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Please HELP: Problem with GK-MB500 (hiss/flutter)

Hey guys, a CONCLUSION to this for any future references:

1. Got a reply from GK advising to ship the unit to any of the closest authorized service center in the US and they would take care of the warranty repairs. Rightfully so, shipping is not covered. Overall I am really happy with their response and services - big Kudos to GK!!

2. In the meantime, Yorkville got back to me in two days, saying that they fixed the problem and it didn't require a wire harness replacement. It had an issue with loose/dirty molex I/O board connectors. Tech said it was a common issue with these amps. Attaching a pic of the original Yorkville tech write up. Total: $60 all in. I am happy.

I would imagine this would be a type of the repair/maintenance that one could undertake on his/her own if handy, so hopefully this thread will help someone in the future.

Thanks a lot to everyone for their feedback/suggestions here and really hope this info helps!
 

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Here is my problem and this has happened over and over again. gav duncanson gk mb500 - YouTube . Except this time, like in over the weekend, I go to use it at a gig, same problem. Good thing I brought a backup. No amount of cleaning connectors is making a difference. Tried 4 and 2 speakon connector cables, tried 1/4 inch, tried various cabinets and bass guitars and the sound is still scratchy, crashy, farty, dull, etc. Jason at GK had me send it to them years ago and it worked for a few months. Had it serviced by The Amp Guys in Altamonte Springs, FL. Got it back and it worked for about a year. It seems to be a recurring problem and I would like once and for all to determine the source of the problem and if so, get a permanent fix. I love this GK MB500 amp head. It's the best sounding piece of equipment I have.
 
Here is my problem and this has happened over and over again. gav duncanson gk mb500 - YouTube . Except this time, like in over the weekend, I go to use it at a gig, same problem. Good thing I brought a backup. No amount of cleaning connectors is making a difference. Tried 4 and 2 speakon connector cables, tried 1/4 inch, tried various cabinets and bass guitars and the sound is still scratchy, crashy, farty, dull, etc. Jason at GK had me send it to them years ago and it worked for a few months. Had it serviced by The Amp Guys in Altamonte Springs, FL. Got it back and it worked for about a year. It seems to be a recurring problem and I would like once and for all to determine the source of the problem and if so, get a permanent fix. I love this GK MB500 amp head. It's the best sounding piece of equipment I have.
Doesn't matter how good it sounds, if it doesn't work. At this point it seems like you are throwing good money into bad. I am a GK guy through and through but you gotta know when to call time of death on things. If you love the MB500, you can get them used for around $300, that may be a good way to go. YMMV.
Rock on.
 
Doesn't matter how good it sounds, if it doesn't work. At this point it seems like you are throwing good money into bad. I am a GK guy through and through but you gotta know when to call time of death on things. If you love the MB500, you can get them used for around $300, that may be a good way to go. YMMV.
Rock on.

I think you're right. I've been looking at getting another one or purchasing the MB800 or the new Legacy's but I sure as hell don't want the same problem to occur. I've seen where others had the same problem with the MB800 and I hope whatever the problem is, GK has resolved it with the new Legacy line they're bringing on stream. Too afraid to purchase another GK light-weight head right now. Thinking seriously about a Mesa D-800+.
 
I think you're right. I've been looking at getting another one or purchasing the MB800 or the new Legacy's but I sure as hell don't want the same problem to occur. I've seen where others had the same problem with the MB800 and I hope whatever the problem is, GK has resolved it with the new Legacy line they're bringing on stream. Too afraid to purchase another GK light-weight head right now. Thinking seriously about a Mesa D-800+.
I really dont have any issues, see my rig below. Pair of MB Fusion 800s and an MB500. I like to believe your situation may be somewhat of an isolated incident. I would not hesitate to buy GK gear again. I had a MESA D800, I rehomed it very quickly, so not my thing. YMMV. Best of luck in whatever you do.
Rock on.
3GK.jpg
 
I really dont have any issues, see my rig below. Pair of MB Fusion 800s and an MB500. I like to believe your situation may be somewhat of an isolated incident. I would not hesitate to buy GK gear again. I had a MESA D800, I rehomed it very quickly, so not my thing. YMMV. Best of luck in whatever you do.
Rock on.
View attachment 3445534
You're helping me to regain my confidence. Very nice set up. BTW how are you using the 800's together? Are they bridged together or you use them separately in different cabs? I've never seen anything like this.
 
You're helping me to regain my confidence. Very nice set up. BTW how are you using the 800's together? Are they bridged together or you use them separately in different cabs? I've never seen anything like this.
I run each MBF800 into its own NEO 212, I use a Helix so I run 2 outputs, one to each MBF800. I have run 1 into the others Return and used a master/slave thing and it works great as well. The MB500 is for practice/rehearsal and I run it into a NEO 115.
 
I run each MBF800 into its own NEO 212, I use a Helix so I run 2 outputs, one to each MBF800. I have run 1 into the others Return and used a master/slave thing and it works great as well. The MB500 is for practice/rehearsal and I run it into a NEO 115.

Nice. Got it. I have two GK Neo 212's that I daisy chain. Nothing in this world sounds sweeter. Thanks for your help. Would love to hear a clip of what your rig sounds like.
 
Hey guys, a CONCLUSION to this for any future references:

1. Got a reply from GK advising to ship the unit to any of the closest authorized service center in the US and they would take care of the warranty repairs. Rightfully so, shipping is not covered. Overall I am really happy with their response and services - big Kudos to GK!!

2. In the meantime, Yorkville got back to me in two days, saying that they fixed the problem and it didn't require a wire harness replacement. It had an issue with loose/dirty molex I/O board connectors. Tech said it was a common issue with these amps. Attaching a pic of the original Yorkville tech write up. Total: $60 all in. I am happy.

I would imagine this would be a type of the repair/maintenance that one could undertake on his/her own if handy, so hopefully this thread will help someone in the future.

Thanks a lot to everyone for their feedback/suggestions here and really hope this info helps!


This really helped. Thank you for posting. Because of your post I was inspired to attempt to fix my MB500 and it worked. Check my post and vid. GK MB500 Problem FIXED !!!!!
 
I really dont have any issues, see my rig below. Pair of MB Fusion 800s and an MB500. I like to believe your situation may be somewhat of an isolated incident. I would not hesitate to buy GK gear again. I had a MESA D800, I rehomed it very quickly, so not my thing. YMMV. Best of luck in whatever you do.
Rock on.
View attachment 3445534


Nice Rig.
Are you using both of those?

That makes my heart palpitate seeing two of those buggers in the same rack.

I recently tried several of my amps in front of this and its scary.
One side of the PLX2 into two CX210 cabs is Earth shattering, just one side mind you.

 
Nice Rig.
Are you using both of those?

That makes my heart palpitate seeing two of those buggers in the same rack.

I recently tried several of my amps in front of this and its scary.
One side of the PLX2 into two CX210 cabs is Earth shattering, just one side mind you.


Yep, use them both together, each pushing its own NEO 212...I can crack foundations with this rig. It is God-awful loud.
Rock on.
 
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I really dont have any issues, see my rig below. Pair of MB Fusion 800s and an MB500. I like to believe your situation may be somewhat of an isolated incident. I would not hesitate to buy GK gear again. I had a MESA D800, I rehomed it very quickly, so not my thing. YMMV. Best of luck in whatever you do.
Rock on.
View attachment 3445534
Its definitely not an isolated incident. I have an mb500 on the shelf with the exact issue. I can't even sell it. I loved it for the 1+ years that it worked (weekends only).
 
I'm really glad I came across this posting. I've had the same problem with my own backup MB500.
I watched both the video posts on YouTube. Both the amp distorting and the one on the actual fix. With a screwdriver and some good contact cleaner, problem is now resolved!
Just to test it, I've had the amp running for the last 3 to 4 hours to simulate a gig and everytime I test it the sound is crystal clear! Not one hiss or distorted note! You saved me a ton of money on having to purchase another amp. THANK YOU
 
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