GK MB800 "push" knobs stink!

[will33]

I've used the electronic cleaner two times I don't think it is the problem ( maybe they are bad pots ... cheap )

He's saying you may not be using the correct, proper type of cleaner.

There are many different chemicals labeled "cleaner". You might be using the wrong one. The wrong one can damage the pots.


Trying to explain here. English is not your native language.

 

[2milehighspike]

I'm not happy with this amp those A B and Master volume pots may be cheap or something like that (are they made in China?) I had to use electronic cleaner two time in 3 months and the amp works but not Reliable! I'll sell it as soon as possible I'm tired of playing and be worry that any minute it will stop working properly, the main problem with my MB is that volume goes up and down by itself! with out moving the knobs of the amp or the bass guitar. I will try to trade in this MB800 for a Fender 500 rumble bass head or if I get some cash for the MB I'll buy a 500 Carvin amp

Not RELIABLE!?! The MB800 is the most stone cold reliable piece of electronics I have ever owned, I have never had the volume go up and down by itself, and yes my MB800 was made in China and is going on 5 years old with hundreds of sessions under its belt.And my MBF800 is just as reliable. The one caveat I will add is that I am a set and forget type of user so I do not fiddle with the knobs once I find my sound. But anyone who tries to tell me that either amps are not reliable will be in for a (friendly) fight.

 

[petch]

Never had any problem with those knobs on the MB800 I owned... a light feel, but no trouble engaging/disengaging at all.

 

[filibertin]

You also can't offer for sale unless you are a supporting member whether it is for dills or dollars.

Ok thanks

 

[DaveB in VA]

I've had a similar issue. Try switching the knobs around. For some reason that fixed it.

Thank you, sir. You have saved me from a trip to the warranty repair center (there happens to be one here in town), much less the hassle of sending my MB800 back to Sweetwater for repair. I did not switch knobs, I just pulled off the affected knob and slid it back on. Works great now. It seems that there is not a "hard stop" on the knob and if you press it too hard it will slide in too far so that it does not have enough travel to engage the switch.

I use this feature to balance the volume between when I play my Carvin PB5 which has a high output and my Carvin B25 which has a relatively low output. The active/passive switch doesn't balance the volume between the two without further adjustment.

 

[spanndrew]

Thank you, sir. You have saved me from a trip to the warranty repair center (there happens to be one here in town), much less the hassle of sending my MB800 back to Sweetwater for repair. I did not switch knobs, I just pulled off the affected knob and slid it back on. Works great now. It seems that there is not a "hard stop" on the knob and if you press it too hard it will slide in too far so that it does not have enough travel to engage the switch.

I use this feature to balance the volume between when I play my Carvin PB5 which has a high output and my Carvin B25 which has a relatively low output. The active/passive switch doesn't balance the volume between the two without further adjustment.

Glad to help!

 

[scubaduba]

@spanndrew What do you mean by "switching the knobs around?"

 

[spanndrew]

@spanndrew What do you mean by "switching the knobs around?"

Just remove a knob from let's say "hi-mid" and also one of the knobs that can be depressed to toggle a setting, like "bass" and then switching them.

 

[scubaduba]

@spanndrew And what problem does that solve exactly?

 

[spanndrew]

@spanndrew And what problem does that solve exactly?

knobs sticking/ not engaging the toggle effect.

 

[bassdrummer]

I had the "push knob prob" with my MBF800... just recently sent it to GK and they fixed it for free. No problems with the Gain A or Gain B knobs. But, the Contour button wouldn't switch when I pushed it in, and the Presence and Deep buttons were inconsistent --sometimes it took several pushes to get them to switch. GK fixed it at the factory....love it!

 

[CaptainWally]

Any idea what they did to fix it?

 

[bassdrummer]

Any idea what they did to fix it?

No idea. When I initially called GK, Jason (customer service) suggested that I pull off the knobs and actually push in the switch underneath the knob. When that didn't work, I went ahead and asked for a R.A. number and shipped it over. I have owned the amp for over 2 years, but GK still covered the repair as under warranty. Awesome!

 

[ModulusFan]

Thank you, sir. You have saved me from a trip to the warranty repair center (there happens to be one here in town), much less the hassle of sending my MB800 back to Sweetwater for repair. I did not switch knobs, I just pulled off the affected knob and slid it back on. Works great now. It seems that there is not a "hard stop" on the knob and if you press it too hard it will slide in too far so that it does not have enough travel to engage the switch.

I use this feature to balance the volume between when I play my Carvin PB5 which has a high output and my Carvin B25 which has a relatively low output. The active/passive switch doesn't balance the volume between the two without further adjustment.

Raising this thread from the dead to say thanks for this - exactly solved my "problem" with a few of the knobs not being as easy to engage the push-functions. Works perfect not. I would bet this is the issue that most are having. Silly design defect. It wouldn't take much of a bump packed in the gigbag to push them on too far.

LOVE this amp, nasty loud and sounds fantastic.

 

[Jim C]

I don't know about switching knobs but I do know that a very small piece of paper balled up between the shaft and the knob fixes the problem for sure. It just needs a shim to take up slack. Like maybe .020" - .030" of space.
I have a very early MBF800 and Jason had thought that the assemblers were being too forceful during installation. History has shown that the knob and switch shaft weren't all that compatible.

 

[fdeck]

I've learned something about push knobs, almost a rule to live by. If a feature of an amp uses a push knob, then I will set it once and never change it. For instance this applies to the "pre/post DI" button on my GK MB200 head. It will be "pre" forever. Another example is my Radial JDI box. If I've pulled it out of my bag, it's because I want the ground lift function. Maybe there's some user interface principle at work here.

Also, I will always accidentally touch those knobs while setting up, and get them wrong.

So I choose the setting for those buttons, and apply a little bit of hot melt glue around them. The glue can always be peeled off, but meanwhile, I never worry about them.