no crossover

[widowgobo]

hello

I was listening to dub-step (heavy bass) music through two full range speakers, on top of them was two old 15" full range just playing 45hz-150hz ish, as well.

I noticed that one of the old cabs, that was only playing bass, had crackling coming from its horn.

I turned off every thing, got the troublesome speaker tested it and it was fine.

could the vibrations cause the crackling ?

I opened it up to see if I could see any thing wrong, and to my surprise there was no crossover.

input-Eminence delta-red wire to horn _

-blue wire to tweeter type thing

that's roughly what I saw, no internal any thing.

thanks

rory

[lightsource]

If I remember correctly, some motorola piezo horns required no crossover, just a large resistor between it and the full-range driver.

 

I would say though, that if it's crackling, then the driver is probably in need of replacement.

 

Make and model of the horn would be useful though!

[widowgobo]

hi,

It is custom made and I think it is all Eminence. I think its a 1" horn it has a spike on the front of it. there is some thing in front of the horn but it looks more like a capactior,it is a little rectangle block, but I would say your right.

it does not crackle when isolated. but will be changing it any way.

thanks for the reply

rory

[themadhippy]

but it looks more like a capactior

Theres your crossover,it crossover frequency can be found from rearranging 1/2pi f c

[widowgobo]

oohhhh I see, im still not sure why the woofer still works :)

[Jivemaster]

It was common to have disco speakers with a cone driver for bass and a piezo for top end. It was also vaguely adequate for there to be a simple resistor in series with the horn. It works but doesn't sound good by pro standards.

[widowgobo]

Do the highs go to the horn because of the resistance posed by the cone driver?

thanks

[Rob_Beech]

No, in this instance the 15 inch driver will see a full range signal, but, as it is no good at reproducing HF, you won't hear it. The way Piezo drivers work means that no LF will be passed through them. But they often need a resistor inline to tame them and limit the power they're given.

[themadhippy]

If theres a capacitor in there then it maybe a simple 6db crossover on a normal tweeter,the capacitor is in series with the tweeter,and as the frequency increases the impedance of the capacitor decreases allowing more signal to the tweeter.

[widowgobo]

thanks for the posts :)

[djandydee]

The 8 ohm resistor in series is only there for protection in the case of the amplifier going into ultrasonic oscillation. A piezo tweeter appears as a short circuit at extreme hf as it is really just a capacitor. The minimum impedance is then 8 ohms which falls within the amplifiers normal load impedance.

 

To reduce the output of a piezo transducer requires a simple potential divider circuit not a series resistor.

[widowgobo]

ultrasonic oscillation.

 

whats that?