They are all in parallel. The idea is, that you can daisy chain (link) a second board to the first board for double mono use (one board for R and one for L) the I2S signal is forwarded by the second set of UFL or the second pin connector. So yes, only one input at a time, it is not multiple I2S inputs
I have to ask. Where are the SMD components here? All capacitors could be made in SMD and certainly behave better at HF than TH components.
fair question, well, all ICs, discrete, some decoupling and resistors are smd…. I kept the capacitors deliberately TH, as this is project for DIY and encourages experimenting and tweaking, hence I kept the most sound determinant parts TH. Also the ones I liked are not in SMD, but that is coincidence…
@dddac for noob DIYers are these construction manuals still valid for mk3
1. https://www.dddac.com/dddac1794_construction.html
2. http://www.audio-creativeshop.nl/wp-content/uploads/dddac1794_pbt_construction_manual_en_v2.pdf
Or it would be different?
There will be totally different manuals, and they will be downloadable from my blog.dddac.com website, as soon as the introduction story is published, which is expected to be next week. It will be very detailed with a step by step instruction and lots of images.
having said so, the manual from Audio creative, contains very valuable general tips on soldering PCBs… those are of universal value.
having said so, the manual from Audio creative, contains very valuable general tips on soldering PCBs… those are of universal value.
Hello, i upgraded my old DDDAC 1794 with 4 decks of the last version. All was working well.
today i replaced the on/off switch and placed it on the front. Nothing else.
Now i don’t get music out. I use SPDiF. 2 Audio Creative transformers.
Power supply is giving 12 volts. All leds on the boards are on (2x2). All boards are on 0,40 mV and on the top deck both the chips get 8,2 V.
What can it be, what can i check?
today i replaced the on/off switch and placed it on the front. Nothing else.
Now i don’t get music out. I use SPDiF. 2 Audio Creative transformers.
Power supply is giving 12 volts. All leds on the boards are on (2x2). All boards are on 0,40 mV and on the top deck both the chips get 8,2 V.
What can it be, what can i check?
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Bello Bart,
when all voltages measure 100% and there is no music, most of the time, the switch connection is not ok. Just try to short directly at the pins on the Mainboard between GND and spdif. if that does not work, follow the signal… simple scope will do. Start at the input and end at the top<board, does all I2S signal arrive ?
when all voltages measure 100% and there is no music, most of the time, the switch connection is not ok. Just try to short directly at the pins on the Mainboard between GND and spdif. if that does not work, follow the signal… simple scope will do. Start at the input and end at the top<board, does all I2S signal arrive ?
Hi Thommy,
It is described on my website: https://www.dddac.com/dddac1794_design.html
look for this part:
Believe it or not, the Chip worked fine till 10 Volts. It smoked at 11 Volts. I also found out by several test, that there was a kind of maximum, in such way, that there was no improvement in headroom, which was like round 8,5 Volt. Therefore I decided that 8 volt would be a great compromise.
I learned, that the following was the optimal situation
It is described on my website: https://www.dddac.com/dddac1794_design.html
look for this part:
Finding the optimum Bias and Output Voltage
Indeed a very tricky business... I quickly found out, that there is no real correlation between the reference resistor value (at pin 20) and the output current. The output current at zero signal level is of course resulting in the output DC voltage, which again is important for the maximum output signal which should not clip against ground and the positive supply voltage. One thing was clear, the higher the analog supply voltage, the more headroom for the DAC internal current sources. The datasheet tells us, that the maximum Vcc (analog supply) is 6,5 Volt. Oh really? This is just a current source, hard to believe after my experience with the TDA1543, that this is really the maximum. This is the most easy test... Play music, connect the VCC to a LAB power supply and slowly increase the supply voltage. Measure the supply current and wait till it SMOKES Believe it or not, the Chip worked fine till 10 Volts. It smoked at 11 Volts. I also found out by several test, that there was a kind of maximum, in such way, that there was no improvement in headroom, which was like round 8,5 Volt. Therefore I decided that 8 volt would be a great compromise.I learned, that the following was the optimal situation
- Vcc 8 Volt
- R ref 6,1KOhm
- R Load 270 Ohm, resulting in a Bias of 2,72 Volt
- Current Output at zero signal ~ 10mA allowing headroom for full scale current (6,3mA)
- Full scale voltage swings between 1,0V and 4,4V (4,5V is max before clipping)
- Full scale voltage RMS therefore 1,2V RMS
- d2 and d3 below 0,2%, which is very good for passive I/V
Hi Bart,
i would say, next to a digital multimeter, a (simple) scope is mandatory for every DIY ;-) you get simple ones for USB use for the price of a good output capacitor.
but did you already tried the other, less costly (zero) tip?