Double Bass Is this normal? GK MB150 hiss and limiter noise

[bass12]

I just bought a new Gallien-Krueger MB150 combo and I'm wondering if what I'm experiencing with the amp is normal. When I switch it on and, after a few seconds, the power/protect light goes from red to blue there is an audible hiss which remains for as long as I have the amp on. When I switch the amp off there is a little "pop" sound which comes through the speaker. This hiss stands out to me because none of my other amps produce any significant hiss (I should mention that the hiss with the GK is consistent and is not affected by my turning up the volume or output knobs).

The other thing is that when I engage the limiter the hiss essentially doubles in volume. This doesn't seem right to me but I've never used one of these amps before so I don't know. Any thoughts?

 

[fdeck]

I've got a 20 year old MB150E-112 combo, so there may have been circuit design changes since then, and it looks like they only sell the MB150S model now. For instance there's no red or blue power light on mine. The amp is fairly quiet, but does produce elevated hiss when the limiter is engaged. It also produces a little "thump" of sound when turned on or off, which has never been a problem.

 

[SF_Bassist]

Agreed. I have a circa 2106 MB150s. There is a noticeable "pop" when I power the amp on/off. Same thing with the hiss. For me , its less from the limiter than from volume input or (maybe) the instrument itself. I have gotten used to it and manage to EQ out most of the hiss. It's a lovely amp and I have learned to live with its quirks.

 

[bass12]

Thanks @fdeck and @SF_Bassist for your responses. Very much appreciated!

 

[bass12]

Funny, I did a couple of searches before starting this thread and I wasn't able to find other threads on the subject - but I just came across this:

GK MB150E noise level

That thread is from 2006 and the issue of the hiss hasn't been remedied in thirteen years!

 

[dannylectro]

I have an older MB150S - it is dead silent except when a Jazz Bass is plugged and one of the pickups is dialed full on and the other full off. More like single coil hum, sorta. The limiter, when engaged, does seem to add an airy hiss, but I don’t use it really ever. It’s does “pop on” and “pop off”. It’s an amazing, rugged, dependable, and surprisingly loud amp that does well with upright, acoustic-electric bass, and most of my basses except the one active I have.