GP-10 - Dual Output Direct Send Causing Noise

Started by rac2112, November 08, 2014, 04:14:47 AM

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rac2112

Hi Everyone,

New forum member here - this website looks like an excellent resource for all things GK and COSM based.

Now, I've recently bought a GP-10 and I've noticed something that I wouldn't mind some other forum members confirming.

I was using the Drop D HiGAIN patch (no 2 of the factory presets) and as part of my initial fiddling-around-to-see-how-things-work procedure I turned off both noise suppressors and to my surprise discovered that my GP-10 makes a serious amount of noise.

I ran this patch (still with the noise suppressors off) through the meters in Cubase, and setting my guitar playing to an RMS of approx -18db showed the residual unit noise of the GP-10 on this patch residing at approx -43db; in other words, approx 25db below the average guitar signal and consequently clearly audible to the point of distraction.

I then turned off the pre-set modeled guitar and used my own guitar pickups (a Les Paul), and the unit noise dropped down to what I would consider perfectly normal for an overdrive into a high gain amp situation e.g loud but within reason.

Now, this suggests to me that the noisy culprit here is the guitar modelling - and I guess might also explain why there are 2 noise suppressors but only 1 FX block!

Of course I could just leave both noise suppressors on, however I was wondering if any other members with a GP-10 could see if they get the same results with this patch - just in case there is something wrong with my GP-10 or set-up in general,

Cheers.

P.S. Not to dump on the GP-10 'though – I'm still completely amazed at what can be achieved with this unit!

Elantric

#1
QuoteI was using the Drop D HiGAIN patch (no 2 of the factory presets) and as part of my initial fiddling-around-to-see-how-things-work procedure I turned off both noise suppressors and to my surprise discovered that my GP-10 makes a serious amount of noise.

Thats normal, and why Roland employs and suggests using the built in Noise Supressors, and why all High gain factory presets have the NS engaged. if you prefer more sustain, the NS Threshold can be tweaked, but there is no free lunch.

Quote
I then turned off the pre-set modeled guitar and used my own guitar pickups (a Les Paul), and the unit noise dropped down to what I would consider perfectly normal for an overdrive into a high gain amp situation e.g loud but within reason.

Correct - anytime a Roland DSP Guitar processor is delivering a High Gain COSM Amp Model/Cab Sim, + Stereo FX+ COSM Guitar Modeling + Alt Tuning) each of those functions contribute to additional workload for the DSP , and means there will be higher amount of hiss and noise which can be heard if you defeat the Noise Suppressor. You can test how much noise each GP-10 function contributes by turning off the Noise Supressor, then engaging / disengaging  individual tone shaping elements in the signal flow.

Frankly when used alone, the Noise on the  High Gain COSM Amp Model/Cab Sim its not much worse than a real Mesa Dual Rectifier cranked up with its high gain lead channel  - the "real deal" makes a lot of hiss and noise too  - and don't believe the folks who say " Roland accurately modeled the Hiss and Noise of the real Amp!"    - its just an artifact of DSP processing.

And know that any source of hiss in your entire 13 pin signal chain has a direct impact on the hiss and Noise that is heard at the GP-10 Output Jack  - this why I avoid the GraphTech Piezo 13 pin Systems ( lots of hiss and noise is generated by the Graphtech Board, and prefer RMC Piezo as these have the lowest noise and highest SNL and high Dynamic Range. The Stock Roland GK-3 is not too noisy either and  benefits with more accurate results for all High Gain Rock/Metal/Blues COSM Amp modeling   

rac2112

Thanks for the reply Elantric - really just wanted to check that the background noise is to be expected, amazing how successful the noise suppressors are, I hadn't noticed any noise at all until I turned them off!

Jerry K

Also, if you are connected to usb, I have noticed that can add some high frequency noise.  Simply unplugging the usb cable makes it go away.


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MusicOverGear

I had that problem. I made a pair of cables that is TS on the GP 10 side, and TRS on the amp side, with the ground lifted. In other words it goes from TS to TR. I have no idea what the bad audio implications might be, but it cleared up the noise problem, and I didn't notice a difference in sound.

Also with that setup if you do unplug the USB cable, there is no ground and I don't think you would get any audio . Maybe there's a way to lift ground on USB, but I have no idea how to do that.

Quote from: Jerry K on November 09, 2014, 02:32:28 PM
Also, if you are connected to usb, I have noticed that can add some high frequency noise.  Simply unplugging the usb cable makes it go away.


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macman70

I am not hearing any problem here with USB cable connected to my GP-10 and recording into Logic

I am frightened i will go listening for it now.... ???

I carry on as i love this thing!!

Elantric

#6
USB Noise often can be traced to a switching power supply.

For lowest noise, Try running GP-10 with a fully charged battery on laptop computer, and no power supply.

Macs have a leg up on most PC, as Apple implemented a filtered power supply to tame noise being injected into the audio stream, while most windows PC makers never bother.

Dornishman

#7
First I'd like to say hi and thanks for all of your participation in this forum, I've lurked for a long time but now I feel the need to ask a question.

The setup I'm trying is two outputs, illustrated below:
Guitar mag -> GP-10 input -> GP-10 Guitar out -> Mesa Mark V -> Mesa Cab Clone -> XLR to interface

Guitar GK -> GP-10 GK input -> GP-10 mono out -> interface

Interface can be anything, this is happening on my band's mixer and my USB interface. As soon as both those chains reach the interface, I get a high pitched, constant squeal on high-gain channels. Is what I'm trying to do inherently flawed? This might seem like an obvious or dumb question but I've never tried anything like this before.

My present workaround is to send the GK output to my amp, but obviously that doesn't work great with the COSM models. My friend wants me to put a DI box between the GP-10 and our board. Any input you guys have would be greatly appreciated. If you're wondering what I'm on about and need more info don't hesitate to ask.

Elantric

#8
Power Supply Switching noise invades the audio when a Ground loop condition exists.

learn to tame it by reading post above, and below

Fix your Audio Ground Loop Buzzes and Noises
https://www.vguitarforums.com/smf/index.php?topic=2078.0


And your friend is on the right track suggesting a Passive DI box with galvanic isolation