Dahlquist LP-1 Passive/Active crossover

I used a DQLP-1 between 1981(started with my Acoustat Model 3's), until 2005(with a wide variety of planars, mostly Maggies). I never found a more transparent unit(many mods over the years), until the TacT RCS 2.2X came along. If you don't have the Dahlquist manual, with it's crossover point/amplifier input impedence matching chart/formulas: Get one and pick/configure your points intellegently. Try calling Frank Van Alstine (651-330-9871), as he could probably either supply one or direct you to a source. He's modded hundreds of those units, and knows them like the back of his hand.

Thanks rodman99999,

I do in fact have the LP-1 manual and have been calculating the necessary capacitor values required, depending on the input impedance of the main speaker amps I use. It apparently doesn't matter what the impedance is of the amp used for the sub(s). Anyway I have a pair of monobloc amps which have an input impedance of 22K ohms which produces a crossover point of 280Hz with the 0.027 mfd factory capacitor. This will allow me to use the stock LP-1 to replace my Maggie 20Rs stock passive crossover providing a high pass of 280HZ (6db slope) which is very close to Magnepans recommended 300Hz high pass point and to then dial in the low pass between the Magnepan recommended low point of 90Hz-150Hz range. Thanks for the info re Frank Van Alstine, I will certainly give him a call.

Bbro- You'll have much cleaner sound if you find either(new) polypropylene or polystyrene caps for the hi pass filters. If you need impedence matching resistors: use Vishay bulk foil. I got mine from Michael Percy. WBT makes some really nice RCA jacks for PCB mounting, that are perfect for the DQLP-1(no modification needed to install). I've forgotten the part number, but will look it up later, if you're interested.

The WBT-0234s were what I installed to replace the cheesy, original RCAs in my DQLP-1: (http://www.wbt.de/index.php?id=73&backPID=73&tt_products=59)

I agree with the need to replace the RCA jacks. Forget the sound improvement, the intermittent sound there - sound gone "Feature" will drive you nuts!

I do have a schematic I made for it in PDF format, if anyone needs it. Just drop me an email and I will send it to you.