Correct parts for my first crossover? (Markwart)

[ao371]

I just picked up a pair of vintage Altec 604-8Gs last weekend and one had the wrong model crossover. After some a little research i decided on one designed by Jeff Markwart (Jeff Markwart's Corner - Phase Corrected Crossovers) It gets great reviews and I like DIY projects. I've hardly ever soldered anything, let alone built a crossover, but I like to try new projects. I've been reading up on how to read schematics and how to assemble them. I think I have a really basic understanding.

The schematic.


This part is a little confusing. What parts are represented here as P1? Is it an l-pad or a resistor?



Here's the parts in my cart, are they all correct? I know I have to double up everything.

[Elitopus1]

P1 is a potentiometer. Its slightly different than a L-pad. Like he says, you can just use one leg of an L-pad instead of a pot

[tysencahill]

P1 is a potentiometer. Its slightly different than a L-pad. Like he says, you can just use one leg of an L-pad instead of a pot

A little late to the game here, but I too am working on this crossover and am having trouble understanding how to wire the L-pad.



Do I connect the R4 resistor to ground leg, and then from the 30ohm leg go to positive? Leaving one leg free, correct?

[Elitopus1]

Usually when hooking up an L-pad the positive wire (signal in) goes to #1, the driver gets #2 wired to its postive terminal, and #3 goes to the negative side of the xover or speaker terminal.



In Jeff's drawing it looks like its only hooked up to two of the L-pad connections. I would contact him directly and ask how to hook it up. I have spoken with him before and he is very nice and helpful.

I am planning on building this same xover for my Urei 604G's. I am going to use a fixed resister in place of the L-pad. When I asked Jeff about this he said a 10 ohm resister is a good value to start at

[tysencahill]

Usually when hooking up an L-pad the positive wire (signal in) goes to #1, the driver gets #2 wired to its postive terminal, and #3 goes to the negative side of the xover or speaker terminal.



In Jeff's drawing it looks like its only hooked up to two of the L-pad connections. I would contact him directly and ask how to hook it up. I have spoken with him before and he is very nice and helpful.

I am planning on building this same xover for my Urei 604G's. I am going to use a fixed resister in place of the L-pad. When I asked Jeff about this he said a 10 ohm resister is a good value to start at

Thanks for the response!

I contacted Jeff, and as you stated, only two of the pins are used. R4 goes to pin #2, and pin #3 goes to the mid point of R1 & R2.


I'll post photos when I'm done and give you my impressions. The supplies from PE is supposed to be delivered tomorrow!

[tysencahill]

Completed the crossovers tonight and installed them.

I used Dayton resistors; Solen caps; Jantzen inductors; and Belden 9497 wire.


Well. Simply put. The crossovers are game changers. Dramatically better. End of story.


My front end is a Scott 296 restored by Craig at NOSvalves. Jolida Tube DAC as my source.


Seriously, these are the best speakers I've heard.