my DI box CREATES a buzz

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tjonau

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hey

i'm doing to be using a d.i. very soon. i have my guitar plugged into the hi-z input, coming out of this hi-z output going to the amp. as simple as things SHOULD go, they never do, there is always one little thing that makes you want to drive your hand through the wall, especially when you're already on edge. anyways, the amp doesn't buzz when i use it, buzzes when i do, and no the ground lift doesn't do shit, swtich one way BUZZZZZZ swtich the other way BUZZZZZZ. i've even tried plugging my amp's power cable into a ground lift itself, BUZZZZZZ. in my head i believe if there is a buzz created by a di you are using the ground life should TAKE CARE OF IT..... the D.I. is a horizon straightline and the amp is an 1st gen, 60's model Roland JC-120, please help me out guys, thanks
 
tjonau said:
hey

i'm doing to be using a d.i. very soon. i have my guitar plugged into the hi-z input, coming out of this hi-z output going to the amp. as simple as things SHOULD go, they never do, there is always one little thing that makes you want to drive your hand through the wall, especially when you're already on edge. anyways, the amp doesn't buzz when i use it, buzzes when i do, and no the ground lift doesn't do shit, swtich one way BUZZZZZZ swtich the other way BUZZZZZZ. i've even tried plugging my amp's power cable into a ground lift itself, BUZZZZZZ. in my head i believe if there is a buzz created by a di you are using the ground life should TAKE CARE OF IT..... the D.I. is a horizon straightline and the amp is an 1st gen, 60's model Roland JC-120, please help me out guys, thanks
Click to expand...

Maybe I lack expreince in this area, but why are you using a DI box on an Amp? Maybe somebody else will come along and educate me, but my understanding is a DI box is only to give you gain for inputs that may require it (like an interface). If that hold true, then it would seem you have too much gain and that would be the buzzing.

Someone else jump in here.
 
plug your guitar straight into the amp and see if it sounds nice

adrian belew used a jc-120 when i saw him with king crimson

adrian belew always sounds good
 
DM60 said:
Maybe I lack expreince in this area, but why are you using a DI box on an Amp? Maybe somebody else will come along and educate me, but my understanding is a DI box is only to give you gain for inputs that may require it (like an interface). If that hold true, then it would seem you have too much gain and that would be the buzzing.

Someone else jump in here.
Click to expand...
Well, if by gain you mean "fractional gain" aka "attenuation" then you're close, except that the rest of your post indicates you meant gain like boost... The two 1/4" jacks on a passive DI are connected by straight wire, and unless there's something connected to the XLR jack, there should be absolutely no change to the sound. The 1/4" jacks are connected to the XLR via a transformer which is meant to reflect a much higher impedance to the source than what a mic pre would have on its own, while reflecting a much lower impedance toward that mic pre than the guitar itself presents. In the process it also steps down (attenuates) the voltage from the guitar, which isn't strictly necessary in most cases, but cant be helped in this passive arrangement. Even with all three jacks connected to their appropriate devices, there shouldn't be any change to the overall level as seen at the amp, though there is usually a subtle amount of treble loss.


To the OP - THAT FUCKING LITTLE THING IS NOT A "GROUND LIFT" PLUG!!! IT IS A 3 PRONG>2 PRONG ADAPTER!!! IF YOU DONT KNOW HOW TO USE IT PROPERLY THEN THROW IT AWAY BEFORE YOU KILL YOURSELF!!! NEVER DEFEAT THE SAFETY GROUND ON ANY DEVICE, ESPECIALLY A HIGH VOLTAGE DEVICE LIKE AN AMPLIFIER!

Did you have the XLR jack connected to a mic pre?
 
ashcat_lt said:
To the OP - THAT FUCKING LITTLE THING IS NOT A "GROUND LIFT" PLUG!!! IT IS A 3 PRONG>2 PRONG ADAPTER!!! IF YOU DONT KNOW HOW TO USE IT PROPERLY THEN THROW IT AWAY BEFORE YOU KILL YOURSELF!!! NEVER DEFEAT THE SAFETY GROUND ON ANY DEVICE, ESPECIALLY A HIGH VOLTAGE DEVICE LIKE AN AMPLIFIER!
Click to expand...

If that doesn't make the OP to take notice, the Darwinism should kick in!
 
I'm pretty sure the ground lift he's referring to is the switch on the direct box which is perfectly safe to use.

OP, does the amp have a two-prong or three-prong power plug?
 
bouldersoundguy said:
I'm pretty sure the ground lift he's referring to is the switch on the direct box which is perfectly safe to use.
Click to expand...
Yes, but it seems pretty clear that he used the ground lift switch and a power cable adapter:

OP said:
i've even tried plugging my amp's power cable into a ground lift itself
Click to expand...
In other words: what ashcat_lt said.

Bottom line:
- There's no reason to use a DI in between a guitar and a guitar amp.
- There's a good reason not to defeat the ground on something that has a 3-prong plug.
 
Didn't see that part. Definitely don't defeat a power ground. Those adapters are made to have the tab connected to a grounded wall plate screw on a 2 prong outlet, not defeat the ground.
 
I have one of those and haven't had that kind of trouble. Obviously if you're going to be connecting the guitar straight to a mic input you'll need that DI, but then you don't get any of what the amp is doing. Are you planning on reamping or does the DI have some other purpose?
 
ashcat_lt said:
To the OP - THAT FUCKING LITTLE THING IS NOT A "GROUND LIFT" PLUG!!! IT IS A 3 PRONG>2 PRONG ADAPTER!!! IF YOU DONT KNOW HOW TO USE IT PROPERLY THEN THROW IT AWAY BEFORE YOU KILL YOURSELF!!! NEVER DEFEAT THE SAFETY GROUND ON ANY DEVICE, ESPECIALLY A HIGH VOLTAGE DEVICE LIKE AN AMPLIFIER!

Did you have the XLR jack connected to a mic pre?
Click to expand...

let me get more into detail, didn't think i needed to. i need the di for going to my console and going to my amp at the same time, there is no other way in the studio at the moment, i live to believe that there is nothing wrong (and i don't think there is) with my horizon straightline DI. it ONLY buzzes when i use it. and i do know how to use the 3 prong to 2 prong GROUND LIFT, i have used it in situations where the amp buzzes just being plugged straight in and it TOOK CARE OF IT... which is what they are supposed to do. so if i use a DI and it starts ti buzz.. well i can't plug a DI into a wall because it doesn't require wall power, but the amp IS the thing that is buzzing, so naturally i figure why not see if the PLUG ground (connected to the amp power cable) lift fixes it because the SWITCH ground lift ON THE DI DOES NOT

the ultimate goal here is to get rid of the BUZZ.. OH I DID NOT MENTION THIS, when i put my had around the DI box or my bare foot on it or hold it in anykind of way, THE BUZZ GOES AWAY, but i can't have my hand on it all the time heh
 
Are the console and the amp on the same outlet or at least the same circuit?
 
and no i didn't have the xlr hooked up, just 1/4 in and out. i didn't bother hooking up the xlr because i need to solve this first
 
tjonau said:
and no i didn't have the xlr hooked up, just 1/4 in and out. i didn't bother hooking up the xlr because i need to solve this first
Click to expand...

It would be kind of funny if the buzz goes away when you connect the XLR. Try it. The outlet question is not relevant until you have the mixer connected.
 
tjonau said:
and i do know how to use the 3 prong to 2 prong GROUND LIFT
Click to expand...
It's not a fucking ground lift! If you did not connect the screw terminal to a grounded screw at the outlet, then you did not use it correctly. And that's a period. I don't care how many times you've done it, I've done it too, but it's dangerous and is never the right solution!

There is no ground loop in this scenario since you haven't got the mixer connected. You should try that, though I'm not convinced it will help. The ground lift on the DI box doesn't affect the connection between the two 1/4" jacks, they are connected via straight wire (or the enclosure, or both) it breaks the ground connection to the XLR, which you haven't got connected to anything.

The fact that you can make the buzz go away by touching the DI box almost leads me to think that you don't have ground continuity to begin with all the from the guitar to the DI. Maybe I missed it above, but did you try different cables? Do you have a meter you can use to check resistance between your guitar's bridge/strings and the amp chassis with the DI in between?

The fact that defeating the SAFETY GROUND on the amp helps is a bit mysterious. Almost makes me wonder if the outlet to which it is connected is perhaps wired the wrong way around? That right there would seem to be an argument against defeating the SAFETY GROUND on the amp... They make those polarity tester things. You might want to use one and verify the wiring of your outlets.

Anyway, these kinds of things can be annoying and frustrating to track down - even moreso to try to diagnose over the interwebs.

I'm really not trying to be a prick about the "ground lift" thing, but it can be very dangerous and it's very important that folks who stumble on this thread down the road understand that. It is possible that you are well aware of the risks (though it kinda sounds like not so much...), and you're perfectly welcome to take that risk if you feel the possible benefit is great enough. Not sure your insurance company would agree, but...
 
It may not be a ground loop. It may be the unterminated secondary windings of the DI's transformer acting like an antenna picking up interference from the AC in the room and feeding it into the amp. Let's see what happens if that XLR is connected.
 
bouldersoundguy said:
It may not be a ground loop. It may be the unterminated secondary windings of the DI's transformer acting like an antenna picking up interference from the AC in the room and feeding it into the amp. Let's see what happens if that XLR is connected.
Click to expand...
Oooo I like that! Makes some sense, even sort of explains why touching the enclosure stops the buzz when touching the strings (further from the transformer) doesn't. Does touching the box stop the buzz even when the ground lift switch is flipped? I'm not sure that explains why defeating the amp's safety ground helps, though...

It's just plain not a ground loop because there is only one grounded component in the system. I don't really like the way that statement reads, but the gist is good enough I think.
 
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