Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: nunonaos on September 05, 2017, 10:56:49 am
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Hello to all.
I will start my first tube amp build and I'm thinking of a few mods.
This will be the build:
http://www.ampmaker.com/store/WF-55-4w-tweed-style-amp.html (http://www.ampmaker.com/store/WF-55-4w-tweed-style-amp.html)
And here is the schematic:
http://www.ampmaker.com/images/ak00kit/ak00sc2.jpg (http://www.ampmaker.com/images/ak00kit/ak00sc2.jpg)
Here is a link to a tonestack i'm copying (but i won't use a middle pot)
https://images.talkbass.com/attachments/a_amptone1-gif.2499258/ (https://images.talkbass.com/attachments/a_amptone1-gif.2499258/)
It's basically a fender tweed champ.
I think it's a good first build project.
I'm thinking of doing the following mods:
-2 switchable boosts (can be treble boost, full range boost or no boost in each switch)
-switchable blackface tone stack
-skeaper impedance selector
I've attached 3 images:
-schematic with tonestack switch marked
-layout plan to put one switchable boost (the second is exactly the same but over the R6 in the original schematic)
-layout to the switchable tonestack
So... can anyone help me check if this will work or has any better ideas to apply these mods?
Thanks a lot
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Should work but the switches may pop loudly.
You may want to consider a raw control rather than the tonestack bypass switch. It accomplishes about the same thing when cranked all the way up. It operates as a standard mid control from 0-5 but from 5-10 it begins to lift the tonestack from the circuit. You can dial in the amount of gain you want. Take a look at page 4 of this pdf...
http://sluckeyamps.com/rocky/rocky.pdf (http://sluckeyamps.com/rocky/rocky.pdf)
I've attached a pic of a boost switch which will operate as your switch except it should not have a loud pop. If you use a DPDT switch you can use the other half of the switch to mount the caps on. Then all four components would mount on the switch so you would just connect two wires to R4.
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http://www.diyaudio.com/forums/instruments-and-amps/311988-help-check-mods.html (http://www.diyaudio.com/forums/instruments-and-amps/311988-help-check-mods.html)
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Should work but the switches may pop loudly.
I've attached a pic of a boost switch which will operate as your switch except it should not have a loud pop. If you use a DPDT switch you can use the other half of the switch to mount the caps on. Then all four components would mount on the switch so you would just connect two wires to R4.
thanks for the schematic, i'll check it out but it seems simple, i just have to "convert" it from schematic to layout so i can understand it better :) thanks again
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I've attached a pic of a boost switch which will operate as your switch except it should not have a loud pop. If you use a DPDT switch you can use the other half of the switch to mount the caps on. Then all four components would mount on the switch so you would just connect two wires to R4.
so if i understood this, even in the center position (OFF) both caps would be in the circuit and grounded, each with a 100K resistence
in one of the ON positions you would have one cap directly connected to ground (although also conected through a 100K resistance) and the other cap going to ground through a 100k resistance
wont this change the gain even when if the center position?
thanks
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but it seems simple,
and there in lies the beauty of it :laugh:
wont this change the gain even when if the center position?
Yep, least gain is center off, most to the right.
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but it seems simple,
and there in lies the beauty of it :laugh:
wont this change the gain even when if the center position?
Yep, least gain is center off, most to the right.
but my intention with the switch is that one of the positions keeps the original circuit of the amp, otherwise, once i mount the boost, i can't ever turn it off...
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When the switch is in the center position neither cap will be doing anything because of the 100K resistors. Just try it. If you don't like it just cut the resistors out and you're back to your original circuit. The loud pop will also be back.
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When the switch is in the center position neither cap will be doing anything because of the 100K resistors. Just try it. If you don't like it just cut the resistors out and you're back to your original circuit. The loud pop will also be back.
one more question regarding your schematic
would it be better to put bigger resistors (like 1M) in the boost circuit instead of 100K so that less signal "chooses" to pass trough the boosts instead of "choosing" the original path (R4)?
thanks again for your replies