'71 Ampeg B-15N dampening

[DjangoKid]

OK, so I'm having my good friend do a checkup on my B15 which has been retired to live in the studio/practice space (meaning it's always in flipped mode). After pulling the amp off I see a Thiele cab with no dampening at all. I forgot to replace the old, dank house insulation that was stapled previously.

So, with the backstory out of the way, how much dampening and along which walls?

I would like to stick with some material I can get at a fabric shop or mattress topper from some store, nothing esoteric or spendy. I have a rare opportunity to gig with this amp next week so I can't order that stuff and hope it will be here in time.

 

[beans-on-toast]

They used to cover the back surface, opposite the speaker. Not a lot of damping is needed. Be sure not to block the port shelf. Experiment with the amount that you use to find what sounds best.

The fabric store products will work well. You want to line the wall, not use a stuffing like you would with a sealed cabinet. If you cut the foam a little oversized, the pressure of the foam will keep it in place. Otherwise you can use strips of double sided carpet tape.

As an alternative, I use ¼" wool felt. Some carpet stores will give you scraps of felt underlaying. I line the back and sides and have a piece that covers the top. I probably don't need that much. The B-15R had a similar felt and they lined the back and sides. As I said, try experimenting.

Let us know how it turns out.

 

[Rick James]

You'll probably get the best result lining the entire box with foam, polyester or felt carpet underlay. Older cabs often used less damping, or none, but the worth of damping wasn't that well known way back when as it is now. Now they know that any bare surface inside the cab will reflect midrange back to the cone at various degrees of phase, causing response peaks and dips.

 

[Bill Hughes]

Its not dampening...rather damping...and no it damps nothing. What you are calling dampening is rather anti reflection of the cabinet walls.

Bill

 

[B-string]

Keep in mind over-damping will cause the cab to sound "dead" or "lifeless", there is a happy medium to be found.

 

[beans-on-toast]

Keep in mind over-damping will cause the cab to sound "dead" or "lifeless", there is a happy medium to be found.

Then the cab would be all wet. I guess that's when dampening comes in.

 

[B-string]

Then the cab would be all wet. I guess that's when dampening comes in.

No, don't Dampen your cab, the speaker cones will get soft .