4CM (Preamp Only)

[ibanez6]

Hey all. So, I've got access to some external preamps I would like to start messing around with and might be purchasing one soon, and I would like to utilize the 4 cable method but also make use of the power amp modelling in the Axe FX III (using the tube pre block as recommended in the wiki) as I'm using a Matrix power amp. I have used 4CM many times in the past with previous rigs (prior to getting the Axe) but have some questions regarding the best way to go about this particular scenario.

I'm assuming I would hook up the 4CM as per usual (any preamps I would be using would have an FX loop) and then run the preamp output into say input 2 on the Axe, into the power amp block and output that to my Matrix power amp? Would there be any level settings I'd need to be wary of doing this to optimize the signal or avoid issues? Curious if anyone has done this before and could chime in with their experiences. Cheers!

 

[sprint]

I do this often with an external pre, and Matrix. I put the external pre (IN via external amp's front input and OUT via the external amp's fx loop send) into the Axfx3's loop3 out/in to take advantage of the unity gain design in loop 3 or 4. The incoming signal from loop3 goes into a "tube pre" amp block set up with neutral preamp settlngs (mostly stock - pre-sag off) and power amp section set as desired. I level the preset in 2 steps:

• with the Axfx amp block inactive and "thru", I adjust the external pre's channel output volume so the levelling tool just barely hits red.
• with the Axfx amp block active I adjust the Axfx "Tube Pre" amp block's output level so the levelling tool just barely hits red.

As far as the Matrix is concerned I set the Matrix knobs at 2 pm and regulate monitoring volume with the Axfx physical output knob1 (if using output 1 to Matrix Input).

My matrix goes out to 2 matching V30 112 cabs so I set the tube pre's speaker page curve to speaker IC parms that match what I think my cabs resonance is. Output mode in this config is "SS Pwr Amp + Cab"

Works well with the "Tube Pre" power section advanced parameters replicating whatever Axfx amp model's power section you want to mimic in combination with the external pre, however, I do find that the "Tube Pre" power section is difficult to drive toward compression (0 on the "Tube Pre" amp block Headroom Meter) compared to the actual models' power sections I've tried to replicate (I have to practically dime the MV/MV Trim on the "Tube Pre" to get it pumping to 50/75% toward clipping on Headroom Meter to match the mimic'd model's power section berhavior (I suspect there are some internal p.a. related parms not exposed to users that limits how close one can get to an exact power section match using Tube Pre)).

 

[ibanez6]

Hey thanks for the reply Sprint, that's very helpful! So if I'm understanding this correctly, you don't even need to use the FX Return on the preamp in this case?

So it would be Guitar -- Axe Input 1 -- Drives, Wahs etc... -- Output 3 -- Preamp Main IN -- Preamp FX Send -- Input 3 -- "Tube Pre" Block -- Parallel Effects (Chorus, Delay etc..) -- Output 1 -- Matrix Input

With regards to the Tube Pre amp model, Leon has a video where he's using his ADA into an amp block with the Tube Pre selected and then copies the settings from another amp block he's dialed in over to the Tube Pre block. Is that essentially what you do as well? This is the video here:

Cheers!

 

[sprint]

Hey thanks for the reply Sprint, that's very helpful! So if I'm understanding this correctly, you don't even need to use the FX Return on the preamp in this case?

No cable to fx return since the external amp head's power section is not used (the "Tube Pre" model is taking care of the power amp character part and the Matrix is taking care of the "make loud" part).

So it would be Guitar -- Axe Input 1 -- Drives, Wahs etc... -- Output 3 -- Preamp Main IN -- Preamp FX Send -- Input 3 -- "Tube Pre" Block -- Parallel Effects (Chorus, Delay etc..) -- Output 1 -- Matrix Input

Yes, + if you are using Full Range cabs (I have a set of these I can point my Matrix to), then you would add a cab block after the "Tube Pre".

With regards to the Tube Pre amp model, Leon has a video where he's using his ADA into an amp block with the Tube Pre selected and then copies the settings from another amp block he's dialed in over to the Tube Pre block. Is that essentially what you do as well? This is the video here:

Yes, I just finished setting one up with a Revv G3 pedal as the external pre and setting up the Tube Pre with power amp settings copied from the "Revv Purple2" amp model - sounds awesome.

Caution: Keep a cab connected to your external amp head even though its not generating any sound via power amp in this config, since the head's power amp will likely still want to see a load.

 

[ibanez6]

Awesome! Really appreciate the insight.

 

[AmbientOwl]

Yes, I just finished setting one up with a Revv G3 pedal as the external pre and setting up the Tube Pre with power amp settings copied from the "Revv Purple2" amp model - sounds awesome.

Sorry for the necro bump but the upcoming EAE/Science Preamp has me considering a purchase. I'm searching for preamp posts here but yours is the only one I'm seeing specifically about a pedal that doesn't have an FX loop.

Just curious how exactly you incorporated the G3 to make this work? I understand running the Tube Pre model after, but where physically is the G3? Before the Axe input? In an in/out loop?

Appreciate if you're able to give me details. Just want to be sure I can do what I'm hoping to do before purchasing.

 

[sprint]

Sorry for the necro bump but the upcoming EAE/Science Preamp has me considering a purchase. I'm searching for preamp posts here but yours is the only one I'm seeing specifically about a pedal that doesn't have an FX loop.

Just curious how exactly you incorporated the G3 to make this work? I understand running the Tube Pre model after, but where physically is the G3? Before the Axe input? In an in/out loop?

Appreciate if you're able to give me details. Just want to be sure I can do what I'm hoping to do before purchasing.

I have my G3 inside the Ax3 Loop3 which defaults to unity gain with front panel knob3 at full (loop3 left OUT to G3 IN / G3 OUT to loop3 left IN - loop3 input is set to "left only" in the audio setup menu). Loop3 OUT and IN blocks (in that order) are located just before the AMP+CAB blocks with AMP set to "tube pre". Pre-fx (ie wah) blocks go before the Loop OUT/IN and post-fx blocks (ie delay) go after the AMP + CAB blocks. My output1 goes to monitors / FRCabs.

I'll post a preset later when home from skiing

 

[AmbientOwl]

I have my G3 inside the Ax3 Loop3 which defaults to unity gain with front panel knob3 at full (loop3 left OUT to G3 IN / G3 OUT to loop3 left IN - loop3 input is set to "left only" in the audio setup menu). Loop3 OUT and IN blocks (in that order) are located just before the AMP+CAB blocks with AMP set to "tube pre". Pre-fx (ie wah) blocks go before the Loop OUT/IN and post-fx blocks (ie delay) go after the AMP + CAB blocks. My output1 goes to monitors / FRCabs.

I'll post a preset later when home from skiing

This makes sense to me. I was hoping it would be that easy. Thank you!

 

[sprint]

Here's a sample starting point Ax3 preset. I have the "tube-pre" amp model set up as power amp (pre off) and tweaked to power amp character of the "Revv Purple 2" amp model. Physical G3 settings also shown (fyi - I don't use my physical G3 much any more since we got the Revv models in Axfx). I have other outboard preamp pedals also working in pretty much the same way (keep them in a loop switcher so that I can midi select individual ones with preset/scene changes).

Edit: Note, my audio setup config for this from the other thread: Output3: "SumL+R", Output3 Pad: "6Db", Input3: "Left Only". In these type patches, only mono config'd blocks should be placed before the loop, and Amp Blocks - stereo is introduced at the Cab block.

The Output3 "boost/pad" set to 6db on output3 to provides some noise floor reduction with the active loop but also allowing sufficient headroom before clipping on Output3 (in case I want to operate a boost model through output3 to push the front of an external physical preamp). Nothing fancy - pretty much "out of the box"

 

[AmbientOwl]

Here's a sample starting point Ax3 preset. I have the "tube-pre" amp model set up as power amp (pre off) and tweaked to power amp character of the "Revv Purple 2" amp model. Physical G3 settings also shown (fyi - I don't use my physical G3 much any more since we got the Revv models in Axfx). I have other outboard preamp pedals also working in pretty much the same way (keep them in a loop switcher so that I can midi select individual ones with preset/scene changes). Note: Output3 "boost/pad" in the audio setup menu is set to 6db on output3 to provide some noise floor reduction with the active loop but also allowing sufficient headroom before clipping on Output3 (in case I want to operate a boost model through output3 to push the front of an external physical preamp). Nothing fancy - pretty much "out of the box"

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This is awesome. Can't wait to tinker with this. I've been exploring all the "in-the-box" stuff in the Axe for so long that now I'm trying to figure out how best to incorporate the preamp pedals I kept to get even more variety out of my rig. This sure made things easier. Appreciate it!