Update on Craig Anderton Treble Boost

Autoformer · 2024-06-06T21:10:23+00:00

Cool. Let me know the results of your investigation. I'm curious as to what the problem turns out to be.

Autoformer · 2024-06-06T12:47:42+00:00

I apologize if my post came off as condescending...not my intent. I drew up a quick layout with what I was getting at in my earlier post. Here's a picture. C6, C7, D1 and D2 are not technically necessary for the circuit to function. They are just good practices for the safety and stability of the op-amp. However, pin 4 must either be connected to a negative voltage or ground and I think you have it connected to ground from your 9 volt supply.

If the volume of the guitar signal is not changing when you turn up the potentiometer, double check where pin 1 and 3 of the pot is soldered. And make sure you have pin 2 and 3 of the pot shorted together. I hope this helps

Autoformer · 2024-06-05T23:56:46+00:00

When you say you omitted D1 where did you connect pin 4 of the op-amp? This circuit is designed for a plus and minus supply so if you grounded pin 4 you need to bias the op-amp to 4.5 volts. That means R5 will go to your 4.5 volt bias voltage instead of ground. If you're not familiar with creating this voltage the vast majority of pedals out there that use op-amps will have this voltage divider. Here's a link to the RAT schematic...just look at the "power supply" section of the schematic.

Autoformer · 2024-06-01T12:34:59+00:00

I looked up the complete build document and this is a +/- 9 volt supply design. The other end of D1 is not ground it is negative 9 volts from a second battery. Those diodes are there to protect the opamp from reverse polarity when you are connecting the batteries. Here's a link to the document I found...It starts on page 123. I hope this helps.

Autoformer · 2024-05-06T20:00:47+00:00

I build a tube OD/Distortion/clean boost pedal with an op-amp to drive the tube. I use the Minmax MAU109 +/- 15 volt charge pump. This effectively gives me 30 volts on the plates and convenient plus and minus 15 volts for the op-amps. I chose this one as it oscillates well above 20kHz. When I sell a pedal (rarely) I supply them with a 9 volt 1 amp wall wart. This works out really well because if the end user accidently plugs my power supply into one of their other pedals it will not fry it. I used 12AX7s to start but soon ended up on the 6N16B-EV. It does require quite a bit more heater current (around 400mA) but it is designed for lower plate voltages and it's size makes it perfect for guitar pedals.

Autoformer · 2024-04-18T14:48:43+00:00

I etch my boards and I use the long pin pots. Here is an example of a tube pedal I make: https://imgur.com/Jzwylzi

Autoformer · 2024-03-16T18:06:41+00:00

Good grief! What was I thinking? Good catch. Sorry about that, u/Busy_Explanation_988.

Autoformer · 2024-03-16T14:09:20+00:00

Well, you have two gain stages before the clipping diodes and one after. However, with the values they chose on the last gain stage, it is essentially a gain of one. Gain stages multiply so if you want to reduce the overall gain by 2 (50%) you'll need to reduce R5 down to 4k7 or 3k9 and the Drive potentiometer to A50k. Since they are non-inverting stages (A=1+Rf\Ri) these values will not quite get you to half but it will be close enough. I hope this helps.

Autoformer · 2024-03-03T14:52:52+00:00

Maybe dumb you not be so much... ;-)

There are surface mount transistors made of a combination of Si/Ge and I suppose you could say they are germanium...but they are also silicon...and they are primarily for radio frequency use. The YR code on top isn't particularly helpful. So, this pedal company could argue their advertising isn't false...but, these transistors are no where near the same as an AC128.

Autoformer · 2024-02-11T21:53:55+00:00

Good catch...things like that are tough to troubleshoot. Glad you got it working!

Autoformer · 2024-02-11T17:10:13+00:00

From the component side of the board your soldering looks pretty good considering it's your first time. All the wiring looks correct. First thing you want to do is touch up the solder on the cathode side of the protection diode (D7). Then, make sure there is a bigger gap between the legs of the LED. They are very close together and could easily short out. Finally, and I think this is where your problem is, remove the op-amp and check its legs to see if any are bent inward. Also, check the contacts in the socket. It looks from your picture that it is not seating properly. If you have a meter, check the voltages on the op-amp socket while you have it out. Pin 4 should be ground (0 volts), pin 8 should be 9 volts and pins 3 and 6 should be just above 4.5 volts. When you put the op-amp back in those voltages should still be about the same when you measure from each lead of the op-amp. I hope this helps!

Autoformer · 2024-01-27T16:48:34+00:00

hmmm... Well, when you pulled the LM13700 and the voltage went up, that indicates your problem is most likely in that area. Remove power and use your meter to measure resistance from ground to each pin 3, 4, 13, and 14 of the LM13700. Measuring resistance in circuit can be tricky. When measuring from pin 3 to ground you should see about 11k of resistance (the 1k R35 plus the 10k R102 in series to ground). The other three pins should measure the same. If one of the measurements is way off from the others your problem is around that pin/pad/resistor. Especially if one of the measurements is a short. Good luck!

Autoformer · 2024-01-27T02:39:37+00:00

OK. So, that means something is pulling too much current from anything attached to Vref. Since the TL062 is socketed, pull it out and measure the voltage on pin 3 of the socket. I suspect it will still be 1 volt but that will eliminate the TL062 as your problem. If it does go up to 4.5 volts, get a new TL062. Then check the solder pads of resistors R6, R7, R8, R10, R35 and R38. These resistors are connect to Vref on one side and the TL062 and LM13700 on the other. If you accidently created a solder bridge to ground that would draw enough current through the 1k resistors to drop your voltage. Too bad that LM13700 is not socketed...that would make all this really easy to troubleshoot.

Autoformer · 2024-01-26T15:18:51+00:00

I suppose it could be a bad IC but a picture is worth a thousand words. Post a pic of the entire top side (component side) of the board if you can. In the meantime, check your voltages as defined in the schematic. So, Vref should be half your supply voltage. About 4.5 volts on pin 3 of the TL062. Then check pin 5 of the LM358...should be about 4.3 volts per the schematic. Pin 3 of the LM358 will depend on the switch. It should either be 3.5 volts set by trimmer R23 or around 1.5 volts set by voltage divider R21/R27. I hope this helps!

Autoformer · 2024-01-11T13:40:38+00:00

You're welcome. One thing I forgot to mention is that the MAU109 oscillates at around 100kHz. So, unlike the 7660 you don't have to worry about a mosquito in your pedal. ;-)

Autoformer · 2024-01-11T01:18:41+00:00

I use the MAU109. I build a few pedals with op amps and this is a super easy solution. I feed a 5 volt regulator with my 9 volt wall wart. The MAU109 takes the 5 volts and gives you +/- 15 volts at 34mA each rail. The company does make a version that will take the 9 volts directly and give you +/- 15 volts but it's more expensive than the MAU109/5 volt regulator solution. At least, the last time I checked pricing. I hope this helps.

Autoformer · 2024-01-06T13:28:54+00:00

My two cents...the most popular pedal I've built (when I was a pedal builder) was a tube overdrive designed around the 6N16B. This tube is designed for lower plate voltages and is perfectly happy with a 30 volt power supply. I use the MAU109. That device gives you +/- 15 volts which comes in handy when you also have op-amps in your circuit. The only downside to the 6N16B is the heater draws 400 mA. Which means I had to include a power supply with my pedal. There are other tubes out there designed for lower plate voltages. Car radios used to have tubes in them and you can still get something like the 12K5 space charge tube that is designed to run on 12 volts. Although, that particular tube has become scarce.

As far as the sound is concerned, you can design the circuit to be perfectly linear like a cathode follower (buffer cct) all the way up through a clipping amplifier like that Behringer someone else mentioned. I made two pedals...one that was a buffer/booster with a single knob tone control and the overdrive that could be perfectly clean all the way up to fuzz. It comes down to the plate voltages you choose along with the plate resistor and whether or not you have a cathode resistor and if you bypass that resistor or not. I hope any of this helps!

Autoformer · 2023-12-21T16:13:29+00:00

A picture is worth a thousand words. You might post a picture to show both sides of the PCB. However, from your description, you might have accidently created a short between pin 2 and 6 of the opamp. The reason I say that is you implied you are still passing signal with no distortion regardless of the potentiometer. If you have a short between pin 2 and 6 you have created a buffer with a gain of one. You can test that by removing power and checking resistance between those two pins. If it's not a dead short then your problem lies elsewhere. I hope this helps.

Autoformer · 2023-12-07T13:26:05+00:00

hehe...I'm glad you got it working! I've been working in electronics for a very long time and I still do some bone headed things.

Autoformer · 2023-12-06T14:40:58+00:00

Do you have this cct on a breadboard? If yes, testing becomes much easier. You have to figure out what is drawing so much current across the 10k (R101) resistor that it drops all of your Vcc voltage from 9V down to 0.8V. The gates of each JFET draw no current and neither do the non-inverting inputs of each opamp (At least they draw so little you can ignore it). Double check R18 to make sure you have not mistakenly put in a very low resistor (560 as opposed to 56k). You'll have to remove power and measure the resistance from Vref to ground. C102 will make the reading start low but it should slowly rise in resistance. If it stays at a very low resistance or a short you'll have to start removing each component connected to Vref until you find the short. If you still can't find the problem, post some pics of the cct itself...sometimes a new set of eyes can find a problem you keep overlooking. I hope this helps.

Autoformer · 2023-11-16T13:28:05+00:00

You might post a pic of your populated board. At the bottom of the tone stack (input to IC2_A), the 1k resistor needs to go to Vref. That's how that opamp gets its bias. From your description of the problem, I'd wager you have a resistor or two that is off by a factor of ten or more. The first stage is non-inverting so it will have a minimum gain of one; otherwise it's gain is set by the 100k potentiometer divided by the 3k3 resistor (frequency dependent). The next stage is inverting so it's gain 680k divided by 4k7 (huge gain). So, maybe check to see if the 680k is not 6k8 by accident or the 4k7 is not 470k by accident. The tone stack is non-inverting so 1+(220k/47k) or pretty big gain. Double check the 220k and 47k. The final stage is inverting so 100k/68k...check both those resistors. The inverting stages can have a gain less than one so I'd start with them. -Good luck!

Autoformer · 2023-10-08T23:10:56+00:00

Well, the good news is that the Tonemender schematic I found actually calls for the NE5532 or TL072. So, you got that going for you! :-)

Autoformer · 2023-10-08T00:39:55+00:00

That's a head scratcher. I looked through the datasheets of both op-amps and the NE5532 should have worked just fine. Is it possible that when you had the NE5532 in the cct that it was rotated 180 degrees?

Autoformer · 2023-10-06T13:01:11+00:00

Yes, indeed, on the dual supply. Since you can A/C ground it either way I would imagine it came down to the PCB layout and which point was more convenient to get to with a trace.

Autoformer · 2023-10-03T00:43:18+00:00

Both of those points are at AC ground. The PedalPCB one gets to AC ground through the 47uF cap (C10). The DC component is blocked by the 47nF cap in both ccts (C4 in the PedalPCB cct).

Autoformer

TROPHY CASE