Mr.DatSubishi

I've never designed or built my own passive x-over and have an interesting way I may wanna try.

I'll be running a set of components in my front stage with plans to add front stage subs. Each speaker (and component set) is 4 ohms. I'm asking for advice on running them both off a 2ch. amp for now. Until I can get another 4ch to run all speakers and just run front subs off this amp. Wondering if Anyones done anything similar?

Disadvantage I see is having to hi pass my components at the lower end of the bandpass for the subs. I was thinking 60-70hz. THe component response is from 20hz to 22khz so I don't see it being a major issue, but I usually hi-pass quite a bit higher as I've never run mid-freq. subs.

The amp advertises 130rms x2 @4 ohms, and 175rms x2 @2 ohms. It comes with a birth sheet but I haven't got the amp yet (it advertises being underrated). The components will take up to 130rms a piece, and the subs 200rms a piece. Seems like plenty of power to run components but lacking to run woofers as well. the main reason I'm asking is I can get a super deal on the small subs I was looking at. I'll probably buy them anyway, I just might as well put them to work immediately if I can.

Sorry bout the long post and thanks for any advice.

Dukk

You don't have to high pass the comps. Just low pass the new front woofers and below that point the amp runs at 2ohms. Should be no big deal for the amp.

Mr.DatSubishi

I was still gonna run the front subs as band pass, but I guess if I hi pass at 60-70hz all I have to do is lo pass the subs. Thanks DUKK you just simplified my life. No point in running 2 hi pass x-overs (amp's and passive) if I don't need to.

What do u think about power? It seems like a low power rating for 2ohm compared to 4. I know it's amp dependent but I guess I'll know true power when I get the birth sheet. Do u think it'll have enough jam to run "4" speakers, or should I just run comps off it?

You said "below that point(passive sub Xover) the amp runs at 2 ohms." Does that mean the amp doesn't even see these speakers above their crossover point?

Mr.DatSubishi

When I'm finding coil values for passive lo pass do I calculate for just the speaker I'm lo-passing or for the total load on the amp? Lo passed sub im calculating for is 4ohm, but the amp will be seeing 2 ohm.

Thanks

Mr.DatSubishi

Bumpitty

Dukk

^ you calculate for the speaker connected to it. In your case a 4ohm low pass for the woofer.

The thing with power is you only have what you have. Try it out.

What really happens with a passive crossover is that beyond it's pass point, in this case above your crossover point, it just gets more and more resistive which is what attenuates the speaker. Technically the amp always sees the speaker/crossover, the impedance is just so high that the speaker gets too little power to hear it.

Mr.DatSubishi

Thanks again for your help. I did find some info on the Internet yesterday but I appreciate your reply.

Dukk

Yeah, it can be hard to ask the internet questions sometimes though which is why people **** so much stuff up - they think they understand until the smoke comes out.

I like passive crossovers and will try to help as needed.

Mr.DatSubishi

I found some "good" calculators on the12volt.com. I've used some of their wiring databases and they seem to be pretty accurate. Thanks for the offer of help. I'll keep us informed of progress.

Dukk

Calculators are great for figuring out values but they don't help with design theory. Without proper design, the chances for success are low.