ProtoDAC TDA1387 X8 project

[michaelagiles]

Another question for those who might know this. 
I am considering buying an canada FifoPiMa rocker.
The manual states that it requires "a standard Linux driver to function" 
"A generic I2S , HiFiberry DAC driver " will not work.
Though HiFiberry DAC+Pro will workZ!
Does the ProtoDAC driver in moode contain this Linux driver or should I consider the more expensive FifoPi Q7?
Thanks for your help with this!
MG

[Tim Curtis]

Iancanada reclocker options are kind of confusing but here is a link to the PDF containing application notes and a cross reference table. https://github.com/iancanada/DocumentDow...alV1.5.pdf

The ProtoDAC operates in I2S slave mode (I think Iancanada calls this SYNC mode), and uses the driver overlay named "i2s-dac" which is the "rpi-dac" overlay renamed.

Code:

Name:   i2s-dac
Info:   Configures any passive I2S DAC soundcard.
Load:   dtoverlay=i2s-dac
Params: <None>

Name:   rpi-dac
Info:   This overlay has been renamed to i2s-dac.
Load:   <Deprecated>

I use an Allo Kali reclocker with my ProtoDAC because I happened to have some Kali's from years past but if I were to explore an Iancanada solution I'd prolly go for a PurePi + Q7 reclocker and for some bling the monitor Pi OLED :-)

[hifinet]

It seems that the Q7 requires a 3.3V supply (from PurePi), whereas the Ma can share the RPi power supply. Ma does not have an isolator like the Q7.

[michaelagiles]

It seems that the Q7 requires a 3.3V supply (from PurePi), whereas the Ma can share the RPi power supply. Ma does not have an isolator like the Q7.

Yes this pwr sup capability is 1 of the attractions - as well as the price.
It sounds from Tim's response that the ProtoDac driver does NOT include a linux driver. But I am still not sure.
Yes I would also go for the FifoPiQ7 but it is 2 X the price!
Thanks!
MG

[Tim Curtis]

It seems that the Q7 requires a 3.3V supply (from PurePi), whereas the Ma can share the RPi power supply. Ma does not have an isolator like the Q7.

Yes this pwr sup capability is 1 of the attractions - as well as the price.
It sounds from Tim's response that the ProtoDac driver does NOT include a linux driver. But I am still not sure.
Yes I would also go for the FifoPiQ7 but it is 2 X the price!
Thanks!
MG

The i2s-dac driver overlay used for the PtotoDAC that I mentioned earlier is a driver included with Linux along with all the other I2S DAC drivers.

Note the ProtoDAC like other slave mode DAC's for example Mamboberry LS, HifiBerry DAC etc won't work with master mode drivers that are required for master mode DAC's like Allo Boss and HifiBerry DAC+Pro.

Another advantage of the Q7 is that it's popular with other DIY audio enthusiasts who can provide help if for example you want to experiment with swapping the clocks.

My advice is to splurge a little and you will end up with an audio device that for a few hundred dollars will prolly best most OEM devices costing thousands plus you can modify and experiment with your device unlike OEM devices where you are effectively stuck with the hardware and software inside the sealed box whether you like it or not.

[michaelagiles]

Thanks for the clarification Tim!
I have gone to the source and asked Ian. We will see what he says.
Thanks again!
MG

[michaelagiles]

Thanks for the clarification Tim!
I have gone to the source and asked Ian. We will see what he says.
Thanks again!
MG

BTW - I installed new 50k alps blue pots yesterday replacing 25k generic
Whether it was the impedance increase and change in loading on the DAC or just the quality upgrade I don't know but it produced a startling increase in clarity! 
Might be worth some investigation. 
MG

[hifinet]

Thanks for the clarification Tim!
I have gone to the source and asked Ian. We will see what he says.
Thanks again!
MG

BTW - I installed new 50k alps blue pots yesterday replacing 25k generic
Whether it was the impedance increase and change in loading on the DAC or just the quality upgrade I don't know but it produced a startling increase in clarity! 
Might be worth some investigation. 
MG

The Alps are very good pots, and clearly better than generic.

[hifinet]

Capacitor trials continue. 

Got a good listen to the Panasonic FR-A EEU-FR0J102 6.3V 56mOhms ESR. Smooth but closed-in sounding with smaller soundstage compared to the EEU-FR1A102L (EEU-FR1A102LB is the same cap, just with bent leads on paper tape. odd that EEU-FR1A102 is a different cap, 28mOhms ESR, too low), which is still my favorite. That's all of the Panasonic FR-A to try.

My PCB is in pretty bad shape from desoldering. One of the 5V traces pulled up, and I really need to baby it from here on. In the future, I will just cut the leads from the cap to be removed. Less heat involved with desoldering bare wire. Abandoning this PCB and using a new one means leaving the RCA jacks, which are very hard to remove in decent shape.

Now back to EEU-FR1A102L. Ah, much better. 

By the way, I tried the PP 0.01uF bypass cap on the electrolytic and could not hear a difference. Listened to it for a week and removed it. Don't miss it. Maybe it's because I am using SMPS.

[hifinet]

More thoughts on the Alps pot.

All resistors in the signal path make a significant impact on sound quality. Not only the series resistor in the voltage divider, but also the resistor to ground. There is signal going through the ground resistor, and what doesn't is your signal.

And yes, Z-foil stepped attenuators are supposed to be excellent, if you could afford it. Even a Z-foil signal load resistor would make a big difference.

Better idea? Limit resistors in the signal path and adjust volume digitally using Camilla VC with dithering.