Building rack rig

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Divide_By_Guitar

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And I'm confused about if certain things will work with certain things.

This is my first post because I have gotten to the end of my rope with searching the Internet and finding half answers or no real answer at all. Hopefully this will help. Thanks for the input in advance.

I'm building a new rig and I'm not sure if some of the parts I have will work together. I'd rather ask than fry something and rack up a huge repair bill or lose the piece of gear. I'm putting a Mesa Boogie mark IV rack mount in with a gmajor 2 and an rmj rg16 for midi switching and pedals. I also have an engl e530 that I would like to use in this if possible. Running it off of the Mesa power section and being able to also use the mesas channels also. Basically A/B between the preamps while still being able to use the gmajor for effects and whatnot. If it's not possible it's not possible and I'm just back to what I have. If it is possible that would be cool. Any input into routing for this would be greatly appreciated.
 
Yeah, once HRI went down last year there really isn´t a natural home for rack questions left out there. The Rack Space over at TGP might become good, though. But anyway, there are still plenty of us running fairly elaborate rack rigs and know how to do it - and I´m happy to report that your proposal actually is pretty basic!

What you need to do is:
A: Split the guitar signal using something with ground isolation to prevent ground noise. The Lehle P-split is a great passive unit, especially if you are splitting after buffers or pedals - otherwise I´d go with a powered option. One side to the Boogie and one side to the Engl.

B: Take the loop send of the Boogie and the main out of the Engl and route one to the IN of a RG16 loop and one to the RETURN of the same loop. Voila, instant A-B switching! When the loop is bypassed the IN gets passed on to the OUT, when the loop is on the RETURN gets passed on. This is the beauty of loops that have the full IN-SEND-RETURN-OUT circuit, you can do tons of stuff with them. The RG16 has four loops that can do this, any of 5-8 will do.

C: Take the OUT of the same RG16 loop into the TC and finally on the the loop return of the Boogie.

D: You may have to lift the ground on the signal coming from one of the preamps. If you make your own cables you can just unsolder the shield on the end going into the RG16 loop. Otherwise there are plenty of commercial options, like the Ebtech Hum Eliminator, and this is also what Fractal charges for as their proprietary Humbuster cable. This is perfectly normal with unbalanced circuits and is not dangerous.
 
Thanks! This rig is so I'm not moving so much to play shows. My other rig is similar but with 2 heads and 2 cabs so the power/switching was a basic a/b between the 2 amps. Also with just pedals in the looper. So it's a half midi half analog pedal type thing. Handy but bulky to move.

This current rig all fits into an 8U rack believe it or not with pedals mounted behind the amp. Only 2 pedals. Not much room. Anyway I'm getting off on a rant/topic.

what you said to do sounds perfect for the application. Just didn't know if I could do the preamp thing. Thanks.
 
Yeah, as long as you take those steps to avoid ground noise you should be fine. Why rack rigs got a bad rap in the 90s and beyond is that people just sort of forgot how to wire them properly and ended up with horrible racks that had tons of noise and crappy tone with heaps of serial AD/DA conversions, impedance mismatches, bad gainstaging, wrong levels and so on...

You can never hurt anything just messing around with guitar or line level signals, in any case, only with speaker signal.
 
Yeah, some of this stuff I've only used a certain way for a certain thing. Not really switched and looped like this. Basically, not knowing how sensitive this stuff is at a certain point.

You certainly can damage an amp in bad ways if you don't have a load on it like a speaker and power it on. I've told a few people this and then had to refer them to the amp guy for a repair.
 
Yeah, like I said speaker signal is something else entirely!
 
-hmmmm... Can you use the same power section-(of the MESA)-with different pre-amps at the same time? or just one at a time??... I want to do something similar with a Marshall 2203KK-(the KK has no provisions for a separate pre section and would have to be modded)-
 
That's what I'm going for is to a/b between the preamps build presets and have it be one touch on the midi controller. This is the "hard part" getting it all in and working together. Once it's all going together building tones and programming is the easy part.
 
You need a small mixer or summer in there to use several preamps going into the same power amp at the same time. No biggie either, entirely doable, just a slightly different approach.
 
Just the engl e530 and the Mesa mark IV. That's the only power/preamp part. I think I have it mapped out from the blank sheets on the rjm website for the rg16. I'll see if I can get a picture up. The only thing I can't figure is the channels on the engl. it's clean/dirty that's it assuming it's just more loops?
 
Good posts by Dave L. As for his suggestion about the in-send-return-out style loops..... that's exactly what I do with loop 4 of my GRX4(the axxess switcher on my pedal shelf) to to a/b the signal from my pedals/pedal switcher to my two amps/heads....to do this, I also use a Lehle P-Split 2, but NOT as a splitter...I use it as a dedicated isolation transformer and it's very transparent this way as well.

For my setup I opt to NOT to have my guitar signal go to the un-selected amp at all times like you would if you used a simple splitter....just my preference. The benefit is 4 fold....1, you won't have your guitar going to an unused amp and have it's preamp working when not it use. 2, on one of the amps you will have a cleaner signal path because it won't be running to another device(in this case it would be the p-split). 3, you eliminate the possibility of crosstalk since both of your amp's sends will be sharing a loop on your switcher. Since the un-used amp won't have any signal going to it from your guitar/pedals when unselected it won't be making any sound when not in use. 4, this would also eliminate the possibility of cross talk within the mesa as well if you had signal going to it's preamp, but you're using the mesa as the power amp for your external preamp.

So you'll have one loop that a/b your guitar to the two amps, and one loop to a/b your amps/preamps to the TC. The p-split, a possible humbuster(for the output of the preamp into the switcher) cable like Dave suggestion and some humfrees should tidy up any ground loops.

So I go guitar to pedals/switcher, use the same switcher to a/b the signal from the pedals in the switchers between two amps...one of the amps has the P-Split II inline as an isolation transformer. When the loop a/bing the guitar signals is on it goes to one amp, when that loop is off the other amp.......same principle as the outputs of the preamps/effects send of your head.

The output of your pedal loops will go into the input of one of your in-send-return-out loops...in that loop connect the SEND to the input of one amp and the OUT of that same loop to the second amp with the p-split in line.

So you really wouldn't need any extra gear from what Dave L said and the way I suggest running it...just a difference in how you set it up. It would cost you one extra loop on your RJM and from the looks of the set up you will have a free one. All you need is a p-split as an ISO-transformer, and some humfrees and cables if you don't have them already.

If you look closely you can see the edge of my p-split on the left side wall of my rack:
 
For sure, using an extra loop to mute the input of the unused preamp is the way to go if you get crosstalk somewhere. You might be in luck and not have any trouble with that, though, and just switching to a rhythm channel when not using that preamp normally works too. It´s the hot lead stuff that can cause trouble.

About the channels on the Engl, sure, you can probably switch the channels using the NC or NO loop jacks of the RJM if the Mesa has eaten up all the normal switching jacks. If that was the question, I´m not quite sure I followed you there.
 
-thanx Dave & purple-(that's a very clean looking set up)-I wish they had this type of thing back in the day!! My set up will be a lot simpler I don't use a lot of effects, nothing programmable-(chorus, delay & EQ)-but by reading this thread I have a lot of-(better)- idea's.. One of the things that used to work miracles for me was a line level mixer, but I don't have a fraction of the pedals, is the line level mixer-(every effect had its own chanel with some tone & volume adjustment shaping adjudtments)- all my effects are analog...
 
Dave L":leqwj5aw said:
For sure, using an extra loop to mute the input of the unused preamp is the way to go if you get crosstalk somewhere.
Click to expand...

It's crazy how much crosstalk you can get even from the nicest amps from "itself", so to speak. Say he's splitting his guitar to both preamps(meaning the preamp part of the head and the external preamp).....When you have the external preamp running into the head's return instead of the head's actual preamp, and the head's preamp is running at the same time it's pretty likely he'll have some crosstalk in the amp's circuit from the head's preamp.. He'll have his levels matched between channels on the head so switching to a clean might not help in this instance...he's probably going to hear it some. I've tried this with some heavy hitters in the amp world and they all do it to some degree....that's not even counting on the crosstalk he might get from sharing a loop in the RJM, which might be less likely but still a good chance. That was #4 I was talking about. Shit was confusing as hell to try to explain and be understandable, I must have edited my previous post about 10 times lol :lol: :LOL:

I did this exact type of setup(using a PT100 and a 3+ preamp) in a previous incarnation of my setup.


sg guy":leqwj5aw said:
-thanx Dave & purple-(that's a very clean looking set up)-I wish they had this type of thing back in the day!! My set up will be a lot simpler I don't use a lot of effects, nothing programmable-(chorus, delay & EQ)-but by reading this thread I have a lot of-(better)- idea's.. One of the things that used to work miracles for me was a line level mixer, but I don't have a fraction of the pedals, is the line level mixer-(every effect had its own chanel with some tone & volume adjustment shaping adjudtments)- all my effects are analog...
Click to expand...

NP and thanks:) Dave did most of the setup outline advice...good suggestions...I probably just made it more confusing :lol: :LOL: Regarding your thoughts on the mixer, it's always a good idea IMO. I almost geeked out on my previous post and was going to suggest a suhr mini mix for his TC but I was like, well....he's probably used to the TC and that would suggest spending more money....it would definitely kill the possibility of tone suck. For my own setup the Switchblade is a damn good mixer....all analog and very clean for line level. I like a clean relay switcher for pedals, and a switchblade for rack effects and line level switching. Best of both worlds! I agree about analog for some effects. IMO, phase, flange, boosts, comps, chorus(actually digital or analog can both be good, the RSP and Eclipse have AWESOME chorus) sound best analog. Post your rig when it's finished, will be cool to see how you have it setup!
 
Yeah, you´re probably absolutely right about the crosstalk, but I think it can be more or less audible and even be a non-factor in some cases. I had it in a previous set-up so I had to do the mutes, but I don´t notice it at all in the rig I have now. But absolutely, muting inputs is definitely better to be on the safe side.

As for the line mixer, that´s where things get properly good! But when running just a single G-Major for everything I think you´re better off using it in serial so you can use the internal routings more freely without having to wonder about phasing. It does have tone suck, though, and if you´re using it just for a single effect I´d say splitting and mixing is right even in that case.
 
This is a lot of good information guys. Thanks a lot. I'm gonna try a little of everything and find what works with what I like.
 
Dave L":1vpwldei said:
Yeah, you´re probably absolutely right about the crosstalk, but I think it can be more or less audible and even be a non-factor in some cases. I had it in a previous set-up so I had to do the mutes, but I don´t notice it at all in the rig I have now. But absolutely, muting inputs is definitely better to be on the safe side.

As for the line mixer, that´s where things get properly good! But when running just a single G-Major for everything I think you´re better off using it in serial so you can use the internal routings more freely without having to wonder about phasing. It does have tone suck, though, and if you´re using it just for a single effect I´d say splitting and mixing is right even in that case.
Click to expand...

Right on :rock: Agreed, he'll just have to experiment and see what pops up. Cool thing about that RJM is I think those may have their click elimination technology so that will be cool for the pedals/muting/ab stuff in front of the amp. I never tried their switchers, but from what I remember being said about them on HRI in the old days and seeing them in a lot of Dave and David's rig builds I remember them being top notch. I never tried their stuff, Mario's stuff at Axxess served and continued to serve me well! Cool to see he's still around and working with Mesa now, he made awesome products.

Divide_By_Guitar":1vpwldei said:
This is a lot of good information guys. Thanks a lot. I'm gonna try a little of everything and find what works with what I like.
Click to expand...
Good luck! Post back when you get it sorted and post your rig, will be cool to see.
 
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