[Gotez]

I’ve listened to this dac for a couple of days now and it is time to share my thoughts on the performance.
 
First of all I would like to thank Cobaltmute for the boards and Tomb for the dac chips. This made it all a lot easier.
 
I’ve never written anything like this before, so please forgive my complete lack of audiophile terminology.
 
The build
 
Sourcing all products was easy. The bom provided is clear and all items are for sale at digikey. The only bad this was that the shipping price to the Netherlands was just as expensive as the items themselves. I was able to buy all items in the Netherlands but this would not have been cheaper. The build is straight forward and simple enough. I did encounter some hiccups (as seen earlier in this thread) but I was able to troubleshoot these and get the dac to work. The tiny parts were posed a greater challenge than my earlier builds, but it was fun to do, and a learned a great deal. My hiccups were all due to me not soldering well enough and this cannot be blamed on the dac or board. Luckily the board provides enough measuring point and this helped me greatly in finding my errors and fixing them.
As to the layout of the board: U4 could use a little more room. This would improve the ability to fix any problems one might encounted after soldering this chip. I would also like to add that RCA connectors would be better. And perhaps a possibility to add a USB-b connection or a standard USB connection.
 
The sound
 
I used my MS1 as headphone for listening. At first I connected it straight to the dac output. It is more than capable of driving 32 ohm headphones and there is little to no hiss.
 
To keep it short: the dac sounds fine. It has a bright and clean sound. It’s strengths are its clarity and its powerful performance. Overall it is a very capable dac and it delivers lots of bang for buck. It does tend to sound a bit ‘sharp’ in the high end and can be fatiguing when listening to longer periods. Also the bass does lack a bit of slam and compared to more ‘sophisticated’ dacs it does miss a certain refinement. This is not meant as a negative, it is just my personal taste in sound.
 
The dac really comes to life when fed to my millitt minimax headphoneamp. The tubes give a bit of warmth to the sound that make it a lot more enjoyable. I really enjoy listening to this combo. I believe that this combination is where the dac can really shine. The clarity of the dac and the sound signature of the hybrid amp make it a very pleasing and enjoyable setup, one that I will listen to for many more albums to come.
 
Summary
 
It is a very good build. The sound is very good, and considering the price probably unbeatable. Especially if paired with a hybrid or tube amp.

 

[c12mech]

I have not finished mine yet, waiting for a few parts, but I have a question.  Would it be possible to by pass the amp section and just run rca's out by wiring directly to C24 and C26?  Just a thought.
 
I would like the option to go with headphone out or rca depending on the situation.  If it is possible is it something that could be added to the production board, there seems to be enough space.

 

[cobaltmute]

Quote:

The sound  
I used my MS1 as headphone for listening. At first I connected it straight to the dac output. It is more than capable of driving 32 ohm headphones and there is little to no hiss.
 
To keep it short: the dac sounds fine. It has a bright and clean sound. It’s strengths are its clarity and its powerful performance. Overall it is a very capable dac and it delivers lots of bang for buck. It does tend to sound a bit ‘sharp’ in the high end and can be fatiguing when listening to longer periods. Also the bass does lack a bit of slam and compared to more ‘sophisticated’ dacs it does miss a certain refinement. This is not meant as a negative, it is just my personal taste in sound.
 
The dac really comes to life when fed to my millitt minimax headphoneamp. The tubes give a bit of warmth to the sound that make it a lot more enjoyable. I really enjoy listening to this combo. I believe that this combination is where the dac can really shine. The clarity of the dac and the sound signature of the hybrid amp make it a very pleasing and enjoyable setup, one that I will listen to for many more albums to come.
 

 
I'm going to sound like a broken record, but while the pupDAC *can* drive headphone, I don't think it *should* drive headphones.  The charge pump puts out 60ma max.  That current has to be split between the two channels for 30ma per channel not providing a great amount of current, especially into low-impedence phones.
 
The sound that Gotez has described driving headphones direct is what I have also heard with the grubDAC direct.  Load the output too heavy for the design and something starts to give.  This is why we build headphone amps and the pupDAC was designed to be a DAC not a headphone amp.
 
Quote:

I have not finished mine yet, waiting for a few parts, but I have a question.  Would it be possible to by pass the amp section and just run rca's out by wiring directly to C24 and C26?  Just a thought.
 
I would like the option to go with headphone out or rca depending on the situation.  If it is possible is it something that could be added to the production board, there seems to be enough space.

Remember that the PCM1794A is a differential DAC.  You could try to run off C24/26 if you were going to drive something balanced off each end. *DO NOT* try to go single-ended off these points - you will find offset at the output.  The amp stage converts the output to single-ended and deals with the offset.
 
Run your RCAs from the headphone out positions.  On the next revision board I'm working on, I am placing positions for RCA and 3.5mm outputs.
 

 

[forsakenrider]

I think you should do away with the 3.5mm jack completely. As I do agree the bom spec part is very robust, it seems to be deceiving people into thinking this is a headamp/dac combo. I cant agree with Gotez's comments at all, but thats probably because I havn't run headphones with it. My pup1 goes into a pre amp/selector which has a unity gain jisbos buffer in it, and then out to a head amp or my gainclone driving full range, open baffle speakers. For me as I have said before this thing has WONDERFUL detail for such a small package.
 
This weekend I will case it and the skeleton dac up, and do some listening. But so far I love it! its really that extra boost over the alien dac I was looking for with out investing crazy amounts of time/effort/and $.

 

[Gotez]

My comments were not meant as a negative, and I think Cobaltmute has a  good point in stating that it is a Dac, not an amp. I will continue using it for my Millitt Minimax amp and enjoying it.I would love to build any new projects your working on Cobaltmute, keep us posted!

 
 
 

 

[tomb]

Quote:

My comments were not meant as a negative, and I think Cobaltmute has a  good point in stating that it is a Dac, not an amp. I will continue using it for my Millitt Minimax amp and enjoying it.I would love to build any new projects your working on Cobaltmute, keep us posted!

 
 
 

Don't sweat it.

  Just remember that offering reviews always opens you up to criticism.

  Please keep doing them, though.  People appreciate one's thoughts - as long as you don't make direct comparisons with competing products, IMHO.
 
At the risk of piling on - but this may be a good remedial for others - remember that outside of cobaltmute's recommendations, low impedance phones like Grado's are very tough to drive correctly with many smaller amps.  Back in the day, user Apheared was compelled to create the first buffered CMoy (A47) because of the original CMoy's limitations with supplying sufficient current to Grado's.  So, if a battery-powered CMoy has an issue with Grado's, a USB-powered DAC is going to have even more.
 
As for the 3.5mm connection, I'm not sure that I agree it's misleading.  The PupDAC as currently configured is a very convenient size to mate up with smaller amps such as the Mini3 (or CMoys, etc.) and the ability to have a very short, 3.5mm patch cord connecting the entire arrangement is a good thing to have.  As for RCA's, I'd like to have them, too (and would use them primarily), but would vote to keep the package refinement the same - as in, no requirement for wiring.

  So, if cobaltmute adds pads for RCA jacks, my preference would be to use PCB-type.  Who knows, we might even come up with a custom case for it - or at least the endplates.

 
 

 

[Beftus]

Who knows, we might even come up with a custom case for it - or at least the endplates.

That would be really good news for people not adept at doing case work. I like the 1455C801 formfactor for this DAC, as it would match the Mini³ perfectly. This DAC is becoming more interesting with every posting! Can hardly wait for kits showing up on Beezar...

 

[c12mech]

Thanks for clearing that up for me.  I figured that there was a reason that it was done that way.  I will use it with the 3.5mm jack out as it is easier and I already have 3.5 to rca cables made up.

 

[forsakenrider]

So im ready to case up my Pup1 and I've got the longer version of the hammond case because I wanted ample room for RCA's. So I'm wondering is theres and improvements I can make and use up some extra space. I know its not "needed", as this DAC already sounds amazing, but maybe larger capacitors somewhere for filtering? or is nothing really worth it here unless changing to external power?

 

[tcpoint]

I put it all together and found a short on U7 (the 2.5 V voltage regulator).  While trying to fix it, I wrecked the chip (Grrrr...).  I am placing an order for it tomorrow.  My Ubuntu box recognizes it just fine.  I'll give you my impressions of the sound, later in the week.

 

[cobaltmute]

Quote:

So im ready to case up my Pup1 and I've got the longer version of the hammond case because I wanted ample room for RCA's. So I'm wondering is theres and improvements I can make and use up some extra space. I know its not "needed", as this DAC already sounds amazing, but maybe larger capacitors somewhere for filtering? or is nothing really worth it here unless changing to external power?

Not a lot I would change.  I'd already done the majority of them on the BOM that you built from.
 

 

[forsakenrider]

Thats what I thought. Would more capacitance help on the 3.3, 4.7, 2.5 or -2.5 rails? the 2.5 and -2.5 are what you changed from your original, correct? I have some Oscon 1000uf that I could put on the +/- 2.5. would there be any ill effect to adding capacitance to any of the rails after or before the regulators?
 
Heres how it is now!

 

[Beftus]

Cool idea for the power LED! Is the plexiglass clear or is it colored red of its own?

 

[forsakenrider]

Thanks! It's clear acrylic, the led is embedded in the center.

 

[cobaltmute]

very nice build forsakenrider.
 
Hammond actually has blue and red end panels for the 1455C801, but to try to get them in small qty is a problem.
 
As for the caps, you could up the ones after the +-2.5V regs.  They are the ones I upped compared to my original BOM and they seemed to help with the bass.