GK MB200 Hiss

[drpepper]

I received a new GK MB200 from MF last night and need to decide whether to try to exchange it for another unit, return it or accept the way it is.

(Edit - Video from post below)

GK MB200 Hiss - YouTube

I did a search in the 1000+ post MB200 thread, and obviously turned up a number of posts regarding hiss, but the subjects in the thread are broad and it started getting a bit dizzying. I got the impression that hissing was more common earlier on and had been eliminated or at least reduced in occurrence.

I unpacked my MB200, connected it to a TCE RS212, centered the tone controls, and powered it up with the gain on 0. I immediately noticed a hiss. I was surprised because there was no volume and no bass plugged in. The hiss seems to remain present regardless of the state...cab/no cab, instrument cable/no cable, headphones or not, and all various switch positions. It is reduced by lowering the treble.

So, the main question I have is are some people getting units that are completely quiet? Is this the norm?

Are there people who are accepting some amount of hiss as an artifact of the relatively bright tone of the amp?

I have to spend more time with it over the weekend, but my initial impression is that it's not acceptable.

[KJung]

I have not played the 200, but the three MB500's I spent time with had the highest 'noise floor' of almost any amp I've ever played. Per your point, I do believe part of this is due to the goosed top end of those amps.

For guys rocking at loud volumes, or those who play using one way cabs, not much of a deal. Way beyond my personal threshold though, since I do use two way cabs, and often play in moderate and even low volume situations.

[sanderic]

I bought my MB200 about three months ago, (November 2011), and have no hiss whatsoever. I have now added a GK 410 ultralight cab w horn, and still have no hiss.

[KJung]

It does seem like there is wide variation in units regarding noise. Maybe moving back to US production will tighten all this up a bit.

[drpepper]

Originally Posted by KJung

I have not played the 200, but the three MB500's I spent time with had the highest 'noise floor' of almost any amp I've ever played. Per your point, I do believe part of this is due to the goosed top end of those amps.

For guys rocking at loud volumes, or those who play using one way cabs, not much of a deal. Way beyond my personal threshold though, since I do use two way cabs, and often play in moderate and even low volume situations.

Interesting points. Thanks for the input.

The "noise floor" comment kind of makes me wonder if "completely quiet" could be different for me versus someone else, based on their experience and expectations..."Oh, you're calling THAT a hiss? That's normal."

I've been running with nothing in the way of backup, and I've also just wanted to experience some different voicing. I've been using an RH450 that I'm about to replace with an RH750.

At $235, it just seemed like a good idea all around...add a backup, sample a different sound, leave a practice amp completely set up at home.

As a practice amp, being used to the complete quiet of the RH, I think I'd find it an annoyance. I might like to try it at gigs too - small bars/classic rock covers. It's hard to say how noticeable it'd be.

[drpepper]

Originally Posted by sanderic

I bought my MB200 about three months ago, (November 2011), and have no hiss whatsoever. I have now added a GK 410 ultralight cab w horn, and still have no hiss.

Thanks for commenting.

I guess I can try for an exchange and it'll just be a crap-shoot.

[jeff7bass]

Make sure you’re not getting interference racket from something in your room. The new energy saving light bulbs cause big time hiss in both my guitar player’s amp and mine, both of which are new class D amps. My dvd player + TV has produced noticeable hiss with my practice amp. I’m not sure if more expensive and/or non-class D amps have some type of built in noise buffers (or not) but these new amps seem sensitive to outside interference, not unlike an un-shielded bass guitar cavity. Tombowlus would be a big help here (expert).

[drpepper]

Originally Posted by jeff7bass

Make sure you’re not getting interference racket from something in your room. The new energy saving light bulbs cause big time hiss in both my guitar player’s amp and mine, both of which are new class D amps. My dvd player + TV has produced noticeable hiss with my practice amp. I’m not sure if more expensive and/or non-class D amps have some type of built in noise buffers (or not) but these new amps seem sensitive to outside interference, not unlike an un-shielded bass guitar cavity. Tombowlus would be a big help here (expert).

Thanks. It's something to try, but the fact is that if it's that sensitive, then it has to go.

I really don't think that it's interference though.

[froghat]

Mine has no more hiss noise than my Shuttle. I guess I got lucky. I bought it used for a good price just to keep in my gig bag as a backup.

[tombowlus]

I have an MB200, MB500, and MB Fusion, and none of them make any audible noise in situations where all of my other amps wouldn't also make noise (some basses in some rooms - typically with fluorescent lighting - seem to always have a certain noise floor with any amp I use).

We've also had numerous iterations of the MB series heads on the bench (Audio Precision system) and have not found them to be any noisier than the competition.

I do know that QA/QC was one of the reasons that Bob Gallien decided to bring production back to the USA, though.

[craig.p]

Hissing almost suggests a problem with the power module's output stage filtering. Off-spec component, wrong component, bad solder joint somewhere in the filter network for any number of reasons, cracked solder joint because a tray of completed units was dropped onto a hard floor -- something like that. To find out for sure, a signal from the DI out jack, with the switch set to post eq, could be run to a power amp, and speakers connected to the power amp. If noise-free, then that would in fact point to the power module as the source of trouble. Maybe GK received a bad run of power modules and didn't find out soon enough, if all these noisy units are clean at the post-eq DI. One of dozens of possibilities, all conjecture..........

[drpepper]

If anyone is interested, I made a quick video just now.

GK MB200 Hiss - YouTube

To the degree that this type of thing can be captured (hardly a noiseless environment or noiseless capture) it does show something.

If you listen on headphones at moderate volume, I think it's pretty clear.

[drpepper]

Originally Posted by tombowlus

We've also had numerous iterations of the MB series heads on the bench (Audio Precision system) and have not found them to be any noisier than the competition.

I do know that QA/QC was one of the reasons that Bob Gallien decided to bring production back to the USA, though.

This unit was made in China.

[drpepper]

Originally Posted by craig.p

Hissing almost suggests a problem with the power module's output stage filtering. Off-spec component, wrong component, bad solder joint somewhere in the filter network for any number of reasons, cracked solder joint because a tray of completed units was dropped onto a hard floor -- something like that. To find out for sure, a signal from the DI out jack, with the switch set to post eq, could be run to a power amp, and speakers connected to the power amp. If noise-free, then that would in fact point to the power module as the source of trouble. Maybe GK received a bad run of power modules and didn't find out soon enough, if all these noisy units are clean at the post-eq DI. One of dozens of possibilities, all conjecture..........

I've decided I can't accept this one. I'd really like to have one of these, but my pessimistic expectation is that I'll get another one that hisses.

MF will take the one back and just grab another box and send it to me.

[nutdog]

Originally Posted by drpepper

If anyone is interested, I made a quick video just now.

GK MB200 Hiss - YouTube

That's loud. I didn't notice anything like that with an MB500 I had for a few months. Hope your new one is OK.

[drpepper]

Originally Posted by nutdog

That's loud. I didn't notice anything like that with an MB500 I had for a few months. Hope your new one is OK.

Hey, thanks a lot. But what I'm rolling around right now is whether it's worth the time and effort to basically gamble on getting one that doesn't hiss.

What I'm gathering is that some hiss, some don't, some people accept it, some don't, some don't notice or realize, etc.

[76Dub]

I took one in last week brand new and I had the same issue.... It went right back and is totally unacceptable. I went with a different manufacturer all together. It would of been nice to have a tiny head at 200 watts but too many problems with this little guy.

[drpepper]

Originally Posted by 76Dub

I took one in last week brand new and I had the same issue.... It went right back and is totally unacceptable. I went with a different manufacturer all together. It would of been nice to have a tiny head at 200 watts but too many problems with this little guy.

Interesting. Did you get the MB200 from Musician's Friend?

What did you end up going with?

[miiitch]

Originally Posted by drpepper

If anyone is interested, I made a quick video just now.

GK MB200 Hiss - YouTube

To the degree that this type of thing can be captured (hardly a noiseless environment or noiseless capture) it does show something.

If you listen on headphones at moderate volume, I think it's pretty clear.

yeah, that seems to be about the same noise level my unit produces at home and in rehearsal room

[76Dub]

Originally Posted by drpepper

Interesting. Did you get the MB200 from Musician's Friend?

What did you end up going with?

Nope Guitar Center. I went with ampeg