Iconoclast FX loop question. Please help!

Hello! I'm new to this whole FX loop thing, and I have what is probably a silly question but I figured I would ask before trying this and potentially ruining my H&K GM36.

I'm trying to set up my GM36 with a Neunaber Iconoclast plugged directly in my Focusrite USB interface. I don't have a cab hooked into this so I'm running straight from the RedBox out on the GM36.

Now Neunaber has a diagram of how to hook up the Iconoclast into the FX loop (which is what I want for my pedal board) of an amp and plug the Iconoclast into a USB interface (I have linked an image of said diagram) However, my concern is that using this method I'm not running my amps DI into my interface and I know that if you don't use that on the GM36 you could damage the amp? Unless I'm mistaken and I can use it in silent mode without going through the Redbox DI.

How would you go about doing this? Can I go straight from the FX loop into the interface without using the DI or do I need to change this set up somehow?


Thanks for your help! again sorry if this is a dumb question but I've never set this sort of thing up before...

"...and I know that if you don't use that on the GM36 you could damage the amp? Unless I'm mistaken and I can use it in silent mode without going through the Redbox DI."

If I have what you are saying there right then no, that's not true. The three systems, Power Soak, Fx Loop and Redbox, are all independent of each other. (And we could add the Preamp Line Out to that as well.)

The speaker connection is the area where damage can occur. A valve amp must NEVER be run without a reasonably matched load attached to the speaker terminals. You can and will damage the output stage eventually if you run it without, particularly if there is no load there at all! On the GM36, even if you make a mistake and power up without a speaker connected and with the Power Soak set to a normal output, the amp will quickly sense the mistake and set itself to Silent. In that mode the Power Soak acts as the load in place of a speaker and everything is happy.

The Fx Loop can be used as an output just as well as the Preamp Line Out or the Redbox DI without any worry of damage to anything. All three give you a signal without disturbing anything about the working of the rest of the amp. The Redbox and the Preamp Line Out are independent outputs you can feed to external equipment without making any change to the settings and sound of the GM36. All you do when you plug a cable into the Loop Send is to pull off the signal from the Loop buffer amp which is doing nothing at that stage without a Return cable plugged in. When a cable is plugged into the Loop Return then the internal connection on that socket is opened up and all of the Power Amp input then comes from the signal from the Loop Send through your pedals, (or from an external preamp if that is where you are connecting it to).

The Redbox will not be harmed by not connecting it no matter how the Power Soak is set up.

The Preamp Line Out gives you the signal as adjusted by all of the amp's control settings except the Master Volume but without any of the Power Amp's tone or the simulated speaker cabinet adjustments. It is on the same signal line as the input to the Power Amp and has its own buffer amp to make sure it doesn't affect that in any way. It is useful when you run the Preamp into another Power Amp which will have its own effect on the tone from there to the speakers so no cabinet adjustment is necessary. The DI circuit section takes its input from the output transformer secondary so it adds to that the Master Volume and the whole Power Amp and simulates the speaker cabinet before giving you a line level output. It is intended for mixing desks for either Front of House feed or recording. I guess the Fx Loop signal is pretty much the same as the Preamp Line Out even though the controller board has it on a different output line. You can't see deep into the controller section as it involves digital manipulation.

Oh, and the DI out is balanced! That's a big plus if you have the option for a balanced input to plug it into. A decent balanced signal means much lower noise than a single sided one. That's why it has a XLR connection.



(Chinese proverb: "A moment of embarrassment is better than a lifetime of ignorance." There are no dumb questions except the ones you want answered but don't ask. )