GK MB212 Problem - Any Suggestion?

[beam2611]

Hey guys,

Long time GK user here, in the past I owned 2 RB800 and a RB700.
Now have a MB212 for portability.

I love how the GK MB212 usually delivers on various gig settings.
However yesterday when I turned it on during soundcheck at a venue.
It only played at 5% of the expected volume when gain & master volumes were set at 12 o'clock, same as usual, sometimes lower.
Check it again this morning, same thing. Sound like a 10 watt amp.
If I turn up the gain, boost & master volume I get a little more volume but a lot of hiss.

I have a soundcheck this afternoon and another show tonight.
Is this an issue anyone else has experienced?
Is there a way to sort this out quickly?

PS: tested with various cables and basses, those were not at fault.

Any suggestion would be welcome.
Thanks
Eric

 

[kpc]

Notify GK.

 

[beam2611]

I have, thx

 

[Kro]

Sorry to hear about that, terrible timing.

Aside from the testing that you've already done, I'm not sure how much is left to do aside from taking it to a tech.

I have experienced issues with my MB amp (not a combo) in the past, but nothing like what you're describing. The types of failures I've experienced are those that tended to put the amp in safe-mode.

 

[BassmanPaul]

Effects loop jacks can cause this sort of issue. If it has one, link Send and Return with a short signal cable to see if that helps.

 

[Thornton Davis]

Effects loop jacks can cause this sort of issue. If it has one, link Send and Return with a short signal cable to see if that helps.

Unfortunately Paul, the GK MB Combos don't have a send and return so beam2611 is going to have to rely on either GK directly or a local amp tech to diagnose and fix the problem. I suggest he take it to the closest L&M in Montreal.

TD

 

[Wasnex]

Hey guys,

Long time GK user here, in the past I owned 2 RB800 and a RB700.
Now have a MB212 for portability.

I love how the GK MB212 usually delivers on various gig settings.
However yesterday when I turned it on during soundcheck at a venue.
It only played at 5% of the expected volume when gain & master volumes were set at 12 o'clock, same as usual, sometimes lower.
Check it again this morning, same thing. Sound like a 10 watt amp.
If I turn up the gain, boost & master volume I get a little more volume but a lot of hiss.

I have a soundcheck this afternoon and another show tonight.
Is this an issue anyone else has experienced?
Is there a way to sort this out quickly?

PS: tested with various cables and basses, those were not at fault.

Any suggestion would be welcome.
Thanks
Eric

Did you check the -10dB pad on the front panel?

 

[beam2611]

Bought it second hand, Just realized I got a first Gen MB212.
No fx loop. no -10db Pad.

However, I got a lead on a good guitar amp repair tech. He says he's dealt with the GK amps issues often. He thinks it's either the pre-amp or output section. Going to see him tomorrow.

 

[BassmanPaul]

However, I got a lead on a good guitar amp repair tech. He says he's dealt with the GK amps issues often. He thinks it's either the pre-amp or output section. Going to see him tomorrow.

Your amp contains three basic sections. Pre-amp, power amp and power supply. Two out of three ain’t bad!