[SOLVED] Please help. Am I overlooking something with 4CM (Diezel VH4 and FM3)?

sprada said:
Connected directly to the amp? It's pretty much silent.
On Channel 2 it's around 59 dbs at gig level.
With 4CM and FM3 at the same level is around 80dbs (with the Morley Humno went from around 80 dbs to around 73/74 dbs)
(these measurments are done with the guitar volume roled off.)
Click to expand...

To be clear, I’m asking about when the FM3 is still connected in the amp’s FX loop, but instead of the guitar going into the FM3 and then sent to the amp input, you just unplug the guitar from the FM3 and plug it straight into the input of the amp. I’d also suggest trying just unplugging the input to the amp entirely and see whether that eliminates the noise (if not, then the noise is originating at or after the amp’s preamp).

I’m trying to isolate whether the noise is originating from before or after the amp’s preamp (in order to suggest what might be adjusted to reduce the noise).
 
I think this is figured out.
Thank you so much for all your help.

I bought a Morley Hum eliminator and it didn't do much for me.
Helped a bit but the problem was actually a very high hiss on the diezel gain channels and not actually ground loop.

What did it for me was using a Radial Pro DI between the amp send and the FM3 In 2L.

I'm using the 4CM Out2 method:

FM3 Out 2L TRS -> Amp input TS (humbuster cable)
Amp FX loop send TS -> Radial Pro Di Input TS -> Radial ProDi Out XLR -> FM3 In 2L (TRS)
FM3 Out 2R TRS -> Amp FX loop return TS (humbuster cable)

Current Audio setup:
1699917013340.png
If I set the Out2 level to anything above 6dB I get into clipping territory.

Out 2 is set to stereo and I'm panning the 2nd row left and 3rd right (see below)
1699917095661.png
Physical Out2 Knob is maxed out.

The Out2 block Level is set to 15dbs (this compensates for the DI volume loss).

With In2 default gate levels I actually have a lower noise that just having the guitar connected directly to the amp.

Thank you to everyone that chimed in.
 
Last edited:
sprada said:
Hi everyone.

After many years not using Fractal products I decided to buy an FM3 to use with 4 cable method with my Diezel VH4.
I was not expecting any problems since the Diezel has a very high quality effects loop (has actually 4!) and I've used 4CM with a Gigrig g3 and "real" pedals without any problem.
It was very silent.

Just tried today the FM3 and it's simply not usable.
It's so so noisy.

I'm kind of hoping I've messed something up.

Rundown of the setup:

FM3 Audio Setup:
Output 1 = +4db (-10db seems way too silent). Physical knob is at around 12 o'clock (less than that and I'm losing volume)
Output 2 = Set to unity gain. Boost/pad set to 18db (helps a little. And it is not clipping). Physical knob is maxed out.
Input 1 and 2 have pad at 0db.

View attachment 129030

I'm using the exact same setup as suggested in the manual.
Cables are very high quality and were custom built to specs by audiocables.eu (humbuster is being used as suggested)

Everything is connected to the same plug.

I've tried a lot of things and nothing is really helping.
Lowering Output 1 helps but having the knob at less than at 12 o'clock I'm definitely losing volume.

Just to have an idea.
With the guitar connected and volume completely rolled off on the Diezel channel 2
4CM I get 74db
Guitar straight to amp I get 55db!!!

I don't know what else to do.
Any suggestions?
Am I doing something wrong?
Click to expand...
Use Radial StageBug galvanic isolator (try putting it before the amp and one channel in the fx loop) ✅
 
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