%20amp/TweedBF6K6Amp_zpsc3df59f0.jpg)
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/AmpBuildNo229_zps64c01c32.jpg)
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/AmpBuildNo228_zps164d9692.jpg)
Same number of gain stages as the Princeton Reverb but without the reverb mixing resistors to tame it. This guy has loads of gain. The PT was out of an old console radio and the insulation at the bell cover was flaking off so I gave it some new leads.
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Very cool stuff. Thanks for sharing!
With respect, Tubenit
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Had another idea. Added a 12AX7 to a Bassman, two switches, what the heck go for a Plexi, might have a 5Y3 fot the 5E3 and SS for the BF and Plexi. Hopefully my next amp when I finish the current one. Oops, forgot to put the master volume on the panel layout.
Had a mistake in the schematic copying and pasting from another. Fixed it, added the master volume on the panel layout.
(http://i406.photobucket.com/albums/pp142/printer2_photo/Guitar%20Amp%2002/5E3BFPlexi_zps059f6b1d.jpg)