Feedback/Hum in Passive mode with overdrive/fuzz pedal

Givenher

Givenher

Oct 21, 2019
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#1
Hey guys,

I'm a fairly new bass player and this my first post here. I picked up a new bass over the weekend, a Yamaha TRBX604FM, and last night had a rehearsal with my band with the new bass. I absolutely love the tone that I'm getting from the bass but I ran into an issue that I could not explain or resolve. Essentially, in active mode everything was working perfectly but when I put the bass into passive mode and activated either my fuzz or overdrive pedals I got a loud humming feedback noise regardless of whether I was playing or not. This only happened with the guitar's volume pot turned up (if it was all the way down there was no noise) and only when the pedals were active (when they were in bypass mode everything worked fine). For reference my setup was as follows.

Guitar --> Polytune 3 tuner --> Bass Big Muff Pi (Effect out) --> Boss Odb-3 --> Amp Input 1 Also, I ran a second cable from Bass Big Muff Pi (Dry Out) --> Amp Input 2

Any advice or input is appreciated. Thanks!
 
#4
You're gain stacking a fuzz pedal into a distortion pedal and you can't figure out why you're getting feedback?
oMJ28xM_700wa_0.gif
 
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#5
yeah cables in your rig can react to a different signal , impedance , gain etc etc so you gotta eliminate or start from zero and try to narrow down the problem , like for ex does the bass do that just going straight into the amp? No right .. next add another cable or pedal . keep going to you find the source , then test that source . I have seen cables cause all kinds of strange things . If one strand of wire in the cable is broken it can be the problem but doesn't really sound off when used by itself . You can test cables with a multimeter but most people do it by ear but they can be the buggers of it all . So yeah go through the rig and ferret out the problem . I'm not saying it's a bad cable though but I think it's something in the chain .
 
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#6
Kriegs said:
You're gain stacking a fuzz pedal into a distortion pedal and you can't figure out why you're getting feedback?
oMJ28xM_700wa_0.gif
Click to expand...

Yes I am, but I'm using the OD mainly as a slight boost to the fuzz and to give it a bit more tonality. I have the gain set quite low so it's not adding much drive on top of the fuzz (which is also set at a moderate amount of gain). It was also happening even when only one of the pedals is active and the other in bypass mode, so no gain stacking going on, yet still humming/feedback.

Furthermore, it was working just fine on my other bass (a passive El Degas) with no feedback or humming noise. I did use different cables last night than my usual so I'm starting to think that could be the main cause.
 
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#7
& report back ! also put a fresh battery in the bass to get the party started . Have fun ! I like sourcing out the problem of a head scratching musical anomaly but Kriegs is right sometimes just plugging in 2 pedals , especially some old fuzz where the impedance can alone cause issues with other pedals .
 
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#8
fretno said:
yeah cables in your rig can react to a different signal , impedance , gain etc etc so you gotta eliminate or start from zero and try to narrow down the problem , like for ex does the bass do that just going straight into the amp? No right .. next add another cable or pedal . keep going to you find the source , then test that source . I have seen cables cause all kinds of strange things . If one strand of wire in the cable is broken it can be the problem but doesn't really sound off when used by itself . You can test cables with a multimeter but most people do it by ear but they can be the buggers of it all . So yeah go through the rig and ferret out the problem . I'm not saying it's a bad cable though but I think it's something in the chain .
Click to expand...

I do have a multimeter, so that would probably be the most reliable way to test my cables. Do you know how I would do that? What multimeter settings to use?
 
#11
testing cables is always a good thing to check , especially over time they can degrade . But stacking gain and the vast differences and oddities of electronics and complex signal chains can be a world of problems . I try to keep it as simple as possible in the signal chain . I'd be fine with a p bass and b15 :D but I can see that isn't for everyone . All the best
 
#14
I have a 505 that was noisy in passive mode.

uhm, it does not have a passive mode now, I've rewired it to active-only with different preamp. and of course isolated the cavities with copper tape.
 
#15
Ran into a similar issue with a germanium fuzz and it was indeed the cable. Sounded fine with the volume up but buzzed like hell with the volume down unless I also rolled off the tone (passive instrument). Thought something was wrong with my instrument but it was totally normal without the fuzz in the signal chain. Then I thought my fuzz was just unmanageably noisy. Didn’t seem like normal behavior for a bad cable, but just to be safe I tried swapping out the one after the fuzz and all was well.
 
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#16
So today I tested my cables with a multimeter and all are good (one of the ones I used the other night was not mine, so maybe it is bad?). I also plugged my guitar into an amp (a different amp) and tested my pedals in the same effects chain and had no feedback or hum. Only the usual noise that I get from my Boss ODB-2 (which is a slight buzz, but is normal). I'm rehearsing again tomorrow so will see what happens when I use different cables.
 
#17
Givenher said:
So today I tested my cables with a multimeter and all are good (one of the ones I used the other night was not mine, so maybe it is bad?). I also plugged my guitar into an amp (a different amp) and tested my pedals in the same effects chain and had no feedback or hum. Only the usual noise that I get from my Boss ODB-2 (which is a slight buzz, but is normal). I'm rehearsing again tomorrow so will see what happens when I use different cables.
Click to expand...

Maybe it wasn't a shielded cable.
Also, a meter will not test the integrity of the ground in a shielded cable.
 
#18
Thank you for all of the input and advice. I think I figured out what was causing the hum. My bass amp (a Ross Fame Series 50) has 2 inputs on the front. I was using both outputs on the Big Muff: The effects out going into the ODB-2 into input 1 and the Dry out directly into input 2. This configuration seemed to cause the feedback in passive mode and it went away when I unplugged the Dry out cable. I don't know why this didn't occur with the active mode on the bass; perhaps the phase of the signal is sent differently so didn't cause the feedback effect?
 
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