Building the ultimate NOS DAC using TDA1541A

[SSerg]

Hi, wlowes

Originally Posted by wlowes

Would it not be better to use a pcb that has most of the chip floating in the air?

This is useful with standpoint of the improvement to insulation, but can enlarge the stray montage capacities.
I think that at given aspect it is more important to pay attention to DEM capacitor insulation.
It is necessary to choose the capacitors with maximum resistance of the insulation, let in the prejudice of the other parameter even.

[SSerg]

Hi, qusp

Originally Posted by qusp

Parasitic leakage will find a way even without a PCB, without a PCB and ground, EMC noise from the i2s and clock signals will have a whale of a time jumping all over the place. depending on speeds they dont even need a conductor to travel on.

It is important for correct working of DEM cells low capacitor leakage of at DC. But you talk about electromagnetic hindrances, which are connected with AC. Of course, advisable reduce these hindrances. But here talk about the other.

[qusp]

no, it is not just connected to AC, it is connected to i2s, a fast analogue signal used to transmit digital, so kinda AC if you want to look at it that way. fast signals without proper layout/grounding = EMC issues. No i'm not talking about 'other' I also wasnt really talking about capacitors, so I really have no idea what you are talking about....

basically, I know what I was saying, either you didnt understand..or you didnt understand.... and about your post...I didnt understand....

[SSerg]

Hi, qusp

Originally Posted by qusp

basically, I know what I was saying, either you didnt understand..or you didnt understand.... and about your post...I didnt understand....

We have not understood each other. I spoke about the DEM capacitor insulation on direct current, but you spoke of electromagnetic hindrances. This is a separate subject.
Let's return towards the insulation quality of the DEM capacitor.Why this it is important? Because leakages of DEM capacitors on direct current (on DC) break the exact double difference of bit currents at nearby bits. This brings appearance of distortion at analog signal.

[jameshillj]

Serg,
I assume from this that Styrene, Teflon or Propylene capacitors for the DEM oscilator are recommended, yes?

[roger57]

Originally Posted by qusp

no, it is not just connected to AC, it is connected to i2s, a fast analogue signal...

Oh, really? I2S, a fast analogue signal? "Contributing" this kind of feedback seems a bit counterproductive. BTW, no guilt saying that.

Just in case you need a bit of background on this new digital stuff, here you go:
http://en.wikipedia.org/wiki/I%C2%B2S

[qusp]

haha man how childish can you be....

seems you completely misunderstood the post, but that doesnt surprise me

I was replying to wlowes suggestion that by removing the PCB you would lower the leakages and improve the decoupling by reminding that without a low impedance ground/ ground plane, the fast signals would cause other EM related leakages

yeah clock wave is sooo digital isnt it? the interpretation is digital, the wave that represents it is not

I suggest you go back and hit the books while I make you disappear

[roger57]

Originally Posted by qusp

haha man how childish can you be....

seems you completely misunderstood the post, but that doesnt surprise me

I was replying to wlowes suggestion that by removing the PCB you would lower the leakages and improve the decoupling by reminding that without a low impedance ground plane the fast signals would cause other EM related leakages

yeah clock wave is sooo digital isnt it? the interpretation is digital, the wave that represents it is not

I suggest you go back and hit the books while I make you disappear

Quote (again) what you wrote..."... it is connected to i2s, a fast analogue signal."

Whatever. I guess I'll get back to my childish Grade 2 reading primer to try and wrap my head around sentence structure.

[SSerg]

Hi, jameshillj

Originally Posted by jameshillj

Serg,
I assume from this that Styrene, Teflon or Propylene capacitors for the DEM oscilator are recommended, yes?

Yes, these capacitors have pretty good insulation, but rather greater size and stray inductance too. The bulky capacitors it is difficult to place and they sensitive to external hindrance.
May suit and ceramic capacitors with good insulation and with enough big working voltage (100V, 250 V and more). The ceramic capacitor inductance is small.
How see, choice of the type capacitor - not open-and-shut case. Here needs the compromise.

[regal]

Originally Posted by qusp

haha man how childish can you be....

seems you completely misunderstood the post, but that doesnt surprise me

I was replying to wlowes suggestion that by removing the PCB you would lower the leakages and improve the decoupling by reminding that without a low impedance ground/ ground plane, the fast signals would cause other EM related leakages

yeah clock wave is sooo digital isnt it? the interpretation is digital, the wave that represents it is not

I suggest you go back and hit the books while I make you disappear

Why is it so hard for people to understand that any digital signal transmission is an analog? Its just basic physics.

As far as the PCB-less TDA1541, the concept is you build it point to point in three dimensions on a copper ground plane , Thorsten calls it "bug" building. The results are aesthetically ugly and not commercially viable but make a lot of "sense" on a science/engineering level, perfect for DIY This is why you see little innovation/offerings of TDA1541 PCB's other than the silly china offerings, they just don't make a lot of sense any more.