Crate Crossover Schematic For PE-15H

[TomCarlos]

MEF members....

I picked up a pair of Crate PE-15H speakers. There is a 15" woofer and Horn Tweeter. It looks like the some of the caps are starting to bubble. These crossovers use Non-Polarized caps. I have some Polarized caps but want to make sure I install them correctly. I believe that the positive side of the caps would always go towards the speaker, correct?

There are 3 caps, 1 resistor, and 2 inductors. I am thinking this must be something like a Second Order (12db/octave) configuration. But... I see a 3rd cap on this board and wondering how that is used. Tracing this out seems a bit more tricky than I expected. It looks like the extra cap and resistor connect (in parallel) to the negative side of the Tweeter? Does that make sense?

I do see a number on the PC board but cannot find any info on that.

I believe the wiring goes like this...

Red = Tweeter +
Black = Tweeter -
White = Woofer +
Blue - Woofer -

Any hints on the crossover schematic?

Thanks in advance... Tom

[Enzo]

No, they are non-polar because ther is no polarity to the audio. The signal goes positive and negative from the rest position.

Tracing it out is not hard, I have done that many times. I should have it, but finding it is another thing,

[TomCarlos]

Ok.... I think I have it.

If you look at a basic Second Order Crossover, there is a cap and inductor (as shown in the diagram). For the Crate Hi Frequency Tweeter, there is a Cap and Resistor in parallel that connects to the Tweeter input and the other side connects to the main cap and inductor connection point. What made this confusing is that the polarity for the tweeter seems to be flipped. On a commonly found configuration, I would have expected to see the "Black Lead" of the tweeter going to the input ground. On this board, it is flipped. The Red lead going to the Tweeter goes to the PC board ground input.

I found some Crossover Calculators on the web. It looks like the Low side is a second order crossover. The Hide side resembles a 3rd order. This tweeter uses the H025N08 diaphragm, commonly found in compression tweeters.

So.... maybe as a test, I simply swap the Red and Black leads to the tweeter and give a listen.... (just for the hell-of-it).

Thanks...

[Jazz P Bass]

A few manufacturers do that 'flip the tweeter polarity' thing.

The 2nd order filter flips the phase to some degree.
But it's frequency dependent.

I cannot hear the difference on a guitar amp.

Now on HiFi audio, it is apparent.

[TomCarlos]

Thank you Enzo and John....

I will swap out the caps and keep these crossovers around for a small powered speaker box. I believe they are rated for 100 watts.

I know there is tons of articles and web sites out there that have info on crossovers. But it would be great to find a small reference book, theory, examples, combinations, etc. Will go searching on eBay or Amazon for something.

Tom

[Enzo]

In PA speakers, the inverted tweeter feed is quite common. Some connect the red to the tweeter negative. Some are sneakier and solder the red wire to the crossover ground and the hot wire is black, so when you do the normal thing and connect the red to + and black to - on the tweeter, it comes out inverted.

You can see on your board, there are unused spaces for additional parts, for when it is used in a three way cabinet.

Parts Express sells complete crossovers, bare crossover boards, and all the caps and inductors you might need to make one up. They also provide some charts/graphs to help you pick values for given impedances to set desired frequencies. So you don't need to understand the electronics to put together a crossover for 8 ohm drivers that crosses at 800Hz... or whatever.

[Leo_Gnardo]

it would be great to find a small reference book, theory, examples, combinations, etc. Will go searching on eBay or Amazon for something.

One good source for crossover caps is Parts Express. They have a line of very affordable in-house film caps branded "Dayton". I've used some and never a problem. Films won't bulge & fail like non-polar electrolytics & by some accounts sound better too. Only problem is mounting, since films are axial and it looks like the caps on your crossover board are radial. I'm sure you can overcome that with some clever wire bending & glue. Parts Express also has plenty of free XO information since they're mostly aimed at hi fi and PA home builders.

edit: whups, I see Enzo already gave PE a good review. Happy shopping & good luck!

The "extra" parts you mention may be to steepen the slope of the horn crossover, the better to leave out low frequency audio that may cause distortion and/or damage the driver.

[TomCarlos]

Hi Leo.... Yes, the "extra" parts have something to do with stabilizing the tweeter impedance. I have seen other circuits where the cap and resistor are in series. I've been looking at other cross over circuits today and running the part values through the various Crossover Calculators that are online. I can't say that I got exact matched results. Oh well, this one works and I am sure someone has done their homework.

I ordered Non-Polarized caps.... should be a quick fix.

Thanks, Tom

[Enzo]

Series resistors to the tweeter also serve to reduce the level. They want the sound level leaving the tweeter to be compatible with the woofer levels.