model 15 crossover schematics

[joe3rp]

Can anyone please help me on the schematic diagram hook-up of an altec model 15. The altec plate says model fifteen, w 2 pots, 2 caps, 2 inductor and 2 resisitors.

I won it in ebay, model 15 crossover with horns, but even after tracing the components of the crossover I cannot seem to decide on the hook-up.

It doesn't seem to be the common 1st/2nd/or 3rd order passive design.

Help please

[Richard C.]

I also bought a pair of Model 15 crossovers from eBay. I bought them for the nice front plate to be used as a chassis to mount different components on, for a DIY speaker. Are you going to use them as is? If so, the input wires are the WHT/BLK pair. The HF horn connects to the the RED/BLK pair. I am pretty sure that RED connects to (RED +). If it doesn't, someone will correct me. The woofer connects to the GRN/BLK pair. Again, GRN should connect to (RED +).

Notice that the input is wired directly to the woofer. The woofer has NO low pass filter in it's circuit. There is something like a 3 pole high pass filter plus HF compensation (EQ) in series with the horn. The horn output is about -15db around 1500Hz and 0db at 20KHz. This is with the two controls set to optimum. I have a program to model crossovers, and it seems able to predict the crossover behavior.

I can send you a .jpg of a printscreen from this program.

Richard C.

[Richard C.]

Actually, it's the signal to the horn that I am quoting. The sound (SPL) output is more flat due to normal HF rolloff. The horn output is probably 10db greater than the woofer; which accounts for the initial -15db lower signal to the horn.

Richard C.

[joe3rp]

Richard,

Thanks for the quick reply.
Yes I plan to use the crossover as is. I was assuming the Woofer had a crossover network connected to it. I would appreciate if you could send me the schematic ( [email protected] ).

So the black wires (3 wires) are the (-) input, (-)woofer and (-)hi.

The white wires (2 wires) are the (+) input and (+) woofer.

Now I understand. In your expereince does running the woofer full range give a satifactory result? Did you add a series inductor?



The red wire (1) is the (+)hi out. Ok, now I can see it.

In you expereince th

[Richard C.]

I am at work today, but I will get the schematic to you soon.

I don't like to run the woofer full range, but there are a number of speaker models that do this. I feel there has to be some interference between drivers with so much overlap. I put a 2nd order filter (12 db/octave), in series with my Altec Model 14 woofers. The resonate circuit caused a sharp peak at 1700 Hz, and it took a zobel network to flatten the LF response. I also modified the HF high pass filter to be more like the Model 19. I am very pleased with my Model 14's. Since I don't have a Model 15 to play with, I wouldn't be able to offer much help in improving the crossover.

I see why you were confused about hookup. I wonder if someone changed wire size and substituted WHT for GRN??? Both of my "stock" model 15 crossovers use a GRN wire. My Model 14 & my Model 19 crossovers also use GRN wires for LF.

Richard C.

[Richard C.]

I will put a link to my webpage tomorrow for the Model 14 & 15 schematic drawings. It just seems to work better that way. I have had times when the hostboard server wouldn't display the pictures, so this is a better way.

Richard C.

[SJ David]

Could you post an image of the schematic? It would be of high to me, as well.

David F

[Richard C.]

OK, I have the Model 14 & 15 info on the 2nd page of my webpage now: Richard's web page

[SJ David]

Great. Thanks Richard.

[Earl K]

Hi Heather,

Here's Richards schematic ( I saved it years back, and safely store it over at LHF );

To see it full size ( right-click ) then open it in a new tab ( or window )




My 2cent swag ( after a quick sim ) is that it probably needs a reworking to bring the response of the horn/driver combo into the 21st century.

Let me know if you want/need some help with that ( my PMs are open to you over at LHF ).

Note the woofer runs full-range .



BTW, RichardC ( though mostly in low profile mode these days ) does have some presence over at the GPA forum.

Here's his brief M14 thread over there.