Finding out crossover values from a vintage DIYloudspeaker: help!

juanito

Member
2006-11-20 8:10 pm
Hello, here I have what is left from a DIY 2 way loudspeakers:

1- a pair of Seas p21 RE-M. They need refoam sorround.

2- a pair of Peerless 811546 tweeters. They look great.

3- a pair of crossovers as seen in the picture. Also I drew a sketch as best possible.

I got some values: the 1,2 mH coil, the 8 uF polarise cap and the PMT/2R cap (sorry, I drew it as a resistor).

Any ideas what could be the other values? Or may be some popular kit from the 80's?
I would like to get the values before refoaming the woofers.
Also I asked the person who gave me the drivers if he still had the contact from the person who designed and/ or build the speakers.... No luck.

Thanks very much in advance! Any ideas or help is really apprciated!


[IMGDEAD]https://s26.postimage.org/ivetq9de1/image.jpg[/IMGDEAD]

[IMGDEAD]https://s26.postimage.org/d1muq3p55/image.jpg[/IMGDEAD]


subirimagenes
 

eriksquires

Member
2013-05-10 4:11 pm
For an understanding of crossovers and how they are drawn, please see my blog post here.

For help upgrading an existing crossover, please see here.

If it's drawn correctly it's a small cap used to improve the performance of the 8uF cap. Using a decent modern film cap you should be able to replace both caps with a single good 8.2uF cap or here.

For direct measurements get Dayton DATS V2 or a multi-meter that has good LCR measurements. Cap values of electrolytic capacitors changes over time so those won't be very reliable.

Once you've read my blog on crossover basics, I think what you have is a 2nd order high and 2nd order low pass circuit.

Try redrawing them that way. If you use XSim you can skip the paper and pencil. :D



Best,


Erik
 
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This speaker uses drivers like in the Mission 737.

8" Polycone bass and soft dome tweeter. Some data below.

You can use second or third order tweeter, and simple bass filter at 3kHz. Well behaved drivers, you see.

Downloads
 

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juanito

Member
2006-11-20 8:10 pm
Thanks Steve!! I'pll check later during the afternoon the visaton app: not sure if will work on Mac OSX...
The values of the drivers are preset in the Visaton app or did you add them manually?

by the way, one of the resistors, the white block, had writen underneath the value: 22 ohm or could be 2,2 ohm. The thing is they glued the parts where the value is writen so when I ripped them off it takes the writing...

Well Steve, I'll stick to your suggestion, also the values skeched with the Visaton app are very similar. Still got to refoam the woofers which is another challenge.
 
Retrace the schematic now you have an idea how it should pan out.

FWIW, the Vifa P21WO-20-08 is a similar unit though more of a reflex driver IIRC.
Vifa P21WO-20-08 Diameter 215mm

I use a modeller to get a rough idea what is going on. TBH, you could tune this one by ear. 8" Polycones usually need less bass filtering than paper cones, but not much in it. You are not clear what the bass shunt is, if fitted, but usually with a biggish resistance in series with the cap. Near Zobel.
 
Hi John, since I tend to drown and overload in my PM box, can I bring this back to the thread?

Looking through woofers which may be really damaged I'm considering to use instead the Seas P21REY polycones they have at Falcon acoustics: should be similar.

Seas P21REY/DD H360-08 Woofer - Prestige Series

Hello Steve, I'm back with the "vintage project" and the woofers I think it's not worth repairing them so I'll probably send them to someone who can make any use of them.

Instead I'm considering seriously the P21REY woofers.
So with box sim and the visaton project you suggested me I can make a new crossover?

The VIB2000GF.BPJ file you sent me is a visaton project 2 way loudspeakers: is the crossover schematic valid for the peerless tweeters and seas woofers?
The two schematics you sent me at the forum thread there are a bit different from the one in the boxsim app with VIB2000GF file.
Thanks, I'll dig a bit more also.
Best regards,
john

http://www.seas.no/images/stories/vintage/pdfdataheet/h0359_p21rey.pdf

That 30L reflex woofer looks a easy to me. Very well-behaved. It really doesn't need much more than a bass coil around 1.5mH IMO. And a port or reflex tube about 5" long and 2" or 3" diameter at a guess. :)

The circuit below will probably work if you skip the shunt element on the bass or change the resistor from 5.6R to 22R for a 3kHz crossover. The red 4.7R is select on test for tweeter level.
 

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juanito

Member
2006-11-20 8:10 pm
Hi John, since I tend to drown and overload in my PM box, can I bring this back to the thread?



http://www.seas.no/images/stories/vintage/pdfdataheet/h0359_p21rey.pdf

That 30L reflex woofer looks a easy to me. Very well-behaved. It really doesn't need much more than a bass coil around 1.5mH IMO. And a port or reflex tube about 5" long and 2" or 3" diameter at a guess. :)

The circuit below will probably work if you skip the shunt element on the bass or change the resistor from 5.6R to 22R for a 3kHz crossover. The red 4.7R is select on test for tweeter level.

THANKS THANKS MANY THANKS:):)
 

juanito

Member
2006-11-20 8:10 pm
Does all this apply to Peerless 833429 woofer? polycone 6". I can still get a pair of theese at a good price. I've seen in this forum quite a long thread about these woofers but can't get the graphic/picture of them. At hifitalo there are for sale but not much info either.