Overdrive Troubles...

[Eric.nail]

I've been attempting to build a Clone copy of a 'little green wonder' for about a month now. I know a particular guitarist who plays one and it's glorious paired with a vox and telecaster combo. anyway...I'v done the Vero layout, and now Two different pcb layouts and still keep coming up with the same result.

My pedal works, but its like its sucking at my tone. Like the guitar's tone knob is off...but surely mine is not. i checked...a few times....

I have no idea what could be the culprit...Any help is appreciated! 

Here's the Schematic:
http://schematic.exteen.com/images/litle.JPG

And here's a couple photo's of what i'v got going on. its not pretty..haha!

[Eric.nail]

The issue could also be described as a lack of high end. it's just really dampering to my over all tone. If i add a compressor before the pedal, it seems to actually regain all its lack of tone and what not, so i'm guessing it could be an issue with its buffer maybe? again, i have no idea though.

[AudioEcstasy]

try putting a buffered pedal/buffer before the unit and see if that doesn't combat the tone suck. is the pedal wired in true bypass?

[Eric.nail]

It does fix the major sucking issue with a buffer in front. If i had the Pinout wrong on the Transistor would i get any output? or could it be a blown tranny in the first place?

[lopsided]

maybe try rechecking R1 and R3.
If a buffer in front of it helps. it might be an issue of input impedance.
J.

[Pyr0]

I agree with lopsided.
It looks like you used this layout
http://3.bp.blogspot.com/-mJ5dSmbWvrI/TxAeFgJSi6I/AAAAAAAAAdw/pwDO1e_jJlc/s1600/BJF1.gif

And R1 and R3 don't look like 1M resistors to me, they look more like 47k, it's hard to tell the exact colours.
They should be brown, black, black, yellow.

[PRR]

> If i had the Pinout wrong on the Transistor

Post your JFET voltages.

You expect +9V at one pin (D), +4.5V at another (G), and a wee bit more (say +4.9V) at the third (S).

[PRR]

-OR-...

The JFET is not essential.

Lift one end of C1 and leave it up in the air.

Lift the "Q1" end of C2 and tack-solder it to R2. (Use a little scrap wire if needed.)

Change R6 to 1Meg.



That TLC272 chip can manage very high input impedance. The low 27K bias to it may be left-over from some lesser op-amp plan. If that's changed to 300K to 10Meg (1Meg is fine and may be convenient since you already have one), the input is high-impedance.

[Kesh]

I agree with lopsided.
It looks like you used this layout
http://3.bp.blogspot.com/-mJ5dSmbWvrI/TxAeFgJSi6I/AAAAAAAAAdw/pwDO1e_jJlc/s1600/BJF1.gif

And R1 and R3 don't look like 1M resistors to me, they look more like 47k, it's hard to tell the exact colours.
They should be brown, black, black, yellow.

yeah, i was thinking they look like 4.7K, yellow violet black brown, which is a terribly low impedance input for a pedal, and half your input is going to ground. it would totally explain the tone sucking

[slacker]

Could just be the design. R10 and C6 roll off highs above 720Hz. Unless I've got a decimal in the wrong place, with the body control at one extreme or the other, the second opamp stage gives some boost above 7KHz. So it's not going to have much top end.

[Eric.nail]

Could just be the design. R10 and C6 roll off highs above 720Hz. Unless I've got a decimal in the wrong place, with the body control at one extreme or the other, the second opamp stage gives some boost above 7KHz. So it's not going to have much top end.

You're very VERY right...My noobieness has done it again! I somehow switched baggies for my 1M resistors and my 4.7k's last project. Unreal how dumb i feel after hours of pooring over my work to find i screwed a simple resistor up!

The thing pumps out drive and volume like a beast, all my highs are in tact, and it's working as well as my buddies real LGW. I'm very happy for the help guys! Thanks so much!