Im going to build the Hotbox.Although i can read schematics fine,converting them to layout is still a bit tricky for me.General Guitar Gadgets has one but ive heard its wrong.Could someone have a quick look and see if there are any obvious mistakes. http://www.generalguitargadgets.com/ind ... &Itemid=92
Cheers
HotBox
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Be careful- that "Matchless" schematic is not the same as my Matchless Hotbox. First, mine has 25amp 100V rated integrated bridge rectifier to run the heaters on DC. +/- 3 Vac is rectified to 6 VDC with at big cap on the DC side- 1000uF. At some point the previous owner had a problem with the power transformer and sent it back to the company- Near as I can tell, they updated the heater supply scheme this way at the same time. I have found a Mouser PN for another project I'm working on- 625-GBPC2501-E4 as the part in the Hotbox in no longer available since it's not ROHS compliant.
Second- There is negative feedback on the second grounded cathode amp past the gain pot in the "Dirt" channel. If I remember correctly, it's a 470K ohm from the node where the .022uf cap meets the 470K res back to the grid at pin 7. I think that this is original. I've prototyped a pedal with similar architecture, but a different circuit, and have had to control the gain in a similar manner. YMMV.
This is a great pedal, though not really a pedal so much as an alternate front end of an amp. I like to play directly through an effects return of an amp to bypass the amp's stock front-end all together. That or through an old Altec 4 X EL34 power amp that belongs to a friend. I find that the channel labels are backwards though. The "clean" channel is fierce when turned up, because there just isn't much to it to weigh the signal down. The "dirt" channel is versatile because of the gain and tone adjustment, but will sometimes get fuzzy/buzzy if the gain is too high.
While talking to Phil Jameson at NAMM, he told me he was thinking about making these again.
Please let us know how it goes!!!
Second- There is negative feedback on the second grounded cathode amp past the gain pot in the "Dirt" channel. If I remember correctly, it's a 470K ohm from the node where the .022uf cap meets the 470K res back to the grid at pin 7. I think that this is original. I've prototyped a pedal with similar architecture, but a different circuit, and have had to control the gain in a similar manner. YMMV.
This is a great pedal, though not really a pedal so much as an alternate front end of an amp. I like to play directly through an effects return of an amp to bypass the amp's stock front-end all together. That or through an old Altec 4 X EL34 power amp that belongs to a friend. I find that the channel labels are backwards though. The "clean" channel is fierce when turned up, because there just isn't much to it to weigh the signal down. The "dirt" channel is versatile because of the gain and tone adjustment, but will sometimes get fuzzy/buzzy if the gain is too high.
While talking to Phil Jameson at NAMM, he told me he was thinking about making these again.
Please let us know how it goes!!!
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