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AK4490 USB Dac with dsd support.

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sonnya

sonnya

Member
Joined 2001
mirand-audio.dk/?post_type=product
Just a short update.

Turned out that some of the relays that i use from Fujitsu is not in stock. So instead of have some boards populated with fujitsu and some with omron. We ordered Omron friday for them all. The arrive tomorrow.
Model number : G6K-2FY 5DC
They are SMT. So we want to populate them in 1 run.

The Preamp uses the exact same firmware as previous board. So no need of work here.

- Sonny
 
sonnya

sonnya

Member
Joined 2001
mirand-audio.dk/?post_type=product
Just assembled one preamp board for check before assembling the rest.

And the same goes for the frontpanel... IMG_20190506_195113.jpg IMG_20190506_195238.jpg
 
sonnya

sonnya

Member
Joined 2001
mirand-audio.dk/?post_type=product
Distortion and cross talk is good...

I would recommend a wall between psu and preamp board... To get maximum out of the noise floor.

Dropbox link instead with high resolution images

Dropbox - preamp v1.1 6V 1k gain -7dB.bmp - Simplify your life

Dropbox - preamp v1.1 6V 5k gain -7dB.bmp - Simplify your life

Dropbox - preamp v1.1 6V 10k gain -7dB.bmp - Simplify your life

Dropbox - preamp v1.1 6V 1k gain -7dB cross talk.bmp - Simplify your life

Dropbox - preamp v1.1 6V 10k gain -7dB cross talk.bmp - Simplify your life

Crosstalk is -109dB at 1KHz.
 

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  • preamp v1.1 6V 1k gain -7dB cross talk.jpg
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Last edited:
sonnya

sonnya

Member
Joined 2001
mirand-audio.dk/?post_type=product
smg43 said:
@sonnya accepting any more orders for the pre-amp at this stage?
Click to expand...

Yes we do.

The motherboard could also be ordered without modules. And people can insert modules like Sparkolabs SS2590... Only limit is size... No more than 28mm width.

Only thing i do not know how other modules perform. But i would choose something with JFET or Mosfet input.... Speaking mosfet.... More to come if the behave like i want them to.

- Sonny
 
S

smg43

Member
Joined 2010
sonnya said:
Yes we do.

The motherboard could also be ordered without modules. And people can insert modules like Sparkolabs SS2590... Only limit is size... No more than 28mm width.

Only thing i do not know how other modules perform. But i would choose something with JFET or Mosfet input.... Speaking mosfet.... More to come if the behave like i want them to.

- Sonny
Click to expand...

You should have an email asking for price of preamp board, gain modules and a chassis if you have one spare. Will be using SilentSwitcher with this.
 
sonnya

sonnya

Member
Joined 2001
mirand-audio.dk/?post_type=product
I got a few emails
..

I am on my way to munich. I will find time answer them tomorrow....

In the mean time, dac and preamp is connected together using oled display.

There is two firmware package for the DAC. Which both runs.

1) simple 7 segment
2) oled display connected to the DAC using 10 way ribbon cable and i2c bus as interface. It is a polling function where the oled display updates 4 times per second.
We will do a third version which is a variant of the simple display. With a few led and a couple of button. Just to keep it simple...
 
L

lateboomer

Member
Joined 2013
sonnya said:
The interfaces present for audio sources is:

SPDIF – RCA (up to 192KHz/24Bit)
SPDIF – Optical (Up to 96KHz/24Bit)
I2S – 3.3V CMOS level (Up to 192KHZ/24Bit)

SPDIF and I2S runs through an SRC4392 sample rate converter where the signal is converted to 192KHz/24Bit. It is to lower Jitter and at the same time the combination of good SPDIF receivers and a good Samplerate converter is difficult to get at a better value and space.

Oscillators:

The oscillators used can be low cost FOX as is in the V1.0 DAC or it can be the expensive and very low phase noise Crystek CCHD-957 oscillators. (There is one crystal oscillator that is not possible to change but it is used as a reference for the SPDIF input to detect the sample frequency)

USB:

USB is galvanic isolated now. We use a DC/DC converter from Murata, but it can be feed with an external +5V source that is isolated. J11 is the input for that voltage. J13 is a control signal for an external source if you want’s to turn it off. Data rates is still the same as for the version 1.0 -> 384KHz/32Bit and DoP 128/DSD 256.
Click to expand...

If refer to above, is that mean if I got i2s source from a rpi transport + spdif/i2s HAT, the highest freq I can play is 192KHZ/24Bit but not usb rate of 384KHz/32Bit and DoP 128/DSD 256?
 
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