TWEETERS!!! I dont know whether to buy these ones or not.

[matthughes64]

Hi I am making a pair of speakers for my GCSE DT project. I am using a Velleman k4003 2X30W amplifier and 2 of these 10cm 25W(or something near that) mid/bass cones:

Rapid Electronics - Electrical & Power

They are actually full range but for the sake of my project and design I need tweeters (plus they will hopefully improve the overall sound). I will be buying a crossover to send mid/bass to the 10cms and treble to a pair of tweeters I have been looking at.

25W Dome Tweeter : Hi-Fi Speakers : Maplin

They are 25W and I'm wondering if thats insanely powerful to go alongside 25W mid/bass cones??? Is there something else I could buy? Should I use a resistor? OR are the 25W ones fine? Please help me. I will be grateful for any advice. Thankyou.

[planet10]

Sure, why not. A store bought XO is unlikely to work well. I'd suggest a 1-2 uF cap on the tweeter and leave it at that to start.

dave

[matthughes64]

Soz i dont know what an XO is, but I'm assuming cap is a capacitor. Does a capacitor do pretty much the same as a resistor (make it quieter)? I looked it up, does it need to be an audio capacitor or just any.

[Joris]

Originally Posted by matthughes64

Soz i dont know what an XO is, but I'm assuming cap is a capacitor. Does a capacitor do pretty much the same as a resistor (make it quieter)? I looked it up, does it need to be an audio capacitor or just any.

With XO, we usually mean cross-over. A cap isn't the same as a resistor, a resistor takes some of the power from the tweeter, a capacitor acts like a resistance in low frequencies and like a conductor in higher frequencies. Thus, using a capacitor limits the freqeuncies going to the tweeter.
I assume your project isn's high-endish, so I guess any capacitor will do the trick. You've only got to make sure it is a bipolar capacitor. (This means there are no plus and minus connections) I agree that the best solution in your case is a capacitor of around 2 uF. Experimenting will show you whether you need to add a resistor or not, when the tweeter sounds too loud, simply add a small resistor (about 4 to 5 Ohms).

Best regards

[matthughes64]

Thanks, you've been really helpful. I'll do that then.

[matthughes64]

Would this do???:

Rapid Electronics - Electronic Components

[matthughes64]

Hang on theyre probably polarized. sites gone a bit funny, that may not have been posted

[Groundloops]

Have a sharp look at the tweeter's side view pic: It already has a cap.

[matthughes64]

Oh yeah, thanks, but I've just realised another problem, how do I get the other cones to just give mid and bass?

[Joris]

Originally Posted by matthughes64

Oh yeah, thanks, but I've just realised another problem, how do I get the other cones to just give mid and bass?

Those cone fullranges usually lack some upper highs, a tweeter will just add those frequencies. So in your case there's no point filtering your midbasses.

The capacitor you provided in the link should work fine, except it's not made for audio, it is a polypropylene though, thus pretty ok.
I saw the tweeter already has a capacitor, so I guess you just have to order them and try them with your fullranges. When they sound too sharp op loud, you can always add extra components, for now, I think this is a good solution for your problem.