PCM1704 DAC with ECC88 output

[sandy]

Hi,

I'm using a PCM1704 DAC with 8414 received. I have connected the PIN 14 of the PCM1704 directly to the ECC88 buffer stage...which is from AudioNote. I have attached the schema.

When i turn on the digital signal to the DAC, i get a big "hiss" sound...with the actual music slightly in the back. When there is not digital signal coming in from the transport....the hiss sound disappears.

Could this is a problem due to impedance. Can someone help me integrate the DAC and the tube buffer....any help would be great.

Regards
Sandy

[rfbrw]

Perhaps at 220K the i/v resistor is a little on the large side.

[mgm31]

See datasheet : http://www.datasheetcatalog.com/data.../PCM1704.shtml

This is a Iout DAC -> needs an I/V converter. The 220k resistor can't be an I/V converter, something is missing

[spencer]

Change the 220k to 50 to 100 ohm - IV resistor.

[rfbrw]

Originally posted by mgm31


This is a Iout DAC -> needs an I/V converter. The 220k resistor can't be an I/V converter, something is missing

I happen to own the dac associated with the shown schematic. The SRPP stage is preceded by a transformer based i/v stage. By connecting directly to the grid of the SRPP stage, the 220k resistor becomes the de facto i/v converter, like it or not, and it is way too big.