Why do some ds dacs have metal shields behind the screen while others do not?
My technician who did the mods on my DSD was not willing to do an additional external power supply without the JKRichards power supply board. I was lucky enough to get one of the last boards. There have been a couple of modded Directstream dacs for sale on the forums lately. The price of these dacs with the external power supplies have been very reasonable.
1 Like
Ok thatâs strange, as many other modders did without problemâŚI just say, normally the board is not needed, it mainly enables a comfortable switching between internal and external supply and automatically cares for an at first switched on analog board. Two comfortable options which are not really relevant in continuous DAC operation.
2 Likes
Those shields are mods people do to control rf/em interference from the display panel and controller.
No, there is a shield in the photo on the daraudio site.
Also, pwt memory player has the same shield.
2 Likes
Thatâs interesting! Did PSA build in some modifications meanwhile and if so, which?
There are many minor versions of the physical hardware with the case that the PWD, DS, etc. use. They changed over time. Things like the variations on the RFI fingers around the top cover, various ways of connecting the safety ground and various shields, including one for the display. Iâve got no idea when they changed but, at times various shields came and went.
5 Likes
Thanks! Would be interesting to have a summary of which shields were applied in sum that make sense. Maybe @jamesh can find out?
1 Like
Perhaps @VEMANOEL can chime in, as I believe itâs his mod.
Another pic from a different angle - post 831 (I think)
Not sure about what that is in the Darko article, but itâs something that is below the power supply board, as you can see by the shadow cast by the capacitors and can see the srews/screw holes in the right angle channel used to hold the front panel to the bottom (sorry about the ugly circles and pointers - I was using my trackpad)
but perhaps @Paul could chime in definitively if some production version ever came with a shield behind the display?
Edit: you can also see the entire back of the display drive board down to the ribbon cable in the Darko image. I am curious of what that is though. It looks like some kind of plastic plate or something. It runs belows the display driver board ribbon cable and stops at the the section for the panel screws.
1 Like
I agree the DS is a very different beast now itâs had new transformers, linear psu on the analogue board and rf absorbing sheets installed. They probably all sound a bit different too.
There are plenty of linear power supplies you can use, either production or diy. Some are very good. You can mount them externally or internally. There are trade-off with both approaches.
Btw my DS is a kit upgrade from a PerfectWave dac and has the metal shield behind the display module.
1 Like
1 Like
Yes, he used the EMI absorbing sheets as well - but I believe he also made the shield.
Hopefully he will chime in on whether the shield is DIY or factory (or someone else thatâs been keeping up with this thread better than me). I do know that many had to DIY it if they wanted it.
A great site link for learning what this material does to electro magnetic eddy current waves. Thanks for sharing. I never thought of using this on Wall Warts but might be another application to clean theses up when used near our audio system.
3 Likes
Maybe one of these would be the ticket:
2 Likes
That is quite the site for EMI / RFI pollution mitigation
2 Likes
Well⌠the bad news is the AD8139 are not very easy to rework in, for me at least. x8. Whew.
The good news is- wow(!)
Did I mention âTextureâ above? Yes I did; but in addition now the sound has taken on a greatly added realism. Highly increased contrast in the sound of everything, which is more correct and real, such that I have not ever heard in a reproduced music system before, anywhere.
Essentially the analog portion of the chain is just getting the h-ck out of the way of the music in a way I have not experienced before.
The new big word summary then is- Realism!
Also, might assume this gives a hint of the flavor of the new DS DAC coming soon. If so, itâs going to be an industry smash IMOâŚ
More work to do. Including getting the transformers out and trying that again with some film coupling caps. We also await the arrival of amorphous trans w/ pure(r) Cu windings. Currently we have the standard amorphous trans still in place. May the best config win.
T
6 Likes
I can order some stuffed boards and pass them on to someone if interested. They would need assembly and stuffed with the power connectors and relays. Would also need some hardware to mount the back panel and an external power connector along with the internal power cable. We would also include the test fixture. We did 50 pieces last time. I donât think it would be worthwhile at this point as there were little interest the last time I offered them. I offered one I had left over and they didnât want to pay the price I was asking which is what it would cost to make one now.
Sorry we wonât be offering complete units any longer as our time and interest has shifted to designing and building a IR remote control kit and an external impedance enhancer for the Denafrips DACâS.
The output impedance of these R2R DACâs are pretty high (1250 Ohms).
3 Likes
As probably Ted would say: if you donât see this by yourself, you shouldnât do this mod 
Adriaan,
This is the pcb assembly you want to replace,
I think.
This idea of employing an external 5 vdc lps has been bugging me for years, so I bought a spare PCB to study, from what I can tell so far, this pcb has to stay since it serves more than a psu, however, I think J3 and J4 ribbon sockets is where the 5 vdc feeds the front display and feeds the digital PCB, but without schematics it is rather difficult to be sure.
Perhaps those who are more qualified will chime in.
