Modifiying your RCD-1072. Superclock3?

[spkerguy]

Hello everyone,
Has anyone out there modified their 1072? I came across this website and it looked interesting. http://www.referenceaudiomods.com/Me...ory_Code=SCLK3 I was wondering what is available for the 1072.

THanks,

Ken

[jim777]

I don't think that the clock is the bottleneck in the RCD-1072. They paid much attention to jitter in the RCD-1072 design. IMO it's weakest link is either the DAC (they picked one that is not top-notch only because it has HDCD built-in) or it's output op-amps (well that is a wild guess, because I don't remember what chip it is).

So I wonder if someone modified the op-amps or the power supply in his RCD-1072??

[spkerguy]

I came across this post from Ram East (they make the superclock3) in reply to someone asking questions about modifying their 1072. Here is goes:

There is alot of mods and upgrade potential for this unit.

For starters, the stock toroid is pretty weak in my opinion and could be definitely replaced with a M6X version from Audio Consulting. This may be too large to fit in the stock chassis, thus requiring a seperate wooden box, but none the less the performance will be significant.

The Stock power supply design is basic and needs upgrading with Ultra Soft Recovery diodes and Jensen 4-pole caps. There are also a couple voltage regulators that can be replaced with the Audiocom Q-powers. These regulators power the DAC chip and the analog opamps.

The DAC Chips are the PCM1732 and I beleive they are located on the bottom side of the circuit board. The Stock op-amps might be good enough to not necessitate a change as the amount of performance will not be worth the actual costs, I dont know though since I have never done this change on this unit.

The PCM1732 is a SINGLE ENDED OUTPUT D/A CHIP. This means that a Coupling Capacitor on the outputs (Pins 13, 16) needs to be the highest quality of your likings. I would try some Rubycon ZA in this application and see how you like them. It wont run more than a couple dollars each and peel the plastic off them for better sound. Mark the negative on the top of the cap with a sharpie. Blackgates N series can be used here and sound good, but I like the rubycons better.
Instead of using the opamps. You could run the outputs from these coupling capacitors directly to a set of isolated high quality RCA jacks. Run a 10kohm resistor from each signal on the output of the cap to ground. Just use a basic resistor for this purpose. This should bring a load more resolution and transparency. The opamp may be needed for more drive, and in this case I would use the Burr Brown BUF634 High speed buffers, which do NOTHING wrong to the sound but plainly pass the music and add current for drive in the signal. The BUF require a +/- power supply here.

I know this is alot to follow but this player can definitely be hotrodded to sound very good. It will never sound GREAT because the DAC chip does not use the most optimal topology.

In addition, a set of copper or silver signal coupling transformers can be used in the output from the cap or from the output of the op-amp or buffer to further increase performance by a wide margin.

Adding a Superclock 3 w/optional PSU will also be a nice change for this player.

I have had one here and have gone through it almost fully but the owner backed out and I returned it to him, he sold it and he sent me a Denon 2900 to mod, which will sound superior to the rotel any day in its fullest modded stage.

Please reply, email or call for more info and if you have questions.

Thanks!
_________________
Doug
Reference Audio Mods
East Location

[Taito]

Personally, I'm skeptical about some of this.

[bleeding ears]

From what I have learned and heard the Wolfson dacs are the latest and possibly the greatest, however as far as I know Rotel dont use them and they apparently wont do HDCD so what you gain (if anything) with the Wolfson you may lose by not having HDCD sound.

As with most things it is probably a compromise.

I think the Cambridge Audio Azur cd players use Wolfson dacs and many rave about the sound they get. Check out audio review web site.

Not owning either the Rotel 1072 nor the Azur I cannot add my opinion on how they compare, However I think the Azur may be substantially cheaper.

Also I doubt those mods done to the 1072 would come cheaply, especially if you must get someone else to do it.

PS just saw a review of the CA Azur 640C Version 2, in AVL magazine.
they gave it 5 out of 5 in all respects.

Something to think about

Pete