Dahlquist LP-1 Passive/Active crossover

I have a Dahlquist LP-1 that I have used for many years. I found that setting the frequency to high will make the bass not sound right, to much bloom. I have mine set on 92 at this time, the level at around 1 on a clock and the equalizer at zero. I suggest starting at 12 o’clock on the level and equalizer, and around 40 on the frequency. Slowly increase the frequency until it sounds right to you. When you feel that you have found a good frequency setting, try slightly adjusting the level control slightly. In time you will find the “sweet spot” in you bass. When you play song that has very powerful low frequency’s, use this as a maximum reference point for your bass and set the Dahlquist LP-1 to your liking. It will take many tweaks.

I would never give up my Dahlquist LP-1. I use a Hafler XL280 driving a pair of DQ 1 subs with it. I have total control over the bottom end and I will still occasionally slightly tweak the dials.

You want to enhance the bass in regards to the room and other speakers, not overpower the bottom end. I get many compliments on how tight and controlled my bass sounds.

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.

Also, I found the original owners manual which I scanned into pdf format and I also have a schematic for an upgrade to it which I have been using for some years now. If anyone wants them they are welcome to them. Just shoot me an email.

Hi does anyone know where I can find instruction manuals for the DQ 1W subwoofer and the DQ LP1 Crossover? Thanks

I am also looking for any up to date schematic or parts source for restoring a Dahlquist DPL-1 and matching impedance to my 33k Ohm Parasound A21.
any help appreciated!

I am also looking for any up to date schematic or parts source for restoring a Dahlquist DPL-1 and matching impedance to my 33k Ohm Parasound A21.
any help appreciated!

The manual gives the matching instructions and formula: https://sites.google.com/site/mpbarney/home/dahlquist-dq-lp1 Some of the original Dahlquist crew, might be able to help, with your other requests/questions: http://www.regnar.com/supported-models.html