4CM Hum Solution

[steveb]

Works for me anyway. In between the AxeFX send and the Amp input ( Boogie Mk IIC+) I put my Whirlwind Direct box in backwards, ie, the XLR end is connected to the Axe send via an adapter, and the 1/4 "input" end goes to the Boogies guitar input. Doing this immediately dropped the hum by about 1/2, and then activating the ground loop switch got rid of the rest of it. I previously had tried a Radial Bigshot in the middle, but its ground loop switch was ineffective. The other big advantage is that the Output 2 control gives much better control over the send level to the amp so that the amp reacts much more like the guitar is plugged directly into it now.

A direct box backwards matches mic signals to instrument level. An actual reamp box matches line signals to instrument level, so I suspect that might work even better, although I don't have one to try at the moment. I think I'll order one of the Radial Pro RMP's and see how that works at some point.

 

[Tabs]

Ok I'm about this close to ordering the Reamp v.2. What I want to know is if there would be an actual concrete way to determine precisely what the correct settings for the Axe-FX Output 2 and the Reamp Trim knobs would be in order to match it with the direct cable to amp guitar signal? Seems like if you could do that then you'd know the gain staging was correct and the hiss should be eliminated.

Ryan

 

[Tabs]

Nevermind, this won't work. The Reamp needs a balanced input signal and Out 2 is unbalanced only.

Sigh.

 

[steveb]

the Radial is cheaper than the Reamp so I'll probably try that one out. Buy it from someplace you can return it in case it doesn't work for some reason.

outside of an occilloscope or some such I'm not sure how you would exactly match the voltage settings, but In this case I think your ears can work well enough. Before the whirlwind, it was pretty obvious that Output2 was only effective for about 20% of its travel before it was overdriving the amp input to the point where it couldnt go anymore no matter how much further Output2 was turned up. In order to get a sound approximating the guitar into the amp I had to turn the preamp gain on the Boog way down, to like 2 or 3 instead of 7 or 8.

After using the reversed DI, Output2 is effective for most of it's travel, meaning I can put the Boog's preamp gain on 7 or 8 like normal and dial Output2 to get the amount of gain I'm used to with the guitar. Output2 is working much more like the Input level control works for the internal amp models. In addition the amp responds to volume control and picking like I'm used to.

 

[steveb]

Nevermind, this won't work. The Reamp needs a balanced input signal and Out 2 is unbalanced only.
Sigh.

Looking at the Radial it also has a balanced XLR. Just means you need an unbalanced 1/4 -> Balanced XLR adapter, which is what I'm using to hook up my Whirlwind.

one of these kind of things ( mines a different brand ). I've also seen similar cables that are 1/4" to xlr.

Looking closer, the Reamp actually has a combined XLR and 1/4" balanced input neutrik connector. My experience has been that you can use a mono cable to connect unbalanced and balanced 1/4" stuff at will. I found this explanation on Harmony Central that seems to confirm this:

"But what if you run 1/4" unbalanced lines, but your gear has 1/4" balanced connectors? No worries. TRS jacks are electronically balanced, so if you plug in a mono plug, they simply turn into an unbalanced output. (The one place where you don't want to plug a mono plug into a stereo connection is the headphone out.) "

Since I don't have a reamp to try it with though, no guarantees obviously.

 

[steveb]

I found a schematic for a line to guitar level matching circuit. I might try to build one just because it looks like fun, and probably a lot cheaper. Doesn't look particularly difficult. There is also a schematic for a similar one on the Jensen transformers website, but the Jensen transformer they recommend is like $70. Other manufactures appear to have transformers you can get for like $5.00.

Here's a link to a thread with the circuit I found:

http://electro-music.com/forum/post-143 ... highlight=

 

[CudBucket]

Steve, which Whirlwind DI are you using?

Thanks.

Dave

 

[steveb]

Steve, which Whirlwind DI are you using?
Thanks.
Dave

It's a whirlwind Direct2. I'm not convinced that there arn't easier ways to go though. I haven't had that hooked up for a while, but I did hook up the other day and just used the ground lift in my Radial BigShot A/B to quiet things down. I'm not currently setup 4cm, but Im going to try some of the stuff in the "ground loops without bandaids" thread sometime. I'm still thinking of building the little reamp box too.

 

[CudBucket]

Steve, which Whirlwind DI are you using?
Thanks.
Dave

It's a whirlwind Direct2. I'm not convinced that there arn't easier ways to go though. I haven't had that hooked up for a while, but I did hook up the other day and just used the ground lift in my Radial BigShot A/B to quiet things down. I'm not currently setup 4cm, but Im going to try some of the stuff in the "ground loops without bandaids" thread sometime. I'm still thinking of building the little reamp box too.

Thanks. I've since pulled the rig apart and started putting it back together to find the source. I used 2 shoulder washers on each screw to isolate the gear from the rails. I've got 2 more pieces to put back in the rig and so far no noise.