Yup! I had to pull the layers apart like you did. Although, I didn't get 20 layers, more like 5-6 at the most. So, I used two layers of my 5-6 layer stacks to make up the 20mm height you recommended. All that denser cotton in there might be the reason I have too present highs and not enough bass. Whatcha think?
I suspect there's a good chance that your highs are too high because your cotton is still too dense. Maybe you can separate them into more layers? The "fluffier" the better.
Here's what I'm using now in place of Rite Aid "Natural Absorbent Cotton" which has been discontinued:
Rite Aid "First Aid Rolled Cotton"
Separated into 20 individual layers. You can see 1 layer at the bottom of the ruler:
Preparing "First Aid Rolled Cotton" for Effective Dampening
1. Separate the roll of dense cotton into 20 individual layers.
2. Divide into 2 parts of 10 layers, each. UNcompressed, 10 layers = approximately 2 cm thick.
3. Cut 10 layers to fit the cups = 2x7x7 cm.
4. Cut 1x7x7 cm fiberglass and place over the top of the cotton.
This is my initial DBV #3 build with "First Aid Rolled Cotton" followed by tuning one or more of the following variables (individually) to achieve the desired frequency response:
* add/remove cotton
* add/remove fiberglass
* tweak the size and number of holes in the stiff felt over the rear driver grids
* tweak the size of the paper treble reflectors
Prepping Rite Aid "First Aid Rolled Cotton" results in 'similar' performance compared to Rite Aid "Natural Absorbent Cotton."
Edited by bluemonkeyflyer - 11/26/12 at 3:19pm