Transformerless Interface
The opamp is implemented as a unity gain follower. Please see Horowitz the Art of Electronics if this is abakadabra for you. With a current feedback you can lower the bandwith by raising the feedback resitor in value. Again see the datasheet.
The chassis of both DAC and CDP are not connected to the digital ground in my case but can be connected. If you insist on using a transformer it should be placed at the DAC as I learned from Fred D. (was Harry Haller then).
Hi Stef.stef1777 said:Yes, both AD810 and AOP603 seems to work at +/- 5V according to the spec sheet. AD810 seems to be "better" at low voltage than AOP603.
If I have understood, low voltage reduce bandwidth. If I remember, we need 8/10 Mhz for spdif. We have enough marging as AD810 can manage 50Mhz at this voltage.
But the most important, what should be the gain? Of this depend the feedback resistor. And I have not really understood how to calculate this.
Just to know, I finished to change all my ecaps. The VRDS works fine. I also replaced c55/c56 by one unique polypro caps. This works. I'll prefer to say that I was not able to ear the difference during my first test.
The opamp is implemented as a unity gain follower. Please see Horowitz the Art of Electronics if this is abakadabra for you. With a current feedback you can lower the bandwith by raising the feedback resitor in value. Again see the datasheet.
The chassis of both DAC and CDP are not connected to the digital ground in my case but can be connected. If you insist on using a transformer it should be placed at the DAC as I learned from Fred D. (was Harry Haller then).
Yesterday night, I tried the VRDS will the news ecaps and the polypro caps in the spdif output. I'm really surprise. The listening was smooth with more bass level and punch. As I have changed all old ecaps and at the same time modified a little the spdif output, I don't know where the change come from.
Very happy with this 35€ modification.
Very happy with this 35€ modification.
stef1777 said:Yesterday night, I tried the VRDS will the news ecaps and the polypro caps in the spdif output. I'm really surprise. The listening was smooth with more bass level and punch. As I have changed all old ecaps and at the same time modified a little the spdif output, I don't know where the change come from.
Very happy with this 35€ modification.
What is the mod u did to your spdif output? simply the change in caps?
commstech said:
What is the mod u did to your spdif output? simply the change in caps?
Yes, as wrote previously.
Changed C55/C56 with one polypro MKP1837. Changed c58, c62, c 68, c63, c64 and c65 for new ones (MKS2, ZA and NPO).
And as well all ecaps of the board with Rubycon ZA and some ZL. c2 replaced by 4700UF
Nothing on the audio board. I don't use it.
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