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Oppo new UDP series players - 203/205 - Discussions, upgrades, modifications
Oppo new UDP series players - 203/205 - Discussions, upgrades, modifications
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Old 10th November 2017, 12:29 AM   #321
zenelectro is offline zenelectro  Australia
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Quote:
Originally Posted by Joe Rasmussen View Post
So the first is a bog standard 'Virtual Earth' I/V converter.

The second shows the added components, five per channel: Two resistors, two small chokes/inductors and a single capacitor.

I would recommend trimming the 0.18uF (or 180nF) down in value and aim for the flattest response at 20KHz. You might find that with 0.18uF it will be down a negligible 0.25dB, hardly a bad result, but some like 0.17uF or 170nF combination of parallel caps, will tweak the circuit.

But just try it with 0.18uF to get you started and if you like what it does, then tweak it.

The 47uH coils, we used some that was rated at 3A, so saturation is not going to be a problem.

Click the image to open in full size.

We also unwrapped the wire and much less than a metre, we remade them with better wire, so that can also be a later tweak, but the coils did work standard quite well.

OK, up to you to try it. Cheers, Joe.

.
Further to my previous post, using passive is a good way to go, especially
if you have low DAC -> IV impedances, the inductors can be relatively small.

I have made many of these both 2nd and 3rd order.

The crucial part is the inductor, specifically core material. You will find that
the 47uH spec can actually be only over a limited BW and that can be quite a
bit higher than 20kHz. Remember that these inductors are mainly used for
mains RF filtering applications.

Obviously the best inductor is an air core one but then the DCR will go up
as you need more turns. It will also most likely need shielding.

This brings back memories. I've got boxes of inductors / coils / transformers
etc that were used for I-V applications.

T
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Old 3rd December 2017, 11:35 PM   #322
Coris is offline Coris  Norway
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Oppo new UDP series players - 203/205 - Discussions, upgrades, modifications
Adding a DC block filter to the LPM...
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Old 8th December 2017, 08:48 AM   #323
heyj is offline heyj  China
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Cool LPS board for OPPO UDP-203

I just finished developing the LPS board for UDP-203.
It is working nicely , perfectly replaced the orig swtching ps.
I use a Nuvotem 35VA onboard trans, opamp + mos reg circuit.
This LPS is suppling a DC12V to the main board only. No power to the DAC board, which I will never use.
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File Type: jpg oppo1.jpg (803.9 KB, 72 views)
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Old 8th December 2017, 09:04 AM   #324
Coris is offline Coris  Norway
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Oppo new UDP series players - 203/205 - Discussions, upgrades, modifications
Nice design.
I would like to point out that in case of not using (powering) the DAC board (203), the flat cable in between main board and audio board it should be disconnected, preventing so possible randomly functional issues (sections of audio board partially powered through the flat cable).
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Old 8th December 2017, 09:21 AM   #325
heyj is offline heyj  China
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Thanks for Coris's recommendation.
I will immediatelly remove the flat cable
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Old 8th December 2017, 10:39 AM   #326
Joe Rasmussen is online now Joe Rasmussen  Australia
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Quote:
Originally Posted by heyj View Post
I just finished developing the LPS board for UDP-203.
It is working nicely , perfectly replaced the orig swtching ps.
I use a Nuvotem 35VA onboard trans, opamp + mos reg circuit.
This LPS is suppling a DC12V to the main board only. No power to the DAC board, which I will never use.
Looks neat. I have a question, how much more heat does it produce and also, can you feel the case being warmer?
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Old 8th December 2017, 10:49 AM   #327
Joe Rasmussen is online now Joe Rasmussen  Australia
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Quote:
Originally Posted by zenelectro View Post
This brings back memories. I've got boxes of inductors / coils / transformers
etc that were used for I-V applications.

T
Hi Terry

Sorry, I was overseas and didn't spot your post, but right on.

Chokes are making a comeback, like also in RIAA EQ.

Cheers, Joe
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Old Yesterday, 02:56 AM   #328
heyj is offline heyj  China
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Quote:
Originally Posted by Joe Rasmussen View Post
Looks neat. I have a question, how much more heat does it produce and also, can you feel the case being warmer?
Yes, it produced more heat than the orig PS. touching the heatsink, I think it is about 50"c. The case is warm if I enclose the conver and play few hours.
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