Can someone tell me what freq. these crossovers are at?

[JZatopa]

http://www.apexjr.com/speakerstuff.html

The JBL crossovers. I emailed them about the crossovers and here is what I was told.

On all 4 of the crossovers the chokes are not marked, however

The picture with the 2 x-overs have these parts

1 – 1.2ohm 5W & 37.5ohm 5W resistors 16uf 100Vnp & 20uf 100Vnp electolytics

and 2- 3uf 250V blue poly caps

Other rectangle crossover has the following;

1ea 7.5ohm 5W & 2.7ohm 10W Resistors,1 ea 7 uf 250V blue poly caps & 15uf 100V

electrolytic.

The 2 crescent shaped x-overs both have 6.8uf 100V caps and the larger one has a

3 ohm 7Watt resistor

All 4 have dual gold plated red/black push binding posts

Anyone have any ideas?

 

[Netlist]

Hi, DJNUBZ
It's impossible to tell with only this info.
From or for which JBL-speakers or box are they?
Do you want to replace them?
Is it for JBL speakers? Home? Pro?
Can't you mail the guys and ask the frequencies curves?
Tell us some more.

/Hugo 🙂

 

[pinkmouse]

Hi, DJNUBZ
It's impossible to tell with only this info.

Yes, we at least need a schematic to reverse engineer them!😉

 

[JZatopa]

I was looking to use them as a cheap set of crossovers for a home setup for a pair of speakers.

I'll email him if he has a scematic but I have a feeling he doesn't.

 

[planet10]

http://www.apexjr.com/speakerstuff.html

The JBL crossovers.

I have traced the circuit on these (3rd order with a zobel across the woof), but haven't had a chance to measure the inductors yet. Once i have i will post the schematic and we can start guessing the XO (which of course is very dependent on the drivers JBL was using) -- Steve will also get a copy -- least i can do for him tossing one in with my last order so i could look at it.

dave

 

[planet10]

It turns out that under each component, the nominal parts value is shown. I confirmed the inductor values and drew up a map.

The values do not correspond to text-book 3rd order filters so let the figuring begin.

dave

 

[jleaman]

OH wait a minit that is the one that i drew out. now isn't it. GRR. well the one that you drew out in 5 min and me 30 min LOL. Practice make's perfect..

If any one knows about speaker building IT is PLANET10.. ( DAVE )

 

[planet10]

you drew out in 5 min and me 30 min

I don't think it took me that long 🙂

dave

 

[jleaman]

that is because your a

 

[JZatopa]

anyone have any ideas on these yet?

 

[JZatopa]

bump

 

[JZatopa]

no one has figgured this out yet??? Anyone have any ideas?

 

[jleaman]

what was it that you were looking for again...?

 

[JZatopa]

the crossover points of this crossover.

 

[jleaman]

email dave he has that exact crossover sittin on his table he would know..

planet0 that is.

 

[pinkmouse]

Well, without knowing the VC Re and inductance, it is impossible to calculate the effect of the RC network on the woofer part of the circuit, so that part will have to be redone unless you use exactly the same drivers in the same enclosure as the crossover was designed for.

As for the rest, it is a standard 3rd order layout, but as Dave suggests, the component values look a little strange. Your best bet is to get one of the PC based crossover sims and model it, to see what happens.

 

[jammer018]

I called JBL and, according to the somewhat helpful contact, the xover is at 2000hz. The JBL price is listed at $53 per unit so at $2.50 these babies are a steal!!!

I recently installed this unit in a bookshelf system and they seam to work fine. There are pre-wired leads off the woofer side so hookup is a snap.

 

[JZatopa]

is that at 4 ohms or 8?

 

[planet10]

is that at 4 ohms or 8?

Given the small value of the caps on the hi-pass its gotta be 8 ohm for the tweeter, and i expect the woof would be the same.

dave

 

[pinkmouse]

It may even be higher, lots of these little pro monitor speakers are 16ohm so you can parrallel loads of them off an amp in an install situation.