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GK MB150E 111/112


fenderlyte

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Hi

 

I am new to the forum so please excuse any breaches of etiquette....

I have a GK MB150E (about 2 and half years old) and I am having real problems with it. I have contacted GK but they cannot offer any solution and my local electronics guru is equally baffled. He has put the amp on soak test but cannot duplicate the problem. After playing for about an hour at mid volume (with breaks between dances) the amp becomes too hot to touch and the sound distorts to a point where there are virtually no bass frequencies and becomes really just an audio "mush". This happens with and without the extension cab and no matter what bass (Fender or acoustic) is used. When the amp cools down, the sound is restored.

Has anyone else come across this problem and, if so, is there a fix? The amp cost me a fair amount but at the moment I feel inclined to bin it!

Al Harris

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i have a trace-elliot combo that had somewhat the same problem. about 10 to 15 min after you turned it on and started playing it became hotter more quickly and then the volume began to drop, especially the bass frequencies. more like harsh, digital sounds kinda like. anyway, i turned it in for repairs, didn't cost me much and i haven't had a problem ever since. strange they can't locate the problem. :confused: maybe try another tech?
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I have the GK, and haven't experienced the problem you are describing.

 

Have you tried blowing a fan across the upper fins?

 

At any rate, here's what I think:

 

1. Are you sure you don't have an extention cab ohm mismatch? I know you said this happens with both, so I doubt that's the problem.

 

2. Are you sending too much signal through? You have a Fender...passive? Are you using any pre-amp circuitry or effects that could overload the input preamp? There is a active/passive circuit...you might be overloading only the pre-amp. You might be able to check this by using the return in the rear...at least one of them is post pre-amp...if you get clean sound you've isolated the problem to the pre-amp.

 

3. Playing dances, eh? My strongest inclination is that you are simply overloading the system. Remember, it's only 90 Watts, 150 with the extension. If you are playing with a balls-out drummer, you don't have enough power in this box. Your idea of "mid volume" and GK specs idea of mid volume might be 2 different things.

 

If that is the case, and you like the GK basic tone, use the amp as your personal monitor (the screws on the side are there to mount the amp to a mic stand with a GK attachment) and send you signal to the house. You'll be able to work with much more amp headroom that way.

 

If you are already going through the house, make sure you are not mismatching line level and mic level. Your DI outta that amp is a really good one in my opinion, and you'd should never run out of signal at any volume level.

 

If you don't believe you are overloading it, try this. Practice in your living room at a comfortably loud volume for a couple of hours. Did you duplicate the problem? Even with the same settings, you may be whackin' those strings with vigor with stage adrenalin, while in your living room your plucking is more mild. Remember...your amplifier will ALWAYS try to give you the same increase in volume whether you strike your strings light or heavy. But an enormous attack, (or 1.5 hours of continuous enormous attacks) could easily send the amplifier 1000 or 10000 times the expected input. The amplifier will faithfully give it's own life attempting to amplify that signal.

"Let's raise the level of this conversation" -- Jeremy Cohen, in the Picasso Thread.

 

Still spendin' that political capital far faster than I can earn it...stretched way out on a limb here and looking for a better interest rate.

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does it have a heatsink? i dont know if amps usually have these or not, but if yours happens to have one and it is broken, you could be causing permanent damage :(

"I'm thinkin' we should let bump answer this one...

Prepare to don Nomex!"

-social critic

"When I install my cannons, I'm totally going to blast their asses back to the 16th century; Black Beard style"

-bumpcity

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Originally posted by BigKahuna855:

does it have a heatsink? i dont know if amps usually have these or not, but if yours happens to have one and it is broken, you could be causing permanent damage :(

A heat sink is a cast piece of metal on the back of an appliance (in this case an amp)to increase the surface cooling area of said appliance.

The only way a heat sink could be broken is if it was no longer attached to the amp.

"Start listening to music!".

-Jeremy C

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I have the amp and ext cab.LOVE IT.

 

The fins on the top of the combo are used to displace the heat.It needs to be open to the air.The amp will cut itself off if it overloads with the wrong impedance.

 

Try new techie or send it to GK.It is a reliable great sounding amp.Keep us posted. :wave:

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quote:

--------------------------------------------------------------------------------

Originally posted by BigKahuna855:

does it have a heatsink? i dont know if amps usually have these or not, but if yours happens to have one and it is broken, you could be causing permanent damage

--------------------------------------------------------------------------------

 

A heat sink is a cast piece of metal on the back of an appliance (in this case an amp)to increase the surface cooling area of said appliance.

The only way a heat sink could be broken is if it was no longer attached to the amp.

oh thats interesting. i had no idea what a heat sink was, i only knew it helped somehow with cooling. :freak:

:D you learn something new every day!

"I'm thinkin' we should let bump answer this one...

Prepare to don Nomex!"

-social critic

"When I install my cannons, I'm totally going to blast their asses back to the 16th century; Black Beard style"

-bumpcity

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