Repurpose Old Crossover Componants

[tube power]

I'd like to re-use these old crossovers...


I want to use them to cross some main speakers for live sound.
300 watts each.
These work, but are rated for 100 watts max.
http://support.radioshack.com/suppor...oc65/65787.pdf

I'm only using them for two way at 3500 hz
Would someone please tell me what cap voltage/value will make them safe for my use?

Thanks

[J M Fahey]

Voltage *is* a factor, no doubt, but I guess your limiting parameter, being a cheap crossover , will be ripple (or AC) current through the capacitors, plus since at least one of those coils is in series with the woofer, a lot of current will pass through it.
Best case, you'll have a relatively high resistive power loss.
Worst case, it will overheat, melt the plastic coil, etc.
I wouldnīt feel 100% safe even in a 100W cabinet, go figure, if itīs used under Pro conditions (6 or more hours a day, at full power), such as DJ or live PA use.
For home use, no problem at all.

[Enzo]

Visit Parts Express site. They sell crossovers, bare boards for them, and all the components. SO you can buy them complete ready to go, or make one. To sell the parts, they provide fomulae as well as some graphic layouts to help you select values for your X-over freq. They sell for example ranges of inductors in various wire gauges, heavier wire for higher currents. Might find something useful there.

[tube power]

Ok, thanks.

I'm going to try this...

Dayton Audio XO2W-3.5K 2-Way Crossover 3,500 Hz 260-146

[tube power]

Here's the "crossover" that came in the cab...



15" is wide open, the resistor and cap go to piezo.
That's probably ok, but I want to limit highs to the woofer.

I have already replaced the generic 15" with an Eminenece Delta
and the tweet with a decent generic titanium driver.

[km6xz]

All the prior responses would have been different if you had revealed that the driver and cross-over in question was including a piezo driver for HF.

If it is a piezo HF driver, it does not need the cross-over that dynamic drivers need since it appears to the outside world as a capacitor which of course has a inverse reactance vs. frequency. Low freq sees a higher impedance so little current flows throw the HF driver. It is much more efficient than the LF driver/cabinet combination so the series resistor is needed to balance HF and LF output. A series capacitor is often used because the Piezo driver is most efficient at frequencies above its self-resonant frequency, usually 1khz-2khz or so and the cap acts as a high pass filter in series with the driver's high-pass response plot.

The reactance of the LF driver is going to be significant for high frequencies so there is a much less hf current flow through the woofer. A cross over type inductor forming a low pass filter for LF is usually not needed.
Designing a speak system for use with a mix of dynamic(LF) and piezo(HF) components is not like using two drivers with similar principles of operation. When concerning yourself with HF energy being dissipated in the LW driver, remember that there is much less energy in upper frequencies in music or human speech. The total of all the harmonics generated do not equal the energy in the fundamental note of any instrument, and no matter how distorted the signal is. Very little energy will from the upper harmonics in the LF driver since the HF piezo driver has higher sensitivity and a lower impedance at higher frequencies than the LF driver. And very little low frequency energy will be expressed across the piezo because at low frequencies, say, 100hz, the impedance of the HF driver will be over 10,000, probably 20-30k ohms.
All that combines to make piezo HF elements a dream for designers of cheap consumer grade speaker systems. What is wrong with Piezo's? Well, their gradual rise in response with frequency above resonance makes building a flat response curve just about impossible for one thing.

[tube power]

km6xz

I appreciate that response.
Excellent explanation of how a piezo effects a woofer.

I had removed the piezo, the resistor/cap combo was what was left over,
so unless anyone assumed there was a piezo in the cab, their answers were actually pertinent.

Do you like that Dayton crossover?
(Given your response to the speaker swap question in that other thread, (good thoughts, especially speaker placement)...
I'm considering the likelyhood that it has been engineered pretty well better than one I might cobble together.

My main consideration is to keep the woofer under 4000 hz and have the tweet driver pick up at that point.

[tube power]

Voltage *is* a factor, no doubt, but I guess your limiting parameter, being a cheap crossover , will be ripple (or AC) current through the capacitors, plus since at least one of those coils is in series with the woofer, a lot of current will pass through it.
Best case, you'll have a relatively high resistive power loss.
Worst case, it will overheat, melt the plastic coil, etc.
I wouldnīt feel 100% safe even in a 100W cabinet, go figure, if itīs used under Pro conditions (6 or more hours a day, at full power), such as DJ or live PA use.
For home use, no problem at all.

The coils are metal.
Other than the cap voltage, I don't understand the difference between the components in this and the 300 watt Dayton.
I thought I could just replace the caps with higher voltage ones and use the same coils, they seem pretty stout.
But I'm just learning about passive crossovers really.
And while I'm not penny wise and pound foolish, I value good old gear and my money
These do not seem cheap at all. The pc boards are massive, the traces are huge. Seems really well built.