Newbie Needs OB and Crossover Help

[FightingForAir]

I am embarking on my first DIY speaker project and need a bit of help. I've decided on the Martin King OB full range enhanced by 15" bass driver in an H-frame underneath.

Here is my problem: I cannot find a pre-assembled 2 way crossover that cuts over at the frequency suggested (200 or 250 hz). I have no experience in electronics and would not trust myself to build my own.

What is my best option here?

#2. I still wanna use my sub for 50 or 60 hz on down, so will using lower Qts 15" drivers in the H-frame really be a problem? If so, how so? Can my full range be lower Qts as long as I have a nice wide baffle.... ??? ... saaaayyyy .... 20" wide?

Thanks much in advance for any help.

[woody]

Did you read the other OB article it explaines why he chose a high QTS driver.
I built it am more than happy although I might like a little more bass BUT when
I say that it may not be a failing of the speaker it's that my room just does not
support bass verry well. Why not just build it and if you just have to have more
bass use your sub. About the crossover I think Madisound may sell blank crossover
boards that should make them incrediably easy to build. By the way I have a pair
of low qts 18" drivers I would like to use too but without electronic EG they just
wouldn't be happy on an OB.

[andb]

I've done exactly this and found that the best way to do this was to implement the crossover at line level, instead of passive speaker XOs. The cost of the components needed to get a passive crossover on the speakers at these low values is surprisingly expensive. If you consider line level, for both channels a total of only 8 parts are required for 1st order XO, 16 for 2nd order, and the total cost for pretty good quality components for this passive line level crossover should run in the tens of dollars, instead of hundreds. Well, ignoring the fact you need a second amp (more info at TLS.org | Passive Line-Level Crossover)

Also crossing it digitally with a miniDSP (Home | miniDSP) is an excellent value proposition, and can help you to deal with any frequency / phase / room problems that might crop up.

[pjanda1]

While in general I agree with andb's approach, I think for your first project you should copy MJK's build exactly (woofer too). DIY is about learning stuff. Building a crossover is not hard, and is a great way to learn to read schematics. I'm sure that a crossover was the first network many of us built (myself included). Get the parts and a DMM. If you stare at them for awhile and can't figure it out, ask! Learning to solder is probably the hardest part. You can get a Weller iron at Home Depot for less than $15. You'll also need a copper pot scrubber (to clean the tip) and safety glasses. It won't be nearly as hard as you think, and you'll feel a sense of accomplishment. Doing it yourself is by far the best option.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

[FightingForAir]

Thanks for the replies and suggestions fellas. It looks like I may just be trying to build my own xovers. That mini dsp sounds like an interesting alternative but I don't understand how I could use that without additional amps. I forgot to mention that I will be using these in a combo music/HT setup off a HT receiver. I don't have separate amp/preamp.