Must try MOD - Foam inside the stamped steel baskets - YES!

plastic_avatar wrote: »

Just so we know where this foam mod is on my end, in relation to whether or not it added negatively to how the box performs, my interior mods include:

- Armacel on all interior basket surfaces (where reachable, and in the upper ring below the surround)
- BH5 behind mws.
- Aluminized rubber pipe wrap on passive chamber walls.
- Same wrap (think of it as Dynamat lite) on exterior of all baskets.
- xschop's semi-rings on mws.

I know it's a difficult comparison, since there is no control in my observation. I'm only comparing to a similarly-structured model. And all we hear is the result of mods on a speaker with no reference.

I do know there is a definition on voices I did not expect. And right now I'm very pleased with that result.

More testing the next couple of days.

My biggest question is:

'If my speakers don't exhibit a negative with all that^, what are the chances the foam mod will mean worse sound for you?'

skipshot12 wrote: »

^
What a great day.

Gardenstater wrote: »

I previously mentioned this in a couple of scattered places and didn't open up a dedicated thread. I suppose I didn't want to stick my neck out until there was confirmation from another who has tried it ✔. I've been living with this for almost 6 mos. now and I still continue to be super pleased with the benefits (I think the foam is still breaking in...kidding)! I used Armacell closed cell 1/8" thick foam but this is open to experimentation with perhaps open cell, composite of open cell over closed, felt over closed, felt alone......just keep it relatively thin like maybe 1/4" max(?). Let's get some more people trying this because it is a super rewarding mod and not all that difficult to do.

I won't get super long winded but I posted my initial report over in the other thread "What did you do to your stereo today" on p. 122.

https://forum.polkaudio.com/discussion/184609/what-did-you-do-to-your-stereo-rig-today/p122

Pictures are always worth more than words. I think the benefit of this is 3 fold: 1) Mechanical vibration dampening of the basket, 2) Sound proofing of the basket preventing acoustical into mechanical excitation, and 3) some amount of reflection attenuation of backwave reflections that would come back and hit the back of the cone. 3) is last but not least because when I did just one speaker initially I had to rebalance with whitenoise by lowering the unmodded speaker's channel by 0.4dB to compensate. I believe that is due to the reduction in reflected backwave which comes out as audible sPL through the cone. That has to be distorted due to time delays and phase differences and varying transmission/reflection for different frequencies.

Anyway, Merry Christmas and let's have fun with this mod. I'll add pictures when I find them.

Initial sizing on a spare driver I had. Settled on 1-1/4" x 1-5/16" but not super critical as long as you don't block the basket windows. You can even trim the windows with an Xacto knife after install:







Completed driver with the Armacell inside of the spokes and the section between spokes near the spider. I cut off the 3 vestigial tabs with a dremel cut off wheel - be careful not to get metal dust inside the driver:

Gardenstater wrote: »

ChrisD06 wrote: »

I wonder. Since I can't put BH5 in my M5JR+ because of the crossover being behind the midwoofer, could I use this armacell mod to kinda substitute the BH5? It obviously won't be as effective but would it work enough?

The BH5 only works on reflections that have exited the basket and standing waves within the enclosure. If you read through this thread you will grock that the armacell inside the basket works on reflections that probably would have never even left the basket but would most certainly reflect back through the cone as distortion.

I'm not sure who you are asking but I would just give the same advice that I gave you before; ask people who have done it, not people who haven't done it and haven't heard it.