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help! modifying the sony sa-wm40 sub.

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6 replies to this topic

#1 of 7 Rich Moorehead

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Posted July 08 2003 - 03:40 AM

hello all. i am gonna buy the sony sa-wm40 sub in a couple days and everyone says to modify it. so i am going to. im just not sure which materials to use. many are saying to use the polyfill. but this one guy says to use foam "egg crate" type sound damping panels, he says that is much better than polyfill. he also says to use mod podge on the front and back of the driver, he says that will make a world of difference. so i need everyones opinion of what is the best thing to do. thanks.

#2 of 7 Matt Odegard

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Posted July 08 2003 - 05:17 AM

Are you buying used? Online? These subs are discontinued, but the replacement is the sawm500. The same mod can be done to it also.

As far as material, I used polyfil. I specualte if there is a difference in actual sound between that and eggcrate. But who know's.

#3 of 7 David Ruggiero

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Posted July 08 2003 - 11:09 AM

I have the Sony sub as well. Never modded it, kind of curious as to what sound improvements can be had from adding polyfil to the cabinet and putting Modge Podge on the driver. Anyone who has done this care to share their thoughts on sound quality, before and after?

#4 of 7 Matt Odegard

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Posted July 08 2003 - 11:14 AM

It makes the sub produce tighter and deeper bass. Supposedly no more boom boom.

#5 of 7 Greg Thomas

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Posted July 08 2003 - 04:12 PM

Here's a good site with photos about how to modify your Sony Sub. I did mine before I found this site but essentially installed the polyfill the same way.


#6 of 7 Cagri


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Posted July 08 2003 - 07:51 PM

Using the search function you can find a bunch of threads about modding the wm40. Here's my experience:

Too much debt...

#7 of 7 Brett DiMichele

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Posted July 08 2003 - 09:11 PM

This is the difference between Acoustical Pannel Material
(A light grey colored material that has the Egg Crate
)and Pollyfill (Pollyester Pillow Stuffing)

Acoustical Foam Pannels are used to line the walls of an
enclosure to break up standing waves in the MidBass Region
of Freqency. Standing waves can propegate in a speaker
enclosure in the higher frequencies and can cause cone
distorsion modes. These foam pannels difract the backwave
of the midrange speaker cone so that standing waves are
never fully propegated.

In a Sub Woofer the frequencies are so low that it takes
many feet to create the standing wave and therfore in a sub
enclosure it's a non-issue.

Pannel Dampening however is a key issue and the foam pannels
can help to minimize enclosure resonance due to shoddy build
construction. There are better ways to dampen the walls of
the sub though.

If I were to purchase this sub I would first measure the
inside dimensions of the enclosure from side to side and top
to bottom. Then I would make braces to tie the sides and the
top and bottom walls together (glue them in place with a
good carpenters glue). Then I would dampen the inside of the
pannels with either a spray on coating such as automovive
undercoat (the cheap way) or with Dynamat sheets (the not so
cheap way).

Posted Image

Posted Image

These images show my own DIY sub. The enclosure is made
from 3/4" MDF which by nature is far more acousticaly dead
than the chipboard used in the Sony sub. The braces that I
used would work very well in the Sony. If you don't have a
way to cut MDF you could go to Lowes or Home Depot with the
dimensions you need and have them cut down a 2x4 to use for
brace material. After it's glued in place you can also wrap
it with Dynamat or spray it with a spray on dampening material.

The Pollyfill stuffing material when placed in the enclosure
slows the internal airspeed down. Essentialy what this does
is to make the driver act like it is in a larger enclosure
with lower tuning. Yes the Pollyfill is beneficial! There is
no "set" amount to put in, the best way is to experiment.

The Sony SAWM-40 (and it's new replacement model) are
certainly terrific value subs. And with a few (relatively)
inexpensive modifications they can sound far better!
Brett DiMichele
brettd@nospamyukonwaltz.com (remove nospam)

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