Join Date: Dec 2000
Location: Melbourne, FL 32940
Re: Need HELP with my very first rack effects unit
I've been running rack units since 1989, so I've hooked things up in all kinds of strange ways.
First you need to understand amps, combos or heads and rack power amps.
A Combo amp or Head, is made up of two parts, the Preamp and the Power amp.
The effects loop is placed between the two.
1. Preamp, the Bass, Mid, Treble, Presence and Distortion
2. FX Loop Send
3. FX Loop Return
4. Power amp, the Volume (The Noise Maker!)
If you only use the FX Loop Return, you are bypassing the Preamp section of the amp, this is why there was no distortion when you switched channels.
This is where I have a beef with Combos and Heads.
The Preamp section of a Combo or Head limits the amount of tone that can be run to the power amp, a bottleneck is created.
This is why they get muddy when you try to add to much EQing to get the tone your after.
Effects and some pickups can cause the same problems on some amps too.
I learned this years ago with my 5150 Head.
I was trying to run my ADA MP-1 and Rocktron Pro-Q (EQ) in the front of the amp.
I was trying to add more bass and it just mudded out on me.
So I bypassed the Preamp and plugged in to the FX Loop return.
I had to use my ADA to control the volume level.
The knobs on the front of the 5150 were useless, no 5150 Preamp.
Then I was able to get more bass without the muddyness now that the preamp bottleneck was out of the way.
This is what rack power amps are, good clean power without any tone.
A good rack power amp should do nothing but blast whatever you are running in to it without coloring the tone at all.
If you want to run this rack unit with your amp, plug the guitar in to the front of the amp.
Plug the FX Loop send in to the input on the rack unit.
Then the output of the FX unit to the return on the amps FX Loop.
You should start with the level control knob on the FX unit down all the way.
If you can bypass the FX Loop do it to listen to how load the amp is.
Then enable the FX Loop and turn the level knob up unit it sounds like the same volume as with no FX Loop.
This way you won't over drive the I/O and end up with line distortion.
If the FX unit has input and output level knobs, run the up until you see the meters at a normal level.
Then turn the output up to match the amps volume level.
On some amps the way it's wired, you need to keep adjusting the input level because the preamp level keeps going up as you turn the volume up on the amp.
This causes the input to the FX unit to clip.
If this happens to you, turn the input level on the FX unit down to compensate for the greater input from the preamp.
Let me know if you have more questions.