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Gallien-Krueger MB800

#461
Jim Carr said:
Sent my intermittently distorting MB800 to GK today. Will keep the thread posted on this...
The MB800 will be in Stockton on the 26th.
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Just an update. Here is a description of the problem:

Intermittently produces very distorted output. I've tried three different Epifani bass cabinets, which sound fine with my Mesa M9 Carbine and GB Shuttle 6.0 amp, but reproduce distortion with the MB800. I have also tried 3 different speaker cables, different instrument cables, and even two different basses—both passive Fenders.

Jason from GK called last week and reported the engineers can't reproduce the problem. :bawl:
 
#464
Jim Carr said:
Just an update. Here is a description of the problem:

Intermittently produces very distorted output. I've tried three different Epifani bass cabinets, which sound fine with my Mesa M9 Carbine and GB Shuttle 6.0 amp, but reproduce distortion with the MB800. I have also tried 3 different speaker cables, different instrument cables, and even two different basses—both passive Fenders.

Jason from GK called last week and reported the engineers can't reproduce the problem. :bawl:
Click to expand...

Any chance you had your cell phone close to the amp while you were experiencing this?
 
#465
Chef said:
Was all your testing done on the same outlet? Could be a dirty power thing; maybe.
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Sadly, did it at home and in rehearsal studio. :crying:

B-string said:
Are the Epifani cabs one ways or do they have a tweeter?
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All have tweeters, though the sound was distorted though all drivers. :hmm:

tombowlus said:
Any chance you had your cell phone close to the amp while you were experiencing this?
Click to expand...

Phones were not present at rehearsal studio test. :eyebrow:
 
#466
Jim Carr said:
Sadly, did it at home and in rehearsal studio. :crying:




All have tweeters, though the sound was distorted though all drivers. :hmm:



Phones were not present at rehearsal studio test. :eyebrow:
Click to expand...

I have started noting a trend with some crossover designs causing instability with class D implementations. Not all class D designs are the same but it seems that capacitive loads can have adverse effects with the basic typology. Crossovers were not a high priority with bass cabs just so long as they block low frequencies from the tweeters. This would not be a "failing" of the cab manufacturer but an unforeseen backlash when used with, at the time non-existent, class D topology. Maybe the crossover type used by Epifini is problematic with class D? Just a thought, to pass on to Jason and Bob that may help (or not).
 
#469
2string1 said:
Gallien Krueger MB-800 vs Gallien Krueger MB-800 fusion?
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They both hit like a ton of bricks and sound great. The MB Fusion 800 has a bit more harmonic excitement, and the MB800 is a tad more solid and "centered." Take your pick. There's no wrong choice, here. :cool:
 
#470
I recently picked up an MB800 lightly used at a great price and it seems to function properly without the dreaded whining or hiss. I'm still learning how to use this amp. I've been reading this thread and the manual and following the advice given. I have noticed a difference in the output of the gain/level B circuit [seems weaker than the A channel at the same knob settings and sounds very similar to the A side when boosted] as previously noted by another poster. My question for experienced users of properly functioning MB800s... is this difference normal? I also don't really hear an overdriven tone thru the B channel either.
 
#471
Scotty DelMar said:
...I have noticed a difference in the output of the gain/level B circuit [seems weaker than the A channel at the same knob settings and sounds very similar to the A side when boosted] as previously noted by another poster. My question for experienced users of properly functioning MB800s... is this difference normal?
Click to expand...

The B channel is pretty much the same as the A channel, only with an attenuator. Turn the output side of the B channel all the way up, and then it will act pretty much the same as the A side.
 
#473
sok monkee said:
Just bought a new MB800 that has the high freq. whine that several people have posted about right out of the box at low vol. with in minutes. This HF wine will change in pitch if I turn master up or down when the noise is present. Sometimes i can make it stop for a short time by switching channels or toggling the headphone/line out switch on the back but it will be return in a few minutes. Chose not to use it this past weekend and plan to call GK today.
I will report their response here.
Would like to hear if any of the previous posters have resolved their issues!
Click to expand...

I just got an 800 as well with the HF whine. I'm looking for an aircraft carrier that I may have forgotten about somewhere at my place.
 
#474
I'm normally a minimal EQ kind of guy, but I found a really promising pick tone yesterday that was a bit bass-shy. I honked on the bass control of my MB800 out of curiosity. Holy schmoo, what a monster tone!

Love that G-K EQ. There are some really great sounds in there, even with the controls nearly maxed out. In either direction...
 
#475
Jim Carr said:
Just an update. Here is a description of the problem:

Intermittently produces very distorted output. I've tried three different Epifani bass cabinets, which sound fine with my Mesa M9 Carbine and GB Shuttle 6.0 amp, but reproduce distortion with the MB800. I have also tried 3 different speaker cables, different instrument cables, and even two different basses—both passive Fenders.

Jason from GK called last week and reported the engineers can't reproduce the problem. :bawl:
Click to expand...

Update 2:

Unit was returned to me in 100% working order, no charge. :hyper:
Some circuit board updates indicated. GK was very generous to treat this elusive problem seriously and not charge me. Wow. Thanks Jared. I dig this powerful little head. I think it is a classic "to be." GK is great. :cool:
 

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