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Old 25th September 2008, 03:37 AM   #1
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Default Deqx PDC 2.6P

Does anyone have any interest in discussing mods for the Deqx? Does anyone here use a Deqx? If yes, anyone have a modified or upgraded unit?

I have one that is extreme in its modifications.

Is there any interest?
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Old 25th September 2008, 05:39 AM   #2
KBK is offline KBK  Canada
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You'll likely get some good arguments going. That seems to work well around here.

The remaining mods are, clocking and..er...yes..a linear power supply.

That's it!

oh. One more.

Heat sink on the on board regulators..and a 1/8th watt resistor across a certain set of pins on the Brown dog stand up adapters to bias all the OPA627's into 'class A'.
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Old 25th September 2008, 08:07 AM   #3
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I own a 2.6, unmodded. So far .
What are your mods?

Jan Didden
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Old 25th September 2008, 08:38 AM   #4
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Default HaHa small world

Now that is funny....

It really is a small world. After seeing you reply KRK, I did a search (maybe should have done that first) and came across several posts including the ones you refer to. Should have known you could be a member here.


Ken P
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Old 25th September 2008, 09:29 AM   #5
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Default Deqx

Quote:
Originally posted by janneman
I own a 2.6, unmodded. So far .
What are your mods?

Jan Didden
Hi Jan

I have seen many posts from you regarding the DCX. I had looked at getting one of those modified a couple of years back but ended up with a couple of Deqx units for my 4-way Boulder amp driven Westlakes. Stunning to say the least. The dual Deqx system is daisy chained using the optional digital add-on boards. One Deqx controls the volume on both units (setup in the software) One deqx drives the low and mid bass amps (balanced outs) while routing the remaining signal out through the digital option board to the digital input on the second Deqx. The signal is then crossed over to the mid high and ultra high balanced outputs to the other amps. Damned expensive setup.....took months of tweaking to get it right. At 450 lbs each, it was impossible to move the Westies and use the auto analysis features of the Deqx to create correction filters. I used a stand alone RTA to tweak the system using notch filters built into the Deqx units. The system is so fricken dynamic it gives people goose bumps. The soundstage is extremely deep and wide. Not to mention very black between cuts. I have been in the recording industry and high end audio since the early seventies and have never heard anything like this. It is truly state of the art. FYI, I am not a rich man but have slowly put the system together over many years. The Boulder amps are simply the finest amps I have ever heard. I have 4 of them.

I just purchased a modified Deqx and am chomping at the bit to compare its performance to a stock Deqx. As far as describing and explaining the mods, I am not a circuit designer and can only say that all the opamps were changed along with many service mount components being replaced with higher quality through hole parts. I believe extensive buffering was done to all input output sections including the dac. Much of the power supply was upgraded as well.

KRK happens to be the fellow who modified this unit and could be far more technical if he chooses to add to my description.

I will definitely post my impressions once I receive the unit and try it out.

Respectfully,
Ken Pachkowsky
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Old 25th September 2008, 10:02 AM   #6
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Default Deqx

Just read the above over and wanted to mention I have the HRX 4 way active crossover specificly designed by Westlake for the HR1's. It was rebuilt and brought up to the latest version by Westlake tech's 3 years ago at a cost of 5 grand. It uses over 100 op amps per filter board combined with many different value polycarbonate caps to create the filters. Each board (2) has over 120 wima film de-coupling caps. It is an excellent crossover but lacks the performance of the dual Deqx system.

I will post some photos of the system if there is any interest.
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Old 25th September 2008, 10:11 AM   #7
Sjef is offline Sjef  Netherlands
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I have owned a DEQX PDC2.6 since 2002 from the first series, later in 2004 upgraded to the PDC2.6P preamp version and recently upgraded with the hardware upgrade offer from DEQX. As far as I know they have changed every opamp in the unit as well as every electrolytic cap.

This was a very worthwile upgrade. The unit has more air now and the slight sibilance in the heighs are almost completely gone now. It's just more easy on the ears now and the soundstage has improved a lot as well.

I still have the stock smps power supply and I think things can be improved here also. The new PDC3 unit uses a smps for the digital section and a linear supply for the analog section. I didn't want to upgrade to the PDC3 because I have allready spent enough money on it. I think it is possible to build a better power supply yourself and the next thing I would like to see is to change the electrolytic (Panasonic FM by now) in the highs output section with something better.
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Old 25th September 2008, 03:42 PM   #8
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Default Re: Deqx

Quote:
Originally posted by Ken Pachkowsky
[snip]I will post some photos of the system if there is any interest.

Yes please! Seems like a killer system you have there!

Jan Didden
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Old 26th September 2008, 12:14 AM   #9
KBK is offline KBK  Canada
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He bought my DEQX that I had, er..relatively extensively modified. The usual. New opamps.

In this case, OPA627's on brown dog adapters, the stand up ones. Each op-amp board has polystyrene bypass caps. Each ceramic cap on the board was removed and electrolytics were added in.

I gave him all the parts required to finish off the one remaining stereo 'third channel' for a three way system. I was only using it for two way and had started the mods for that section, but stopped-as it was not in use.

The balanced input section needs to be modded, it is stock. I never used it, so no need to (for me). I gave him the parts to put in there as well.

The power supply is of the original digital type, and that might be upgradable to a linear supply, for a minimal sonic quality increase. I gave him some decent high pulse capacity non magnetic 20uf polypropylene caps to put between the PS and the main board, to possibly remove any hash that the digital PS might still have.

The digital/analog and clocking sections also have their capacitive mods to clean up their PS situations. All os-con sp type, right at the local ceramic buffer locations.

The entire Chassis is critically damped and the essential ground mod is in there as well, as the input/output signal ground is very remote from the actual PS level grounding point. I ran a wire across the ground pins of the RCA jacks and over to an unused screw mount post that is in the chassis. This brought the ground noise down to a much lower level.
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Old 26th September 2008, 07:24 AM   #10
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Well, sounds quite extensive. I've been modding DCX2496's now to the point that they are hardly recognizeable at the inside. Maybe time to crack the DEQX open.
The DCX is fully documented with schematics etc. Are there schematics available for the DEQX as well, that you know of?

Jan Didden
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