Would Acoustic Foam improve any Cab or Combo?

[Bodeanly]

Just another thought........

Are you using an active bass ? - If yes, how new is the battery?

Yes. All my basses are active. I replaced all batteries and cables once this started happening.

 

[Bodeanly]

Test the speakers individually. See you don't have a dead one in there just flopping around in sympathy with the others.

Cool! Something else to do when I open her up again. Thanks.

 

[Linnin]

They're farting out at bedroom volume level. I'm at my wit's end.

Sure sounds like blown woofers to me.

 

[Big Brother]

It started a few weeks ago. Progressivley worse at lower and lower volumes. I've done the push and listen testeroo and used an ohm meter. I've never heard of this crease thingie. Guess I'll be pulling it apart again. Thanks, man!

I solved a similar problem with a new speaker cable

 

[Bodeanly]

I solved a similar problem with a new speaker cable

Tried that. I'm thinking it's one of my speakers. Thanks though!

 

[Stealth Fighter]

Check the wires from the terminals on the speaker (not the cabinet) to the voice coil to see if they are broken. I had that happen to me once, and it drove me crazy until I found the problem. The wires made just enough contact to make sound, but it was fart city.

 

[Big Brother]

Definitely sounds like a problem with a solder joint or a crushed wire that is barely making contact. You just have to find it

 

[NightCat]

I opened up the Rumble and added polyester batting (loose fluff) under the amp. If you haven't looked inside a rumble, the amp portion is about 2" thick and extends half way done the back portion. I filled the 2" void with the fluff batting and then covered the whole back with this quilt filler my wife had. The filler is only about 1/4" thick and is like a loose felt sheet. The amp part only has @ 1/4" but under that is the 2+" of batting and quilt backing. All this is tacked in place.
I folded the quilt backing to get about 3/4" and tacked that to the bottom.

I can't say I noticed a huge difference. It does seem to sound better louder and for some reason the Vintage channel on the amps sounds more authentic and "Ampegy". It could be real or I could just be hearing what I want to hear. That polyester batting is so light it is hard to imagine it will effect the sound waves a whole lot.
What do you think?

 

[AstroSonic]

I opened up the Rumble and added polyester batting (loose fluff) under the amp. If you haven't looked inside a rumble, the amp portion is about 2" thick and extends half way done the back portion. I filled the 2" void with the fluff batting and then covered the whole back with this quilt filler my wife had. The filler is only about 1/4" thick and is like a loose felt sheet. The amp part only has @ 1/4" but under that is the 2+" of batting and quilt backing. All this is tacked in place.
I folded the quilt backing to get about 3/4" and tacked that to the bottom.

I can't say I noticed a huge difference. It does seem to sound better louder and for some reason the Vintage channel on the amps sounds more authentic and "Ampegy". It could be real or I could just be hearing what I want to hear. That polyester batting is so light it is hard to imagine it will effect the sound waves a whole lot.
What do you think?

A quarter inch is a bit thin. I've never found less than 1/2 inch to be effective. Also, try lining one side to kill side to side resonances. For a major change in bass, try plugging one of the ports - lowers F3 and decreases bass peaking.

 

[Bigskybassguy]

Test the speakers individually. See you don't have a dead one in there just flopping around in sympathy with the others.

Nice topic highjack, boys and girls!

 

[NightCat]

A quarter inch is a bit thin. I've never found less than 1/2 inch to be effective. Also, try lining one side to kill side to side resonances. For a major change in bass, try plugging one of the ports - lowers F3 and decreases bass peaking.

To be clearer, it is only 1/4" think on 1/2 of the back. The other half is 2" of very fluffy batting and is held in place with the 1/4" quilt backing. The amp electronics only reach half way down the back panel. I guess I will put some more on top of the amp section too. I will add a bit to one of the sides also.

 

[Eric Guthrie]

Would installing something like Sonic Barrier 1" Acoustic Foam to the inner walls of my combos automatically make it sound "better". There isn't a problem that I'm trying to solve I just like messing with my gear.

I have an Ampeg B-100R and a spankin' new Fender Rumble 40. I have NO complaints about the tone of either of them, it's more that I am a chronic fiddler. It's been a long time since I've opened the B100R and I don't remember if it has insulation or not. I think not.

So, waste of time or well worth the few bucks?

Single speaker cabinets and port type/ orientation are important. But, most importantly, there should not be a need for a half-pound of damping material of any kind in a bass cab. Main thing is to interrupt reflections in the cabinet back to the woofer speaker cone, and at the same time not soaking up too much sound energy. Since many cabs are basically a rectangular box, proper treatment to scatter (not dampen) behind the speaker(s) and careful placement on sides/corners is critical. The area of port emission should be kept clear of any acoustical treatment.
One such study found that in a single 15" cab, only 35g of lambs wool was required, with the proper placement of underlying "acoustical wedges" to lift the wool higher than it's base thickness, then teasing it to adjust its density to somewhere less than it would be in a pile. A low density but reflective, convolution type treatment is preferred behind the speaker(s) to "scatter" direct reflection away from back into rear of the speaker(s) cone.

 

[agedhorse]

Single speaker cabinets and port type/ orientation are important. But, most importantly, there should not be a need for a half-pound of damping material of any kind in a bass cab. Main thing is to interrupt reflections in the cabinet back to the woofer speaker cone, and at the same time not soaking up too much sound energy. Since many cabs are basically a rectangular box, proper treatment to scatter (not dampen) behind the speaker(s) and careful placement on sides/corners is critical. The area of port emission should be kept clear of any acoustical treatment.
One such study found that in a single 15" cab, only 35g of lambs wool was required, with the proper placement of underlying "acoustical wedges" to lift the wool higher than it's base thickness, then teasing it to adjust its density to somewhere less than it would be in a pile. A low density but reflective, convolution type treatment is preferred behind the speaker(s) to "scatter" direct reflection away from back into rear of the speaker(s) cone.

It very much is determined by the intent of the designer and the performance goals of the speaker. There are no hard and fast rules, I have designed commercially successful cabinets with a lot and a little acoustic damping depending on the design goals.

IMO, the "study" is just somebody's opinion and in practice may or may not be "proper" for a particular design.

 

[phipop]

This talking is very interesting! But after reading it all, a good part whitch i didnt understood, i still dont know what to do with my rumble 100...I would like to get rid of the 'woofy'.
What i think to do:
polyester foam on half the back and on one side,
maybe changing the speaker if necessary...but i dont need too much quality in this one, so maybe some foam and that's it!
Anyway, thanks a lot everybody and have a nice sunday.

 

[agedhorse]

That's pretty much the inherent tone of the Rumble 100.

 

[phipop]

Yes, you are right, actually i dont know a lot about bass amps, i have a boss 210 katana witch is too heavy to transport to rehearsal now, but i like it, and if i could play it louder to our little gigs without fart, it would be very fine, and my rumble 100 will arrive on thuesday... so i must apologize to ask too many questions even before having the amp, but i had a rumble 40 before and ...and... it will be very interesting to test it! I play a precision MIM Fender and i like clean bass tones, so i may have bought the wrong amps, but it is also a question of money, and i am not a pro, so until now i am very happy! talkbass is super. Thank you