Redoing some 15 inch Surrounds - to Foam or not to Foam?

Archived from groups: rec.audio.pro (More info?)

I have some old Pioneer 15" woofers to play with, thought I'd learn how
to recondition speakers.

From looking into drivers over the past few years I have seen foam
surrounds get replaced by (butyl?) rubber surrounds for increase
durability, and no doubt other benefits.

Any way to source, or should I even bother with, some surrounds in a 15
inch diameter? (Actual span of the cone is 13.5".)



TBerk

Archived from groups: rec.audio.pro (More info?)

"Scott Dorsey" <kludge@panix.com> wrote in message
news:ck0qf9$hci$1@panix2.panix.com...
> In article <d2K8d.5765$JG2.4752@newssvr14.news.prodigy.com>,
> > From looking into drivers over the past few years I have seen foam
> >surrounds get replaced by (butyl?) rubber surrounds for increase
> >durability, and no doubt other benefits.
>
> If you do this, you are changing the driver parameters. Most of the
rubber
> surrounds are stiffer than the original foam, and therefore the resonant
> frequency of the driver will increase.

Probably not by as much as you think. As Dick Pierce has pointed out many
times, the stiffness of the spider is the dominant factor here.

> If you are using them in existing cabinets, that's bad. If you don't mind
> having to remeasure the driver parameters and having them a little
different
> than they were before, that's fine.

A little retuning possibly. If you can replace surrounds then retuning
should be no problem.

TonyP.

Archived from groups: rec.audio.pro (More info?)

Arny Krueger wrote:
> "TonyP" <TonyP@optus.net.com.au> wrote in message
> news:4164d24b$0$1024$afc38c87@news.optusnet.com.au
>
>>"Scott Dorsey" <kludge@panix.com> wrote in message
>>news:ck0qf9$hci$1@panix2.panix.com...
>>
>>>In article <d2K8d.5765$JG2.4752@newssvr14.news.prodigy.com>,
>>>
>>>>From looking into drivers over the past few years I have seen foam
>>>>surrounds get replaced by (butyl?) rubber surrounds for increase
>>>>durability, and no doubt other benefits.
>>>
>>>If you do this, you are changing the driver parameters. Most of the
>>>rubber surrounds are stiffer than the original foam, and therefore
>>>the resonant frequency of the driver will increase.
>>
>>Probably not by as much as you think. As Dick Pierce has pointed out
>>many times, the stiffness of the spider is the dominant factor here.
>
>
> Agreed. Also, driver suspension compliance shifts aren't such a biggie in
> most smaller boxes.
>
>



OK folks.

Thx for the replies.

I'll likely go with foam for two, no make that three reasons;

- Foam will get the job done and It's enough in itself of a learning
experience to avoid retuning a speaker. (Well, the enclosures were
destroyed anyway prior to my getting the actual drivers, but still.)

- I'm having a hard enough time finding a small or thin enough foam
surround to fit in the space between the cone and the frame (spider?) of
this particular speaker.

- Foam is cheaper. If the speakers were high end and not just some old
Pioneer 25W 15"ers I wouldn't be experimenting at home but get them
professionally redone.

Thx again,
TBerk

Archived from groups: rec.audio.pro (More info?)

T <tberk@sbcglobal.net> wrote in message news:<69P9d.1292$6q2.459@newssvr14.news.prodigy.com>...
> Arny Krueger wrote:
> > "TonyP" <TonyP@optus.net.com.au> wrote in message
> > news:4164d24b$0$1024$afc38c87@news.optusnet.com.au
> >
> >>"Scott Dorsey" <kludge@panix.com> wrote in message
> >>news:ck0qf9$hci$1@panix2.panix.com...
> >>
> >>>In article <d2K8d.5765$JG2.4752@newssvr14.news.prodigy.com>,
> >>>
> >>>>From looking into drivers over the past few years I have seen foam
> >>>>surrounds get replaced by (butyl?) rubber surrounds for increase
> >>>>durability, and no doubt other benefits.
> >>>
> >>>If you do this, you are changing the driver parameters. Most of the
> >>>rubber surrounds are stiffer than the original foam, and therefore
> >>>the resonant frequency of the driver will increase.
> >>
> >>Probably not by as much as you think. As Dick Pierce has pointed out
> >>many times, the stiffness of the spider is the dominant factor here.
> >
> >
> > Agreed. Also, driver suspension compliance shifts aren't such a biggie in
> > most smaller boxes.
> >
> >
>
>
>
> OK folks.
>
> Thx for the replies.
>
> I'll likely go with foam for two, no make that three reasons;
>
> - Foam will get the job done and It's enough in itself of a learning
> experience to avoid retuning a speaker. (Well, the enclosures were
> destroyed anyway prior to my getting the actual drivers, but still.)
>
> - I'm having a hard enough time finding a small or thin enough foam
> surround to fit in the space between the cone and the frame (spider?) of
> this particular speaker.

The "spider is the part that holds the voice coil in place. Nowadays
it's usually a corrugated ring bolted or glued at it's rim. In the old
days it was held in place by 3 or 4 curved radial arms bolted in the
centre to the central polepiece. It looked sort of spiderish.

> - Foam is cheaper. If the speakers were high end and not just some old
> Pioneer 25W 15"ers I wouldn't be experimenting at home but get them
> professionally redone.
>
> Thx again,
> TBerk

Steve