Double Bass New faith in GK 200MB

[damonsmith]

I recently bought an AI Clarus head and I don't regret it, it is a great amp. However, I finally got to hear New England bass legend Mario Pavone came to Cambridge with his trio and pulled a huge dark, full sound out of his 200MB with one of the strongest jazz drummers alive - Tyshawn Sorrey.
It made me consider that I had just not been pushing it hard enough. I brought it to a gig last night and pushed the lows and volume more and it was an amazing sound!
I am glad I have the AI, but it is nice to know there is more to this little guy after 20 years!

 

[Ric Vice]

I had two of the 200MB's and loved them both. They aren't especially powerful amps 100 watts RMS into Ohms, but the Pre Amp is very

Double Bass friendly. It's EQ voicing is ideal for the instrument and the analog power amp is warmer than the later ones in the MBS. Of

course they have their limitations, but working within those limitations you can get a great sound.

 

[damonsmith]

I was just too "delicate" with it for the last 20 years! It can be pushed pretty hard.

 

[Ric Vice]

I was just too "delicate" with it for the last 20 years! It can be pushed pretty hard.

As long as you don’t drop it I found that out the hard way. The transformer is mounted below the speaker at the bottom of the cabinet.

 

[Fretless55]

Honestly, I think the 200MB is the bestest combo amp EVER!

 

[HateyMcAmp]

I’m always surprised they don’t make a high-end reissue of this thing specifically for DB players. The MB150S is still in the catalogue but it seems like the MB150E has been discontinued.

 

[Ric Vice]

I’m always surprised they don’t make a high-end reissue of this thing specifically for DB players. The MB150S is still in the catalogue but it seems like the MB150E has been discontinued.

Just guessing here, but their newer amps probably sell more units and are easier builds. I’ve mentioned this before but the topology and design of the 200MB and 200RCB is very complicated. I’m not sure they would be profitable for GK to build now.

 

[Ric Vice]

Here's the schematic for the GK200MB/RCB as you can see it's a discreet component device.

 

[B String]

I love my old MB200. My only issue is that the box starts buzzing at a pretty low volume.

 

[Francois Blais]

Maybe you’re just overloading the preamp.

 

[Povl Carstensen]

I love my old MB200. My only issue is that the box starts buzzing at a pretty low volume.

Is it possible to take it apart and reassemble it, looking for possible causes for buzz/rattle and tighten everything extra good? I never had an GK, but I just thought about it.
Once every several years, I retighten every visible screw on my AI loudspeaker and WW amp.

 

[B String]

This issue is the major weakness with this combo. The metal box design is prone to buzzing once opened. This is a rather old piece of gear that has been opened a number of times.

 

[Povl Carstensen]

Perhaps soft washers could help? Isolating (foam) tape? Ok, I'll stop here...

 

[Ric Vice]

Perhaps soft washers could help? Isolating (foam) tape? Ok, I'll stop here...

I believe cabinet has/had a seal to keep it airtight as the 200MB is a “infinite baffle”. It will degrade over time.

 

[Povl Carstensen]

Perhaps it could be scraped of and replaced...

 

[Ric Vice]

Perhaps it could be scraped of and replaced...

I believe it can, but in truth I don’t think they really anticipated how difficult it would be to reseal that unit. Througn years of wear, the aluminium sides and back get bent and bumped around. Once

you get it apart, it's hard to realighn all the screws that hold the back and sides together, so that the seal air tight. Torquing the screws is problematic because they aren't aluminum so they can rust.

So, it's a great little amp that's pretty difficult to repair.

 

[B String]

I believe cabinet has/had a seal to keep it airtight as the 200MB is a “infinite baffle”. It will degrade over time.

This! I know the only way to fix it is to open up the whole thing and redo the foam. It's a huge pain. I've done it. It has to be perfect, or you get buzzing.

 

[Space Pickle]

Here's the schematic for the GK200MB/RCB as you can see it's a discreet component device.

View attachment 3053669

I have no idea what any of this means.

 

[Ric Vice]

I have no idea what any of this means.

The 200MB dosen’t have a Digital Switching Power Supply or Digital Power Amp It’s entirely analog.

 

[Povl Carstensen]

This! I know the only way to fix it is to open up the whole thing and redo the foam. It's a huge pain. I've done it. It has to be perfect, or you get buzzing.

I wonder if anyone has ever taken the whole thing out and remounted it in a new box. A nice plywood box of the same dimensions...