This build is looking awesome. I am interested in the PCB and details as well. Please let me know in PM when it is available
Finally; The first sound was heard from V2.0. More detailed and more silent. Awsome!..
I will continue with the tests tomorrow...
I will continue with the tests tomorrow...
An externally hosted image should be here but it was not working when we last tested it.
Today we tested it on another friend's system.
(Diy Troels gravesen design speakers, Gamut power amplifier, Diy valve preamp.)
We listened to PCM1704 and ESS9018. PCM1704 is more musical, more detailed and more natural
There is a small demo here;
https://youtu.be/khO4s12TPOg
(Diy Troels gravesen design speakers, Gamut power amplifier, Diy valve preamp.)
We listened to PCM1704 and ESS9018. PCM1704 is more musical, more detailed and more natural
There is a small demo here;
https://youtu.be/khO4s12TPOg
Even on my crap computer speakers that sounds like it's got the goods.
Got some questions if that's alright.
I take it that was with discrete I/V as the opamp sockets are empty?
What is the input impedance of the I/V stage that the output of the PCM1704 sees?
What is the output buffer?
Have you got >2v at 0dbf on the output?
What kHz is the -3db point HF filter at?
And where is this filtering done?
Cheers George
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From farnell. But now, out of stock. There are some sellers on ebay. But not sure that chips are original.
Goes to show, new tech no matter how good the specs
maybe does not mean great sound. Think the old boys
have yet to reach its limits of discovery.
maybe does not mean great sound. Think the old boys
have yet to reach its limits of discovery.
These will be original, good solid company, didn't check to see if they actually in stock.
Audio DACs - for online sales of Data Converters| RS Components
Cheers George
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I have a pair of PCM1704 and looking for a board for it. Will you sell these boards? If so I'd buy one.Thanks.
hi georgehifi,
Yes; opamp socket empty because use discrete I/V
I don't measurement. IV resistor is 2.7 k %0.1 tolerance
Tube buffer. We tested 6n3p-dr and jan5670. jan5670 much better than 6n39-dr
PCM1704 have 1.2 ma current output max @ 0dB. So, 1.2 ma x 2700 ohm (output resistor) x 0.707 (root of 2) =~ 2.3 v rms
have no any digital and active analog filter.
Except for the 330 pf output capacitor.
Yes; opamp socket empty because use discrete I/V
I don't measurement. IV resistor is 2.7 k %0.1 tolerance
Tube buffer. We tested 6n3p-dr and jan5670. jan5670 much better than 6n39-dr
PCM1704 have 1.2 ma current output max @ 0dB. So, 1.2 ma x 2700 ohm (output resistor) x 0.707 (root of 2) =~ 2.3 v rms
have no any digital and active analog filter.
Except for the 330 pf output capacitor.
All tests are ok. I started to set the chassis.
I plan the box layout as follows; Pcm1704 board, raspberry pi 3, usb to i2s board, coax/opt spdif to i2s board, tube buffer, digital volume kontrol, lcd and mcu board with remote control and shunt reg. boards vs.
Digital volume control pcb
I plan the box layout as follows; Pcm1704 board, raspberry pi 3, usb to i2s board, coax/opt spdif to i2s board, tube buffer, digital volume kontrol, lcd and mcu board with remote control and shunt reg. boards vs.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Digital volume control pcb
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
So the current output pin 14 (soic) of the PCM1704 is seeing 2.7Kohm, is it not much better sounding for it to see around 15-30ohms??
Which then will drop the 1.2mA output, and you won't have 2.3v output.
Cheers George
I am using discrete IV and Tube Buffer stage after pcm1704. not use only one resistor passive IV after pcm1704. Tube buffer stage output 100-150 ohm.
This is TI pcm1704 evm board
When I asked what is the loading the 1704 sees you replied
"IV resistor is 2.7 k %0.1 tolerance"
So you don't know what loading the 1704 sees, as to still get the data sheet 1.2mA output it must be very high, which is not ideal from what I've been led to believe, it should be around 15ohms, for it's best performance.
Cheers George
Hi George;
We use Pedja Rogic's Discrete Diamond Non-Feedback I/V Stage.
I think this is the answer to your questions
why we use 2.7 k on I/V ? Because some friends in our group no use preamplification stage on their systems. They need more gain.
The value of the capacitors and resistors used can be optimized with the ear and the system used.
🙂
We use Pedja Rogic's Discrete Diamond Non-Feedback I/V Stage.
I think this is the answer to your questions
why we use 2.7 k on I/V ? Because some friends in our group no use preamplification stage on their systems. They need more gain.
The value of the capacitors and resistors used can be optimized with the ear and the system used.
🙂
Wouldn't it be better to give that gain needed by the buffer instead, and keep the I/V resistance as seen by the 1704 low.
As I also use no active preamp with no gain and my output buffer after the I/V stage has the gain needed to give the >2v at the output.
Cheers George
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Very little work left. After, I plan to add digital volume control and mcu/lcd card
An externally hosted image should be here but it was not working when we last tested it.
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