DIY Altec N1500A

[sparks12kv]

Hi all, I'm trying to build a set of N1500a's from scratch for a pair of 604e. I've used Markwarts excellent site, but this is my first crosssover from schematic. My question is this: there is no lpad on the parts list, but one is used in the vintage crossovers, is it the 25ohm R-2 component?

http://home.earthlink.net/~jmarkwart/sitebuildercontent/sitebuilderfiles/n1500a.pdf

[Earl K]

R2 is not an Lpad, it's a variable resistor ( Potentiometer / Rheostat (http://en.wikipedia.org/wiki/Potentiometer) ) .

This part (from Ohmite) http://www.galco.com/images/ohm/rhs25r_p.jpg (http://www.galco.com/buy/Ohmite/RHS25R) will do the job .


:)

PS ; I think you should ask JeffM( via his website ) for clarification about installing his HF contour circuit to the N1500a ( since it's mentioned at his web-page but not committed to a drawing ) .


The N-1500A with MF EQ?
I next wondered what the addition of Mid Freq EQ would do to the behavior of the N-1500A filter, so I modified the CALSOD filter model with a contour circuit consisting of a 6uf cap paralleled with an 8 ohm resistor, which was then placed in series with the compression driver voice coil. The mid-point of the resistor was tied to ground with a variable resistance of 10-50 ohms. See Fig. 3 below:
http://home.earthlink.net/~jmarkwart/sitebuildercontent/sitebuilderpictures/n1500eq.gif