Carlsbro PA / Celestion - and tweeter ohms

[MuddBass]

Hi, 

I have some old Carlsbro PA speakers. I'm trying to work out the ohms of each. 

The Celestion speakers are BL400x and are marked up as 8ohm. 

The tweeers are only labelled as APT super tweeer no. 0103.

What I need to know is what each cabinet is in terms of ohms (combined tweeter and celestion). 

Cheers 

Greg 

[MuddBass]

[MuddBass]

[goingdownslow]

Are they working? The wiring to the pc board doesn't look right.

[MuddBass]

Yes, they are working. They seem to have two jack inputs which seem to do the samr thing. Here is the other one.. 

 

 

[stevie]

The overall impedance of the system will be eight ohms.

[goingdownslow]

In the first pic the yellow (horn) and black with white tape on (speaker + ?) look to be crossed, but if it is working....

 

Edited May 26, 2019 by goingdownslow

[Bill Fitzmaurice]

Impedance is not affected by using a tweeter and a woofer. Below the crossover frequency the impedance of the woofer is what the amp sees, above the crossover frequency the impedance of the tweeter is what the amp sees. Now, for the bad news. You don't have crossovers, you have first order high pass filters. That means high frequencies that the woofer can't reproduce are going to them, while the protection of the tweeters is almost non-existent. I'd get rid of what you have and replace them with these:

https://www.bluearan.co.uk/index.php?id=EMIPXB2-3K5&browsemode=category

If you have any electronic chops you could make your own for perhaps half the cost of a pre-made. While you're at it the cab appears to be bare inside. It should be lined with an inch or so of open cell foam or polyester batting.

[MuddBass]

Cheers, many thanks.

Looks like I've got a small project on my hands! 😁

[Bill Fitzmaurice]

I can supply a crossover schematic that will work much better than what you can buy, at a lower price, but it won't do you any good if you don't know how to assemble it.

[MuddBass]

Thanks Bill, elecs not my strongest point so a ready made unit is best 

 

[Stub Mandrel]

A proper crossover will send more treble to the tweeter, but depending on the choice of drivers this might make the system sound too bright.

Main thing is that the woofer impedance is what matters in terms of system impedance. The energy in the HF part of the signal is relatively small.

[Phil Starr]

Looking at your pics what I think you are looking at a very simple circuit to protect the tweeter. The beige circular component is a thermistor IMO opinion. It's resistance rises quickly when it gets hot and reduces the power to the tweeter. The yellow component is a single capacitor that reduces the low frequencies by 6dB/octave effectively reducing the bass below certain frequencies. The horn is simply being used to add to the sound of the bass unit. The fact it has survived probably means the protection is adequate. A proper crossover will probably clean up the midrange but a commercial crossover will only get you part way. If you are planning on using these as bass speakers they are probably going to do fairly well as they are.

The APT 50 is an Eminence horn driver, it may be one of those the BL400 was designed as a bass guitar speaker by Celestion  If it is an APT 50 then it is a very modest driver, you cant make it into a silk purse so the right crossover may improve things but don't expect miracles

[MuddBass]

Cheers for the reply. No, I'm not intending on using for a bass speaker, rather use them for PA for a small jazz band. I've owned these for years but not used them much. Hopefully the new crossovers I've ordered will help extend the life of these PA speakers!