KEF Subs Question

[mdr]

Hi,
Just picked up a pair of the KEF KAR 200SW subs. These are the subs
which are encased in a small ported box, where the port is a flexible
tube which extends out the top. I've seen literature which states that
these are coupled cavity, but that is not apparent to me.

In any case, PO cut down the flexible tubes to a much shorter length
than they originally came with (and they are two different lengths!).
Does anyone know what the proper length of the tubes are?

Thanks,
Murray

[Keith]

The idea of these subs was to port them into the cabin of the car... I
don't know anymore the original length, but I was able to find out a few
years back with a little internet snooping. I'll see what I can dig up.
keith

mdr wrote:

> Hi,
> Just picked up a pair of the KEF KAR 200SW subs. These are the subs
> which are encased in a small ported box, where the port is a flexible
> tube which extends out the top. I've seen literature which states that
> these are coupled cavity, but that is not apparent to me.
>
> In any case, PO cut down the flexible tubes to a much shorter length
> than they originally came with (and they are two different lengths!).
> Does anyone know what the proper length of the tubes are?
>
> Thanks,
> Murray

[mdr]

Keith,

Thanks for your input. On further examination, the subs seem to be
simple first order ported boxes, with the port extending out of the
top. I have also heard that the point of the flex tubing was to port
the output into the cabin, but given the box design, it appears that
the tubing is a port, 4" in dia.

Again, thanks for your input and I'd appreciate any additional info.

MDR

On Fri, 08 Aug 2003 21:28:10 -0700, Keith
> wrote:

>The idea of these subs was to port them into the cabin of the car... I
>don't know anymore the original length, but I was able to find out a few
>years back with a little internet snooping. I'll see what I can dig up.
>keith
>
>mdr wrote:
>
>> Hi,
>> Just picked up a pair of the KEF KAR 200SW subs. These are the subs
>> which are encased in a small ported box, where the port is a flexible
>> tube which extends out the top. I've seen literature which states that
>> these are coupled cavity, but that is not apparent to me.
>>
>> In any case, PO cut down the flexible tubes to a much shorter length
>> than they originally came with (and they are two different lengths!).
>> Does anyone know what the proper length of the tubes are?
>>
>> Thanks,
>> Murray

[twest]

KEF's coupled cavity design was essentially two sealed woofers playing into
another box with a big port. Don't mean this to contradict other replies,
only as clarification. Picture three chambers, 1, 2 and 3. Chamber 1 has a
driver that "points" to chamber 2. Chamber 3 has a driver that points to
chamber 2. Chamber 2 has a port that vents to the outside. My guess is the
tube you describe extends the port so that the bass energy is dumped into
the car's cabin.


"mdr" > wrote in message
...
> Keith,
>
> Thanks for your input. On further examination, the subs seem to be
> simple first order ported boxes, with the port extending out of the
> top. I have also heard that the point of the flex tubing was to port
> the output into the cabin, but given the box design, it appears that
> the tubing is a port, 4" in dia.
>
> Again, thanks for your input and I'd appreciate any additional info.
>
> MDR
>
> On Fri, 08 Aug 2003 21:28:10 -0700, Keith
> > wrote:
>
> >The idea of these subs was to port them into the cabin of the car... I
> >don't know anymore the original length, but I was able to find out a few
> >years back with a little internet snooping. I'll see what I can dig up.
> >keith
> >
> >mdr wrote:
> >
> >> Hi,
> >> Just picked up a pair of the KEF KAR 200SW subs. These are the subs
> >> which are encased in a small ported box, where the port is a flexible
> >> tube which extends out the top. I've seen literature which states that
> >> these are coupled cavity, but that is not apparent to me.
> >>
> >> In any case, PO cut down the flexible tubes to a much shorter length
> >> than they originally came with (and they are two different lengths!).
> >> Does anyone know what the proper length of the tubes are?
> >>
> >> Thanks,
> >> Murray
>

[mdr]

On Sun, 10 Aug 2003 06:43:06 GMT, "twest" > wrote:

>KEF's coupled cavity design was essentially two sealed woofers playing into
>another box with a big port. Don't mean this to contradict other replies,
>only as clarification. Picture three chambers, 1, 2 and 3. Chamber 1 has a
>driver that "points" to chamber 2. Chamber 3 has a driver that points to
>chamber 2. Chamber 2 has a port that vents to the outside. My guess is the
>tube you describe extends the port so that the bass energy is dumped into
>the car's cabin.
>
>
>"mdr" > wrote in message

twest:

Thanks for your description of the coupled cavity design. These subs
are much simpler, two uncoupled small boxes, each a single chamber
with a driver. The box has a 4" diameter hole in the top, with a flex
tube extending from it.

As I mentioned in earlier posts, this seems like a typical 1st order
vented box design. However, the port tubes are flexible. Others have
said that the port tubes are designed to mount to the rear deck and
carry the bass energy into the cabin. The outstanding question is
whether the flex tubes must be a specific length to function
effectively as ports. If they are 1st order designs, I think they
must, Any comments?

TIA

MDR

[Happy Guy]

I had a pair of these when they were first available and enjoyed them for
years. I only removed them before selling the car they were in. They use 8
inch drivers that I measured at surprisingly near 2 ohm. They were
otherwise very inefficient. I had asked repeatedly for T/S parameters from
KEF but they would never give the info.

Due to the 4" size of the tube, I was easily able to fashion an adaptor
plate for using the 4" duct and a 4" mid in a 6x9 opening in my rear deck so
they fired directly up into the passenger compartment through the rear deck.
The 4" size means there are a lot of options using standard hardware store
4" ducting accessories.

They are designed to used the entire trunk cavity as a sealed rear chamber,
with the actual boxes being used as a vented front chamber. The tubes
extended up to around 2 feet but were used at any length that fit the
installation. No optimal length was ever given in their literature. I had
used them at around 1ft and they sounded quite good. A review of them from
that period raved about them and their sound with classical music
particularly with pipe organ used in a test CD. I used the same test CD
(Alpine CAN II) and agree fully. (great CD by the way, I still use it today)
They probably would not provide the low end boom that is so augmented in
today's pop music though and would probably not be a good choice if that is
what you are looking for. Ok for Jazz or Classical or if you don't intend
to push the volume up too high. Their magnet and voice coil are pretty
dainty.

Unfortunately yours are cut. The ducting is pretty hard to replace as I
cannot think of any other ducting that would have the same mix of
flexibility and rigidity.

They were a nice system that that sounded very musical and used very little
trunk space.

[mdr]

Great, thanks for the info. Your explanation makes the most sense to
date; I'm glad to have found someone who has direct experience with
them.

On Mon, 11 Aug 2003 09:47:25 -0700, "Happy Guy" >
wrote:

>I had a pair of these when they were first available and enjoyed them for
>years. I only removed them before selling the car they were in. They use 8
>inch drivers that I measured at surprisingly near 2 ohm. They were
>otherwise very inefficient. I had asked repeatedly for T/S parameters from
>KEF but they would never give the info.
>
>Due to the 4" size of the tube, I was easily able to fashion an adaptor
>plate for using the 4" duct and a 4" mid in a 6x9 opening in my rear deck so
>they fired directly up into the passenger compartment through the rear deck.
>The 4" size means there are a lot of options using standard hardware store
>4" ducting accessories.
>
>They are designed to used the entire trunk cavity as a sealed rear chamber,
>with the actual boxes being used as a vented front chamber. The tubes
>extended up to around 2 feet but were used at any length that fit the
>installation. No optimal length was ever given in their literature. I had
>used them at around 1ft and they sounded quite good. A review of them from
>that period raved about them and their sound with classical music
>particularly with pipe organ used in a test CD. I used the same test CD
>(Alpine CAN II) and agree fully. (great CD by the way, I still use it today)
>They probably would not provide the low end boom that is so augmented in
>today's pop music though and would probably not be a good choice if that is
>what you are looking for. Ok for Jazz or Classical or if you don't intend
>to push the volume up too high. Their magnet and voice coil are pretty
>dainty.
>
>Unfortunately yours are cut. The ducting is pretty hard to replace as I
>cannot think of any other ducting that would have the same mix of
>flexibility and rigidity.
>
>They were a nice system that that sounded very musical and used very little
>trunk space.
>

[Bill Spencer]

I will confirm this, it's no different than rear-deck drivers except the
drivers are round, it will fit the smallest cars with a trunk, and you're
supposed to end up with 4 identical grilles, 2 for the woofers and 2 for the
mid-hi's. Probably can glue in a new pipe.