Radial X-Amp output level.

rfahey86

Death Be Not Proud
Jan 15, 2010
221
0
16
Dickson City, Pa
More specifically those using it with an interface such as the mbox 2 with unbalanced outputs. This is a long post so you can skip to the fix if you want to.

I bought my x-amp about 2 years ago and have only used it a few times because the output signal was always very low. I would turn the gain all the way up on the mbox 2 output and it would distort it. Needless to say I stuck it in a box and forgot about it. Until the other day.....

The user's manual for the mbox 2 says the mbox has balanced outputs so i used a 1/4" trs to xlr adapter to xlr cable to connect the two units as I had been doing before. I had the same results as before. I decided to start poking around online to see if i could find a fix for it. I found nothing except other people having the same problem and that all the big retail sites (such as american musical, musiciain's friend, zzounds, etc.) listed the mbox 2 as having unbalanced outputs.

So I decided to modify the adapter I had that was originally 1/4" TRS to XLR, and make it a 1/4" TS to XLR. It worked great. The x-amp worked like it was supposed to.

Here is how I fixed it:

There are three wires inside the adapter. (this will work if your making a TS to XLR cable as well)The are listed as follows.

TRS
Red (hot) - Tip
Blue/Green (cold) - Ring
Black (ground) - Sleeve

XLR
Pin 1 - Ground
Pin 2 - Hot
Pin 3 - Cold

Connect them as follows:

TRS red - XLR pin 2
TRS black - XLR pin 1
TRS blue - Remove completly from TRS (This is not used)
Jump Pin 3 to pin 1 on the XLR.

Your TRS adapter/cable has now become a TS to XLR unbalanced adapter.

Sorry for the long post. I just though this might help someone else who is scouring the site for a fix to the problem.
 
Interesting. I got rid of mine because the output signal was too low and it created a shit ton of noise. Got the Line 2 Amp for $30 or whatever it was and couldn't be happier :p
 
What people don't realize is that cheap interfaces don't have the output that is required for going back into an amp, and will blame the DI for being too low in signal. Reamp transformers typically have a 1:1 ratio, the the output voltage is that of the interfaces output. The issue you had is the result of a cheap interface where some modifications are in order to rectify the issue, but at the end of the day, Avid probably wasn't thinking that users of the mbox would be reamping, especially not high gain metal music. Tsk Tsk on them, but hey what can you do.

A small explanation, if you have a balanced configured transformer and the cold connection isn't connected and you have no current flow in the transformer (the reamp). The fix is to short the cold connection of the transformer primary to ground give the signal the hot connection to ground so current can flow, allowing for the transformer to charge and allow it to do its job, transferring the signal to ground.

Good little post BTW.
 
It`s only 6 db of gain (or so), not too much, especially considering that X-Amp itself probably have 11-12 db of gain reduction (similar to unmodded ProRMP).
 
Interesting. I got rid of mine because the output signal was too low and it created a shit ton of noise. Got the Line 2 Amp for $30 or whatever it was and couldn't be happier :p

Fucking THIS. Built a Line2Amp early 2012 and have never worried about output to amp. All the math is there, and isn't a box of "this can't possibly fuck up an input stage, solid state or tube, sell that shit". It's all in the trafo, the L2A uses an Edcor with a value of 10k:150 and a 200R resistor as an instrument output shunt. WORKS.
 
Fucking THIS. Built a Line2Amp early 2012 and have never worried about output to amp. All the math is there, and isn't a box of "this can't possibly fuck up an input stage, solid state or tube, sell that shit". It's all in the trafo, the L2A uses an Edcor with a value of 10k:150 and a 200R resistor as an instrument output shunt. WORKS.

That would be great if you have a balanced line out that has an output of +20dB which is typical of most decent quality interfaces, but cheaper interfaces, or even unbalanced interfaces (or worse, both), then the output of the L2A won't be high enough due to the winding ratio. As good as the L2A is, a passive device won't fix the lack of signal from a cheap interface.
 
A small explanation, if you have a balanced configured transformer and the cold connection isn't connected and you have no current flow in the transformer (the reamp). The fix is to short the cold connection of the transformer primary to ground give the signal the hot connection to ground so current can flow, allowing for the transformer to charge and allow it to do its job, transferring the signal to ground.

Good little post BTW.

That's an excellent way to sum it up. I was just trying to put it in a form that even someone with little or no experience in wiring could understand it. Kind of like a paint by numbers.
 
I bought an X-Amp a few years ago and noticed that the output was too low, so I called Radial and asked them about it. They said they had a bad run on accident and that the wrong components were used, resulting in less-hot an output. Give them a phone call and tell them your serial number on the unit. I think I paid shipping to, but I think they paid shipping from, and they fixed it for me for free. Now the thing's blazing hot. You might want to give them a shout and see if yours falls under that set of circumstances.