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GK MB115 problems (please help)

#22
Paul, in post 15 he said he tested the speakers with another amp and they're fine. I'm assuming the plural means he tested both the fifteen and the tweeter. This problem's bugging the hell out of me and I'm not even the owner. Only other thing I can think of is the cable that connects the amp to the fifteen is flaky, but then again, if he's getting anything at all out of the fifteen (even if it's distorted), that's got to mean the cable's ok. Unless somehow it's developed an extremely high resistance. An ohmmeter check would be in order.

It occurs to me that the relationship between the plane ride and the amp fault could be coincidental, not causal. Could be something's gone wrong in the amp, and would've gone wrong even if the amp had stayed put.
 
#25
I can try and put it through a different cab... just this problem is so weird... In the states it worked perfect! It sounded great and I bring it here and its well um... not working as hoped??
So the tweeter works fine and is getting an ok signal... I will put a video up soon. hopefully that can shed some light...
I wish I knew more about electronics then what I do...
shalom,
matthias
 
#26
Sorry if you've already done this & I missed it, but have you checked the line voltage at the outlet to see if it meets spec for the amp?

I don't know how switchers behave under low-voltage conditions. Do they even start up? Is start-up on these things a "binary event," i.e. they either start up fully functional or don't start up at all?
 
#29
Well this hiss is a comman problem with the tweeter in this amp. Its not a huge deal and that was present in the States. The tweeter still has a hiss even when powered by a diffrent amp. That problem is the tweeter. So not involved with the what is wrong with the amp.

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ITs possible it could be a control, but there is only one control it could be and that is the master volume control since that is the only control knob after the aux input. If it was anything else only the bass sound would be messed up not the aux inputs...

So it is the main amplifier unit for the woofer I guess... does anybody know how to fix this? Does anyb ody know what is wrong? :help:
Should I take some more pictures? I am going to try to get a video soon so you guys can hear what is up. Haven't able to yet... hopefully soon.

I hope this can get working:eyebrow::crying::rollno::confused:



that would be good then it is back to the playing and hopefully some teaching of the bass ;):hyper::bassist:
 
#31
meinl said:
Well this hiss is a comman problem with the tweeter in this amp. Its not a huge deal and that was present in the States. The tweeter still has a hiss even when powered by a diffrent amp. That problem is the tweeter. So not involved with the what is wrong with the amp.

-------------------
ITs possible it could be a control, but there is only one control it could be and that is the master volume control since that is the only control knob after the aux input. If it was anything else only the bass sound would be messed up not the aux inputs...

So it is the main amplifier unit for the woofer I guess... does anybody know how to fix this? Does anyb ody know what is wrong? :help:
Should I take some more pictures? I am going to try to get a video soon so you guys can hear what is up. Haven't able to yet... hopefully soon.

I hope this can get working:eyebrow::crying::rollno::confused:



that would be good then it is back to the playing and hopefully some teaching of the bass ;):hyper::bassist:
Click to expand...

Maybe RAG or Brian will correct me if I am wrong, but the MB series is not a H.M.S. amp. It has no seperate power amp for tweeter and woofer. Just a passive crossover (switchable) from the power amp.
 
#33
Finally finished the manual download of over 36megs! The horn is switchable from the front panel but no crossover. Piezo horn so it relies on the nature of piezos to not conduct at lower frequencies. So you said earlier that the sound is full range at the Aux inputs? Do the gain, contour, eq or boost have any effect on the sound at the normal inputs?
 
#34
Yes all the controls affect the sound, but the problem persists if I use the passive/active inputs or the aux inputs.
The master volume and the main amp is the only thing after the aux in besides the limiter and the tweeter.

The tweeter control obviosuly works.
The limiter does something, but doesn't stop the problem...:confused:

Does that help at all?
 
#35
Hmm don't have an actual schematic to look at (just the block diagram in the manual) but it appears that the amp is a bridged output so no lead to the speakers should be grounded. Have you tried inserting an empty 1/4" plug into the phones jack? If that shorted in transit that would short the positive half of the output through a resistor.
Need more pics of the amp overall, might help.....
 
#37
meinl said:
Ok I can take some more pics soon.
So Do you want me to plug a 1/4 cable and have the other end not plugged into anything? What do you meant to by empty?

or did you want me to see if I am getting signal through the headphone out?
Click to expand...

If you don't have a spare 1/4" plug just use a cable with the other end not connected or touching anything. I believe you already said the phones out didn't work? Also make sure no wires to the speakers rubbed through on the metal chassis during shipment.
Sorry "empty" meaning no wires attached to it yet.
 
#38
Make sure you turn all the knobs back and forth several times and push all the buttons a bunch too. I have experienced bad or dirty connections causing a similar sounding issue.
 
#39
OK sorry it took so long to get back with pictures I got really sick... I don't think the Spaniards should have attacked Montezuma... :D

Anyways I put up pictures of the whole board and a closer shot or two of the crossover. Sorry if any of them are blurry.
you can look at them here. http://s1227.photobucket.com/albums/ee435/meinl/
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so B-string if I plug in the empty 1/4 that should short something? or what does that do? What am I supposed to see from that. Sorry still a little confused on that.

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jonschwenke I have done that, but its brand new so not a dirty connection at all the knobs work perfectly.

thanks again for the help guys :-)

shalom,
Matthias
 

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