MB500 - does yours hiss?

basss · #1 03-31-2011, 10:38 AM

I just received one of these yesterday. The amp sounds great but has a hiss that increases as I turn up the master. I've had other amps that hiss a bit and it hasn't bothered me - this one hisses a bit more than others and almost seems like it *could* be normal but there is enough hiss there that makes me think that something could be wrong. Is this normal for this amp?

jnewmark · #2 03-31-2011, 10:43 AM

This subject comes up alot here, not only with this amp. Usually it is tweeter hiss, which is pretty common, especially if you dial in alot of upper end treble. Some tweeters hiss more than others, especially if they have their own attenuator cranked up. Luckily, most of the time, you don't notice the hiss in a band situation. How about some more info on what you are playing through ?

basss · #3 03-31-2011, 11:05 AM

Quote:

Originally Posted by jnewmark

This subject comes up alot here, not only with this amp. Usually it is tweeter hiss, which is pretty common, especially if you dial in alot of upper end treble. Some tweeters hiss more than others, especially if they have their own attenuator cranked up. Luckily, most of the time, you don't notice the hiss in a band situation. How about some more info on what you are playing through ?

I'm playing through a GK neo 112 II which does have an intense tweeter. Comparing it to my Genz 3.0 it seems to hiss quite a bit more. I have the EQ flat on both amps when comparing. GK recommends starting with the Master at 3 and adjusting the gain to the desired volume (different than other amps). If I do this the hiss is clearly audible when I'm playing at any volume and at lower volume can be heard over the sound of the bass. The Genz hiss increases only slightly as I turn up the master and can't be heard at all while the bass is sounding.

greenboy · #4 03-31-2011, 11:11 AM

So if an amps' baked-in default voicing is brighter than you like, then you can either turn the tweeter down on the cab, or cut some treble EQ on the head. Simple, no?

basss · #5 03-31-2011, 11:19 AM

Quote:

Originally Posted by greenboy

So if an amps' baked-in default voicing is brighter than you like, then you can either turn the tweeter down on the cab, or cut some treble EQ on the head. Simple, no?

Actually, no

The treble knob doesn't affect the hiss much. It adds a bit if I crank it but doesn't do much if I turn it down.

The Genz head has plenty of treble and I'm not getting near the same hiss from it with the amp cranked.

BassmanPaul · #6 03-31-2011, 02:20 PM

All high gain electronics create noise. It's what the designer does to mitigate that noise that makes the difference between a good amp and a great one.

jelwood · #7 03-31-2011, 02:30 PM

I have a neo 412 and a 2000rb, it's a similar setup to the one you have in the sense that I'm using a GK neo cab and a GK head that doesn't have their modern biamp system. Have you tried adjusting the tweeter on the back of the cab? Does the hiss come from the speakers or the tweeter? You really shouldn't be hearing that much hiss, Bob designs his preamps with tons of headroom for the very reason of making them quiet when operating. I can crank my 2000rb and you would never even know it's on if you were to strut by my rig on stage...until I drop a low E

Anyways, the only thing I can say is that yours came with perhaps a lemon filter cap(s). Maybe B-string will stop by and grace us with his GK wisdom? I say if the amp is new go ahead and return it and if it isn't new and no longer under warranty, go replace the filter capacitors.

johnnybass01 · #8 03-31-2011, 06:50 PM

I have an mb500 also , same thing it does have a hiss to it also depends what cab your using it with. From what I have read the amp has a very hot gain stage ?? that is all i have found out about it though..

greenboy · #9 03-31-2011, 06:56 PM

If it's like most GK's there is a climbing response baked in, ie bright.

Timi · #10 03-31-2011, 06:58 PM

My MB500 is dead quiet, but I don't use horns/tweeters.

Marko5657 · #11 03-31-2011, 07:21 PM

Quote:

Originally Posted by Timi

My MB500 is dead quiet, but I don't use horns/tweeters.

Same here.

johnnybass01 · #12 03-31-2011, 08:16 PM

With my horn off mine is dead quiet too

audiomitch · #13 03-31-2011, 10:44 PM

I've found every GK product I've ever owned to be a little more "hissy" more than other amps and cabs.

My current rig is a Sansamp VT Bass pedal in to a Crown XLS 1000 DriveCore Power amp (bridged) driving GK Neo 212 and Neo 115 cabs. It can get pretty hissy, even with just the power amp alone connected. My other cab is an Ampeg 410 hlf, which isn't nearly as hissy.

At the volumes I play, a little hiss is really meaningless.

basss · #14 04-01-2011, 07:27 AM

Thanks all

The reason I'm concerned is that if I set up the gain structure as GK recommends (master at 3 and adjust the gain to desired volume) I get a ton of hiss - much more than other amps I've owned and so much that I can't really use it this way at lower volumes. Turning down the master and boosting the gain helps but since GK recommends doing it the other way I'm wondering if something is wrong.

I'd like to know if those of you that use tweeters have this hiss when you start with your master at 3. I'm trying to determine if I need to return it or not.

greenboy · #15 04-01-2011, 07:34 AM

IF you can easily compare to other amps at a dealer, that's what I would do if I thought perhaps my particular sample had a malady.

basss · #16 04-01-2011, 07:35 AM

Quote:

Originally Posted by greenboy

IF you can easily compare to other amps at a dealer, that's what I would do if I thought perhaps my particular sample had a malady.

I'm hoping to do that soon. These seemed to be sold out everywhere at the moment.

jnewmark · #17 04-01-2011, 07:40 AM

Quote:

Originally Posted by basss

Thanks all

The reason I'm concerned is that if I set up the gain structure as GK recommends (master at 3 and adjust the gain to desired volume) I get a ton of hiss - much more than other amps I've owned and so much that I can't really use it this way at lower volumes. Turning down the master and boosting the gain helps but since GK recommends doing it the other way I'm wondering if something is wrong.

I'd like to know if those of you that use tweeters have this hiss when you start with your master at 3. I'm trying to determine if I need to return it or not.

I use this method with my GK RB700II, although I usually set the Master at 12 or 1, and the Gain at 9 or 10. There is hiss coming from the tweeter, but not an ungodly amount, and, not even noticeable on the gig. Maybe it is the amp. The only way to know is to try another one.

greenboy · #18 04-01-2011, 07:48 AM

The specs on s/n for bass-oriened gear are so often "relaxed" compared to pro audio gear. It's somewhat understandable when you are running multi-stage overdrive/distortion, but clean tones? That's one reason some guys design their own preamps, methinks, and use them with good pro power amps.

lbwdog · #19 04-01-2011, 07:55 AM

As a long time user of several G-K models, I've found them to be slightly hissier than some other makes, especially when using cabs with tweeters. But this is only apparent in a dead quiet environment. On the gig, it's never been a problem since the ambient noise of most venues will mask the audible effect, even when not actually playing. Once the downbeat hits it's a non issue, period.

I've used my 800RB in many recording sessions, and the engineer never had an issue with it either. Modern speaker cabs with tweeters will obviously reproduce frequencies that aren't apparent with tweeterless cabs, but I find that a lot of players generally have their tweeters "full-on" when it might not be necessary. Try using your attenuator to cut out some tweeter. There's not usually a whole lot of usable content up in that range anyway. (For most players, that is.)

basss · #20 04-01-2011, 08:17 AM

I do run my GK cab with the tweeter at -2 db. I wouldn't say there is an 'ungodly' amount hiss but it is loud with the master up - again moreso than other amps and enough to have me concerned. I could definitely live with it by setting up the gain structure differently but would rather return it if I could get one that was a bit less noisy. The tone of the amp is great and it seems extremely loud.