Vox - AC30 Amplug [schematic]
Two of them actually, but they don't seem complete. I haven't seen them over here though so I thought I would share.
One thing I don't get at all is what is happening off of U1A with all of the transistors. Not sure what that's accomplishing.
Still, I had been wondering about this circuit for a long time. I was going to go through it with my meter and get the cap readings. Not sure if I would (or could!) attempt a straight up clone, but maybe something with a similar setup (Buffer-> Soft Clipping Stage -> Tone stack -> Hard Clipping Stage -> Cut Control -> Recovery stage -> Volume) might be interesting to try.
One thing I don't get at all is what is happening off of U1A with all of the transistors. Not sure what that's accomplishing.
Still, I had been wondering about this circuit for a long time. I was going to go through it with my meter and get the cap readings. Not sure if I would (or could!) attempt a straight up clone, but maybe something with a similar setup (Buffer-> Soft Clipping Stage -> Tone stack -> Hard Clipping Stage -> Cut Control -> Recovery stage -> Volume) might be interesting to try.
- B Tremblay
- Breadboard Brother
Information
http://www.muzique.com/lab/gyrator.htmamonte wrote:One thing I don't get at all is what is happening off of U1A with all of the transistors. Not sure what that's accomplishing.
- darthoverdrive
- Breadboard Brother
Nice find, thanks for posting.
- mozwell
- Breadboard Brother
do you have the capacitor values ?
Measured values after desoldering (take with care):
C61: 10nF
C62: few pF (?)
C63: about 2.2nF
C64: about 470pF (?)
C65: 22nF
C66: 1nF
C67: few pF (?)
C68: about 1nF
C69: 220nF
C70: 220nF
C71: 22nF
C72: few pF (?)
C74: 1uF
C73: 10nF
C75: 22nF
C1: 100nF
C3: 1nF
C4: 10uF / TANT. POL.
C5: 74nF (?)
C8: 74nF (?)
C9: 10nF
C10: 100nF
C11: 10nF
C12: 4.7nF
C14: 1uF
C15: 1uF
C16: 1nF
C61: 10nF
C62: few pF (?)
C63: about 2.2nF
C64: about 470pF (?)
C65: 22nF
C66: 1nF
C67: few pF (?)
C68: about 1nF
C69: 220nF
C70: 220nF
C71: 22nF
C72: few pF (?)
C74: 1uF
C73: 10nF
C75: 22nF
C1: 100nF
C3: 1nF
C4: 10uF / TANT. POL.
C5: 74nF (?)
C8: 74nF (?)
C9: 10nF
C10: 100nF
C11: 10nF
C12: 4.7nF
C14: 1uF
C15: 1uF
C16: 1nF
They are gyrators made with transistors. They wanted to shape a complex eq. curve to emulate the cabinet response and they make it pretty well. http://en.wikipedia.org/wiki/Gyratoramonte wrote:Two of them actually, but they don't seem complete. I haven't seen them over here though so I thought I would share.
One thing I don't get at all is what is happening off of U1A with all of the transistors. Not sure what that's accomplishing.
Still, I had been wondering about this circuit for a long time. I was going to go through it with my meter and get the cap readings. Not sure if I would (or could!) attempt a straight up clone, but maybe something with a similar setup (Buffer-> Soft Clipping Stage -> Tone stack -> Hard Clipping Stage -> Cut Control -> Recovery stage -> Volume) might be interesting to try.
It's only one: Rev 0B is a correction of Rev 0A. The source is (German!):amonte wrote:Two of them actually, but they don't seem complete.
http://forum.musikding.de/vb/showthread ... 30-zerlegt
But you can view them only as a registered user.
The schematic goes only until the Aux In point so the headphone amp and Aux In are missing.
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- Posts: 18
- Joined: 01 Sep 2009, 14:54
- my favorite amplifier: Vox Pathfinder 10
- Completed builds: • Honeytube (Danelectro Honeytone tube conversion);
• M014 (self-split push-pull 6P14P amp);
• Vox Pathfinder 10 (soft clip & top boost mods); - Location: Brazil
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[UPDATE] The original forum from that link has moved, here's that post in their new forum: http://musikding.rocks/wbb/index.php/Th ... #post18986sonicwarrior wrote: It's only one: Rev 0B is a correction of Rev 0A. The source is (German!):
http://forum.musikding.de/vb/showthread ... 30-zerlegt
But you can view them only as a registered user.
The schematic goes only until the Aux In point so the headphone amp and Aux In are missing.
Also, has anyone checked the voltages on the op-amps? Because I'm skeptical they would even be able to drive the clipping LEDs if they were only being powered directly by the batteries...
From the circuit board photos on that forum, it looks like it has a switching power supply, since there's an inductor next to the power switch, the only 16v-rated electrolytic in the board next to it, and an IC on the other side of the board in the same area. Maybe they are stepping up the voltage to power the preamp (possibly to 9v)? Hard to really tell otherwise, since you can't see the IC's name on those pics.
blackcorvo.com
She/they as of August 2021
She/they as of August 2021