Need Help Using Pedals with VH4(fixed with iso power)

[eonblue]

Alright, Ill try to explain this as thoroughly as possible.

I bought a MusicomLab EFX MIII, a pedal looping system, to run into the front end of my VH4. When I got it and plugged it into the front of my amp I noticed a buzzing noise. In fact, I can simply plug in the EFX and run a single cable from its output to the front of the VH4(no pedals plugged into the EFX at all) and I get the buzzing buzzing sound on every channel. The buzzing is most audible on CH3, obviously amplified by the gain on that channel, but again, it exists on all channels.

So, I sent the unit back to Chris at RockBox thinking it was defective. He tested the unit on multiple systems and was unable to reproduce any noise whatsoever. He told me that given his test results and my experience with the unit, it sounded like an impedance mismatch or something of that nature. I was pretty bummed at the prospect of an issue with my rig, but I decided to run some more tests and see if I could reproduce the sound with some of my other pedals. Most don't make the sound, but one of them does.

The chain this time is an Empress Superdelay plugged in for power with a single cable from its output into the front of the Diezel(this is simply for test purposes as I run delay in the parallel FX loop under normal circumstances). This reproduced the same sound, lending credence to the idea of some sort of dislike between the Diezels front end and certain pedals.. Furthermore, the Empress Superdelay through the FX loop produces no noise whatsoever.

So, Chris mentioned a possibly a buffer or something called an Ebtech Hum eliminator, but I wanted to see if Peter or anyone else knew how to best resolve this issue.

Thanks.

 

[Capulin Overdrive]

i'm guessing you're getting some kind of ground loop.

i'd get that when i had me stuff in the garage practice space, but not in the house.


i'd suggest trying to plug your effects into a completely deferent outlet.

if you can run some of your effects with battery power, try that and that should tell you if it's the power supply that's messing you up.

 

[elfredoo]

you will sometimes have a ground loop when connecting two audio devices per audio cable when they both are outlet powered (instead of battery powered like some pedals). you can break this ground loop by using an ebtech hum eliminator for example. it works best before the inputs of an amp (input, loop return). place the ebtech near the amp but not near a transformer. use a trs cable from the device to the ebtech an d a short ts from ebtech to amp in.

this CAN work, but sometimes doesn't... but worth a shot! i got my rig (VH4 (or any of my amps) with tc g-system) quiet with this little miracle box... and wouldn't know what to do without it.

 

[Peter Diezel]

Alright, Ill try to explain this as thoroughly as possible.

I bought a MusicomLab EFX MIII, a pedal looping system, to run into the front end of my VH4. When I got it and plugged it into the front of my amp I noticed a buzzing noise. In fact, I can simply plug in the EFX and run a single cable from its output to the front of the VH4(no pedals plugged into the EFX at all) and I get the buzzing buzzing sound on every channel. The buzzing is most audible on CH3, obviously amplified by the gain on that channel, but again, it exists on all channels.

So, I sent the unit back to Chris at RockBox thinking it was defective. He tested the unit on multiple systems and was unable to reproduce any noise whatsoever. He told me that given his test results and my experience with the unit, it sounded like an impedance mismatch or something of that nature. I was pretty bummed at the prospect of an issue with my rig, but I decided to run some more tests and see if I could reproduce the sound with some of my other pedals. Most don't make the sound, but one of them does.

The chain this time is an Empress Superdelay plugged in for power with a single cable from its output into the front of the Diezel(this is simply for test purposes as I run delay in the parallel FX loop under normal circumstances). This reproduced the same sound, lending credence to the idea of some sort of dislike between the Diezels front end and certain pedals.. Furthermore, the Empress Superdelay through the FX loop produces no noise whatsoever.

So, Chris mentioned a possibly a buffer or something called an Ebtech Hum eliminator, but I wanted to see if Peter or anyone else knew how to best resolve this issue.

Thanks.

Our loops works flawlessly since 18 years with no mismatching
of impedance or level. The loops are designed with the big effort
of two 12AX7, means 4 triodes.

Several manufactures of effect units don´t take care about
ground loops. I´m sorry to sound a bit rude but the topic should
read "Need help working out a buzz with my effect unit".

Best,
Peter

 

[slyvren]

I´m sorry to sound a bit rude but the topic should
read "Need help working out a buzz with my effect unit".

Best,
Peter

 

[eonblue]

Peter, Ill be happy to change the title or delete the post, doesn't matter to me at all as long as I can get this worked out. If I knew what the problem was then I wouldn't be asking the question and would be better able to title the post.

So, if this is a ground loop, I should be able to plug the pedal into a separate outlet than the amp and if I get no noise ive found my problem?

 

[eonblue]

Our loops works flawlessly since 18 years with no mismatching
of impedance or level. The loops are designed with the big effort
of two 12AX7, means 4 triodes.

Peter, I always lose a litte bit in translation with you, so I apologize if I misinterpreted what you are saying. If you read my post, Im not talking about the effects loops, Im talking about running these units directly into the front of my amp. The Musicomlab does in fact have a ground lift on it for when you are running effects in the effects loop of the amp, but again, thats not what Im trying to address.

 

[eonblue]

Alright, so I plugged the VH4 into one outlet, and plugged the Empress into another outlet, ran a 1/4" cable from the Empress Output into the front of the VH4 and the sound was still present. Does this rule out the ground loop theory?

 

[Peter Diezel]

Our loops works flawlessly since 18 years with no mismatching
of impedance or level. The loops are designed with the big effort
of two 12AX7, means 4 triodes.

Peter, I always lose a litte bit in translation with you, so I apologize if I misinterpreted what you are saying. If you read my post, Im not talking about the effects loops, Im talking about running these units directly into the front of my amp. The Musicomlab does in fact have a ground lift on it for when you are running effects in the effects loop of the amp, but again, thats not what Im trying to address.

Sorry Eonblue,

so the noise is caused in front of the amp.

 

[eonblue]

Our loops works flawlessly since 18 years with no mismatching
of impedance or level. The loops are designed with the big effort
of two 12AX7, means 4 triodes.

Peter, I always lose a litte bit in translation with you, so I apologize if I misinterpreted what you are saying. If you read my post, Im not talking about the effects loops, Im talking about running these units directly into the front of my amp. The Musicomlab does in fact have a ground lift on it for when you are running effects in the effects loop of the amp, but again, thats not what Im trying to address.

Sorry Eonblue,

so the noise is caused in front of the amp.

Yes. And the chain is simply a plugged in Empress Superdelay and one 1/4" cable into the front of the VH4. Certain powered pedals don't produce any noise, but the Delay and most importantly, the Musicomlab do. Its not very loud, but the VH4 is normally so quiet that I immediately noticed its presence.

 

[elfredoo]

ground loop sometimes is being produced by the fact i mentioned earlier. if you feed this noise into a highly amplified channel (distortion) then it gets louder and can be as loud as your guitar sound. if you insert this same pedal into the loop there is less amplification and therefor less noise level.

this is not a diezel or vh4 issue, but a general issue in audio linkage. you can also have it when connecting a fx-unit to a mixer or a keyborad to a mixer. most times you don't hear it since it is not that loud. but using high gain amps brings the noise wayyyy up.

so: regarding the "using different outlets" story: it can help but most times doesn't. so the only help is to lift the ground when there is a ground lift switch ( did you use this by the way?) or to cut the ground loop with the little helper (ebtech hum eliminator for example). also be sure to use good cables with intact shieldings.

 

[slyvren]

The other outlet has to be on a different circuit breaker. If you have a chance to run the effects off battery try that first. If not.. Try another power adaptor. Last, if you have spare junk audio cable just for testing... Remove the ground (sleeve) between amp and pedal for testing only.

 

[elfredoo]

ps: removing ground is a testing manner. do not ever leave it that way. you can risk your life.

 

[eonblue]

The other outlet has to be on a different circuit breaker. If you have a chance to run the effects off battery try that first. If not.. Try another power adaptor. Last, if you have spare junk audio cable just for testing... Remove the ground (sleeve) between amp and pedal for testing only.

Alright, I can do this for testing and this may be a silly question, but that pedal is expensive, so there isn't any chance of damaging it with this test is there? So, if I do this and the noise goes away, does that prove that the issue is a ground loop?

 

[eonblue]

so: regarding the "using different outlets" story: it can help but most times doesn't. so the only help is to lift the ground when there is a ground lift switch ( did you use this by the way?) or to cut the ground loop with the little helper (ebtech hum eliminator for example). also be sure to use good cables with intact shieldings.

The ground lift switch on the Musicom is purely for taking care of the pedals running the the FX loop of the amp, when I was running all effects I did in fact use this switch and it did indeed work to reduce noise. However, the chains Im describing now are stripped down to the bare minimum to reduce variables, so the ground lift on the EFX isn't even in play with this testing chain.

 

[slyvren]

With just audio ground lifted? No. If it's still not clean it's not proof. If it is clean then yes it's proof. I would try different guitar and also try isolated power source. Pedal power or run extension cord to neighbors.

 

[slyvren]

Oh forgot to ask. Have you tried different cables? Are they high quality cables?

 

[eonblue]

With just audio ground lifted? No. If it's still not clean it's not proof. If it is clean then yes it's proof. I would try different guitar and also try isolated power source. Pedal power or run extension cord to neighbors.

The noise is present without even having a guitar plugged into the input. Also, I checked a couple different cables including an Evidence Audio lyric cable to no avail.

 

[slyvren]

Did you try cable with ground cut from pedal to amp yet?

 

[eonblue]

Did you try cable with ground cut from pedal to amp yet?

No unfortunately I wont be able to give that a try until tomorrow. At work now and got band practice tonight. Ill post my results.