How to connect guitar preamp?

[cronnin]

Ok, this is a technical question.
Couple of months earlier, the bassist couldn't get a good sound just from the amp, so he tried to send a portion of a signal from his amps line-out jack, into the PA. That burned down his amplifier.

He got this idea, because other guitarist was using his amps FX loop send port, that way exactly. Now I am wondering how to know when is it possible to mix equipment, is there any general data about resistance and nominal input levels (dVb, mV,or whatever) that one should fallow.

My latest idea was to try a high gain SS preamp plugged directly into the FX-loop receive jack at the back of my low gain amp, in order to use only its tube power section, but I am afraid not to burn the amp down. You can get the idea from the pic, sorry for bad drawing

 

[crguti]

Re: How to connect guitar preamp?

the drawing in the picture is correct. I am running my Engl E530 tube preamp into my Engl Thunder return FX loop without problem.
You need to check what type of FX loop you amp has, serial or parallel, and check the impedance values of both output and input.
You wrote that the bassist "tried to send a portion of a signal from his amps line-out jack, into the PA. That burned down his amplifier". I'm wondering what wrong did he do? it's safe to do that, so i don't understand what was the problem. Probably he disconnected the cab and that burned the amp's output transformer.

 

[Chickenwings]

Re: How to connect guitar preamp?

RE: your bassist friend...Line out should work fine, but did he have a speaker cab connected? No speaker cab means no load. No load means the amp will implode.
Your picture looks fine. That system will work.
However- why dont you just use a pedal for gain/distortion?

 

[cronnin]

Re: How to connect guitar preamp?

I'm not sure what happened in the bass amp, maybe it already had a malfunction like loose cable/contact, whatever.

My amp has "FX loop : side chain type, nominal 750 mV level ", so I suppose it's a parallel loop.

@gibson 175: I do use pedal for distortion, but I may have a chance to grab a friend's tube preamp soon, and I have no experience with that kind of stuff so I had to ask. Knowing myself I will probably try all three different configurations and then decide what'll work best for me

1. guitar>preamp>(amp's preamp+amp's power stage)
2. guitar>preamp> amp's FX-return
3 guitar>amp ( preamp in FX loop)

I just wasn't sure if it's safe to run configuration 2.

I suppose this is a serial loop in Fender Deville?
http://elderly.com/images/fmic/130N/FBDVTR_controls.jpg

What difference does it make if it's serial or parallel?

 

[crguti]

Re: How to connect guitar preamp?

1st and 3rd configurations are bad. It's bad idea to use 2 preamps in series. The second preamp will introduce a lot of noise in your signal path. The 2nd configuration is the best choice, and with a multi effect would looks like: guitar>preamp>multi effect>power amp (fx loop return).
You may have other variations as well, e.g. pedals in front of the preamp, using 2 power amps, and some other funny stuffs, but the above configuration will be a perfect starting point.

 

[DrNewcenstein]

Re: How to connect guitar preamp?

I've heard from others who run 2 preamps in series with no trouble. One guy said he runs a tube preamp into a Boss GT10 or somesuch (I forget now exactly) and he gets no overloading, which I thought he would.

Of course it all depends on your settings, too. Obviously a Puppets tone running into a Holy Wars tone will end up as a flaming mess of gear.

 

[cronnin]

Re: How to connect guitar preamp?

I too suppose it's gonna be preamp into FX return.

Yes, if you run two preamps in series, at least one of them HAS to be low gain or you get too much mush and noise.