Crossover??

[fouchagalaga]

Hi, I will attempt to make a crossover although I really am not quite sure how. I have not yet received my drivers. I know that many things impact what I should use for the crossover but my main point in making this is to not blow up my tweeters. I wanted to know if it really is as simple as the picture I have attached. Can you just wire caps and inductors and that's it? I know that I will not get the optimal sound but I'm ok with that. Please tell me everything I need to know. I really am a newbie

[Cal Weldon]

Originally posted by fouchagalaga
Please tell me everything I need to know.

Where to start? What you have shown is the schematic for a basic 2nd order (12dB/octave) XO.

1) You need to match the components to the drivers. This means knowing the Theil/Small parameters of the units and understanding inductance and capacitance.
2) The drivers have to match each other or the tweeter might be louder and will require an L-pad.
3) Without knowing anything else we can't tell you if there is a need for baffle step compensation, shelving or notch filtering.
4) If you have never done this, it can be a frustrating and very unrewarding project. You need to ask assistance from someone well versed in XO making.

[fouchagalaga]

Cal, Is buying one just easier, and will it work well?

[fouchagalaga]

And also.. if i ever were to try this. I'll be using

Cone tweeters
Power handling: 35 watts RMS/50 watts max *Impedance: 8 ohms *Fs: 1,500 Hz *Frequency response: 3,000-20,000 Hz *SPL: 90 dB 1W/1m
and
speakers that I found
15 watts RMS
8 Ohm impendence
90 db SPL
I don't have the frequency response for the second ones but umm... yeah I don't. If it's too complicated to make a fully functional crossover, will I be able to make only a high pass filter to not blow my tweeters?

[PeteMcK]

Getting started in Crossover Design

The basics (You've got to understand the rules before you can break them :-)
http://sound.westhost.com/lr-passive.htm
choosing xover point:
http://www.speakerbuilder.net/web_fi...xpointmain.htm
Baffle Step Compensation: http://sound.westhost.com/bafflestep.htm

Getting it done:
Jay has a page on designing xovers using manufacturers specs without measuring:
http://www.geocities.com/woove99/Spk...esigningXO.htm

Calculators:
http://ccs.exl.info/calc_cr.html#second
http://www.sengpielaudio.com/calculator-Lpad.htm
box calculator:
http://www.linearteam.dk/default.aspx?pageid=winisdpro

Measurement freeware:
Synrta - http://libinst.com/SynRTA.htm
ARTA http://www.fesb.hr/~mateljan/arta/download.htm
ARTA Jig - http://zobsky.blogspot.com/2008/01/s...t-jig-for.html

Examples from the designs of others can be quite instructive:
http://www.zaphaudio.com/
http://www.troelsgravesen.dk/Diy_Lou...r_Projects.htm
http://www.rjbaudio.com/projects.html
http://www.humblehomemadehifi.com/

[Cal Weldon]

Buying one assumes the nominal impedance of the driver usually 4 or 8 ohms. It does not account for the fact that the drivers are not likely to have these figures where you wish to cross them over. You can do it but it's far from a good way.

The specifications you have shown do not tell us what we need to know before beginning the design. The ones we need are called the Theil/Small parameters and deal with more of the in depth parts of the drivers.

If you want to just save the tweeters, you can make a high pass filter and run the woofer full out (not the best way) but we really need to know more about the woofer. Is there anyway to find out more about them?
Are they a full range driver or a woofer?
What size are they?
Can you post a pic or two?
On top of these questions, we need to know what sort of cabinet you are intending to build. The woofer usually requires a box to achieve any sort of bass.

Any info you can pass on is helpful.

EDIT: I see Peter has posted while I was typing. Have a look through those links and see if you're at that stage of understanding or if you are looking for a quick fix.

Thanks for the links Peter.

[PeteMcK]

Cal,
I feel the need to post the above screed quite often ,
xovers aren't hard with the basic knowledge under your belt.
(& that's about all I've got)
I'd put the above in the Wiki but that's beyond the limits of my computer skills...

[fouchagalaga]

Thanks guys this is really helpful, I'll read all the links you posted and reply soon. The only thing is... I'm only 15 years old and don't quite have all the equipment necessary to calculate stuff. But I have been reading on this subject for a while and am really developing a passion.

[Cal Weldon]

The offer stands if you want to take the easy route but that will depend on your woofer unit and whether you can get away with a simple high pass filter. ie: cross it over rather high.

[Inductor]

Originally posted by fouchagalaga
The only thing is... I'm only 15 years old and don't quite have all the equipment necessary to calculate stuff.

Don't worry, I will ask the moderators to open up the Summer Camp... (and move your thread there)