Crossover Math

[John48]

I have started planning a speaker system that will be based on the GPA 604III. I could buy a crossover like GPA?s own or the Selah, or build from one of the good designs out there. Either way, I will be rolling parts over time. I do, though, have a few questions about how I can use caps and inductors.

1. How precise do I need to be in cap/inductor values? It is sometimes difficult to get exact values with your parts of choices. How close is close enough?

2. In general, I understand the affect of putting capacitors in series. Two 5 uf gives you 2.5 uf. Three 5 uf in series gives you? Two 5?s and a 1 gives you? What is the formula?

3. What minimum cap voltage value should I be using? Is it the same requirement for AC and DC caps?

4. What is the affect on cap voltage ratings relative to series or parallel usage?

5. Does the rules apply to inductors?

It is probably simple, but I can?t seem to get my mind around it. Any comments are appreciated.

[aditya]

You are welcome....

There are two things here.....
1)Crossover designing
2)Crossover cloning

Crossover making/designing is a very very daunting task. It calls for a lot of skills and experience at the same time. It is also very time consuming a venture, and hence calls for a systematic and methodical approach from the very beginning. It though looks very simple on the surface as a combination of few inductors and capacitors.

As regards to your questions.......they are the basic ones. And by answering to them here will not serve the purpose, b'coz you will again have more such questions. What is needed here is that you should go for some knowledge in "basic electronics". Just google "basic electronics", and you will find hundreds of sites, ready to explain in the detail. One of such sites (I have just googled for you) is this one...

Basic Electronics

Pls also do some research on crossovers in a similar manner, and sharpen your insight.

Crossover cloning is slightly easier, and needs mostly a good knowledge of the components being used.

Hope this helps.

Aditya

[donaldpatten]

John48
caps in parallel add
coils in series add
caps in series and coils in parallel follow this formula":

1/Ct = 1/C1 + 1/C2 + 1/C3 + ... 1/Cn

Cap voltage 200 v or higher. The voltage rating for caps in parallel is the lowest one in parallel.

Try to be with in 5% of value

So eg: 4uf and 6uf in parallel = 4+6=10uf

In series: 1/4 + 1/6 =3/12 + 2/12 = 5/12 = 10/24
Ct = 24/10 = 2.4

Don

[John48]

Thanks for your replies. Very interesting link.