Anyone here or anyone has a friend who is an electonics expert? I have problems with most of my guitar pedals, many of them distort. Even new ones that I buy. Tried them with different guitars, amps, interfaces, the problem remain. Have been asking this on forums for years, but haven't found a solution so far. And the discussions always end in debate and anger because no solution can be found and people think I am fooling them. Do you know anyone who is a real expert in the circuits of these and could have some suggestion what parts to check where the problem can be? I have access to laboratory test tools but I am not an expert, I need directions that I can tell to my technician friend, then he checks what I tell him about.

 

rather has something to do with your energy/electric home grid or however its called in english...

 

Have you tried a different power supply, or powering them with batteries?

 

Not this is much more complicated than that and happens even outside home, with the guitars of others, too, if I try with these pedals.

 

Where do you live and where are the pedals from?

 

Distortion pedals?

 

Use a pedal with a good buffer at the beginning of the chain.

Check the voltage of the power supply. Had a similar thing happen with a pedal that was supposed to work on 9v, but was being fed 18v.

 

Please be more precise. What pedals exactly? Usually these are powered by a 9 V battery or 9 V DC power adapter. So the absolute maximum level you can reach before clipping is 9 Vpp which equals +12.3 dBu or +10.1 dBV, but in real world scenarios it's a few dB less because most op amps used aren't whats called "rail to rail" and so clip below the full supply voltage. If you've got a real "hot" guitar pickup, it may already clip the input buffer of the circuit. Therefore some circuits or active pickups can be powered by 18V, raising the headroom by 6 dB.

 

Sounds like a power management issue.

I'll assume you have more than one pedal and are using the same power supply (PS from now on) for all of them. If that's the case, there's an easy way to find out:

Plug the PS into just one pedal. If that sounds fine, it might be an amperage issue. This means that while you have the correct voltage, your PS doesn't provide enough power to run all of them at once -- which you can easily fix it by getting a stronger PS.

Now, if the pedal sounds like shi-distorted, try testing all your pedals one by one. If every pedal sounds distorted, it could be a faulty PS or, less likely, all your pedals are damaged.

Also, make sure all the pedals are the same voltage as your PS -- that could be a factor too.

 

I have a problem with certain compressors all the time, I would like to know if my favourite one could be modified to solve that problem. I am looking for solutions, preferably an expert for that.

Here is a video. I am showing the mentioned compressor: GURUS OPTIVALVE, an LA-2A inspired item. The problem is what you can hear right away: it is distorting. My guitar has humbucker pickups. What happens in the video:

1. The volume pot on the guitar is at max. The compressor is set to average/high compression. You can hear it is distorting. You may think it is because of the amount of compression but no. You can see me turning down the Input, it is distorting. If you turn down the Input to the level that no compression is indicated, it still distorts.

2. After the flash, you can see the Optivalve again. This time, I turned down the volume pot on the guitar. I am demonstrating, that you need to turn down the volume pot to nearly 0, that way the pedal stops distorting. But that volume level is not very favourable from the guitar. Any higher setting starts distortion in the pedal. But even so, at the highest notes, you can still hear some distortion.

3. You can see my Carl Martin pedal. I am demonstrating with that it does not distort. The volume pot is at max again. I am showing 2 situations: one is with slower attack, other is with faster. Both are okay, you cannot hear the distortion.

The PSU used is the factory supplied 12V PSU for the Optivalve.

I experienced the same distortion with many pedals, not only compressors. Now I have only compressors, I found these pedals distort: Keeley Compressor+, Marshall ED1 and this Optivalve. The Carl Martin Compressor you can see in the video does not distort. I also have a Demeter with a trim pot, that one is interesting: with a new 9V battery, or with a 9V PSU it distorts. Even if the trim pot is at 0. I have a home made 12V PSU with filter built in, with that one the Demeter does not distort, even on higher trimpot settings.

Guitars: you may say my guitar has very high output, but it is not only my guitar I experienced this distortion with. These guitars also distorted with the mentioned pedals: PRS Custom, Cort kx508. Just like you hear in the video.

I have the Optivalve MKII. There is a test on Youtube for the MKI, with humbucker guitar, you can see they test it with every kind of combinations of the knobs, even maxing it out, no distortion:

I have been asking to solve this thing for a while now at various places, but very likely I will need a pedal expert to solve this. If you know any who is specialised on these and may have a clue, I would appreciate if I could contact him.

 

Did you swap cords?

 

You mean the jack cables?

 

To me it sounds like it's intended to sound, asymmetric tube saturation, no harsh clipping due to overloading. Most compressors or limiters come with at least some kind of harmonic distortion, explicitly "tube sounding" devices do this on purpose. So using something like this and expecting perfectly clean sound is the wrong use scenario. Better think about what you want to achieve.

 

Okay but you see the videos of those japanese guys. That video is going against what you write now. Moreover, if it is so as you write, why do the manufacturers never reply this? The replies I get is always to send the pedal back for check. Never that it was intended to work like that.

Anyway With Single Coil pickups they do not distort. But again, those Japanese guys use Humbucker. And manufacturers nevery reply to use it with Single Coil.

 

Because it's the standard reply. You really expect technicians to read and analyse every single question in 2024? That's a thing of the past.

Generalizing that single coils won't distort but humbuckers do is not very helpful either. I'm no guitar guy, just a technician and developer, so I'm out.

 

I don't generalize, just mentionning that when we tried these problem pedals with single coils, the distortion was gone. So these compressors can definately be used without them distorting. Moreover I had chorus pedals like the Behringer UC100 and the Visual Sound H2O Chorus/Delay, that distorted the same way. I doubt pedals of those kind were meant to be distortion pedals.

Anyhow, I don't want to force you to accept this what I write or tell me the solution, that's why I titled the post: looking for expert. I am trying to find people who know about the technical side of this stuff and can reveal what's going on here.

If I don't manage to find any, I will just look for a shop where they sell the same pedals, go, show them the problem and try to have them ask the manufacturer what's going on. They will need to give an explanation because I doubt they will offer to replace all problem pedals for the shop.

 

Good luck...

 

If all your pedals distort, you have a bad signal going into them, or they are over voltaged. its not rocket science. there is only 2 reason for distortion, 2 much gain, 2 much voltage, or both.

 

True, the only problem is the guitar as a source of problems is ruled out (meaning the guitars tried are not bad), the extra voltage actually does good for some pedals. My Demeter compressor stopped distortion when powering with 18V istead of 9 (the factory spec). Another pedal that has a tube was found to have a different tube in than indicated by the manufacturer, during manufacturing something may have happened. So theoretically it is simple, in reality not.

 

I'm no expert but if you've ruled out the guitars (pickups, gain etc) and also ruled out the power supply, and checked and replaced all the cables.. then your best bet is probably as you said.... get someone to check the pedal(s) in person probably quicker as well