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ES9023 / WM8804 S/PDIF DAC Group Buy

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Hi,
My second version, I changed the :
C10 BG 1uF NX
C31 Oscon 100uf 16V
C10B Oscon 100uf 16V
C12 BG 1uF NX
C14,C15 RealCap 6200pF (sold out on 4200pF)
C9,C32 changed to 2.2uf large file cap (MusicCap)
C8 changed to Tant 47uf 10V

To me, C9 and C32 made a big different. try it if you have time.

I've got mine playing with:
C16, C10B & C31 Oscon 100uf 20V
C14,C15 4700pf 63v WIMA film
C9 100uf 25v Panasonic FM
C32 1uf 50v Silmic II

I like the sound a lot, but find the high end has very good detail but sounds a bit recessed. I didn't assemble the spdif stuff since I'm using an Amanero USB with it. The PS is the group buy one. Any suggestions to add a bit more of presence to the highs?

syklab, C9 & C32 made the most difference when going to big film cap, or any change in electrolytic cap (I was thinking of going to 10uf Cerafine)?
 
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another one working

I've finished building a 2nd DAC from the v2.6 Subbu DAC boards. The 1st build was shown in post # 560 and used a point to point wired PS for the DAC consisting of an LM317 preregulator and FET cap multiplier for the DAC. I also hand wired a JG buffer and +-15v supply.

This build used the JP/Subbu PS for the DAC and the Xen Audio JG buffer board. Power supply for the JG buffer is handwired using LT1963 to give +-15v.

It's still burning in, so it's too early to make any comments on sound quality vs. the first build. When first powered on it sounded a bit strident but after running for 24 hours or so, it's smoothing out and sounds quite similar to the 1st build. I'll wait a few more days before making any final judgements.

Attached is a picture of the latest build, which is housed in an ABS plastic box from Poly case with dimensions 222mm x 146mm x 55mm.

---Gary
 

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Sorry but the 115 V mains wiring is not done in a safe way (uninsulated wires, wires not suitable for 115 V etc. Where's AndrewT when you need him ?). You better position the mains connections of boards near the IEC receptacle. The mains switch is already at the backside so things could have been done better with shorter wiring. The 5 V output is very close to the mains connector too.

A metal case is better for shielding ! In fact the DAC should be in a metal case as it has a 50 MHz oscillator in it and the DAC itself does not like cell phone RF noise from the outside world too. Shielding works two ways.
 
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Sorry but the 115 V mains wiring is not done in a safe way (uninsulated wires, wires not suitable for 115 V etc. . . .). You better position the mains connections of boards near the IEC receptacle. The mains switch is already at the backside so things could have been done better with shorter wiring. The 5 V output is very close to the mains connector too . . .
JP,
Thanks for the feedback . . . although it does seem a bit harsh. To be sure that I understand it completely, I hope it's OK if I ask a few questions and make a few comments of my own. You make the following points:

1) Wiring is unsafe because there are uninsulated wires
Comment - the only uninsulated wires are the exposed terminals on the IEC connector for AC and the wires connecting the 2 halves of the DPST switch together. Is your point that I should use shrink wrap to cover any place that carries 120v? If so, then guilty as charged. I don't normally operate the DAC without the top cover so I had considered that protection sufficient.

2) Wires unsuitable for 120v
Comment - I don't understand this one. All of the wires that I use that carry 120v have insulation rated at 600v. Is there some other parameter or type of wire that I should look for. In addition, any wire carrying any high voltage is positioned to be relatively far away from any other wire so the insulation isn't tested.

3) Transformer input should be position right next to the AC input.
Comment - I might look and see if I can find an alternate layout. There is always a compromise between finding the shortest signal wires, the shortest DC supply wires, and the shortest AC wires. I prioirtized short signal wires and short DC wires over the shortest AC wires. In your experience, should having the shortest AC wires be the highest priority?

4) DC output from PS board is too close to the AC wiring.
Comment - the perspective of the photo makes this seem worse than it is in real life. When viewed from a different angle, one can see there is a decent spacing.

5) DACs must be built in a metal chassis for shielding.
Comment - I've heard this idea but my experience has been that DACs don't seem to be that sensitive to the chassis material. The DACs work and sound fine even when breadboarded, i.e. sitting in open space. Even with a metal chassis, unless one is very careful, it's quite easy for signals to leak in and out.

Once again, I appreciate the dialog, even when not 100% positive.

---Gary
 
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Hi not harsh but in safety we should not go the easy way.

1) Wiring is unsafe because there are uninsulated wires
Comment -

a. No shrink wrap.
b. many 115 V wires that can be touched as they stick out of their connector without sleeve
c. mains carrying wires soldered to each other or to a blank copper wire and then in to the connector without insulating cable pins like the ones on the picture. Bad one.

2) Wires unsuitable for 120v
Comment - Thought it was solid core 90 V PVC wire from the look of it. Sorry if I got it wrong. Flexible cabling breaks a lot less easy than solid core cabling....An IEC receptacle with insulated faston/Amp connectors would be a tad nicer and again less risk for touching mains carrying wiring.

3) Transformer input should be position right next to the AC input.
Comment - DC picks up nasty signals less easy than AC. I would keep AC wiring short so it is away from the PCBs and/or electronics.

4) DC output from PS board is too close to the AC wiring.
Comment - OK if the picture gives a wrong impression. Still I would turn the power supply PCB 90 degrees to the left and I would move the DAC PCB to the left somewhat. You will have both transformers and their primaries close to each other and the IEC receptacle and far away from audio signals carrying wiring and electronics. Less possible hum and a smaller spot where 115 V is around.

5) DACs must be built in a metal chassis for shielding.
Comment - Building electronic devices in a metal casing is not just an idea that can be heard but it is simply good practice in electronics (certainly with an onboard 50 MHz oscillator). I know wooden cases can sound different and in most of the cases better (oops what am I confessing here) but even then I would shield sensitive stuff. Before you know it you will be dipping caps in bees wax !
 

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Tough one and I am no expert in choosing the right material. Aluminum offers little magnetic shielding (it shields RF) but it is the most easy material to work with. Steel is fine too as it shields RF and it offers magnetic shielding. Steel is better than aluminum but it is heavier, tougher to work with and it needs painting. I use aluminum a lot but I shield internal stuff with mumetal when I can. Other metals like copper (one of the best materials for EMI shielding) are too expensive or impractical to work with as they are soft, sensitive to fingerprints, corrosion etc. (for me at least so this is a personal choice).

You can put the electronics in a small metal casing that can be built in a wooden/plastic case. A case in a case so to speak. It gives the advantage that you can make the case exactly like you want it to look and the device is shielded. Wooden cases look very good.

http://en.wikipedia.org/wiki/Electromagnetic_shielding
 
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