Hi guys.
Just finished mine today!! I have had great time working on it! Spent about 6 hours taking PLENTY of time soldering it all perfectly. It just came to life at once, as usual with all your kits Tom! I may be the first French Puppy breeder as well!! Yeahhh!!
I have to say that this thing sounds outrageously good!! I used to have a GrubDAC customized to my needs (caps and clock), but I wasn't suspecting such a big difference in sound with the Puppy.
The sound is definitely more transparent. I started with an opening track of ambient music, where there is a water noise. I know this track very well having heard this record again and again (flac file with Foobar exclusive output mode). The record is called "Voices from the lake" and is from a collective of minimal DJ from Italy. It is really amazing if you're into ambient and minimal stuff. Anyway, this water sounds on the Pup incredibly real compared to the already excellent rendering of the Grub that I knew so well. I also tried it with Anthony Rother's "The Machine Room" album. Synth modulations are freakingly real you can feel the texture of the sound. Overall, the highs are much more detailed and airy. Really amazing how they detach and take room. The low frequencies go really LOW. They are abyssal!!. On my gear they are lacking a very tiny bit of definition, but this is definitely due to my setup or to the tweaks I conducted (see below). I have a tube headphone preamp (Project Sunrise with Amperex Buggle Boy ECC88 from Holland) and I only tried my headphones so far (Beyer DT990Pro 250 Ohms).
The sound is incredibly spacious and vast. Almost out of this world!! I have difficulties stopping listening to this DAC. I've been stucked to it for the last 12 hours!! I will try it tomorrow on my Adam monitors.
On the list of remarks
-I have implemented the improved 2836 Opamp as suggested, not many hesitations about it. Too bad I can't find a simple way to roll the opamps. I haven't found any SMD to DIP8 adapter. If someone knows where to get this please let me know. Maybe a future version will include this. It would be great, but less useful than let's say on a CD player due to the limited number of possible opamp choices for such a low voltage.
-Silkscreen may have a little numbering issue for R5 on the back of the PCB, it should read R6 (I thought my eyes were dead but no...). Really not much of an issue if you know what you're talking about when handling the iron, but maybe for the beginners it may lead to confusion. Probably already noticed by someone or it really my eyes that are dying...
-For the soldering of the PCM1794 chip, it is quite difficult I have to say as the pins are really close and the chip is high as a cliff. The secret is to have a good flux pen. I accidentally soldered 3 pins well together (Dohh...) with a BIG UGLY drop of solder. I almost thought I had Murphy's law striking... I wicked as much as I could (be careful not to pull the wick on a hard solder or you'll pull the pins out!!), but I couldn't get the bridge to leave because of thick solder texture. Then I grabbed my pen, and Voila!! It just melted the solder perfectly and had it climb up the pins by capillarity just like magic. I touched up all pins afterwards to have a perfect finish. I fluxed every single solder afterwards (Voltage regulator, USB chip even some ceramics). It's just mandatory to have one of these for SMD work. Because after you mess with solder too long it tends to loose it's flux, and behaves like a paste. If you add flux again it goes back to liquid. VERY USEFUL!
-I confirm, the reference I found for the mini-jack connector goes perfectly. I had spent a couple of hours reading data sheets to find this one... I am not completely useless Yeah!!
-I couldn't help but to change the supplied electrolytics by some Oscons (that's the way I do things sorry, don't blame me!!) I just find the oscons to sound unbelievable and I believe I can hear the difference!! Arf...
But Tom, where can I find detailed explanations for the electrolytics choices of values. I would be very interested!!
There are 4 types, One (C22) is the main PSU buffer (upgraded to Rubycon MBZ 1500 uF at 10V), 2 are for output decoupling (C26, C27 upgraded to oscons SEPC 470uF 6.3V), one is not yet understood (C10 upgraded to Nichicon KA 225uf 25V) but seems to have an important role in filtering (I need to read more of the manual and of the blog sorry!), and the last 4 Voltage decoupling for the DAC chip (C2 C9 C16 C19 upgraded to Elna SILMIC II 22uf 25V, but I acknowledge the FM panasonics are really good too).
But Tom, why on Earth did you specify 63V value on these? I mean there must be a reason, but when I look at the diagrams I only see 5V class voltage there. I really scratched my head for good on this... Does 63V value bring something to this decoupling function such as higher ripple tolerance? DAC technical note only states 10uF value there but doesn't recommend higher voltage value so I am puzzled. I am planning to replace these 4 by oscons too by 47uF at 16V or maybe large Tantalums they may be adequate there. Is there a problem going to 16V? I can't see any it works fine at 25V with my ELNAs, but you're the master!
Anyway, the PupDAC is a really wonderful piece of equipment I have to say probably sounding like multi KUSD DAC!! I will keep you updated for more tweaks in the future.
All the Best!!
Close match on all caps
That's a close one, perfect fit with Rubycon MBZ 1500uF 10V
It's ALIVE...