havata
Hi guys!!
I am a guitarist in South Coast. I have a huge problem with hum/buzz on my guitar recording set-up. I will describe it in detail, and hope that you can give me useful advice on how to solve the problem. I do feel it is probably a minor simple thing that needs to be done, but I am stuck!
Guitar into Boss GT8 - stereo out to Yamaha AW4416 workstation.
GT8 is powered by its own supply (220V to 14V, all purchased here in SA, no modifications).
AW4416 was bought in the US, and I am using it with a dowconversion transformer from 220 to 110V, US made, brand: RadioShack(The AW4416 is on 110V). The power line from the transformer to the unit itself is a 2-wire thing, not a three wire like the ones in South Africa. I presume there is no ground wire?).
Problem is as follows:
When I plug into my GT8 and play on headphones, the guitar is absolutely noise-free. The moment I switch the AW4416 "on", a huge buzz appears, messing up all my recording afforts. If I unplug the cords connecting the GT8 to the AW4416 - noise disappears, i.e. the only time the noise is there is when the GT8 is connected to the AW4416, and the AW4416 is switched on. The noise is there regardless of whether I use the GT8's phones output, or the AW4416's phones output.
Both units are plugged in the same AC outlet. The is only 1 outlet in my room ?)
Please, any ideas? I am frustrated, have work to do, but can not do it because of this huge buzz! I presume the workstation should be grounded, but how does that happen with power supply only on 2 wires?
Regards, urgent help will be appreciated!
Ivan
AlanRatcliffe
Definitely a ground loop between the two. If you plug in only one cable as a mono connection, does the problem go away? If so, lift the ground on one of the two cables and that should work.
I can't remember if it does, but if the GT-8 has balanced outputs, you can use those and the problem should go away.
Also make sure that the power lead to the AW isn't one of those that looks like a two pin, but is actually a three pin with the earth pin being on the socket side (although I think that is a European 230V plug). But the AW has a metal chassis IINM, so I would think it has a ground.
If all else fails, you can use a stereo DI box between the two to isolate them from each other - a surefire fix.
havata
Hi Alan! And thanks for the reply!
The problem does not disappear if I unplug just one of the two cords, both got to go.
The GT8 has only phone jack outs, and digital out. Tried the DTI by ART, made it worse!
Actually opposite - The AW power cord is a three pin on the AW side, like the one amps usually come with, but only two pins connect it to the 220-110V transformer on the other end. Could it be that it is not grounded? Can I take the middle pin on the AW and connect it with a wire to one of the other grounds in the AC outlets? This sounds to me all to be a ground thing, but I don't know which ground is missing. Any further thoughts adfter this?
Thanks!
havata
Yes, I see what you mean, the Aw power cord has 3 pins on the AW side, and 2 pins on the 110V transformer side.
I have a feeling the problem lies there?
AlanRatcliffe
Well it sounds like an earth loop from what you describe, but that would imply that both units are earthed, where it would seem that neither have an earth, so I suspect a complete lack of earth to be the problem.
Usually you want only one point in a system to be earthed to avoid loops - and that is usually via the power amp OR the console. Am I right if I assume that you have no amp (or powered monitors) hooked up at all? Test by rigging up a plug with only an earth wire and touching the other end of the wire to the chassis of the mixer. If that fixes it, you simply need to figure out a safe and reliable way too get an earth to the system.
havata
Silence, sweet silence! Bared the wires on the transformer side, giving enough length to put an additional plug only on the ground wire, which had been cut short by the american. Removed the other two (active and passive) from the plug, and plugged it (the plug) onto another slot in the power board, thus grounding the system. There isn't a single crackle or buzz! Will post a photo to you, don't know how to do it here.
Cheers, thanks, and long live rock 'n' roll!
havata
Something that also works, tried it now: the grounding wire can be clipped with a paper spring to the plumbing. However, not sure if it wont pick up other noise, especially at night, when all lights and TVs etc are on in the neighbourhood!
