Noob questions about crossovers

[johnt2001]

Hi

I dont know if this is a silly question or not, if the output amplifier is 4ohm and there is two 8ohm speakers wired in series to a 2 way crossover whiich is 4ohm and 100w does that mean that the speaker ohm will be half ? with the the speakers and the crossover being wired in series? what is the maximum wattage the speakers/amp can be with the crossover being 100w?

i guess the question is does the crossover ohm add to the speaker ohm? just so it can match the ohmage of the amplifier

Any help would be great

[Cal Weldon]

Not really sure what you've got wired up there. Can you show us a picture? That might help us understand.

[chris661]

A 4ohm amplifier will be fine driving 8ohm.

The idea of a crossover is to divide the frequencies between the speakers. Generally speaking, the frequencies they play don't over lap. Because of this, their impedances don't have much (if any) effect on each other.

Something else to remember - series speakers add their impedances, in parallel, they do something else, which has a long explanation.

For your example, firstly, it wouldn't be advisable to use a 4ohm crossover with 8ohm speakers - the frequency will be different for different impedances used. Apart from that, your power handling will always be the lowest of all the components involved.
For example, if I have a 200W PA driver with a 50W hifi tweeter, the overall power handling is 50W, because that's the most power you can put in before something fails.

Chris

[johnt2001]

nice one cheers for that, dont worry i'm not making any speakers yet, just researching it. haha

you said the impedances add when the speakers are added in series. so if the 2 speakers are 8 ohms would it have to be 8 ohm crossover? and what would the impedance out put on the amp have to be?

Do you know where i can find any electrical diagrams of this?

[Loren42]

Originally Posted by johnt2001

Hi

I dont know if this is a silly question or not, if the output amplifier is 4ohm and there is two 8ohm speakers wired in series to a 2 way crossover whiich is 4ohm and 100w does that mean that the speaker ohm will be half ? with the the speakers and the crossover being wired in series? what is the maximum wattage the speakers/amp can be with the crossover being 100w?

i guess the question is does the crossover ohm add to the speaker ohm? just so it can match the ohmage of the amplifier

Any help would be great

As usual, one has to read between the lines to really understand what the question might be.

In this case I have some concern that you might be considering just buying a crossover and mating it to some set of drivers in a box.

While there are off-the-shelf crossovers you can buy, none of them are worth the money or time.

Each speaker system you design must have a custom designed crossover. The crossover impedance is meaningless, because the crossover is designed specifically for the system as part of the system. It's not like going to the store and buying a tire for your car and mounting it.

Designing a crossover is a big challenge and you need to juggle a lot of design parameters at the same time. There are a number of software programs out there that can help make the task easier.

However, these tools are only a part of the whole story. While they may turn what looks like a valid design, you must do a lot of additional footwork to make a crossover that's beyond just plucking components into a crossover tool and making pretty graphs.

Crossover design software is nothing more than a calculator. A calculator alone will not give you a passing grade in mathematics, but it can be a valuable tool towards that goal. The same is true with any crossover software.

From the sound of the question you are just getting started with the hobby. If this information is new to you and you want to DIY your own speakers, I would humbly recommend you start with a speaker kit that already includes the drivers and the predesigned crossover. There are a number of outfits that sell these and it is a good way to get started and maximize your chance of success.

A first time builder will find that the learning curve is very, very steep to make an acceptable sounding system from scratch. As a beginner you would not want to start out by climbing Mount Rainier without adequate training and experience. The same goes with building speakers.

I encourage you to keep asking questions and don't worry too much about stupid questions. There really isn't a stupid question anyway and people will always try to help anyone who is sincere about learning.

Best of luck and welcome to the group!

[PeteMcK]

First you need an understanding of basic electronics components:
Beginners' Guide to Electronics, Part 1 - Basic Components Explained
then, an understanding of how they are used in crossovers:
Passive Crossover Network Design

[jorsan]

Sorry to interrupt this thread but I was searching here for an answer that can be related to this topic: because crossovers are matter of math AND lots of listening, are there in the market a good quality external crossovers that I can use with any project?, for example, a unit that can be used with 2 or 3 way system and with lots of frecuency selectors and different "orders" (2nd thirth, etc.) to choose from? I really apreciate if you can post some brands and models that you consider could do the job. thanks in advance.

[Pano]

If you want the "Swiss Army Knife" of crossovers - look no further than the Behringer DCX2496. Very, very flexible. It can help you learn a lot.

[prickears]

Allow me to use myself as an example, I built my first system from scratch. Best part of ten years of tinkering, tweaking and I was only getting close then! 'How hard can it be', I thought back then....., Very hard, as it turns out, (to go completly from scratch), your best bet is, as mentioned earlier, is to build an exsisting design, and learn, 'Why is it so?'
This will hold you in better sted to get your own design off the ground.

Meanwhile, ask plenty of questions, keep an open mind and don't dispair, It will happen!

Mick.

[jorsan]

Thanks for your help Panomaniac but I was looking something more in the analog domain, not digital so ... any options there? thanks