Oracle DIY DC power supply upgrade - diyAudio
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Old 10th May 2004, 12:37 AM   #1
Gaucho is offline Gaucho  Canada
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Cool Oracle DIY DC power supply upgrade

I have constructed a power supply for my Delphi MKII. The new power supply resulted in better sound stage depth, sharper focus and deeper more powerfull bass. The difference in bass can be felt as well as heard!

The supply as I built it is just a slight rework of Mr. Pass's BOZ powersupply. I used a single Avel-Lindberg D4007 (30VA) transformer with the secondaries in parrallel to give full capacity at 30 volts AC. Refering to the BOZ PS schematic I used three 9.1 volt zener diodes plus a (green) 2.1 volt LED to replace the six 10 volt zener diodes to create a new reference voltage of 29.4 volts. For C2 I used 220uF instead of 100uF. I used 1.5K for R1. I removed R2,R3 and C4 from the circuit. For Q1 I used a D718.

Under load the new supply is with in a tenth of a volt of the stock Oracle supply which BTW meaures higher then its rated 27 volts. I strobed the table and both supplies run at the same speed.

I first built the supply at a little lower voltage with just the three 9.1 volt zeners and no LED and although I could still get the correct speed just by adjusting the pitch contol on the table the sound was worse than the stock supply. What the h*ll?

Warm regards,
Gaucho
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Old 10th May 2004, 01:47 AM   #2
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Default Re: Oracle DIY DC power supply upgrade

Quote:
Originally posted by Gaucho
I have constructed a power supply for my Delphi MKII. The new power supply resulted in better sound stage depth, sharper focus and deeper more powerfull bass. The difference in bass can be felt as well as heard!
Color me a skeptic.
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Old 16th May 2004, 01:42 AM   #3
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your new power supplu is better than witch one from oracle, regular or turbo?
Daniel
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Old 16th May 2004, 03:44 AM   #4
Gaucho is offline Gaucho  Canada
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The new supply performs better than the stock MkII DC supply. The MkV motor is a synchronous type and thus requires an AC supply.

I ordered some of the upgrades from Oracle and will report any improvements. I am getting the acrylic hard mat, suspension upgrade, MkV clamp and replacing the acrylic arm board with the newer type.

Cheers,
Gaucho
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Old 30th May 2013, 07:50 PM   #5
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I am currently developing a supply for the Delphi MKII DC motor that is inspired by Mark Kelly's work on a compensating supply using error correction. I have the board design complete and the prototype seems to improve the performance and speed stability quite well. Most of the components are high rel mil type components with very high tolerances. For instance most of the resistors are .5% tolerance Dales. That's a point five, or 1/2 percent.

The drive has fixed output specifically calibrated to the specific motor, so no variances due to potentiometer soft spots and such. The DC input voltage to the driver circuit are pre-regulated by an LT1086. The voltage reference is a highly temperature stable AD REF02CP. All the caps are very low ESR, Elna RSH series.

We shall see how this goes.
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Old 2nd June 2013, 02:46 AM   #6
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The Oracle Turbo power supply is pretty simple.

An capacitor Emi filter feeds a one of those blue torroid transformers.
A standard diode bridge feeds a 10,000 uf cap, then a power resistor, another 10,000 uf cap, then a power resistor, and the final 10,000 uf cap then a heat sinked fet with a zener to ground connected to the gate - appears to be in parallel with the final cap and the output - a simple shunt regulator possiby. There isn't $100 in parts in the case, yet the cost to upgrade from the standard supply is $925.

I was able to increase the AC filter cap, the diode bridge to discrete soft recovery and double the size of the filter caps for a lot less..........

The MK V motor maybe AC , but the Turbo supply puts out DC. The motor controller in the base of the turntable creates the AC waveform

Last edited by ticknpop; 2nd June 2013 at 03:03 AM.
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