Grandmeister Deluxe 40 with Headrush pedalboard

I'm sure this has come up before but it would have been a long time ago so no problem in not finding it.

In the GM36 and we have to assume the GMD40 the order of applying processing is as follows:

1 )  Input Buffer/Overdrive
2 )  Gain Control
3 )  Valve Preamp Stages
4 )  Tone Controls
5 )  Volume Control (NOT Master)
6 )  External Effects Loop
7 )  Modulation Effects
8 )  Resonance/Presence Controls
9 )  Reverb
10) Preamp Out

There is no way of altering any of that.  You always have the option of placing pedals before the whole amp, (just bear in mind that with high signal levels and/or the amp's Boost applied you will have kicked in a pseudo-overdrive pedal in that buffer amp).  Any other effects go into the loop and must then be placed at stage 6) in the order of processing.

I'm not sure what you mean as "If I place any effect after the FX Loop block...".  Do you mean within the Fx loop?  As far as I can see, if you have the Fx Loop Send/Return system wired in correctly and you make sure to apply the GMD40 Fx Loop you should have your Pedalboard working.

It's not something simple like having the Send/Return the wrong way round is it?  (I'm sure it's not but it never hurts to check).  GMD40 Fx Send -> Headrush Return Left (Mono) -> Headrush Send Left (Mono) -> GMD40 Fx Return.

Are you using the Headrush to actually control the Fx Loop of the GMD40?

This is confusing me too. It would seem to me that if the GMD40 Fx Loop is engaged and you have sound then the rest should be down to the Headrush, that is unless you are using the GMD40's own effects. I've assumed up until now that you want to use the Headrush effects exclusively. All the GM can do is to accept what gets intercepted and passed on to it from the Headrush at its input, work on that as a plain amp internally, send out that signal via the Fx loop Send, then take back what is given to it from the Headrush after that processes the sound as you have it set to do so. The Headrush has to be incapable of sending the sound in that Fx Loop section anywhere other than back to the GM's Fx Return after it processes it as it has been told to do.

Let's go back to first principles here with the GMD40. It has absolutely nothing special about its Fx Loop other than to note that its own internal effects are Post Loop, they are all applied to the signal only after it returns from the loop. It should behave just as any other amp would without any special setup or control, the only option is to activate or bypass the Fx Loop.

H&K GMD40 Manual wrote:Tip: If you’re a stomp-box user, you may want to try the four-cord method: For devices that work best plugged into the front end of the amp, simply connect the guitar to the input of the first pedal in the chain, and the last pedal’s output to the amp’s Input. [In your case that is the effects you have programmed to work on that guitar input path within the Headrush]. Now do the same for devices that work best in the FX loop: connect the pedal’s output to the amp’s FX Return and the amp’s FX Send to the pedal’s input. [That will be the effects the Headrush has been told to work on the later loop section from the amp's Fx Loop]. This lets you route chorused, phased and other modulated signals into GrandMeister Deluxe 40’s preamp and time-based effects such as reverb and delay after the preamp.

If your multi FX unit features amp models, you can patch these straight to the GrandMeister Deluxe 40’s power amp via the FX Return. In combination with the Power Soak and the Red Box Recording Out, this gives you a powerful recording front end that offers very interesting reamping and sound-shaping options for just about every conceivable signal.

This matches my own view that the Headrush should simply be capable of being set up to have the effects you select working on the input signal from the guitar then feeding this to the amp input, and the effects you select working on the signal from the amp Fx Send and then returning that to the amp Fx return. That's pretty standard stuff and the amp is set up to do that naturally.

Like I said, I'm confused as to why this isn't happening, the GM is simple and standard in its Fx Loop setup.

That pic looks wrong to me!

I think you should have the Guitar In as pictured but then the Headrush output to the amp's Guitar Input is taken from the wrong socket.  The Headrush's central sockets are the Fx Loop Input and Output.  Look at the Headrush User Manual Page 5 which shows the sockets on the rear panel.  The guitar goes into socket 4 on the end as you have it.  The Output Left Mono which is the next one along the line is the one to the Amp Input.  The next along, Socket 12 Send Left Mono is the one to the amp's Fx Return socket.  Then Socket 13 Return Left Mono takes the cable from the amp's Fx Send socket.  This is just as I described it earlier in Post 2.

Just try switching the two mixed up cables on the back of your Headrush and hopefully everything should be fine. I know you say it is working but it may just be limping through in some odd state. Check the manual against your own wiring and have a rethink. If you don't have the manual here is a link: Headrush User Manual

Here is the page:

I think you may not be hearing what you think you are hearing at the moment.  The way you have the connections you are getting the following process:

Your guitar is going into the Headrush.
It is being processed by any effects you have set to "acting on input signal pre the Fx loop", not sure how you would describe that but I'm sure you know what I mean.
That signal is then being passed to the amp's Fx Return.
It goes straight on to the amp's internal effects, master volume, power amp and speakers.
If the Headrush cuts the signal through the unit when a plug is put into the "Mono Out To Amp Return" socket then the Headrush Fx Loop is responding only to the signal it is getting from the amp's Fx Send and that is nothing so far.
The Headrush Fx Loop then processes that signal and passes it back to the amp's Input.
It passes through the amp's preamp until the Fx Loop Send and gets routed back to the Headrush Fx Loop Return again.
It goes no further in the GMD40 because when a plug is placed into the GMD40 Fx Return (which you have) it cuts out the signal from the preamp so there is no way to get that signal through to the power amp and speakers.

Here is a little more info...

H&K GMD40 User Manual wrote:Heads Up: You can bypass GrandMeister Deluxe 40’s preamp by routing amp models into the FX Return. However, when you switch channels its power amp is re-voiced to deliver the best tone for that channel. This means every channel sounds different, even if you decide to use only the power amp!

Note:  "Only the power amp."

It really looks like you have shortened your processing chain to only the Headrush Pre-Fx Loop Effects and direct into the GMD40 after any of the preamp circuitry.  The whole of the GMD40 preamp circuitry and the Headrush effects set to act in the Fx Loop shouldn't be doing anything as they have been isolated by the amp's Fx Return socket switching.  I could easily be wrong on this as the Headrush may be doing something unusual but that is what the wiring diagram you posted seems to show.  The sound you are getting may very well be exactly what you want but it would be best to be sure it is being generated by what you think for your future work.

And please note here, I'm not arguing to be right, only trying to figure it out to make sure you are getting what you think you are.  

  Can someone else please check the logic of what I am saying here against Keetonian's diagram in Post#5 please?  

Sounds fine Keetonian. As long as you have the info there and you are getting the sound you want that is what is needed. I'll drop out now and you can see if there are any other users who have anything to drop in with. Happy strumming.