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I just finished an Angry Llama build and after balancing the drive characteristics between the 2 switched resistors (R3 & R4) the pedal sounds fantastic. I built several of these pre-covid and after building multiple various other projects since then, I find myself back full circle with this great sounding circuit.
However, after going over the entire circuit: reflowing all solder points, checking all components, making sure all the pots are the correct value, making sure all the pot connections match pot pinouts, I am still unsure of why the Volume is well past unity gain at only 9 O’clock!
Looking at the schematic I successfully replaced the C5 capacitor thinking maybe it was a bad cap but to no avail. I also changed out the 4049ube from my stash in case I had a bad IC.
Also, please don’t chide – I know, I know, I should have rocked it before I boxed it! Something I almost never do but I got a little excited to get this on my pedalboard!
I would appreciate any insight.
Thanks in advance,
John
Seems like it is not truly a build issue at all.
It will be different based on different guitars/pickups but if you want the Volume to be unity at 12:00 instead of 9:00 or 8:00 then roll the Boost control back. It is a separate gain stage on its own which alleviates the complaint of the original circuit not having enough available gain. The more you roll the Boost knob back the higher you will be able to turn up the Master Volume control. With the Boost all-the-way counterclockwise it is essentially a stock Llama circuit.
If rolling off the Boost has no effect then you would have a build issue. Then I would recheck every resistor value by stripe and also recheck the bias transistor voltage and make sure it is between 4.5v to 6v.
Thanks Barry.
I checked all resistor values in circuit with power disconnected and they all measure correctly to verify this I also checked all values against your resistor color band chart and they all check out to be correct as well. The Boost is turned down to 0 (completely CCW) and should have no effect. None the less, I verified the transistor is biased at 5v.
I’m stumped! Has anyone come across this issue before and/or any insight would be greatly appreciated. Other than this issue the pedal sounds great and I am anxious to get this build up on my pedalboard.
John
Be sure the pots are not wired backward. So when turned all the way down it is actually all the way up.
Sounds silly maybe but it happens. Also, it seems as though the pots are hand wired which makes me think it is a possibility. There is a small 1 by each potentiometer pad (back of the board) that should be connected to Lug 1 and so on.
Hey Barry,
Yup. As I mentioned in my first post all pots are correct value and wired correctly – lead #1 to pot pin #1, lead #2 to pot pin #2, etc. I use color coded hookup wire to facilitate proper connections – Purple is #1, Black #2, Gray #3. Same for any switches. Input tip is Green, Output-Blue, Power-Red, Black-Ground. Routine and consistency makes it harder but not impossible to screw up. This circuit is a low part count so pretty simple and straight forward.
I also always build 2 circuit boards at a time measuring each component on my multimeter for correct values before installing. My second board has not been boxed and after going over it part by part and testing it on my breakout box it suffers the same issue with no apparent cause from improper component values.
Here are my 4049ube pinout voltages:
pin1-8.76v pin16-0.0v
pin2-3.01v pin15-8.76v
pin3-3.0v pin14-0.0v
pin4-3.0v pin13-0.0v
pin5-2.99v pin12-8.76v
pin6-8.76v pin11-0.0v
pin7-0.0v pin10-8.76v
pin8-0.0v pin9-0.0v
Any insight would be greatly appreciated.
John
So I see the issue now by double-checking your stripes.
Recheck R3 and R4? Try the stock values of 330k and 10M respectively.
Right now it looks like you have a 100k resistor in both locations.
R4 must be 10M. = Br, B, B, Gr, Br
R3 and R4 directly affects the Gain of the circuit.
Let us know how that works out.
Hey Barry,
I started out with the correct values in both r4-10m & r3-330K when I first tested the circuit. The pedal had excessive output at that starting point. Since then I have played with multiple resistor combinations going so far as to try a 33k in R3 & 100k in R4 with NO change in the volume output issue. Changing the resistor values & playing with the balance between the 2 resistor values only effects the start of breakup or clean headroom and/or the disparity between the 2 choices. I played with these values in previous builds (previous circuit board version) none of which had an excessive output issue. Also, the Boost control in those previous builds had the effect of reducing the overall output (less than unity gain) when turned CCW. In these 2 current builds it has little to no effect on reducing volume when the Boost control is turned CCW only increasing output when turned CW past 12 o’clock.
Comparing the 2 schematics the only difference I noticed regarding the Boost circuit is the addition of the R9 – 33K resistor off the A110K Boost pot to ground.
I have 2 more of the new version circuit boards on hand and I will be populating those boards today and testing through my breakout box and see what results I get and compare.
John
I checked out my version.
I get anywhere from “off” to “below unity” between 8:00 to 9:00 (with switch in hottest mode) and Gain Full Up. Also hottest pickups guitar.
From 9:00 to 10:00 it hits unity.
10:00 to 11:00 is slightly above unity.
When you built your stock version I am guessing you wanted unity to be at 12:00 maybe?
If that is the case then you do not have a build issue. You just need to put the Volume at 9:00 and leave it there. (This will vary based on pickups) My Strat I can easily go to 11:00 before reaching unity.
Once you pulled the 10M and started using variables of (K) resistors then that would have not been near enough resistance since you need 10M (million) at the bare minimum. This would explain why you heard no difference in distortion anymore.
As for the boost, it is not a volume boost so much as a distortion enhancement or (tone boost).
Here is a quick video I made. Gain = full up / All stock values
At 5 seconds Volume = 9:00,
at 9 seconds in Volume = 10:00,
at 20 seconds in Volum = 11:00.
If this is similar to yours then you do not have a build issue.
Pickups will make a difference and where you put the Gain knob will make a difference.
If all of that sounds like you and you need to have unity at 12:00 instead of 9 or 10:00 you can kluge a resistor between lug 3 of the volume pot and the wire going to the board for lug 3.
What that resistance is for you I am not certain but that is what I can recommend.
I hope that all helps.
Two identical builds with pre-verified component values and they both suffer the same high output problem? That is a conundrum! To me tho, that sounds like a win. As long as the controls still exact their influence on the sound as they ought, I’d leave ’em as they are.
But if getting the volume down is important . . . . . . Regardless of the R3 & R4 values, I would focus on that afterburner section with the JFET. I would argue that the 22µF cap adds a considerable boost (and dirties up the signal significantly) and could be pulled temporarily to see how the pedal performs (volume-wise). Pretty sure it will sound a bit less “dirty” with that 22µF cap removed, but it might provide another clue to the high output issue.
I also wonder about the JFET itself. I didn’t see which specific JFET was used. And even if it is the stock value of a J113, I’d suggest swapping it and reset the bias trimmer. If it’s NOT a genuine J113, what did you use in its stead please?
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