ok here is the deal,i have zoom effects and when i use in in a tube amp it doesnt sound great... but if i use it on a just a ordinary clean amp it sounds right . and my theory is that because my my tube amp has high gain output ,when I use the effects like,reverb,delay or drive, it changes the output sound because the amp itself is changing it....as a result the reverb delay drive, sounds like crap.it sounds blurry.
Ive overheard someone using it and he said dont connect it directly on amp. but not sure what is he talking about....
Why would you use a modelling unit (especially a crappy zoom one) on a tube amp?
my tube dont have effects in it.....i wanna add reverb or delay..............
Try plugging it in to the effects loop of the amp.


Guitar - > Amp Input -> Loop Send -> Effects Pedal Input -> Effects Pedal Output-> Loop Return

There's some crazier variations of this I use on my Boss GT-8 and Tube Amp to make it sound 'right'.
^^^what he said. from my past experience with friends' multi-effects pedals, modeling units like your zoom are only good with solid state amps. for tube amps, you're better off with analog effect pedals. make use the tubes of the tube amp. it will sound way better than digital modelers.

edit: if you just wanna use modulations, use the effects loop of your amp, if you have an effects loop.
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Okay, as McDizzy said, try it in the effects loop of the amp (if its got one), dont use any of the amp/cab modulators (if that pedal has them, I wouldnt know) because your tube amp will sound better than a modellor immitating a tube amp. If you want to use a little reverb/delay then thats cool. But beleive me when I say that you wont be using the tube amp to its full potential putting a digital multi-effects in front of it.