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If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by Krontab on 2012-01-08 17:21:53

I have a HD500 L6 linked to a DT25. I'm running into a strange noise issue. If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise.

What I'm trying to accomplish is this chain:

GTR>HD500 WAH>FX Loop Send>Boss MT-2 (External)>FX Loop Return>Pre Amp Model>DT25 Power Section

For a test I plugged in my guitar and rolled the volume completely off. I then set up a treadplate pre in the amp block for a noise baseline (see No Loop.bmp).

When I add the FX Loop Block the is a hop in noise whether or not a external pedal is in the loop. In other words if I jump the out to the in, put the MT-2 in chain in bypass mode, or Leave the inputs with no jump I get noise added (see With loop.bmp).

Now if I dont remove the loop but turn the module off the Noise remains (see Loop Off.bmp).

This doesn't make sense is this a software bug? I would like to get this sorted before my return period is up on the 24th.



Re: If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by jimsreynolds on 2012-01-09 05:41:46

There is a switch on the back of the HD that sets the loop level to 'Line' or 'stomp'.   I would expect this to be set to 'Stomp' for the MT-2.

I found, while setting up 4CM, that having the loop set to 'Line' causes a jump in the noise threshold.  This is not too noticable on cleaner or mid gain tones  (or when the FX loop goes after the amp model/real pre-amp) but is a real dog when you are running the loop before a high gain amp where all extraneous noise gets boosted.

Where is yours set?



Re: If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by Nick_Mattocks on 2012-01-09 06:41:18

+1 to Jim

Additionally, remember that the Treadplate Pre is a very high gain amp model and can be noisy anyway, so any tiny bit of additional noise you add in front of of it will be amplified by quite a margin.  You may need to look at adding the Hard Gate NG immediately after the loop as well as looking at setting the loop level to Stomp as Jim suggested.

Nick



Re: If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by Krontab on 2012-01-09 12:59:52

No matter what way it is set the noise exists. This was set to stomp initially though. It is set pre the amp model. At least you have confirmed my concerns about cabling. Since the audio is in the digital realm adding the fx loop should have no more noise addition than adding a pedal in bypass mode in front of the guitar input. I think there is a software issue here.



Re: If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by Krontab on 2012-01-09 13:02:08

I agree but if the loop is not turned on (as in Loop Off.bmp) it should not add additional noise. That is what is baffeling me.



Re: If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by jimsreynolds on 2012-01-09 17:03:20

Ah !  

RIght, there is a setting in the first page of the System menu: 'Trails'.

When Trails are turned on then  the FX loop return remains on even when the loop is turned off.  The point of this setting is to allow effects like delays that are in the loop to ring out naturally.  Try setting this to 'off' and see if it helps.



Re: If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by Krontab on 2012-01-10 07:53:16

Nice I was wondering what trails meant. Thanks for the assistance. I still thinks its quite noisy but this helps.



Re: If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by jimsreynolds on 2012-01-10 08:10:28

Cool.   Be aware:  trails is applied per patch so you need to set it wherever you use the FX Loop. 



Re: If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by gregr on 2012-01-10 08:13:54

Also, in order for the change to the trails setting to take hold, you need to toggle the state of the FX block.

I was also thinking there might be a ground-loop issue which can be taken care of by lifting the ground on your amp or using an isolation transformer.  Is the noise just hiss or is it humming?



Re: If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by Krontab on 2012-01-10 10:38:29

Not 60 cycle hum. Just hiss, what it points out is that the return input is noisy. I love listening to the background radiation of the universe as much as the next guy but this doubles the noise floor when active. Theoretically if you just jumped the send to the recieve with a 3 inch cord you should not get much noise increase at all but in this case you do. It makes me think that there is a subtle bump in gain on the return rather than being in unity with the send. Before you ask, I did make sure that the return level was set to 0,0. Essentially this really only poses an issue with the high gain models so with the trails off, it's acceptable to me as I'm just running distortions pre the amp model. If I really need it I can use the noise gate just post the loop. It doesn't have any signifigant increase when the loop is post any amplifier model. Bottom line is if I use the Heay Distortion model instead of my stand alone pedal I have no issues. Although the real MT-2 does sound best as its tone shaping is better.



Re: If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by gregr on 2012-01-10 10:45:25

How do you have the inputs configured?  Depending on where the block is placed you may have a 6 dB increase in gain if you have them both set to same.



Re: If I insert the FX Loop block before the pre amplifier block I get a lot of additional noise
by Krontab on 2012-01-16 20:40:44

Gregr can you explain this a bit. The inputs are input1 = Guitar, Input2 = same




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