Got Rid Of Some Hiss. Found Some More.

[dfrattaroli]

I've really made some strides in getting the noise in my rig removed. This weekend, I removed all the Dimmers on the circuit that my gear is plugged into. I was shocked at how much noise they created.

But then I found something else. I run 2 rigs and switch between them with a GCX. One rig is the Egnater M4 into an RT2/50 and the other is an Axe FX into a Carvin DCM150. I run my signal like this...

Guitar -> GCX Guitar In -> GCX Guitar Out -> Loop1(BB Preamp) -> Loop2(Whammy) -> Loop3(On: M4, Off: Axe).

Yesterday, I tidied up the wiring a bit. Shortened some AC cords, tie wrapped them, etc.

Long story short: If I run straight into the M4, it's very, very quiet now (after ground lift, no dimmers). However, when I feed it from Loop3 of the GCX, I get alot of hiss. As soon as I plug the Send from Loop3 into the rear Input on the M4, the hiss starts. So, something between the M4 and either the GCX or something plugged into it, is amiss. The hiss happens even when the Axe is not in the Loop with it so I'm fairly certain it's not the Axe an M4 sharing a loop.

It's not a ground loop hum/buzz. It's a hiss.

I've read that this could be a level mismatch or something like that. Any pointers?

Thanks.

Dave

PS The signal is never passing through both the Axe and M4 at the same time.

 

[RACKSYSTEMS]

The Egnater has a very low series resistor inside the amp. The lower value resistor the lower noise. This is only true when the guitar is plugged in straight. If you introduce say a buffer in front the noise will increase a lot. Now if the Egnater had a bigger series resistor it would have more hiss on its own and when you would add the buffer you would not really notice a change. It really is all about the thermal noise of the resistor. Dave

 

[bds9487]

Is the rear input on the M4 a guitar input or part of the loop? In other words, is that input "line level" or "instrument level"? If it's line level I can see where you might get some hiss.

 

[Jeff Hilligan]

Rear is guitar input #1 and then front is #2 then audio.

 

[dfrattaroli]

The Egnater has a very low series resistor inside the amp. The lower value resistor the lower noise. This is only true when the guitar is plugged in straight. If you introduce say a buffer in front the noise will increase a lot. Now if the Egnater had a bigger series resistor it would have more hiss on its own and when you would add the buffer you would not really notice a change. It really is all about the thermal noise of the resistor. Dave

Interesting. So then, if I use the "through" jacks on the GCX and bypass the buffer, I should get no added hiss?

Dave

 

[dfrattaroli]

Is the rear input on the M4 a guitar input or part of the loop? In other words, is that input "line level" or "instrument level"? If it's line level I can see where you might get some hiss.

My M4 is a newer one with no loop. As Jeff said, both are instrument level.

 

[dfrattaroli]

Bypassing the buffer in the GCX (by using the "through" jacks) has no effect. So I guess I need an ISO box between the M4 and GCX?

 

[steve_k]

The GCX does not have the best transformer isolated loops in the biz. I had the same thing with mine trying to run two high gain amps, which is why I went to a Bradshaw switcher from Custom Audio. Dead quiet....and you don't have to fool with y-cables, just a send to each amp.

Steve

 

[dfrattaroli]

The GCX does not have the best transformer isolated loops in the biz. I had the same thing with mine trying to run two high gain amps, which is why I went to a Bradshaw switcher from Custom Audio. Dead quiet....and you don't have to fool with y-cables, just a send to each amp.

Steve

I can't really spring for the Bradshaw. I just want to deal with the noise in some way. Would a GRX4 be better?

 

[muudrock]

The GCX does not have the best transformer isolated loops in the biz. I had the same thing with mine trying to run two high gain amps, which is why I went to a Bradshaw switcher from Custom Audio. Dead quiet....and you don't have to fool with y-cables, just a send to each amp.

Steve

I can't really spring for the Bradshaw. I just want to deal with the noise in some way. Would a GRX4 be better?

I think it would work. Might want to look at the RJM RG-16 or Effects Gizmo as well. I switched to an RG-16 a while ago an it is an definite upgrade in tone. Great buffer and dead quiet running 2 amps, 5 pedals and an FX box.

 

[dfrattaroli]

The GCX does not have the best transformer isolated loops in the biz. I had the same thing with mine trying to run two high gain amps, which is why I went to a Bradshaw switcher from Custom Audio. Dead quiet....and you don't have to fool with y-cables, just a send to each amp.

Steve

I can't really spring for the Bradshaw. I just want to deal with the noise in some way. Would a GRX4 be better?

I think it would work. Might want to look at the RJM RG-16 or Effects Gizmo as well. I switched to an RG-16 a while ago an it is an definite upgrade in tone. Great buffer and dead quiet running 2 amps, 5 pedals and an FX box.

I'll check out the gizmo. The RG-16 is sweet but at $650 it's more than I want to spend. Especially since I'm at the point where I say, "screw this fancy switching crap". I'm not gigging and I only play in my house so if it's an easy switch ($$), I'll do it. I'm just in one of those "simpler is gooder" moods and may opt to just sell some superflous gear.

 

[Klark]

Dfrattaroli, on your DCM150 and the RT2/50 are you running the attenuators all the way up, or even above 12 o'clock ??

And where are the output controls of your M4 and AxeFx ?? If your amp controls are way up, then I would presume your M4 and AxeFx output controls are way down ??

 

[dfrattaroli]

Dfrattaroli, on your DCM150 and the RT2/50 are you running the attenuators all the way up, or even above 12 o'clock ??

And where are the output controls of your M4 and AxeFx ?? If your amp controls are way up, then I would presume your M4 and AxeFx output controls are way down ??

On the DCM150, which powers the Axe, both channels are full up. The Axe's Output 1 control is where I control the over-all level. It's usually around 10:00. On the RT2/50, both channel outputs are at 50%. The Master on the M4 is low around 9:00. The module volumes are around 50%.

 

[Klark]

You have a loading issue. Bear with me..

I've found the M4 has input & output loading issues. My old CAE 3+ was super sensitive, my guitar practically played itself. With my M4, I have to beat the shit out of my guitar to get anything out of it. I solved the problem my adding a buffer and leaving my compressor on all the time.

Same thing with the M4 output. When I ' Y ' the ouput of my M4 to drive a DRY side, and the other side to drive a delay unit for WET, the tone goes to shit because the output of the M4 has either a too low or too high output impedance, or my delay unit has either a too low or to high input impedance. Whatever the case, I never had any of these problems until I switched from my 3+. Anyway...

You're definitely experiencing the same type of thing, a definite loading issue. The send of the GCX is changing your impedance up or down, not sure which way, as I don't know the true spec of the GCX or the M4. And not to piss on your picnic, but adding an iso or buffer will not help as the iso & buffer will most likely load/unload the input of the M4 just as much as the GCX send.

Bob Bradshaw will confirm the unusual input & output impedances of the M4 as well. His exact words were, "Those things sound & play like you have dead strings."

How to fix the problem? Good question. If you don't want to spend any money or upgrade anyhting, you'll just have to start experimenting. Maybe try two loops - One for your M4 and one for you AxeFx ??

One fix for sure would be an upgrade to an RJM Effects Gizmo. The last four loops are transformer iso'd and work very with the M4s that I have. I have one M4 in loop 11, and the other in loop 12. No hum, hiss, buzz, or loading issues at all. They sound and play exactly as I'm plugged into the M4 inputs.

 

[RACKSYSTEMS]

Ok so what you are saying is gtr into a loop and then take the snd to the pre and the sound is different? No cant be. All you are going through at that point is 2 jacks. The gcx loops are a hard contact relay no impedance of any kind. So try that first. We are talking hiss right?

 

[RACKSYSTEMS]

plug into loop 1 and and come out your a/b loop to the preamp with nothing else connected. Is that quiet? ok then add 1 thing at a time and see when the noise starts.

 

[dfrattaroli]

Ok so what you are saying is gtr into a loop and then take the snd to the pre and the sound is different? No cant be. All you are going through at that point is 2 jacks. The gcx loops are a hard contact relay no impedance of any kind. So try that first. We are talking hiss right?

Hey Dave. No, the sound is the same. I just get way more hiss. My signal hits loop 3's In. The Loop 3 Send goes to my M4 Rear Input and the Loop 3 Output goes to my Axe Input. So, Loop 3 On is the M4 and Loop 3 Off is the Axe. In this config, I get hiss. If I remove the jack from the rear input of the M4 and plug the guitar straight into the front input, I then have no connection to the GCX, I have no hiss.

 

[dfrattaroli]

plug into loop 1 and and come out your a/b loop to the preamp with nothing else connected. Is that quiet? ok then add 1 thing at a time and see when the noise starts.

Dave, I want to make sure I get what you're saying. Am I plugging my guitar straight into Loop1 In on the back or into Guitar In on the front -> Guitar Out -> Loop1 In -> Loop1 Send -> M4 In?

I'll give this a try when I get home tonight.

 

[dfrattaroli]

One fix for sure would be an upgrade to an RJM Effects Gizmo. The last four loops are transformer iso'd and work very with the M4s that I have. I have one M4 in loop 11, and the other in loop 12. No hum, hiss, buzz, or loading issues at all. They sound and play exactly as I'm plugged into the M4 inputs.

I was just looking at one of those. Thanks for the info.

 

[Klark]

Even with hard wire relay, there's still a considerable resistance increase compared to just a guitar cord. The input of the M4 looks for a much narrower or wider input impedance, not exactly sure which. Stray away from that too far and it'll load/unload the input, raise/lower the noise floor, and cause problems. Get out your meter and try this:

Measure tip to tip of your guitar cord, it'll be very low.

Now, touch the red lead of your meter to the tip of your guitar cord plugged into the INPUT of loop 1 on the rear of your GCX. Then touch the black lead of your meter to the tip of a short cord plugged into the send of loop 3 on the rear of your GCX. I guarantee there will be a major difference, well more than enough to wreak havoc on the input loading of the M4.