GK 1001RB-II Distorting at Low Volume

"If it sounds fine with the 412, is it normal for a stronger amp to distort a weaker cab even at low volume?"
No. You proved the Behringer cab was fine. Either the head has a problem (likely) or there's something else going on. If the head needs work I hope can can return it for a refund.

 

Agreed. Sounds like the GK is toast.

 

That's a bummer. They should pay for shipping and send you a new one.

 

First thing I'd probably want to check is that you're not distorting the input. I knw you said you tested with the pad, which should rule that out, but do you have a pic of the settings you were using just to be certain?

 

Hang on—are you familiar with how gain, volume, and the boost knob work on RB heads specifically? If so, and you have the settings right, then I agree it may be a bad head.

if not, try turning the boost knob all the way down, and make sure the woofer knob is set lower than than the master volume. If it’s clean, you’re probably ok. The boost knob adds gain and distortion, and can distort at low volume if it’s turned way up while volume is way down. Hope I’m explaining it right—it’s worth looking up the manual to understand how it all works.

 

Woofer is master. Generally, for the absolute cleanest tone you want maximum woofer, minimum boost, and "low" "volume"... and at some point you may need to dial in a little boost to compensate for such a low volume.

I'm still assuming there's either an issue with the amp, or something is distorting the input (even before "volume" plays a part).

 

Oops, right you are!

 

Are you plugging straight into the head, no pedals?
These heads dislike pedals in the front end. Put them in the effects loop instead.

 

They dislike what now??? That doesn't make any sense. Some pedals may work better in front, and some may work better in the loop, and many will just come down to personal preference.

But to say that the head doesn't like pedals in front is just silly.

 

I'd follow Kro's advice and if you still have an issue, return the head. IME that GK should play well with most any combination of cabs, pedals, and basses.

 

Yeah it's possible I have another issue related to contacts in the effects loop.
I was having a similar issue the sound breaking up and rattle from woofers new NEO 4x10 and was pulling my hair out. I plugged straight into the input and issue gone; but I did plug my Warden compressor into the effects loop. I read these heads have a problem with pedals in front of the pre and ass u med.

 

I apologise and take my comment back. I had two blown drivers in NEO 410 that only showed in certain notes. Nothing to do with the head.

 

Just a wild idea: are your speaker cables good? Were you using the same one(s) with both heads? A bad speaker cable can sometimes make you think an amp is blown.

 

I brought it back to the store i purchased it from 3 days ago, and used their cables and passive p bass to the same conclusion.
Long and McQuade replaced it on the spot.
It's a great combination. 1001rbii NEO 410.

 

I feel like within the last few days, I read a post about someone having unwanted distortion when they really dug in on a GK, possibly 1001. They found the ground connection inside the head loose. Once tightened, that fixed it for them. That may be something to check if you are comfortable doing it.

 

Sounds like the cab is not the problem.
I would check the effect send to a different power amp to see if the distortion is
coming from the preamp or the power amp.

If the power amp has distortion it could be many things.
Could be as simple as corrosion on the ouput jacks.
Or it could be the bias isnt right if the bias pot has corrosion.
Also could be as bad as a output device has blown open and not popping the fuse.
Or if there is a soft start or anti pop relay or safety relay in the speaker out signal path.
The relay contacts could be corroded or have arching pitting.
Or as simple as a corroded ground connection.
Or any simple corroded or loose connections in the amp

Its the internet ...so its always a guessing game.