MB 500 master/gain settings

8stringfunk · #1 04-08-2011, 06:23 PM

I know the manual says to turn master to 3 o'clock, and then adjust input gain to desired level, and I have been doing this, however there is a lot of noise through the cab. It's just a high pitch hiss but it is quite loud (for what it is).

I tried setting the master and gain knobs in a more traditional way (master for overall volume and gain for, well, gain) and it did actually reduce this hiss. This doesn't necessarily mean that I will set the amp like this from now on. What concerns me is if the DI will carry the noise to FOH.

TomB · #2 04-08-2011, 06:30 PM

I have the MB Fusion 500 (same power section). I can't imagine turning the master to 3:00, regardless of what the manual says. I've been using the gains between 11 & 1 and the masters around 10:00 or so, in a medium volume setting. I haven't noticed any hiss, but it's not a quiet environment.

I can't be certain, but I expect the DI is not afffected by the master setting in any case; certainly not in pre, and I suspect not in post setting either. Check out the block diagram.

8stringfunk · #3 04-08-2011, 08:04 PM

Yeah the diagram says the DI is well before the power amp, even before the pre gain I think.

I did feel a little strange setting the amp the way the manual says, being primarily a guitarist I was surprised to read that in the manual, even the guys in the store were unaware of this when I went back to try the amp again.

The hiss I'm getting would be from the master running high output to the cab, but the input gain is low, eg. if I were to push the amp and have the master that high along with the input level I'd expect to get a normal amount of background noise from the amp, as it would be running at high volume, but the way they say to set it just seems so strange to me.

jasper383 · #4 04-08-2011, 08:16 PM

Quote:

Originally Posted by TomB

I have the MB Fusion 500 (same power section). I can't imagine turning the master to 3:00, regardless of what the manual says. I've been using the gains between 11 & 1 and the masters around 10:00 or so, in a medium volume setting. I haven't noticed any hiss, but it's not a quiet environment.

I can't be certain, but I expect the DI is not afffected by the master setting in any case; certainly not in pre, and I suspect not in post setting either. Check out the block diagram.

I have had several GK heads, and I too can't imagine having the master turned to 3 o'clock. Does the manual mean turned to 3 with 10 being the max? I always set the input at about noon, and then the master to whatever volume was needed. If it sounded too "hot" I backed off the input, if it sounded too "thin", I boosted the input until it no longer did.

edit: I just looked at the manual, and it does say master at three o'clock.

JonnyAngle · #5 04-08-2011, 08:23 PM

I have had the master at 3, but the gain is at like 8:00. They're is no growl either

**DougD** · #6 04-08-2011, 08:27 PM

Quote:

Originally Posted by JonnyAngle

I have had the master at 3, but the gain is at like 8:00. They're is no growl either

You will have to use the boost function on the MB500 if you want growl.

**DougD** · #7 04-08-2011, 08:35 PM

Quote:

Originally Posted by 8stringfunk

I know the manual says to turn master to 3 o'clock, and then adjust input gain to desired level, and I have been doing this, however there is a lot of noise through the cab. It's just a high pitch hiss but it is quite loud (for what it is).

I tried setting the master and gain knobs in a more traditional way (master for overall volume and gain for, well, gain) and it did actually reduce this hiss. This doesn't necessarily mean that I will set the amp like this from now on. What concerns me is if the DI will carry the noise to FOH.

The MB 500 is a hissy head with all the eq knobs at noon. Only way to get rid of it is to turn down your treble and contour. You may also need to turn down your speaker's tweeter knob too. Adjust eq to taste and that should get rid of it. The hiss is really not noticeable when playing with a band (at least it wasn't for me) but it can be quite annoying when practicing by yourself. I hope they fix that with the new MB 800.

JonnyAngle · #8 04-08-2011, 09:04 PM

Quote:

Originally Posted by DougD

You will have to use the boost function on the MB500 if you want growl.

I usually keep the boost about noon

**DougD** · #9 04-08-2011, 09:25 PM

Quote:

Originally Posted by JonnyAngle

I usually keep the boost about noon

I don't remember exactly how the MB works, but for my 1001RBII the suggested setting is around 2-3 o'clock for the distinctive GK growl. Try that and see if it helps.

keyboardguy · #10 04-08-2011, 10:16 PM

From the Manual:

"5. Level and Master Volume settings:
Set the Master Volume to 3 o’clock. Turn the Input Volume knob up as you play to the desired output
level. If the clip light (pad button) flashes more than occasionally, press the -10db pad button in and
turn the Input Volume knob up. If it is still lighting often, try turning the volume down on your bass."

regards,

Mike

8stringfunk · #11 04-08-2011, 11:17 PM

Quote:

Originally Posted by keyboardguy

From the Manual:

"5. Level and Master Volume settings:
Set the Master Volume to 3 o’clock. Turn the Input Volume knob up as you play to the desired output
level. If the clip light (pad button) flashes more than occasionally, press the -10db pad button in and
turn the Input Volume knob up. If it is still lighting often, try turning the volume down on your bass."

regards,

Mike

Yeah the manual says to operate it in this way, but what's being suggested is that while this may be the GK way, it may not be optimum for all users of this amp. Obviously many people prefer to run the amp differently to what GK advise. I'm going to experiment some more, in different settings/volumes etc.

**DougD** · #12 04-08-2011, 11:36 PM

Quote:

Originally Posted by JonnyAngle

I usually keep the boost about noon

Hope this helps you.
From the MB 500 manual
Boost/Master B:
Turning up the Boost control will add a little growl
to your tone by adding a small amount of ever
order harmonic distortion. This is an unmistakable
GK trade mark sound that you will surely grow to
appreciate. Raising the Boost while lowering
Master B will add more growl while keeping the
sound level the same. You can use Master B to
increase or lower the overall output volume when
switching the Boost on via the front panel or from
the included foot switch. In either normal or boost
mode, the cleanest sound is obtained with Master
Volume settings at 3 o'clock.
__________________
What I say is just my opinion. What I do, is just my way.
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8stringfunk · #13 04-09-2011, 12:09 AM

So could we say that the master at 3 thing is to allow easy use of the boost channel when switching to it?

8stringfunk · #14 04-09-2011, 04:17 AM

Ok, I have been running the head for a while now, still at a conservative volume, but louder than I have been lately, while setting gain at roughly 10-12 o'clock and master to suit.

The hiss is way less audible, and interestingly the fan hasn't come on at all yet. I posted another topic yesterday about the fan being curiously loud and intermittently coming on, even at very low volumes, but since I've been running the power amp section much lower (I think I'm right in saying this?) the fan hasn't kicked in at all.

I'm now a little sceptical of what the manual says, not saying "it's wrong", but I think maybe they didn't want people driving the pre-amp too hard in order to allow for the boost channel to be properly utilised and not overdrive the power amp. I dunno', I'm kinda fishing there cos I don't know much about this stuff, but it's just a thought. I am however going to run the amp like this from now on, it just makes sense to me.

floatingaxe · #15 04-09-2011, 04:51 AM

I had an MB2-500 (bought use, died) and now an MB500.
Both have the hiss with Master at 3. EQ and Gain don't affect it.
It must have to do with the power amp.
However, since the Gain affects the send throught the direct and DI I've never been able to have the Gain above 12 without the sound guy barking at me.
So that puts the Master at about 11 or 12 for normal stage volumes. No hiss then.
I have a 12/6.5 cab and a 2x10 with tweet.

TomB · #16 04-09-2011, 04:59 AM

Quote:

Originally Posted by floatingaxe

I had an MB2-500 (bought use, died) and now an MB500.
Both have the hiss with Master at 3. EQ and Gain don't affect it.
It must have to do with the power amp.
However, since the Gain affects the send throught the direct and DI I've never been able to have the Gain above 12 without the sound guy barking at me.
So that puts the Master at about 11 or 12 for normal stage volumes. No hiss then.
I have a 12/6.5 cab and a 2x10 with tweet.

This is about the same way I'm running the MB-Fusion. I don't know if it hisses at 3 on the master because I've had no need to find out. With the gain and the master both at 11, it's loud and still clean, or at least not into any kind of distortion, and the "growl" is very nice indeed. I'm not sure how different the MB 500 preamp sounds from the MB-F, but I would expect their power sections to act the same.

**DougD** · #17 04-09-2011, 08:56 AM

Quote:

Originally Posted by 8stringfunk

So could we say that the master at 3 thing is to allow easy use of the boost channel when switching to it?

Setting the master at 3 will give you the cleanest sound. Or so says the guy that built it

4Mal · #18 04-09-2011, 09:08 AM

I have a little different take on it. I run the run my input gain around 10:00 on the dial and set my master appropriately for the room. My EQ is generally at noon and I have no audible 'hiss'. I run a fairly simple front end chain. Pitchblack+ tuner, SansAmp ParaDriver (dry to the amp, wet to the house). For acoustic stuff I add Fishman Pro Platinum Bass EQ (could they have a longer name for that thing ?) for use with my ABG. I often cable 2 basses for those gig's so there is an EQ/DI for each.

TomB · #19 04-09-2011, 09:46 AM

I just realized the MB Fusion has a different master volume scheme from the MB 500; it has a separate master for each channel A & B, and has no "boost" knob. So, in spite of similarities between the 2 power sections, my advice above may not be useful. ...but I haven't heard any hiss!

johnnybass01 · #20 04-09-2011, 12:29 PM

The master should always be set higher than the gain ,I had a problem with an mb212 that resulted in a thermal shutdown , caused by having the gain at 12 oclock and the master at 10 oclock. If you are pushing the amp to higher volume levels then the 3 oclock setting on the master is the way to go . you don't want to have the gain higher than the master , this puts unwanted load on the gain stage and makes the amp work harder..