Help to troubleshoot buzz

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ChrisB
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Joined: Wed Oct 09, 2019 5:17 am

Help to troubleshoot buzz

Post by ChrisB » Wed Oct 09, 2019 5:58 am

Hi,

Could anybody please help me with some troubleshooting advice on how to determine the cause for the buzz I get when activating certain pedals. My setup is as follows:

- Dingbat board with 4x4 pedal power already mounted when purchased
- Evidence Audio Monorail SIS patch cables + Evidence solderless jacks throughout

Pedal sequence:
Guitar -> Thorpy FX Fallout Cloud -> Analog Man King of Tone -> Cali 76 Compact Delux -> MXR Univibe -> Boss DM2 waza craft delay -> Strymon Big Sky

The boss is connected to the standard Boss AC PSA power adapter all the other pedals use the PP 4x4. Wattage and polarity is correct for all pedals.

The problem:

The Thorpy, KOT and Cali when activated individually create a buzz this increases if all three are engaged. Out of the 3 the KOT is the quietest, the Thorpy the loadest and the Cali somewhere in between. There is no buzz from the other pedals.

What I have tried:

- Removed the delay, univibe and Strymon from the signal chain
- Isolated each of the 3 problem pedals from signal chain
- I can't test battery as this is not supported in the Cali and Thorpy
- Swapped patch cables on the 3 "problem" pedals
- Different lead cables (Mogami Gold and Mogami Platinum)

Any help would be much appreciated!

Thanks
Chris

JohnClark
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Joined: Tue May 05, 2009 2:33 pm
Location: The Lab

Re: Help to troubleshoot buzz

Post by JohnClark » Wed Oct 09, 2019 2:23 pm

Sorry you are having troubles...

When isolated, did each of the three problem pedals perform the same as when they were in the full chain? You mention that two of these can't be tested against a battery, but does the KOT perform the same when powered with a battery?

Is the buzz affected by the volume knob on the guitar? Also, how loud of a buzz are we talking about here, how does it compare to the level when playing the guitar?
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ChrisB
Posts: 4
Joined: Wed Oct 09, 2019 5:17 am

Re: Help to troubleshoot buzz

Post by ChrisB » Thu Oct 10, 2019 5:12 am

Hi there and thank very much for the response!

Please see my answers to your questions below:
johnclark wrote:When isolated, did each of the three problem pedals perform the same as when they were in the full chain?
Yes, the pedals perform in the same way i.e. there is no change to the level of buzz.
johnclark wrote:You mention that two of these can't be tested against a battery, but does the KOT perform the same when powered with a battery?
You are right, I could have tested the KOT with battery and haven't done so. I will do it and revert back with the outcome.
johnclark wrote:Is the buzz affected by the volume knob on the guitar?
Yes, the buzz gets louder as I increase the volume. The same happens if the pedals are set to higher output or gain levels.
johnclark wrote:Also, how loud of a buzz are we talking about here, how does it compare to the level when playing the guitar?
It is not noticeable when playing but really quite loud when not. In terms of how loud, it would definitely be louder than a person talking in a room at normal levels. One thing to mention is that if I mute my strings the buzz becomes almost inaudible, it's still there but very subtle.

Thanks again

Regards,
Chris

JohnClark
Posts: 7399
Joined: Tue May 05, 2009 2:33 pm
Location: The Lab

Re: Help to troubleshoot buzz

Post by JohnClark » Thu Oct 10, 2019 10:06 am

Ohhh now were getting somewhere!

The reason you are hearing this most with these pedals is that they are your gain pedals. They are greatly amplifying the noise that is already present in the signal path. It is possible that if your amp has any higher gain settings that you might hear the same buzz with just the guitar plugged directly into the amp.

We can skip the battery test as now I am certain it will yield the exact same noise.

That the buzz changes with the guitar volume, and that the buzz goes away when muting the strings is certainly showing a grounding problem. If we are confidant the cables aren't the problem then the next place to look is to the guitar itself, check, or have checked, the grounding connections inside. There are typically connections between all the cases of the pots and switches that lead back to the bridge somehow. What is this guitar anyway, and as a possible quick test, can you try the rig with a different guitar?

Also possible is the amp itself. It could have a failing connection at the input, but my gut says this is not terribly likely here. However, is the amp connected to the mains power wall outlet with a grounded plug?
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ChrisB
Posts: 4
Joined: Wed Oct 09, 2019 5:17 am

Re: Help to troubleshoot buzz

Post by ChrisB » Thu Oct 10, 2019 1:44 pm

Hi,

I have already performed the battery test and it was as you predicted, the buzz is still present. One thing that I did noticed though is that the noise it at its most intense between 6 and 8 on the volume nobs (identical on both pickups). Below and above those settings the buzz is much lower! Also when plugged directly into the amp there is a lower buzz although this was also present when plugged into a different amp (via the pedal board), at rehearsals the other day. With regards to the guitar it is a Gibson Les Paul R9 (2018 so new :? ). I also have a Gibson ES335 and to tell you the truth I can't remember if the buzz was also present with that guitar so I will certainly test it!

I think you are right about the grounding issue as I notice that there is a lot of static when I touch the tail peace. By cables do you mean the patch cables? Also to ensure that I avoid any potential grounding issues coming from wall sockets or power strips is there any kind of isolation device or filter that I can get? I tried searching online but haven't been able to find anything like that. I live in Italy and I found out today that grounding issues with power outlets are quite common here!


Thank you!

JohnClark
Posts: 7399
Joined: Tue May 05, 2009 2:33 pm
Location: The Lab

Re: Help to troubleshoot buzz

Post by JohnClark » Tue Oct 15, 2019 12:17 pm

You shouldn't need any isolation devices unless you are running multiple amplifiers... Guitar -> Pedalboard -> Single Amp should not need any additional devices inserted in the signal path or anything on the power feeds.

About cables, I was referring to any of the audio cables really. Any cable between the guitar and amp with a failing Sleeve connection can cause problems. For testing, keep it simple with as few cables as possible and check the cables used for testing to be completely sure they are not the problem.

I believe a Les Paul typically grounds the strings via the treble side stud for the bridge with a wire that comes from the body of the pot for Neck Volume. This is where I would look (or have checked out) if the problem happens only with this guitar.
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ChrisB
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Joined: Wed Oct 09, 2019 5:17 am

Re: Help to troubleshoot buzz

Post by ChrisB » Fri Oct 18, 2019 8:54 am

Hi there,
Apologies for the delayed response and thank you once again for your invaluable help on this. I have learnt a lot already from these exchanges.

Okay, so I have tested the 335 and the buzz is still there albeit it is not as loud as the LP. I have also tested three different guitar leads. I think it is quite possible that the issue lies with the Evidence cables as I constructed them myself. I will check them again.

Have a great weekend!

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