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Lineout Humm to Interface

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Lineout Humm to Interface

Postby pitchwest » Mon Apr 06, 2020 1:30 am

Hi all,
I have a high end guitar amp head with a lineout. I also have a Weber Mass200 attenuator with a lineout. I'm running a patch cable from one of the lineouts to my Zoom H5 input. Either of them create humm. It's humm like as if I was cranked up to 10! I shouldn't say humm, more like noise. But the same level of noise is there running into my interface (H5) if the amp is on a clean setting or high gain. Since it's the same outcome through either the attenuator or amp I figure it must be an interface setting I'm unaware of. I've also tried shielded and non shielded patch cables from the lineout. That doesn't seem to make a difference. I've tried turning the input way down and also tried the amps volume way down but no mix seems to give me a clean volume. I feel I'm missing something very simple. Any ideas? Thanks.
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Re: Lineout Humm to Interface

Postby Mike Stranks » Mon Apr 06, 2020 9:03 am

A bit more info would help otherwise you'll be overwhelmed with, "Well it could be...", "Have you tried...?" responses.

So, for example:

* What precise amp are you using?
* Are you you using the amp and the attenuator at the same time? If so, how are they connected?
* Please describe all the cables that you're using - particularly what plugs are on each end.
* Which precise outputs and inputs are you using in the equipment connection chain?
* Are you running the Zoom on mains or battery?
* Are you using the Zoom as a recorder or as an audio interface connected to a computer?
* If a computer, link, what's the computer - and if a laptop - are you running on mains or battery?

As much of that info as you can supply will be really helpful.

Thanks :thumbup:
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Re: Lineout Humm to Interface

Postby pitchwest » Mon Apr 06, 2020 6:00 pm

Engl Savage 120w MK2 amp. I'm running straight in and then the output to my Webber Mass 200 attenuator then into a 4x12 cab. I've tried with and without the attenuator and it at multiple values. I've tried both lineouts from the attenuator and amp separately with the same results. My interface is a Zoom H5 I'm using as an interface powered by the computer which is an iMac. I'm using Garage band. As for plug ins I've tried the Garage band guitar in preset and mic in preset. I've also tried for outputs, computer speakers, computer headphones and the headphones out on my interface.

The sound is clean through the 4x12 cab but running into the computer it's noisy. I'm fairly confident it's not a hardware issue but a user issue. Maybe a setting or something? I thought it might have been the amp since it's model is new and maybe that was a bug but since the noise comes from the lineout of the attenuator as well that leads me to believe that it's usser error.
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Re: Lineout Humm to Interface

Postby allpurposedw » Tue Apr 07, 2020 1:26 am

Try recording directly to the recorder and then transferring the audio file to your computer. If you still notice a buzz the problem is the recorder and if you don't notice a buzz the problem is anywhere between your computer input and your audio program.
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Re: Lineout Humm to Interface

Postby pitchwest » Tue Apr 07, 2020 4:57 am

allpurposedw wrote:Try recording directly to the recorder and then transferring the audio file to your computer. If you still notice a buzz the problem is the recorder and if you don't notice a buzz the problem is anywhere between your computer input and your audio program.

That's really interesting. I hadn't though of troubleshooting that way. So I've narrowed it down. The noise seems to be from the interface being powered by the USB. If I run it on batteries that the noise is gone. If that is the solution I'm in trouble! The plug in power inlet is USB so my only option would be to always run it on battery. I'll message Zoom and see if they have a workaround, unless anyone here has any advice?
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Re: Lineout Humm to Interface

Postby allpurposedw » Tue Apr 07, 2020 5:18 am

The USB cable or either USB port may be bad. If the noise occurs when you power the recorder with USB power and you are not sending signal or lining in to the recorder the problem is between the USB port on the recorder and the USB port on the computer. If the noise only occurs when you are powering the recorder with USB and sending audio in real time to your computer program with that same USB then it is the USB cable or my original answer.
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Re: Lineout Humm to Interface

Postby Mike Stranks » Tue Apr 07, 2020 8:39 am

Ah! You have a hum loop... a very common problem so no need for too much angst. Nearly all of us have encountered them in some form during our recording lives! (I'll spare you the detailed technical explanation, but the various mains connection grounds are interacting with each other causing a current flow which is getting into the audio circuitry.)

The experts will be along shortly with suggestions as to how to fix in your situation, but an easy fix may be to insert and isolation transformer on the inputs to the Zoom. It acts as a buffer/isolator between the items of kit and inhibits current flow.

The performance/cost choice here tends to be the ART DTI.

Watch this space... :)
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Re: Lineout Humm to Interface

Postby ef37a » Tue Apr 07, 2020 1:00 pm

Since we are only dealing with a mono signal...http://orchid-electronics.co.uk/trans.htm

Orchid also make a two channel version. Beats me why amp makers don't fit a wee transformer in their line outputs these days? Don't they ever read of the growing incidence of ground loops? Before someone shouts"COST" the transformer can be pretty cheap, a £5.00 retail inc VAT jobby would serve since guitars need neither an extended bass nor treble response.

Dave.
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Re: Lineout Humm to Interface

Postby pitchwest » Wed Apr 08, 2020 9:41 pm

Mike Stranks wrote:Ah! You have a hum loop...

The performance/cost choice here tends to be the ART DTI.

Watch this space... :)

I bought an ART DTI and tried it out today. It did eliminate some of the noise but there's still an electric noise. I hooked the DTI up between my line out and interface. It's so strange because it's only there when using my amp and the interface is powered by my computer. I don't have another amp to test but I'm confident it would yield the same response. Maybe I'll have to jimmy rig a power source and hook it up to the battery terminals. I guess the lesson here is not to buy things without a dedicated power source input.
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Re: Lineout Humm to Interface

Postby Ariosto » Thu Apr 09, 2020 1:57 pm

pitchwest said -I bought an ART DTI and tried it out today. It did eliminate some of the noise but there's still an electric noise. I hooked the DTI up between my line out and interface. It's so strange because it's only there when using my amp and the interface is powered by my computer. I don't have another amp to test but I'm confident it would yield the same response. Maybe I'll have to jimmy rig a power source and hook it up to the battery terminals. I guess the lesson here is not to buy things without a dedicated power source input.

I did try a an ART DTI a while back and it was no good. Apparently it works in some situations and not in others. I returned it for a refund. I think Hugh gave reasons why it did not work, but it was way back and I can't remember the date or the post.
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