Gallien-Krueger MB2-500: Part II

[wvbass]

Hey guys,
I'm not sure if this was the "fix" for any issues that I was having but -
with my A05 I had to engage -10db with an 08 Am Std P
with my A06 I don't - although I can get it to clip if I really hit it hard (which I don't usually do)
I did post that the A06 seems 'wider' more 'open' -
but now I believe that it's because of the extra 10db of headroom...
It took a couple days to get used to the new knob positions...

Maybe....just maybe GK gave it that super Hot input stage to fully utilize the headroom of the amp (I don't know)
maybe they found that by doing this, it opened up some issues, ie;
In my case random shutting off, even when cool to the touch or picking up odd noises and outside frequencies

Simon, maybe you should talk to Jason, He worked directly with me,
he seemed to have a grip on this 'issue'...
IMO being 'sarcastic' or 'condescending' might not help,
If you talk to Jason, He'll help you out (he's a cool cat)

In any case, I haven't had any issues with my A06, and I've really pushed it hard these last few weeks

This post bothers me. Not that I can say whether you are right or wrong about the changes in the A06 revision, but it made me remember an earlier post in this thread. I did a little digging and found the post I remembered:

There are no changes between the 05 and 06 rev. We just adjusted the interior layout for manufaturing purposes. There is no change in features or functionality.

So, if unclekebm's post is true, I see three possibilities: 1) his A05 head was defective, which would not speak well of the A06, because according to Brian, there were "no changes," or 2) Brian's information is wrong. This is disturbing, because Brian works for GK. Maybe he didn't have all the correct information at the time of his post, or 3) unclekebm is hearing what he wants to hear, which I find unlikely, given his comments about problems with his A05.

Don't get me wrong, I am a fan of this amp. It IS a good sounding amp. But clearly, I (and at least a few others are as well) am having difficulty understanding an unusual gain structure.

 

[Saluki]

So, if unclekebm's post is true, I see three possibilities: 1) his A05 head was defective, which would not speak well of the A06, because according to Brian, there were "no changes," or 2) Brian's information is wrong. This is disturbing, because Brian works for GK. Maybe he didn't have all the correct information at the time of his post, or 3) unclekebm is hearing what he wants to hear, which I find unlikely, given his comments about problems with his A05.

Don't get me wrong, I am a fan of this amp. It IS a good sounding amp. But clearly, I (and at least a few others are as well) am having difficulty understanding an unusual gain structure.

Or, it is still possible that were some isolated problems with the gain on A05 models and when he sent it back to get that fixed they upgraded tp the A06 model. One thing we know is true is this amp has some problems, but so do some other amps by other manufacturers. What we don't know for sure is if GK has been totally forthcoming with all the information. I felt better about the while situation when they were posting here regularly, but seeing how they responded with their CS is what is important. I bought one because I knew they would stand behind there product even after reading every post. Would it have been better if they didn't need their CS, yes, but am I going to lose sleep over the fact they are not posting here anymore or haven't made all the details or numbers available-no. This is a great sounding head and GK has the CS to back there product, that is what is important to me.

 

[unclekebm]

I think maybe they reduced the HOT input by process of elimination ??
but I don't know for sure...

This whole process has been very linear, Things change quickly
I was told many things that where later changed (which is why I was soo frustrated early on)
I believe GK has been as honest and forthcoming as they can be,
considering customers have had various issues...

The 'truth' I know is; my A05 had to have -10db engaged & My A06 doesn't
And so far the A06 is flawless
Whether or not it's because of the input revision, I don't know and haven't been told any different
I was told that I posses the latest revision, so if I don't have any issues the MB2-500 is good to go

 

[unclekebm]

To wvbass -

by hearing what i want to hear you mean;
halfway through a 'rockin' high energy set my amp starts to shut off randomly while still cool
causing embarrassment and a panic situation...

I'd say, that's not really what I want to hear

as for your other points;
I'm sure Brian was doing his best to accomodate the various 'puzzling' issues presented to him
Sometimes it takes more & more input to finally isolate a problem

I think the first A06 probably was not issue related - then the issues started coming in

 

[wvbass]

To wvbass -

by hearing what i want to hear you mean;
halfway through a 'rockin' high energy set my amp starts to shut off randomly while still cool
causing embarrassment and a panic situation...

I'd say, that's not really what I want to hear

as for your other points;
I'm sure Brian was doing his best to accomodate the various 'puzzling' issues presented to him
Sometimes it takes more & more input to finally isolate a problem

I think the first A06 probably was not issue related - then the issues started coming in

Exactly, which is why I said (3) was "unlikely." I am very curious whether Brian's earlier statement was accurate, or whether he was the victim of bad information.

I curious about this, but it is academic really; I have an A06. I am struggling a bit with the gain structure - it seems that some basses will drive the input too hard even with the 10dB pad. I don't get a clip light, but I hear the clipping - Or is that the elusive GK growl that I've been reading about? It doesn't sound bad, but it isn't crisp and clean, either.

Either way, the only way to tame some basses is to turn the bass itself down - and that's something I've never had to do with any amp I've ever owned.

 

[unclekebm]

Exactly, which is why I said (3) was "unlikely." I am very curious whether Brian's earlier statement was accurate, or whether he was the victim of bad information.

I curious about this, but it is academic really; I have an A06. I am struggling a bit with the gain structure - it seems that some basses will drive the input too hard even with the 10dB pad. I don't get a clip light, but I hear the clipping - Or is that the elusive GK growl that I've been reading about? It doesn't sound bad, but it isn't crisp and clean, either.

Either way, the only way to tame some basses is to turn the bass itself down - and that's something I've never had to do with any amp I've ever owned.

yea, I was funnin' with you...

As long as your 'boost' is off, you should have a crisp, clean sound
where's your master vol?

IME - a little bit of 'contour' will take the 'edge' off...

 

[wvbass]

I've run it with the gain low and master low, gain high master low, gain low master high. My Dingwall can simply overpower this thing - I get some clipping that doesn't light the light, but I can hear it in the horn of my cabs. (I've had the same result with both Epi and GK cabs.) I assume that, with no clip light coming on, I'm clipping somewhere after the initial input stage.

Most of the basses I've tried with this amp are fine, but I certainly wouldn't accuse this amp of being crisp and clean - regardless of settings, it always sounds like the midrange is about ready to start breaking up - even when it is not.

 

[KJung]

I've run it with the gain low and master low, gain high master low, gain low master high. My Dingwall can simply overpower this thing - I get some clipping that doesn't light the light, but I can hear it in the horn of my cabs. (I've had the same result with both Epi and GK cabs.) I assume that, with no clip light coming on, I'm clipping somewhere after the initial input stage.

Most of the basses I've tried with this amp are fine, but I certainly wouldn't accuse this amp of being crisp and clean - regardless of settings, it always sounds like the midrange is about ready to start breaking up - even when it is not.

That's what many call the GK grind, and is somewhat built into the sound of the entire GK amp line. Even the little MB150 has that 'warm, grindy' sort of mid voicing when pushed just a little bit. Not my thing, but many like that sort of mild distortion in the midrange. It is a unique tone to GK, and it works pretty well in some contexts IMO!

 

[Simon Langley]

I've run it with the gain low and master low, gain high master low, gain low master high. My Dingwall can simply overpower this thing - I get some clipping that doesn't light the light, but I can hear it in the horn of my cabs. (I've had the same result with both Epi and GK cabs.) I assume that, with no clip light coming on, I'm clipping somewhere after the initial input stage.

*I don't think that this is the "GK grind". I get the same kind of distortion from the horn of my cab even without lighting the light anytime the 10 db pad is not engaged. WVBass, you don't say anything about weather or not you were using the 10 db pad while trying all these different settings. Did you?

*After my initial rants about input level I went back to "the lab" and ran some more tests. One thing I have come to realize is that a lot of my problem is in my right hand. I play pretty aggressively. I think that anyone with a heavy hand or a high output bass is gonna make this thing clip without the pad engaged.

*My theory, and this is only my opinion mid you, is that GK did set the input as high as they could to get the most performance out of this amp (not a bad thing) but maybe they didn't take club-fisted fools like my into consideration. I am also sure that they were not able to test every bass on the market to make sure it wouldn't overload. Now that this issue is surfacing they are taking care of it on a case by case basis. Not to save money or anything like that but because every player and every bass is different and not all MB owners would have a problem with the input level as it is.

Most of the basses I've tried with this amp are fine, but I certainly wouldn't accuse this amp of being crisp and clean - regardless of settings, it always sounds like the midrange is about ready to start breaking up - even when it is not.

*This may be the GK grind that is the sound I have been looking for all these years and thought only a hybrid could provide. Dang, all those wasted years with SWR, Eden and Hartke. Again I would ask if the 10 db pad was on or off when you were feeling this issue. I did find that with the amp set the way the manual advises (master at 3:00 and preamp turned up as needed, in my case with the 10 db pad turned on) the amp was very clean until I really started digging in. Then the GK grind starts to take hold. This is exactly the kind of response and tone I want but maybe you don't. We all have different tastes.

 

[unclekebm]

I've run it with the gain low and master low, gain high master low, gain low master high. My Dingwall can simply overpower this thing - I get some clipping that doesn't light the light, but I can hear it in the horn of my cabs. (I've had the same result with both Epi and GK cabs.) I assume that, with no clip light coming on, I'm clipping somewhere after the initial input stage.

Most of the basses I've tried with this amp are fine, but I certainly wouldn't accuse this amp of being crisp and clean - regardless of settings, it always sounds like the midrange is about ready to start breaking up - even when it is not.

Have you tried turning the contour up, It should mellow out that upper mid grind
but IMO, Too much will scoop out some much needed mid-mids though
turning the Hi-mid down a little should help as well
Also turning down the Tweeter on your cab will help...

I agree with Kjung to a point,
But I can get my MB or any of the GK amps I've had to run super clean

As said, That GK sound is not for everyone
although, I can get a LMKII, Shuttle 6, Hartke3500, LM-F1, 700RBII, 1001RBII, 800RB, sansamp w/QSC all to give me my exact tone
if I manipulate them...

 

[B-string]

If you play that aggressive drop your pickup height some.

 

[Simon Langley]

If you play that aggressive drop your pickup height some.

*Good idea!

 

[B-string]

*Good idea!

No problem, I have been known to play a little heavy as well. It worked wonders for me (added some sustain also).

 

[wvbass]

WVBass, you don't say anything about weather or not you were using the 10 db pad while trying all these different settings. Did you?

Have you tried turning the contour up, It should mellow out that upper mid grind
but IMO, Too much will scoop out some much needed mid-mids though
turning the Hi-mid down a little should help as well
Also turning down the Tweeter on your cab will help...

I think I've confused things by talking in two directions at once. Let me clarify.

1) With my Dingwall, I do have to engage the 10dB pad. In fact, I've found that it is generally better to make "in" the default and only use "out" on a particularly low output basses. Even with the pad engaged, I can get some audible clip (no clip light). Not constant clip, but if I play a bit aggressively, it will clip, and the light will stay off. Not overly aggressive, mind you - it is not very hard to make it clip.

2) The midrange sounding like it is "about to break up" is the other topic, and this was not so much an issue as an observation. It is not exactly distorting or overdriving, but it is a little "grindy." It is weird. It almost sounds like it is overdriving in the midrange, but when you listen closely, you realize it isn't really; it just becomes more "complex" in the midrange, for lack of a better way to describe it. This may be the GK growl, as Ken pointed out. I've noticed this with my main bass (Lakland 4-94). Its not a necessarily a bad thing, and in some situations it could be a good thing. But this is not a super-clean amp, IMO. I have not messed around much with the contour knob, but I will. I shy away from knobs like that - I'm a long time SWR user, and the "Enhance" on an SWR is pretty much should have been labeled the "Suck" knob.

And, after a few weeks with the MB2-500, and a week or so with a pair of Neo112-IIs, I've turned one tweeter off and the other to -2dB. Still have plenty of top end if I want it.

 

[MIJ-VI]

CONTEXTUAL REMINISCENCE:

The intermittent problems a minority of MB2-500's have exhibited in the field has resurrected a trouble-shooting tale related to me a long time ago by a guitarist/recording engineer who worked at a studio here in town.

Said studio took delivery of a new-fangled (at the time) automated mixing desk which turned out to have a malfunctioning channel strip.

The studio's engineers trouble-shooted the strip and narrowed the potential cause of the problem down to one component which they removed, tested, and found to be good.

They then reinstalled the vetted component and the strip still misbehaved so they called the board's manufacturer who sent a technician.

When the tech arrived, the studio guys didn't tell him about their trouble-shooting efforts, only that the strip wasn't working right.

They then stood back and watched as the tech performed the same trouble-shooting sequence that they had done which culminated in him also narrowing the problem down to that same component which he removed, tested, and found to be good.

But then he did something they didn't do: he replaced the component anyway, and et voila, the strip began working properly.

So what was the problem?

The slight +/- tolerance variable of that 'good' component, in conjunction with the slight +/- tolerance differences of all the other components in the strip, caused said strip to skew outside of its design parameters resulting in its misbehaviour.

Replacing the component with another seemingly identical unit whose +/- tolerance was slightly different resolved the issue.

SPECULATION:

I suspect that the intermittent and varying issues being experienced by a minority of MB2-500's may be symptomatic of a similar cumulative component tolerance issue further exacerbated by the performance drift which some electronic components experience after a burn-in period.

Then there's the added variable of these amps being subjected to an occasional out-of-spec AC supply courtesy of local power utilities - not to mention that bane of many an amp-using musician: stage-wiring-by-club-owner's-brother-in-law - which would further aggravate underlying problems in a random manner.

(An abundantly obvious) STANDARD DISCLAIMER:

I am not a tech.

 

[Simon Langley]

Shipped my MB2-500 off yesterday to see about the input gain clipping issue. Will let you know what the outcome is when it returns.

 

[Gtrslngr]

Shipped my MB2-500 off yesterday to see about the input gain clipping issue. Will let you know what the outcome is when it returns.

I've been out of town, but when I got back I plugged in the Roscoe and "disengaged" the -10 and set my Roscoe EQ flat with volume maxed and I played finger style and slap with no clip light. The only way I got it to clip was to slap the low B kinda hard. I don't like leaving the on-board pre flat, so I just keep the -10 engaged. My MB2 is the A05 version and everything about it works great. I'm sure GK will quickly get yours up to speed as well.

 

[Simon Langley]

Heard back from Noli today. He said that the input gain was indeed too high on my amp. he lowered the input gain and raised the output gain of the preamp so the overall level is still the same. Should be getting it back tomorrow and will let you know the result.

 

[Simon Langley]

Little brown truck delivered it this morning (to work) so I won't get a chance to try it till alter. Still has the A05 serial number but the R/O included with it says "Updated" on it.

 

[Simon Langley]

*Looks like Noli got her fixed. Sounds the same but doesn't clip the signal with the 10db pad off anymore. Very happy! Thanks GK!

*The funny thing is that now that I can use the amp without the 10db pad I can't get the volume low enough to play it through the Neo 212 in my apartment. I have to engage the 10db pad to get it down to neighbor friendly levels. Just amazing how much power they have packed into such a little package.