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lolojr1 14th July 2005 01:58 AM

i have drivers what can i do with them ?
i want to try to build some tqwtl or a horn of some sort i have been reading about them for a while and now that it is summer i would like to get out and build them .
i will list the t/s parameters i have from the woofertester2 and hopefully some one can come up with a good idea on what to do with these speakers

i have 2 radioshack 4" woffers drivers from the old linaeum speakers and 4 polk 4" drivers from the old ls/fx dipole bipole surround speakers with matching tweeters.

i have built sealed and ported boxes and have had good results so far but i think it is time to try something a little harder.

i am wonering if it is at all possible to use the 4 polk woffers and the tweeters that came along in those speakers to build the 4 main channels of my home theater, and possibly using the rat shack drivers as a center speaker just adding a tweeter

another question i have is instead of building 4 speakers can i build 2 with 2 woffers each because of the small size of the polk woofers like a sealed or ported box by adding more drivers you get more output ???

i am trying to build something that i can set on the floor and not use a stand and if that means adding extra height in the form of a empty sealed box of the same size to make them taller i will

here are the ts specs


fs 63hz
revc 6.35ohm
zmax 26.34ohm
qes 1.1332
qms 3.5631
qts .8598
le .4512mh
vas .2076cuft
bl 3.8183tm
mms 6.5544g
cms 970.6567uM/N
kms 1030.2303 N/M
rms .7293 r mechanical
efficency .1256%
82.9913 db @1w/1m
83.9891 db1@2.83vrms/1m
the piston area from half of surround to half of surround is roughly 3.6"

and here are the rat shack

fs 54.14
qms 3.906
vas .365 cuft
cms 1.376 mm/n
mms 6.28g
rms .547 kg/s
qes .574
re 4.718 ohm
le .437 mh
zmax 6.558 ohm
bl 4.19 tm
qts .5
efficency 0276%
86.41 db1w/1m
88.7 2.83vrms/1m

size is 3.8" from surround to surround

any other details i forgot to add or things i have missed ?

Bare 14th July 2005 02:48 AM

A 4" driver is only a woofer if you are a Field Mouse.
It's Really Tough to build a Decent speaker out of ****.

lolojr1 14th July 2005 08:39 PM

so i take it they are usless ?

lolojr1 17th July 2005 04:39 PM

so if only one driver is not enough can i use 2 drivers per enclosure ?

tomtt 18th July 2005 12:20 AM

Originally posted by lolojr1-
so i take it they are usless ?


you realy ought to build these,

and show us pics of how you do

lolojr1 18th July 2005 02:38 AM

i really want to build them im just not sure what design to go with .
i want to use the polk mids and tweeters as the 4 main channels of my home theatre and possibly use the rat shack mids with a nice tweeter from partsexpress for my center channel.

i just would like a nudge in the right direction .

so do i do a voight ? labaryinth? back loaded horn ? i just cant decide

i saw these today and i am intrested can anyone give me more details ?

does adding a second driver change the desgn a lot? if so how do i account for it ?

i like the design and look of those are they a good choice for these drivers?

if all else fails i can just build a set of really nice computer speakers right ?

tomtt 19th July 2005 07:57 PM

Originally posted by lolojr1
i really want to build them im just not sure what design to go with .

i just cant decide
not to decide, is to decide


if all else fails i can just build a set of really nice computer speakers right
`````````````````````````````````````````````````` ``
heck yes -
better maybe to build somthin than nutn

lolojr1 19th July 2005 08:22 PM

not to decide is to decide .....

funny i do that alot

i dont want to just jump in head first and not know what i am getting in to

i like this idea
and this idea
but i dont know how to design a t line with 2 woofers?

do all the traditional rules still apply ?
doi just design it to act as if there was only 1 driver and just add a second

what about this
the polk surround speakers i have are a dipole /bipole design with a switch that changes the di/bi setting and a crossover and tweeters all included

can anyone tell me if there is a different design to use 2 woofers or do i design it like a single woofer speaker ?

if so how much of a difference does the location of the woofers play a part in the sound that they produce?

GM 19th July 2005 10:37 PM


At a glance, the Polk drivers are best suited for either sealed, aperiodic, or TL while the RS drivers could also be used in a ML-TL or BLH.

BTW, for my records, which model drivers are these?

WRT to using all these in a HT app, the mains/CC should be the same and you can probably get away with mixing them in side, rear surround channels. Not being familiar with these drivers AFAIK, I don't know which have the best SQ overall, so that's a choice you'll have to make as you want the best ones for the mains/CC.

Since none of these will probably go very low at any decent SPL, I assume you'll have a sub for the LFE channel and set the mains/CC/surrounds to 'small'.

Adding a second driver increases the speaker's output 6 dB if wired in parallel and your amp can handle the lower impedance/provide the necessary current, which typical HT receivers can't do so figure 3-4 dB gain. Still, it's usually enough to compensate for baffle step loss, so IMO worth the effort/space with such low efficiency drivers. Unfortunately you don't have enough drivers to do HT with bipoles though. :(

WRT to designing for two drivers, just design for one, then double the Vb and add a second vent. Or if using a box program that allows multiple drivers, then design one big vent. If doing a pipe design, then only change the cross sectional area (CSA), leaving the height the same. The easiest way to figure the new size whether straight or tapered is to multiply the width and length dims by the SQRT(2), or ~1.4142 and round it off to the next higher fraction or whatever scale you use.

WRT dual driver placement, mounting them either as close as practical on the front or on the same plane in a front/rear layout is the norm, though if you know what you're doing you can use different locations to achieve various responses. In a pipe design you ideally want to suppress the 3rd harmonic, but this often places the driver too low, so either the pipe needs to be spaced up or make do with a non-optimum location. Since most designs posted don't have optimum driver placement and sound fine (I assume due primarily to the fact that damping required is done by ear), positioning it (them) where needed and try different vent locations to smooth it out as best you can before using any damping in the sim.

I haven't had time to 'run the numbers', so don't know how well suited your drivers are for the designs listed, but since you have measured specs why not do some designs of your own using MJK's worksheets?


lolojr1 20th July 2005 02:31 AM

i would like to use the same speakers for center and main l and r
i dont really have the budget right now so i will probably stay with the one that i have althought i know it would be optimal

of course i have to use a sub what self respecting diyer hasent built a sub or two i have 2 in use now and i think i have a new angle on the 1/4 wave if you are intrested ill send you a few pics and how i did it i havent found anything like them out there

so if i do a tl keep the length the same and double the CSA?
is SQRT squareroot?

how do i supress the 3rd harmonic i havent heard of that and dont know what you are telling me to do can you lead me in the direction to do some reading about this

i just dl the mjk worksheets and havent really figured them out yet
any help would be greatly appericated

thanks a bunch

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