Want to build bookshelf speakers

ziv_r

hello,
A store next to my house went bankrupt and sold a few drivers with a very low price.
i bought the following:
3 x BD5801-W (MW5801 Driver)
2 x BD0124-W (SL6503 Tweeter)
1 x BD0713-W (MW7005 Driver)

i know that i have uneven number of drivers but i got them all in a package deal from the store.

i would like to build a pair of bookshelf spekaers.
for that i will use:
2 x BD5801-W (MW5801 Driver)
2 x BD0124-W (SL6503 Tweeter)
(all the other drivers i have no use for them).

Can someone please help me with the planning of the speakers?
i have some experience with buillding 2 subwoofer's, but this is my first try for bookshelf speakers.

I am ready to give away the spare MW5801 Driver for whoever help me.

ziv_r

all drivers are polk audio

danger boy

there must be books at your local library on how to build speakers.. and many other projects for the DIY'er.

Zen Dragon

Here are some useful online links.

http://www.diyspeakers.net/

http://www.diyaudio.com/

Lots of good reading and info.

Early B.

Do you have the specs for those drivers? If not, do you know which Polk speakers they were used in?

You'll need to design a crossover for them and without much info, it'll be a difficult task.

ziv_r

the drivers are new, they are very heavy and looks solid.
i contacted polk audio tech, but tell told me that their spec is private.

jcaut

You're going to need measurements in order to acheive decent results. There are a few options in that regard, but there's probably going to be some cost involved. I could give you a little guidance if you're interested in trying to run impedance curves and determine the T/S yourself. At any rate, the crossover is going to be the hard part.

First I'd suggest trying to find out what Polk models used the drivers you have-- Polk might tell you that-- then you can decide whether or not it might be worth your time to go further. It's possible that you could copy the box design and the crossovers from the models that used those drivers, but even that doesn't assure good results.

Where are you located?

Jason

ziv_r

im located in israel.
i've contacted polk audio tech personal and they told me that the drivers are used with their line of the inwall speakers.
the crossover should be 2000-3000 hz and that i should build a sealed box.

jcaut

From my limited research -- just looking at the parts lists posted on the website-- I don't believe that particular midwoofer and tweeter were used together in a two-way. I could be wrong. That doesn't mean they won't work together, but there may not be a Polk crossover to copy. I'll be honest though: I think it's going to be difficult for you to acheive really good results. You might acheive results that are acceptable to you-- It just depends on your expectations. For the time and effort involved, you would be better off just selling the drivers on e-bay and buying a set of speakers.

I could understand wanting to build something with them, though. First thing is to determine some T/S specs for the midwoofer, and at least the resonance of the tweeter. Here is a good link: http://sound.westhost.com/tsp.htm. Alternatively, you could look into the SpeakerWorkshop software (free, http://www.speakerworkshop.com/). Assuming that you have a computer with a compatible soundcard, it will allow you to run impedance curves to compute T/S parameters using just a few easily sourced parts. It can also be used measure frequency response (more accessory components required), and it includes a powerful crossover modeling function.

If you assume that the Polk midwoofer doesn't have nasty breakup (all the ones I have measured are pretty smooth) and if you know the impedance curve, you should be able to calculate a second order lowpass (maybe 1st order with impedance comp) at about 2.5K that would work. Speakerworkshop can do this for you, if you use it to measure the impedance.

The highpass on the tweeter is a little trickier, but again, if you can run an impedance curve, you can probably get close enough to tweak it by ear. Tweaking crossovers by ear requires that you have access to a decent selection of resistors, capacitors and inductors-- A sizable investment, if you have to purchase them.

Do some reading at those two links I posted. If you feel that you want to continue, let me know and I'll try to offer some more help.

Jason