tube amp, is it safe to not complete the fx loop

winter_reverb

Sorry if this is a really stupid question, but I want to record my guitar on my computer, not getting great results with a mic, and want to use my pedals and amp rather than the modelling stuff in logic. I thought a good compromise would be use my amp and pedals and plug into my computer interface and just used a modelled cab.

There is no line out on my amp, but it does have an fx loop, so I was wondering whether it is ok to have the send from my amp go into my interface, or is that bad for the amp in some way?

Engager tweaker with a tube buffered fx loop if that is relevant

thanks

viz

I think amps are basically two amps - a preamp and a power amp. If you just run the preamp on its own and use it to power something else (via the send) it should be fine, just as it's fine to use the power section of an amp on its own, powered by some other preamp (using the return as an input). What's bad is if you don't put a load onto the power section (eg forget to join the speakers up to the power amp's output).

ICBM will be along in a mo to tell us that's all rubbish probably!

ecc83

Yes, That will be perfectly ok as far as amp safety is concerned*. There is however a possibility of forming an earth (aka ground) loop when you connect to the computer, even if it is a laptop since most of them earth through the charger.

I won't go into the issues and fixes at the moment but come back if you do get a hum. Not dangerous BTW.

*Note: when playing around with FX ins and outs and most of the Blackstar range you must have a dummy plug in the input to turn on the OP valves.

Dave.

winter_reverb

cheers, i'll give it a try

ICBM

It's safe to use it like that, but you must still connect the amp to a load (speaker or dummy load). If you don't have a dummy load and sound comes out of the speaker that you don't want, you need to put a mute in the FX return - if you don't have a purpose-built one, a buffered (Boss-type) pedal with nothing connected to its input will work nicely. Of course if you want the speaker to work then it's fine anyway.

thomasross20

What if you have a valve amp output stage connected to the speakers but forget to bypass the fx loop and you haven't corrected your pedals? Is something going to blow? 

ICBM

thomasross20 said:

What if you have a valve amp output stage connected to the speakers but forget to bypass the fx loop and you haven't corrected your pedals? Is something going to blow? 

As long as the amp is connected to speakers the worst that will happen is an extremely loud noise when you're not expecting it. Depending on your domestic arrangements that may cause something to blow, but it won't be the amp…

winter_reverb

ICBM said:

It's safe to use it like that, but you must still connect the amp to a load (speaker or dummy load). If you don't have a dummy load and sound comes out of the speaker that you don't want, you need to put a mute in the FX return - if you don't have a purpose-built one, a buffered (Boss-type) pedal with nothing connected to its input will work nicely. Of course if you want the speaker to work then it's fine anyway.

Thanks, I will give that a try. I was also wondering, could I use a signal splitter so that I can have the signal go from my amp to computer as well as back to the fx loop send, that way I could hear my playing through the amp speaker (which I am more used to), and also allow my to mic up the amp and have a real version to play with as well

ICBM

You shouldn't need to - the FX send doesn't usually cut off the power amp, it's the FX return that does, so the send jack is a splitter already.

thomasross20

Thanks @ICBM. ;
Having mainly played solid state amps I'm really going to have to remember and keep the speakers connected ..