Hi. This Algar_emi, I finally managed to install my Buffalo II into an enclosure, but I'm still having the noise problem, sound like white noise on the Legato output (or Balanced and Single ended output.

My setup is: MUX CS8416 (USB, Optical, Coaxial, AES/EBU inputs), Buffalo II (with Trident shunts), LCDPS supplies for Buffalo & MUX with separate transfo, Dual mono Placid shunt regulators (with separate transfo) for dual Counterpoint I/V converters, custom Legato (only the headphone section) amplifier. Volumite volume control, custom MUX source selector switch/Led PCB.

Everything is working except there is a small noise (about 10-3 mvac) at the output. It is very frustrating. First I thought it was because I was using just one Placid and it was running out of power because the noise disappears if I'm using an external linear lab power supply to supply the Counterpoint. SO I ordered an other Placid and both supplies are not working with a comfortable 50-60ma overhead.

On my Placid (version 2.1.1) there is a provision to install an RC filter (C4-R7) on IC1 pin 2. The schematic is marked 'open' for both parts. I found that if I install C4 220pF/R7 2K2 )N JUST the Positive supply of one channel, the noise almost completely disappear on this channel. But if I try the same thing on the other Placid, the noise remains the same on the other channel.

As you can see my setup is very thing and I cannot use the new Placid HD. I want to use these two Placid really but at this point I'm about to ditch them...
Also the noise is reduce if I touch with a DVM test lead the Buffalo Current Output pin. Very strange.

All my supplies ground are star connected at just one point.

Any help appreciated.
Thanks
SB

Also look at the Front panel. I put your logo and Cie name ;)

My best guess is the I2C lines from the Vol. to the dac.

Try physical separating this line from anything else.

(here illustrated with both red and yellow :-)

You should be able to test this as well by simply de-powering the Volumite. You will have full-volume output though.

By the way, when there is no noise on the defective channel, I measure 0.2mV ac of noise on the output (16mv of noise when the problem is there). Also using a Test CD with 1Khz, 0dB FS signal, With the Volumite at full volume, I measure THD = 0.07%, including at the output of the headphone amplifier.

Very good! I can't wait to fix this defective Counterpoint.

SB

I found this post of 5 years ago, the Counterpoint (CP) is not the latest thing I'm afraid: http://www.twistedpearau...RG1-RG2-to-GND-pad.aspx,
an other user had exactly the same problem as I do. It was great because Russ White designer of the CP worked with him to find his problem. In his case changing CC4-CC5 from 10pF to 1nF solved the problem. Not for me. Then Russ mentioned to make sure to install the 4.7nF caps at the output, directly at the connector.
On the schematic, and on the PCB silkscreen these caps are there but in the middle of the PCB. This where I installed mine. I installed new 4.7nF caps on the output. BINGO no more noise at all :)

There is no manual for the CP and with only the schematic, it was not clear that CF1-CF2 had to be mounted directly on the output connector, not on the PCB marked location!

Now my Buffalo is playing wonderful music, without any noise, even with the I2S flat ribbon and the MUX connection with wires.

Russ also explained where to connect the RG resistors, again it was not clear on the schematic. I join the image showing these two final touch.

If anyone had noise problem with the CP, that is the solution ;)

I made a quick Counterpoint User manual that includes all I learn about the Counterpoint., It may be usefull to others, see: http://www.twistedpearau...---SB-version.aspx#21626