Build Your Own Clone Message Board

hi and welcome!

Part of your problem is certainly that you have not grounded the PCB to the enclosure. The jacks, battery and PCB must all share a common ground. You can accomplish this by hooking up the DC power jack as shown in the instructions, even if you don't plan to use it. That alone, along with closing up the case, might take care of the RF problem. If not, there are other methods that involve adding a capacitor from input to ground (I think!) but I'm no expert on that having never run into this problem.

As for the squealing, I'd better let somebody more knowledgable than myself comment.

good luck! that thing will look great when you're done.

I think your wiring may be too long and acting like antennae. Can you post a pic of the mounted pcb without the cardboard? I'm having a tough time visualizing how you're mounting it. Please post the pic in the forum using the IMG function instead of linking.

I've built three of these circuits, all with the stock BYOC layout, and none had any problems whatsoever. There have also been a good many kits sold and this is the first time your symptoms have shown up. Gotta think that it has to do with the layout.

Normally, for RF interference I'd suggest installing a small 22pf cap across R101; however I'm not sure it'd help in this circuit since there is already and input resistor and input cap in series following the pulldown resistor. I think that would take care of squelching interference. You can certainly try it though.

What about this; will the pcb fit into the enclosure if you turn it 180 degrees (still solder side up), so that the little square crook of the pcb that connects to the AC adapter sits close to where the adapter goes, between the jacks? As it is now, you have lots of wires carrying varying amounts of signal and voltage all criss-crossing each other. It you're able to turn the pcb, you can make the footswitch, input, output, and power wiring very short and get rid of a lot of that potential crosstalk. Also, you've got the treble pot directly below the input jack, where the signal is unshielded. Some shielding tape on the back of the treble pot, or shielding the input wire may help too.

In short, if it were my build, I'd look into turning the pcb around and making the footswitch, input, output, and power wiring shorter, touch a small value cap (10-50pf) across R101 to see if you loose any frequency response and see if it helps with interference, and shield the treble pot if possible.

Great looking build by the way! Nice work.

Nah, plastic enclosed jacks aren't going to do any better. You want to shield tape the back of the pot, not the jack, as it's the pot that has a ton of high level, high frequency signal that is probably interfering with the input jack or lead and causing the oscillation that is manifesting as squealing. And maybe run shielded wire from the jack to the pcb. I don't see how trying to shield the actual jack with tape would gain you anything.

You guys may remember that I have changed the layout of the pots on this pedal, forcing me to run wires to the pots and tone cut switch rather than PCB mounting. I have completely rewired the pedal from my first posting when I was having issues with picking up a radio station and had a high pitched squeal when cranking the volume and treble pots all the way up. After rewiring, the wires from the input/output jacks to the PCB are approximately 3" in length, as are the wires from the foot switch to the PCB. Each must cross under the PCB to the other end due to clearance issues that forced me to rotate the PCB 180 degrees. I have significantly reducing the amount of wire that was used from my first attempt, however, there is still a lot of wire compared to the stock pedal layout.

The radio interference I was getting is all but gone and the squeal as well. I now seem to have an issue with background noise. It seems more pronounced than the first time I wired this pedal. If I turn the volume, bass, and treble all the way up, I get a fairly significant amount of background hiss through the amp, especially if I plug into a single coil guitar. I get a much lower level of hiss with my Humbucker guitar but it's still there. The hiss does not occur when the pedal is in bypass.

What's interesting is that the first time I built this pedal, it didn't work when engaged. No sound. I eventually resolved that by reflowing the switch wires. The same thing happened the second time. I think I do a decent job of soldering so I'm not sure what that's all about.

Obviously this is an amplifier pedal so maybe some level of hiss when cranked up is normal. Can anyone who has built one of these tell me if they get any hiss? I can just start hearing it even if the volume and treble are only half way up.

Thoughts:
- The PCB is free-floating in the case but I'm assuming is sufficiently grounded through the input/output jacks, but when I hear hiss, I think grounding issue or shielding issue, but I'm no expert.

- I have a sheet of adhesive copper shielding foil as is used to shield inside guitars. I have yet to shield the backs of the pots but will do so. I don't think this will make a difference in the hiss as it occurs even when I remove the assembly from the case and can place each component well apart from each other.

- Obviously the length of the input and output jack wires doesn't help the situation. I currently have the conductors braided. I'm not sure if that makes a difference one way or another. I was simply trying to keep it neat and tidy. I could try using the copper shielding tape to wrap them if you guys think it might help. I could also find some multi-conductor shielded cable and replace them.

- The wires to the foot switch are also an issue. If I lightly pinch those with my fingers, I can get a bit of hum out of them. Would shielding possibly help that situation?

- Is there any point in shielding the interior of the pedal with copper, the same way you might shield the cavity of a guitar (since I happen to have a sheet of guitar shielding copper)? It may not solve the hiss but might prevent picking up anymore radio stations.

Worst case I could try and flip the PCB back around into the correct orientation but I'd have to replace at least one of the tall caps and lay it down flat on the board to create clearance.

Any suggestions are welcome. I'd especially like to know just how much hiss, if any, is inherent with this pedal. I don't want to do a third rework if this is normal or if the hissing problem likely has nothing to do with long wires from the jacks or foot switch. What's the most likely cause of volume related hiss in a pedal like this?

OLD Wiring - this is now GONE. What a mess.



NEW Wiring - note the greatly reduced amount but still not ideal. Orange wire is to a secondary LED indicator for the tone cut switch.



Component Layout (pots have since been replaced with Lug type equivalents rather than the kit-provided PCB mounts):

The pedal circuit appears to be mounted inside an aluminium enclosure and the circuit ground is connected to that enclosure (or should be) so it is already shielded. Adding copper tape all over the place will be of no advantage - absolutely none. Also shielding has no effect on noise if by noise we mean audible hiss. However what can happen is high frequency instability where wiring from two sections of a circuit come into close proximity and there is a fair amount of gain in the circuit. Although this high frequency instability itself may be outside the range of human hearing, it can produce an audible effect that sounds like audio noise. In which case placing a grounded shield between the offending parts of the circuit can be a solution. It is often apparent that there are high frequency instability problems in a circuit because you get kind of frying noises that change when you place your fingers near the wiring.

As far as noise in that pedal is concerned I have no direct experience, but it is a gain pedal with fairly powerful EQ so I wouldn't be surprised if you get some hiss with the treble turned up. The degree of circuit noise you get can change depending on the individual active components used and it is possible to select FETs, ICs and transistors for lowest noise. Most of the circuit noise will probably come from the input FET and a socket fitted for this component would allow trying different FETs.

Another common problem with op-amp circuits driving long lengths of screened cable is that the collective phase effects of the cable can cause the negative feedback path around an op-amp to become positive feedback at some high frequency. The solution to this is to place a low value isolating resistor in series in the signal path somewhere between the output of the op-amp and the cable. In the FET pre-amp that is the purpose of R11 the 470 ohm resistor on the output of the pedal.

Thanks for the great education. Very helpful. If I had known in the beginning what I know now, I would have done more to avoid long wire runs and sadly, pot layout reconfiguration.

I suppose I could make one more major effort to flip the board but I'll have to get creative in replacing a tall cap or two. I'm beginning to regret my desire to change the pot configuration to match the original Boss FA-1. I tested it again and it's definitely a cross between background hiss and electrical hum. I also get a disturbing pop through the speaker when activating the foot switch.

Before I do major rework and try to flip the board 180....

1. Can anyone with this completed pedal weigh in on whether it is inherently noisy at mid to high volume and treble levels?

2. Is there a problem with braiding or twisting the leads from the input/output jacks - would it cause extra interference?

3. Is there any point in trying to wrap the input/output jack wires with copper tape and somehow ground it or use shielded multi-conductor cable for those instead of the standard single conductor wire I used?

Regarding the foot switch noise, continuity tests on the switch say it's functional but I question whether it needs to be replaced, or maybe that's just a result of the long leads from the switch to the board. However, the leads in my first build were longer and I don't think I had that problem.

4. Anyone had issues with foot switch noise on any of their pedals, especially this one? Suggestions on resolving? Maybe it's just amplifying the underlying noise issue.

Here's a couple of poor quality videos that at least give you the idea of the sound. I did not capture the sound the foot switch creates but think "pulling out your guitar jack while at playing volume". Ouch.

I apologize for my long winded postings on this topic. I'm just incredibly frustrated with all the time and money I've spent on this only to have issues I can't seem to solve. I hope you guys understand. I appreciate the help everyone has provided.

I have a FA-1 clone, built stock from the BYOC kit.

1. No appreciable noise from the treble UNLESS I have the boost all the way up. The boost amplifies everything, so if you have a pedal upstream from the FA that is noisy, you'll hear it!

2. Don't know, my leads are not braided.

3. Probably not, but that one is a try-it-and-see I think. *EDIT* I would try shielded cable first...

4. Some pedals have a definite thump - there are many topics dealing with this issue and no single cure-all. It can be pedal-dependent, amp-dependent, or something entirely different Sorry if that is vague (and probably unhelpful) but it is a big topic...

+1!

The unique thing about this circuit compared with other BYOC circuits, is that the EQ controls are active. When you crank the treble and bass controls, the circuit is amplifying those frequencies, not just letting them pass through as with passive EQ controls. When you crank all of the knobs, you are taking your original signal along with any background hiss inherent to passive guitars and cable runs, and amplifying that many, many times. And you are boosting treble frequencies which contain the hiss on top of that! You will typically get an increase in hiss with any gain pedal; this one actually amplifies more than most out there. I would find it hard to swallow not having a large increase in background hiss with this circuit with all knobs cranked.

Also, I'm not sure this circuit was designed with that purpose in mind. You're not going to hurt anything using it that way, I'm just saying the EQ controls are there to tailor your sound as desired, and the level knob is there to match, boost, or cut your level. I've just not heard of anyone grabbing an FA-1 to crank every knob on it. I see it as a more subtle effect. But that's probably just me...

But what I'm saying is that you can expect a good amount of hiss from this thing with all of the knobs cranked. That's the nature of the beast. Mine hisses plenty with everything cranked.

Hey bud, my FA-1 build does none of these buzzing things. I bet you made multiple tiny errors or something, alos your wires are alot and long so sometimes running your hot DC wire next to say an input or output wire can have noise issues, sometimes................

Yeah, I would never run it wide open. Typically when I used it before my rewire I put the volume between 9 and 11. I put the treble and bass between 10 and 12. I just want it to give me a bit of clean grit. Just enough to give a slight tube breakup sound. Thanks.

I still think it's noisier in some ways than before the rewire, especially the foot switch. Maybe the pcb pads can only take so many reworks. I'm getting concerned another rewire might require me to just order another pcb and board components.

I'll see if I can find some 24ga shielded cable or contemplate just biting the bullet and rotating the board. Ugh!

With all the time and money, I could have just bought a vintage FA-1....but wheres the sense of accomplishment in that?

So if I go with shielded, can I use multi conductor to the jacks and foot switch our single conductor everywhere?

NOTE that the EQ controls boost past 12 o'clock and cut at less than twelve. Twelve itself is no boost or cut. The way you have your dials, you're cutting bass and not boosting or cutting treble. You do have the Volume up a bit - that will boost. I find on mine that unity gain is at around 9 o'clock.

Shielded cable would only be required for the tip of the input and maybe the output if you want to go that route. Maybe a better strategy is to concentrate on dressing the wiring, perhaps looking at the original pedal and using that as a model.

yeah the DIY route must never be to save money, because you wont

Well I dunno - I bought an Overdrive 1 PCB, populated it and put it in a box - cost £35. Cost of the cheapest brand new TS-808 pedal - Maxon OD-808 - £ 98.92 + shipping.

I don't think any messing around with screened cable is going to make any difference with your pedal. The whole thing, wires and all is inside a grounded (at least it should be grounded) aluminium box - it is screened.

I'd guess you have some kind of problem with your ground connections. This may even be to do with the way you have your amp and any other pedals grounded. Are you using a battery (I see you have one in the pics) or are you plugging in to an external PSU. If so is there perhaps less hum when using battery power?

Rework follow up....
I went to replace the input/output leads with shielded wire but decided to just do it right and rotate the PCB if I could. I managed to do that and now the leads to the IN/OUT are very short. Leads to the foot switch are a little over an inch now. The only wires under the board are to the pots, lights, and cut switch. The hiss/interference is gone unless cranked all the way up but it's barely noticeable. Per a couple people here, that's normal. Putting the volume and treble at 12 or below is totally silent.

The foot switch is much quieter but I can repeatably get a "chirp/pop" when turning the pedal off if the volume is above 9. Again, this only happens if the pedal is on and I'm turning it off and only with the volume above 9. This is not a pedal I would typically turn on and off in the middle of a song so it's probably no big deal but I'd eventually like to fix the switch noise. I've heard a resistor in the right place might solve the problem. I also wonder if my switch might be partly to blame as it's been soldered and de-soldered 3 times now and I know that the #8 lug got too hot the second time I worked on it. Ooops.

Thanks everyone for the help. Many of you said turn the PCB and/or shorten the wires, and you were right.

I'll let you know if I fix the foot switch chirp but I'm finally going to focus on paint/decals. I've got an amp effects loop mod that showed up in the mail a couple days ago so I got to get this thing done!! Will definitely post pics when done.

Close but not quite....

OK, so I know my previous post said I was moving on to paint (and I was) but after reading about pull-down resistors and a voltage leaking, and other various footswitch pop fixes, I figured I'd do what I can to troubleshoot now so I don't ding the new paint.

Symptoms:
- loud pop/chirp when turning OFF the pedal
- does NOT pop when turning it on
- depressing the footswitch partially produces a nasty noise, almost a squeal or buzz (same tone as the chirp but extended)

From what I can tell, this circuit already has pull-down resistors on both the input and output. Correct? Both are 470k if I read the schematic correctly. I also see the caps on input and output. From what I read, those should not be allowing voltage to bleed through to the switch. Is that right? It also looks like the LED is isolated on the switch so it should not be a factor as some articles claim is a common cause of pop.



I ran across a posting about a clean boost pedal that had a major pop problem and the solution for 2 different owners was to replace the output cap with a slightly higher value. A third had an issue with this cap being leaky. Replacing it solved the problem.

Another couple of postings fixed their footswitch pop by replacing the switch. In both cases, they had overheated one of the switch lugs when desoldering. That happened to me when one of the wires got stuck. I didn't think it was overheated too bad but it was enough to slightly melt the red insulating material on that pin.

The footswitch is easy enough to replace. Just time consuming to wait for a new one. Locally they cost $12! In the mean time, I'll check for voltage leaks first. Am I correct in saying that I should have no voltage on footswitch pins 5 and 7 but do I check that with the pedal on or in bypass?

If there's no leakage and the switch replacement doesn't solve it, is there any merit in adding a larger cap to the output? If so, how much larger? Stock is 10u

One last question that I've had throughout this troubleshooting. When I built this pedal, I was meticulous about checking continuity with every single component and connection as I went. Is it possible to have a problematic solder connection even though is passes a continuity test?

It seems to me that since it only happens when switching OFF the pedal, that should give some clue as to the source of the problem. Maybe not. Any thoughts or suggestions from you guys are always greatly appreciate.

Thanks!

Switch pops occur when there is a voltage difference between the contacts. Unfortunately with audio circuits this only has to be a small difference to be audible and it does not need to be from a DC source, even a charge build up on a contact can be a problem and it is not easily measured because the very act of sticking a meter on to the contact can drain the charge. In the FET Pre-amp pins 5 and 7 of the switch have pull downs, but depending on what you plug in to, the Input and Output of the pedal may not be pulled down. You could for example try a pull down on pin 8. Fitting more pull down resistors at the input however has an unfortunate consequence. The input impedance of the FET buffer is 3.3M, which would probably be high enough to use the pedal for passive acoustic piezo pickups, but the existing pull down cuts that right down to 470K. Add another pull down right at the input and that goes in parallel with the 470K and the input impedance drops again.