Should I build a ProtoDAC?

[MJR42]

I just discovered the ProtoDAC, and since I want to create another budget moOode box I’m wondering whether to build a ProtoDAC or buy a cheaper DAC like the Raspberry Pi DAC Pro. Building a ProtoDAC isn’t a problem for me, but it is a more expensive option.

My main system right now uses a HifiBerry DAC Pro. I’m not an audio expert, but I do have higher standards for sound quality than the others in my house. If the ProtoDAC is worthwhile, I’d build one for the main system and demote the HifiBerry to the secondary system. How noticeable would the difference be?

I’d welcome general thoughts and recommendations, but what I’m trying to get at is, how would folks rank the sound quality from each of these (scale of 1 to 10, or relative to each other)?

- Raspberry Pi DAC Pro (or IQaudio DAC Pro) (CDN$35)
- HifiBerry DAC Pro+ (now DAC2 Pro) (CDN$60)
- ProtoDAC (CDN$135 est. with shipping etc.)

[hifinet]

I just discovered the ProtoDAC, and since I want to create another budget moOode box I’m wondering whether to build a ProtoDAC or buy a cheaper DAC like the Raspberry Pi DAC Pro. Building a ProtoDAC isn’t a problem for me, but it is a more expensive option.

My main system right now uses a HifiBerry DAC Pro. I’m not an audio expert, but I do have higher standards for sound quality than the others in my house. If the ProtoDAC is worthwhile, I’d build one for the main system and demote the HifiBerry to the secondary system. How noticeable would the difference be?

I’d welcome general thoughts and recommendations, but what I’m trying to get at is, how would folks rank the sound quality from each of these (scale of 1 to 10, or relative to each other)?

- Raspberry Pi DAC Pro (or IQaudio DAC Pro) (CDN$35)
- HifiBerry DAC Pro+ (now DAC2 Pro) (CDN$60)
- ProtoDAC (CDN$135 est. with shipping etc.)

You can build a ProtoDAC for under $25 USD if you use metal film resistors, instead of the expensive metal foil TX2575 resistors supplied with the kit. Gerber files for the PCBs are provided. The modules are available here . I provide the kit, primarily because the TX2575 are somewhat difficult to source. Parts Connexion in CA sells TX2575. Metal foil resistors do improve sound quality significantly compared to metal film. The other two DACs use modern OS DAC chips (oversampling), like almost every other DAC these days. ProtoDAC uses NOS (nonoversampling) multibit DAC chips from the 1990s. It is PCM 16 bit 384kHz capable.

[MJR42]

Thanks @hifinet, I’m going to price out my options. The US/CAN$ exchange rate is what’s killing me, so I’ll see what AliExpress can do for me.

Just to be sure, when you list a resistor as “420R” does that mean 420 ohms?

I’m finding foil resistors at https://www.mouser.ca/c/passive-componen...ough-hole/ (in Canadian $$) - these are what you’re recommending for high performance, right? I’m assuming you didn’t find a better option at AliExpress or eBay, is that correct?

How would a site like this identify “audio quality” capacitors? Should I just go by the brand/part names you listed in the original post?

Your help is appreciated. I have a basic experience with electronic circuits, but not with audio electronics.

[hifinet]

ProtoDAC is a pretty low entry price for an NOS DAC.

420R means 420 ohms. The value should be less than 430 ohms. Some modules may clip with 430R at 5V supply at 0dB.

I don't think you can get the metal foil at Digikey or Mouser without a special order.

If you go with the 390R resistors at Parts Connexion (since they are out of 430R), you will need to increase the value of the decoupling electrolytic capacitors (C3/C4). Estimate they need to increase to 2200-2800 (total of C3 + C4) for 390R I/V resistor. If the value is too low, dynamics are weak. Too high and soundstage depth narrows.

Parts Connexion has Nichicon KA . I picked the Panasonic EEU-FR1A102L, because they seem to me to add the least color. Elna Silmic II really bloat the bass. The Audio Note Seiryu were OK, but expensive. The Kaisei (I have no experience) have been reported to sound very good in the ProtoDAC thread, but even more expensive.

Output coupling cap recommendations https://www.humblehomemadehifi.com/Cap.html

Supplied with the kit are Audiophiler MKP 6.8uF 250V from Ali. These are getting better since I first supplied them. The manufacturing quality and consistency have improved. Prices of coupling caps can get crazy. These are very good, but will double the cost. Fairly large in size also.

[hifinet]

If you are a casual listener, I would just go with the Raspberry Pi DAC Pro. I have never listened to one.

Looking at the PCB, it appears to be a slave DAC (I don't see any onboard clock oscillators). The PCM5242 datasheet says "the integrated PLL on the device removes the requirement for a system clock (commonly known as master clock), allowing a 3-wire I2S connection and reducing system EMI."

The HiFiBerry DAC2 Pro does have "integrated dual-domain low-jitter clocks".

Why NOS?

More of an analog sound character.  I realized that my original Allo Boss sounded best with SoX upsampling to 32/384, which turns off internal chip oversampling. All of the OS DACs I tried seemed to have annoying digital artifacts. "Digital horns", for example. An NOS DAC was the answer for me, which all seem to have a more analog sound character.

[hifinet]

Usually I don't find YT sound comparisons helpful. In this case, I think the difference is pretty obvious. The OS DAC has the typical OS sound character that just grates on me. The saxophone sounds edgy. The digital horn effect. A live saxophone sounds smooth. The poster prefers the OS DAC, and he is actually sitting in front of the speakers. Is the OS nastiness "detail"?

The holiday season is a great time to hear live acoustic music. OS clearly ruins the sound of brass instruments, which sound very smooth live.

[Guido57]

I bought the ProtoDAC as a kit. For the roughly $55 USD kit price it is a good DAC but not as good as my Schitt Modius, all things being stock. The Modius is of course four times as expensive. How it compares to the other DACs you mentioned I have no idea.
The overwhelmingly great review of the ProtoCAC on utube featured a bunch of upgrades from stock, including a reclocker and power filter. One could build a ProtoDAC and upgrade the power and clock at a later date. Currently I'm building a regulated 5V linear supply as my next step, my cost being mitigated by using an old Radio Shack 12V supply for the transformer and case. See how that works out.
I've got to wonder if it would be possible to make a reclocker that gives better results than using the Pi's clock without resorting to the the high end clocks found on the few reclockers available. Maybe if someone is going to spend money on a reclocker the savings wouldn't be significant to enough people.

[hifinet]

The Innomaker HiFi DAC HAT for Raspberry Pi has "dual low jitter oscillators(45.158M and 49.152M)" , extension GPIO, and is a master DAC that will reclock the I2S. It is inexpensive as a reclocker. Better than the RPi's clock. You also get a PCM5122 OS DAC with TPA6130A2 headphone amp. The oscillators are made by Shenzhen SCTF Electronics.

[Guido57]

FWIW I completed my regulated linear power supply project to power my Pi/ProtoDAC combination. Subjectively, with this PS the ProtoDAC is in the same league as the Modius. I would be surprised if this wouldn't help other I2S DACs on the Pi. Cost for PS board was about $20, add five more for cables and jacks.

[hifinet]

FWIW I completed my regulated linear power supply project to power my Pi/ProtoDAC combination.  Subjectively, with this PS the ProtoDAC is in the same league as the Modius.  I would be surprised if this wouldn't help other I2S DACs on the Pi.  Cost for PS board was about $20, add five more for cables and jacks.

That's good to hear. Which PS board are you using, if you don't mind me asking?