Volume issue with my diy rat

compuwade · September 02, 2009, 05:53:01 PM

Hi there, I recenty finished my DIY Rat using the layout found at Tonepad.com. Everything works just fine including all the mods I added. The only issue I'm having is the output level. While I can tweak the amp or use a preamp after the Rat to recover some of the volume loss, it doesn't seem like the Rat is boosting the signal very well. Is this common with the Rat? It seems like it would be a little annoying if it is, because once you bypass the pedal you have a HUGE jump in volume.
I used all proper values in the schematic, with the exception of the output buffer FET. I used a mpf102 due to the lack of a 2n5458 which I didn't think would make much of a difference.
Would the 560 ohm resistor cause a major volume issue?

Thanks
Wade

frokost · September 02, 2009, 06:07:14 PM

Are the pinouts the same? If "yes", see "DEBUGGING". If "no", make sure the pins go where they're supposed to. If "I don't know", find out

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compuwade · September 02, 2009, 06:32:50 PM

yes, the pinouts are the same. I'll check out the debugging page. In the mean time, any other suggestions would be great.

Thanks
Wade

compuwade · September 03, 2009, 03:03:03 AM

Hmmm...This is really puzzling! The pedal sounds great, but has no boost at all. It's like the difference between having a BMP with a tone control and then switching it out of the circuit. I don't get it.

Please help is you can.

Thanks

grolschie · September 03, 2009, 06:57:36 AM

My factory Rat doesn't have a huge amount of output. It's unity at around 2-3 o'clock.

compuwade · September 03, 2009, 02:36:41 PM

Quote from: grolschie on September 03, 2009, 06:57:36 AM
My factory Rat doesn't have a huge amount of output. It's unity at around 2-3 o'clock.

Hmm..I never reach unity. Maybe I'll just build another one and see how that one goes. I'll try a different layout and leave out the mods. Plus I'll use a different opamp just for the hell of it.

Thanks for you help.

-Wade

frokost · September 03, 2009, 05:52:05 PM

What mods?

compuwade · September 04, 2009, 04:17:34 AM

Quote from: frokost on September 03, 2009, 05:52:05 PM
What mods?

I added a 6 way switch for clipping diodes, and replaced the 47ohm resistor with a 1k pot. Other than that everthing is the same.

compuwade · September 06, 2009, 05:40:39 AM

I debugged the board and found that I had two resistors near the output buffer soldered together. Oops!

I thought it was weird that it all sounded pretty good but had no boost. Now, however, it's a whole new beast. This is one hell of a pedal!!

-Wade

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Volume issue with my diy rat