Thought I might have burnt the horn's voice coil so I popped off the front to check the horn. Noticed that there is no acoustic material in the cab at all. Is this an ok thing?
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Just opened up my 210MBE...
- Thread starter miner49er11
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billfitzmaurice
Commercial User
- Sep 15, 2004
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- Owner, Bill Fitzmaurice Loudspeaker Design
Absolutely not. IMO there's no excuse for cost cutting measures of that sort, especially when the manufacturer's savings would be less than $5, including labor.
- Mar 24, 2003
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- Robert A. Gallien, President Gallien-Krueger
There is plenty of bracing in these cabinets, they are very stiff which is why they sound a good as they do. Also do not add any material to the inside, they are designed to work best just the way they are!
Bob Gallien
There is a distinct lack of bracing, in my opinion. In comparison to my Aguilar and Eden cabs... well, no comparison. It would be interesting if someone who knows cabinet design would make recommendations for improvements. At 30 lbs, an additional few lbs added to the cab means little.
I will take a trip down to GC and tap on the outside of one of these soon, but my memory is that they were pretty resonant on the outside when I rapped my knuckles on one, leading me to suspect the bracing was pretty limited.
If someone wants to post a pic of the inside of one to prove me wrong I'd love that.
Also, please explain more about this lack of lining. I've read a lot on the subject and never ever heard anyone suggest that leaving an enclosure unlined (or unstuffed in the case of a sealed enclosure) was a good idea.
billfitzmaurice
Commercial User
- Sep 15, 2004
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- Owner, Bill Fitzmaurice Loudspeaker Design
As noted by rpsands the simple 'knuckle test' is all you need to determine if there's adequate bracing. If you rap the middle of a panel with your knuckles the rap should sound high pitched and solid, not low pitched and hollow.
As for the cabinet damping, its adequacy can be tested with a 9v battery. When connected and disconnect to the speaker the sound should be heard as a 'click', not a 'boom' or 'thump'. The lack of damping will result in added boom in the midbass and erratic midrange. One can of course test response with and without damping, but few have the capability of doing so. In any event cabinet damping isn't a subject for debate, it's long been recognized by the acoustical engineering community as a necessity, not an option.
For the longest time, I've been debating adding some batting to my Avatar B212. The cab is most definitely boomy. It passes the "knuckle rap test" with no problem. The cab is made of 3/4" birch. It's heavy and solid like a brick. It's just boomy. It has two strips of really thin (maybe 1/2" thick) batting about 10" wide x about 18" long stapled to the rear wall of the cab but that's it. I wish I could reliably predict whether adding batting would help or hinder the sound w/o actually opening up the cab and doing it.
Would someone knowledgable like to make a recommendation as to how much padding there should be in that size cab? Mr. Fitzmaurice?
Please?
Would someone knowledgable like to make a recommendation as to how much padding there should be in that size cab? Mr. Fitzmaurice?
Please?
billfitzmaurice
Commercial User
- Sep 15, 2004
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- Owner, Bill Fitzmaurice Loudspeaker Design
You may use one inch thick polyester fiber furniture upholstery batting, or inch and a half thick convoluted polyurethane (not latex) mattress topper foam, both available at local department stores. Half-inch thick felt carpet padding also works well. You don’t need 100% coverage, but 90% coverage of all the internal cabinet surfaces is a good idea. Cut the stuff to size and staple it in with a heavy duty stapler.Would someone knowledgable like to make a recommendation as to how much padding there should be in that size cab? Mr. Fitzmaurice?
This may not fully cure a boomy cab, since boom is also the result of a cab that's too small for the drivers it contains. But it will make it better.
Thanks very, very much, Mr. Fitzmaurice! I appreciate the detailed reply. 
"Convoluted foam" is that the "eggcrate" looking stuff? I think I can find that pretty cheaply where I'm at. I remember from my car audio days that stuffing a box makes the box appear larger in size to the driver. I know it works that way for sealed boxes; don't think it works that way for ported boxes though. Thanks again.
"Convoluted foam" is that the "eggcrate" looking stuff? I think I can find that pretty cheaply where I'm at. I remember from my car audio days that stuffing a box makes the box appear larger in size to the driver. I know it works that way for sealed boxes; don't think it works that way for ported boxes though. Thanks again.billfitzmaurice
Commercial User
- Sep 15, 2004
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- Owner, Bill Fitzmaurice Loudspeaker Design
Yes, though it doesn't have to look that way.Thanks very, very much, Mr. Fitzmaurice! I appreciate the detailed reply.
Stuffing a sealed cab lowers system Q, which helps to tame boom. It's not the same as what happens with a larger box, but is similar, which gave rise to that notion.
Lots of love and hate for the MB series GK is putting out. Why do people consistently expect the quality of a thousand dollar cab from a 300 dollar one. I'm confused.
I hear you, but I wouldn't consider this a quality issue. It's a matter of right or wrong.
If you had the option of paying X dollars for something done wrong, or 2 or 3X for something done right, what would you do? Instead of putting your hard earned dollars to waste, keep saving and spend that on something worth while.
According to Mr. Galliens post it wasn't done wrong. It was made that way by design. So who is wrong here?
