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I just completed a major upgrade to my DQ-LP1 crossover. For those not familiar with this unit, it allows seemless blending of a subwoofer with mains. High pass to mains is passive with 6 dB roll-off and low pass to sub is active with 12 dB roll-off.The project - started when I heard a scratchy noise in the left channel, found out the RCA connector plastic housing was broken and the cable was not getting a good ground connection, replaced all RCAs with premium Vampire OFC panel mount connectors. Then while its was open I replaced all original electrolytics with Nichicon KZ Muse. Then I replaced all pwr supply diodes with Fairchild 'Stealth' devices (lower switching noise). Then I put in sockets and upgraded to Burr Brown op-amps (quieter and faster). And finally, all other capacitors were replaced with audio grade polystyrene or polypropylene film capacitors.
Results - very very quiet noise background now; very clear, clean and airy main speakers, I'm hearing low level details now I didn't know was there; bass is now very punchy and tight with much more texture to the sound.
I highly recommend this mod to all who have a DQ-LP1. It will transform your sound experience.
Sales Pitch - The odd and small value film caps were like unobtainium to get. However, I did manage to source some Orange Drop 715P capacitors with the exact schematic values and 1% tolerance for left/right channel matching. Unfortunately, I had to buy 10 of each cap to make it worth while for the seller. So, if anyone wants a set of Orange Drop film capacitors for the DQ-LP1, contact me.
Follow Ups:
I would like to have the same upgrade. Do you know anyone who would do it for me? Want to sell yours? How about a parts list and source, if I do it myself. Thanks!
I also have one of this unit lying around for years. Do not know how to use it. Any member interested, email me. Cheers!
I am looking for an LP-1. Anyone have one that they would part with?
The low pass is 18dB/oct.The opamps are only in the sub path, you were hearing opamp noise from the sub?
The only component that comprises the high-pass filter is one capacitor, for each channel, that are easily changed by anyone with entry level soldering skills ... and should be to adjust the crossover point as needed and to adjust for main amp input impedance.I always eliminated that extra connection and interconnect by putting that high pass cap on the second output of my preamp and from there directly to the main amp. No reason to go through the LP1 at all for the mains other than convenience.
I have had a DQ-LP1 for many years and it failed a year ago and I went with a marchard xover and equalizer which I am happy with for now. I would be interested in resurrecting this unit. I am pretty sure it is an op amp that went bad. It got hit with a pretty high DC voltage which also took out an amp and a woofer. Which opamps did you use? I had upgraded the RCA and the caps when I got the unit back in 1985. I paid $50 for it then. I have know idea what they are worth today, but I hate having broken equipment lying around.
So it goes.........
I used Burr Brown OPA2604 devices. Available through Parts Connexion.
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