VRDN: bipolar regulator PCB for line level ckts: ±11V to ±20V @ 1.5A with "De-Noiser"

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#743
rikiheck said:
Part of the reason I asked is that, e.g., the XP-20 is said to draw about 25W. That's an order of magnitude greater than the BA 2018. Out of curiosity: Where is all that power going?
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This is probably due to a misunderstanding. 25 watts probably only means the maximum power consumption of the built-in 25 watt transformer, not the device.
However, the XP-20 power supply and preamp combo is a bit more power intensive than normal. The right and left channels have a separate power supply, which of course also means that a bit more power dissipation is required. The electronics in the XP-20 are also somewhat more complex and extensive, which also means higher power consumption.
Due to the separate power supply, the XP-20 also has a significantly lower crosstalk that you can also achieve with your preamplifier if you operate the left and right side with separate VRDN power supplies.
 
#744
Mark Johnson said:
I wouldn't worry too much about a $50 multimeter whose displayed output voltage flickers between 18.00V and 17.99V. But if you remain deeply, deeply concerned/worried, you could (A) load the outputs with resistors-to-ground which draw approximately the same current as your final audio gear will draw from VRDN; and also (B) monitor the output waveform with an oscilloscope instead of a multimeter.

For example, if your application calls for VRDN to deliver 25mA to the left channel +18V supply, and another 25mA to the right channel +18V supply, that's a total of 50mA from VRDN's +18 output. Ohm's Law tells us that a 360 ohm resistor has the same current draw {math: 18V = 0.05A * 360 ohms} so if you've got a 330 ohm or 390 ohm or 360 ohm resistor, connect it between VRDN +18V and ground, to achieve a same-current load.
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I am having a similar problem with a build that is using an AC wall wart.

V+ I can lock into my desired voltage but the V- dances around and ranges between about 30mv.

is this more of a concern than Namgihinook’s experience?
 
#745
Update on some things I tried this morning.
  • Re soldered all joints on the V- side of the board
  • cleaned all the flux off the whole board
  • checked orientation of my diodes
  • I am using TI regulators, so made sure I had the correct resistor and cap changes

Still no luck getting the V- to stabilize. However, after adding the jumpers to bypass the denoiser, the V- stabilized... Hopefully that helps trying to troubleshoot my issue.
 
#747
Ok. I realized I just plugged in a 22N I found in my parts draw that probably does not meet the ESR requirements

I used a Wima MKS2 in my other VRDN builds so I will try that cap first.

I used the Rev A2 values below.
 

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#760
Hello! I'm about to make my own VRDN version with some few tweaks (adding a 5V rail, different heat sinks, connectors, etc...).
So first of all thanks a lot for sharing the design, it made me gain a huge amount of time and head scratching!
I'm still left with a few questions, so here we go:
1 - Does the design really benefits from having 4 layers or could I go with just 2 (with 2 ground planes)
2 - What about earth? Would it be a bad idea to tie it to ground in this design?
3 - I can't decide which trafo to use, there are too many lol. Any recommendations?
- http://www.hammondmfg.com/pdf2/1182J18.pdf
- http://catalog.triadmagnetics.com/Asset/VPM36-1390.pdf (or) http://catalog.triadmagnetics.com/Asset/VPT36-1390.pdf
- https://talema.com/wp-content/uploads/datasheets/Open-Style-230V-Primary-0050VA.pdf
- https://sklep.toroidy.pl/en_US/p/TTSA0050-Transformer-AUDIO-TSA50VA-voltage-to-50V/309

Thanks!
 
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