A little Denon DAC mod

[210]

Why would you do that? It's a no-no with totem pole outputs.

Increasing the slope (dV/dt).
But if they don't swich identical enough,
th possible drawbacks (at least jitter) are important.

I wonder about the two signalwise unused gates
and how to use them to improve the seemingly bad signal quality of the input circuit.
Maybe switching them to 'high state' (with an additional gate) when the other gates switched to 'low state'
can somehow compensate the switching load on Vss, or something like that.

 

[210]

Now I think that parallizing output stages increases di/dt (if needed!) and dv/dt will only change if the load didn't get enough current from a single output stage. Btw., it's said that the YM3823 receiver is jitter sensitive, so I use a SRC2000 to ensure low input jitter to the DA500. I get a tighter and (unexpected) bassier Sound with coax wire than with toslink. At the output I use a Jensen transformer, who adds a few dB k3 that gives the sound a more realistic attack (prob. steeper dv/dt). .

 

[210]

The unused second output of the power transformer (U=8.5V without load)
can be used for digital supply with a low voltage drop
5V regulator etc. (L7805 won't work because Io=250mA).

 

[jean-paul]

7805 will work OK, I used it for this purpose. You will need a bridge and filter cap of course. And a heatsink.

 

[stephensank]

Any standard TO-220 package 7805 type is capable of 1A with proper heatsinking.
The problem with the YM3623 is not so much jitter sensitivity as poor PLL phase noise performance, inducing more jitter. I know at least ASE sells an adapter board to take YM3823 to DIR9001 or CS88414(forget which, maybe both), which would be a worthwilre upgrade on this dac, which can sound really terrific with the right work done and a respectable transport/server.

 

[210]

7805 will work OK, I used it for this purpose. You will need a bridge and filter cap of course. And a heatsink.

Thank you for the infos!
The voltage drops below the needed 2V difference of the 7805 (tested with 2) with my DA500. I think, this is the reason, why Denon finally didn't use the second wiring
of the transformer for digital supply (as they planned,
there are a few more 'workarounds' in the layout).
I use a coil with common mode cancellation wiring to avoid coupling digital and analog via the transformer.

Any standard TO-220 package 7805 type is capable of 1A with proper heatsinking.
The problem with the YM3623 is not so much jitter sensitivity as poor PLL phase noise performance, inducing more jitter. I know at least ASE sells an adapter board to take YM3823 to DIR9001 or CS88414(forget which, maybe both), which would be a worthwilre upgrade on this dac, which can sound really terrific with the right work done and a respectable transport/server.

Thank you for your tip to upgrade to DIR9001.
Latest when 3623 died and hard to get, I'll try it.
I use myca caps for the oszillator, rubber-damped the quarz
and use a little, grounded steel case screen above them
till then.

Regards,

 

[DocScholz]

Hi, I just got a DA-500 which is already somehow modified. The PSU has two big 10.000uf capacitors, so that I ask myself how the rectifying diodes have survived.

I have now seen that there is a "kill the clock mod" possible, which surpresses disturbing signals from the clock. In this thred are two schematics shown. I have seen, the the small diode 1N41448 is linked to pin 21 once in this and once in that direction. Is this a printing mistake?

Kind greetings,

Werner

 

[Alex Schroedsen]

Sorry to resurrect an old conversation. I just got a DA500, I'm really a modding rookie, but I successfully installed sockets in place of all four OPamps and filled those fours sockets with OPA2604AP chips. I then installed a grounded power receptacle and isolation transformer. Unfortunately the ground isn't isolated. I am also thinking of installing Jensen caps on the output stage. First of all does anyone think the Jensen caps will make that much of a difference (and are they proper for an output stage) 2pcs Jensen 0 1uF 400V Polyester Film Foil High Grade Audio Capacitors MA | eBay and second, where should I put them? One more question, how might I go about cleaning up the ground? I have looked into things like this 1pc 6 10000uF 2 WIMA0 1 400V Filter Capacitor Power Amplifier Assembled Board | eBay and I'm wondering if they'll improve the ground significntly.

One other idea I really like is replacing that Yamaha SPDIF receiver with a DIR9001 or something by cirrus logic, if anyone knows where to get an adapter board I would really appreciate a pointer.

here are some pictures of my DA500 so far https://www.mediafire.com/folder/o466mi6ze6cb1/DA500