Broken 700RB-II Input?

[prophet178]

Hi, I ran into a problem today and I've been stumbling trying to figure it out.

Long story short, when I plug my bass into the input on my GK 700RB the sound is muffled, as if nothing is even coming out. Even if I put both the master and volume at full the sound is barely heard.

However, when I plug the bass into the effects return, it works perfectly.

I realized that the cable I'm using may not be an instrument cable. So here's the stupid question, would the lack of an instrument cable be preventing the main input on the GK amp from properly outputting to my cab?


Edit:

Well I went out and bought an instrument cable and tried it out. Same thing. The sound of the input is low and muffled, while the output from the effects return is very loud.

I can notice the difference in sound between the instrument and speaker cable when I use it on the regular input though, but it the volume differs very slightly.

Do you think there is a problem with my input, or is the difference in volume between the input and effects return just because of the EQ? Even with the EQ to full the input sounds low compared to the effects return. If I set the EQ, volume and master all at noon the output is barely adequate for practice.

 

[RickenBoogie]

Possibly, yes. Instrument cable is shieled, speaker cable is not. Use the proper cable for the application.

 

[Wes Whitmore]

I had a problem with a 700RB head when I got it, but it didn't matter if I plugged it into the instrument input, or the effect return, I didn't get much sound out of either. All muffled and really low volume. Turned out to be the preamp board. That board is a pop in replacement. I think it was $100 from GK. Fixed the problem, but since you return works, I'm not sure. I have had dirty 1/4" inputs in the return and instrument input cause what you are describing though.

 

[prophet178]

Hmm that sounds like the same problem I'm having. Strange that my return works still though...

 

[WingKL]

It's not so strange. There is circuitry before and after the effect return on the preamp board. If the part before the effects return is broken then the effects return itself may still work.

 

[prophet178]

Yeah you're right. I was looking at the block diagram in the manual and the effects return completely bypasses the preamp volume. I contacted GK so hopefully they can help me out.