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the MB212 "kit-built" project (intro.).......

#61
Still checking whether I can put in any more bracing - then glue, cure and do the "twack test"!
It will be some days yet..........

In the meantime, how about damping?

"greenboy" suggested the acoustic "egg crate" foam from PE.
A possibility - comes in 2 sizes - 1/1/2" and 2 1/2".

"rpsands" suggested batting - also a possibility.

BFM said "sonic barrier" (also from PE) no good except on metal (cars etc). Noted (with thanks).

I've found another (expensive) possiblity - "No Rez" (GR Research) - especially for (supposedly) damping resonant panels.
I have no idea if this stuff is really worth the price or even does what it says?
Anybody have any experience with it?

For sure the addtional bracing done on this cab will help a lot, but I'm not convinced that there will not STILL be an issue with panel resonance?
I'm wondering if there is anything on the market (that I am obviously NOT aware of) which could not only combat standing waves, but would also combat panel resonance - perhaps along the lines of CLD (constrained layer damping)?

Any ideas on that?

Thanks.
 
#62
Did you ever think to yourself that the combo's so called boomy sound could be in any way contributed to the voicing of the preamp. Or do you think of yourself as a sound engineer ? If so why don't you just build your own cabinet, IMO you are leading some people in a totally wrong direction. Why take a cheap 700 combo to make the ultimate combo , there are better place's to start, as far as your credentials , ( i have not seen any ) . Bass cabinets are not audiophile cabs , by no means and they should not be. If you think that adding bracing and damping material is going to change the sound, more than likely it will sound better to your ear. but in reality did you really inprove anything. With the amount of money these companies invest in r&d and the testing equipment they use, You really know better (i don't think so )
 
#63
johnnybass01 said:
Did you ever think to yourself that the combo's so called boomy sound could be in any way contributed to the voicing of the preamp. Or do you think of yourself as a sound engineer ? If so why don't you just build your own cabinet, IMO you are leading some people in a totally wrong direction. Why take a cheap 700 combo to make the ultimate combo , there are better place's to start, as far as your credentials , ( i have not seen any ) . Bass cabinets are not audiophile cabs , by no means and they should not be. If you think that adding bracing and damping material is going to change the sound, more than likely it will sound better to your ear. but in reality did you really inprove anything. With the amount of money these companies invest in r&d and the testing equipment they use, You really know better (i don't think so )
Click to expand...

There's a lot of reasons that someone might want to do a project like this, but probably at the bottom of the list is 'to prove you're better' then the amps manufacturer/designer. I think we can assume that the OP will put in the time/effort/cash that he feels are 'worth it' and knows that the outcome will be within a specific range.

Of course, GK users can still feel free to feel offended and put out that someone's second guessed 'their' brand. ;)
 
#66
It is funny that nobody gets the Idea that maybe the way the preamp is voiced has something to do with this. And they think that the only difference that can be made is to the cabinet. When I worked at JBL we designed all kinds of cabinets and the sound changed with the different types of amplifier preamp combinations we tried , same cabinet different signal , completely different sound.
 
#67
johnnybass01 said:
It is funny that nobody gets the Idea that maybe the way the preamp is voiced has something to do with this. And they think that the only difference that can be made is to the cabinet. When I worked at JBL we designed all kinds of cabinets and the sound changed with the different types of amplifier preamp combinations we tried , same cabinet different signal , completely different sound.
Click to expand...
Pre-amp voicing obviously makes a difference in sound, but so does the cab. If your job at JBL was other than on the loading dock you'd be aware of that, as well as the need for adequate bracing and damping. Just ask Don Keele.
 
#68
Why doesn't anyone ask Bob Gallien why there is no damping , He designed it and obviously knows why he chose to leave it out , he is on these forums. There are no needs for personal attacks , and you should know that if this is a pre amp issue , yes you can make it a little less pronounced by damping the cab and bracing it better but it will not simply dissapear.
 
#69
We asked him and he said it sounded better without damping or bracing. Pretty much a non-answer. The accurate answer is probably "It saves us X dollars per cabinet, and it didn't make that much of an apparent difference to us."

It's possible that the preamp is partially at issue here. Trying to make amps sound huge down low when set "Flat" is a long time bass amp manufacturer gimmick.

What that doesn't change is that bracing and batting a cabinet is always the right thing to do. A subjective listening test is not going to reveal every consequence of failing to do so. It's the established method for a reason.
 
#73
I paid less than $600 for my MB212, and I just cannot justify doing all of these mods to an amp that I "only" use for practice and at church on Sunday mornings. It is not my "gigging" rig!

Mine has been back to GK once already, and the cabinet was replaced, however it still buzzes and resonates, and it does not produce an adequate bass sound - though I know it is a GK - and it has the potential! The only way I can get a decent sound out of it is to turn the bass and mid bass down to 9:00 or less, the mid is down to about 10:00, and the the treble is up to 12:00. I don't play a crappy bass through it either - it's a Lakland 5 stringer!

I read on here that some people "do" get a clean and articulate sound reproduction out of their MB212 . . . I wish mine did, as I really like that 37 pound weight versus 196 pounds for my gigging rig.

I do plan on going through the MB212 though - insure that all the screws in it are tight, and no doubt will add acoustical insulation, though the GK techie said it wouldn't do any good!

That said . . . good luck with your rebuild of the MB212!
 
#74
I've used selfadeshive rubber composite material, intended for reducing discbrake noice in cars, inside my Fender Bassman 250/210 combo + plywood bracing, glued with epoxy, baffel to backside of the speakerbox. = no more vibrating back on my combo and better sound.
 
#76
vince a said:
I paid less than $600 for my MB212, and I just cannot justify doing all of these mods to an amp that I "only" use for practice and at church on Sunday mornings. It is not my "gigging" rig!

Mine has been back to GK once already, and the cabinet was replaced, however it still buzzes and resonates, and it does not produce an adequate bass sound - though I know it is a GK - and it has the potential! The only way I can get a decent sound out of it is to turn the bass and mid bass down to 9:00 or less, the mid is down to about 10:00, and the the treble is up to 12:00. I don't play a crappy bass through it either - it's a Lakland 5 stringer!

I read on here that some people "do" get a clean and articulate sound reproduction out of their MB212 . . . I wish mine did, as I really like that 37 pound weight versus 196 pounds for my gigging rig.

I do plan on going through the MB212 though - insure that all the screws in it are tight, and no doubt will add acoustical insulation, though the GK techie said it wouldn't do any good!

That said . . . good luck with your rebuild of the MB212!
Click to expand...



I spent some time taking apart a 410MBE cabinet and adding some stuffing.

http://www.talkbass.com/forum/f15/gk-410mbe-mods-785123/

Note: this is a sealed cab so stuffing it is okay, the MB212 is a vented cab so you should stick with lining the cabinet

I noticed a few things:

1. All of the speaker screws were loose on two different cabinets. Not so loose that the speaker could move, but I was able to tighten them all down about 1/4 turn without stripping them.

2. All or the other hardware screws were also loose. I tightened virtually every screw.

3. I have two cabinets. The grill on the first one was just installed with screws. The second one had a bead of caulking material around the sides where it comes into contact with the sides, top and bottom of the cabinet. (neither of my grills rattled. GK has a nice simple method of installing the grills with 4 screws through the side)

4. Stuffing the cabinet made a noticeable difference in the sound for the better. Especially at high volumes. Less boomy and cleaner mids. You can check out some sound clips in my thread.

5. The GK speakers look good and seem to be high quality. I have some pictures at the beginning of the thread.
 

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