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my DAC design - pup1 DAC - Page 43

post #631 of 674

Just an FYI, but I updated the RMAA testing on the pupDAC website:

http://www.diyforums.org/PupDAC/PupDACrmaa.php

I had never tested a fully cased version with the OPA836.  I sitll have a sh*tty testing environment - I think the pup would easily do 10-15% better on all measurements if done by someone else. redface.gif  However, it's superiority to the grubDAC in a direct comparison is quite apparent.smily_headphones1.gif

post #632 of 674

Another FYI - all PupDAC kits (full and short) will be supplied with the OPA2836 from now on. biggrin.gif

 

With a bandwidth of 205MHz, a slew rate of 560V/us, and current drive of 50ma, it's simply superior in every way.  Even though I have the other opamps already, it seems to me that everyone deserves the best we can do if they order a kit. wink.gif

post #633 of 674

Nice one Tom.

 

Must put my order in soon !!!

post #634 of 674

Another PuP DAC livesbeerchug.gif. I finally got a few hours of free time and a little ambition and assembled the kit I bought several months ago. It went together in a couple hours without a hitch. I only dropped one of the 805 caps on the floor and amazingly enough it was right at my feet with no cussing and searching, That's about my best, minimum-clutz SMD project yet. The PuP passed voltage and offset tests without a problem on the first try and is playing music now.

 

I'm using it with an O2 amp driving HD800's for a "break in". The O2 is my only cap coupled amp and I'll give it few hours before it gets full trust with a DC coupled amp. Early impressions are it's sounding pretty nice with a "detailed and revealing" signature. Definitely has lots of "air" and extension on top. I'll try to post some detailed impressions after I get some hours on it.

 

Thanks to Cobaltmute and Tomb for another fun project.


Edited by bada bing - 4/19/13 at 4:37pm
post #635 of 674
Quote:
Originally Posted by bada bing View Post

Another PuP DAC livesbeerchug.gif. I finally got a few hours of free time and a little ambition and assembled the kit I bought several months ago. It went together in a couple hours without a hitch. I only dropped one of the 805 caps on the floor and amazingly enough it was right at my feet with no cussing and searching, That's about my best, minimum-clutz SMD project yet. The PuP passed voltage and offset tests without a problem on the first try and is playing music now.

 

I'm using it with an O2 amp driving HD800's for a "break in". The O2 is my only cap coupled amp and I'll give it few hours before it gets full trust with a DC coupled amp. Early impressions are it's sounding pretty nice with a "detailed and revealing" signature. Definitely has lots of "air" and extension on top. I'll try to post some detailed impressions after I get some hours on it.

 

Thanks to Cobaltmute and Tomb for another fun project.

Cool!  Glad it turned out well and you're enjoying it.  You should be able to simply measure the offset between the PCB ground pad and one of the output connectors to satisfy your concern with an amp that doesn't have filtering caps.

post #636 of 674

If only it had volume pot. frown.gif

post #637 of 674
Quote:
Originally Posted by akgfan View Post

If only it had volume pot. frown.gif

It's not intended to amplify, where a volume pot would be appropriate.  Just an FYI, but the ODAC has no volume control, the Gamma 1 has no volume control, neither does the Gamma 2.  The AlienDAC, BantamDAC, GrubDAC, SkeletonDAC, EasyDAC, OPUS DAC, Monica DAC ... none have a volume control.  I could go on, but maybe you get the idea. wink.gif

post #638 of 674

So... you're saying that you're gonna add a volume control? :-)

post #639 of 674
Quote:
Originally Posted by Misterrogers View Post

So... you're saying that you're gonna add a volume control? :-)

Ha. tongue.gif

post #640 of 674

Yeah, I know. But that's the problem. I would need usb powered combo DAC/amp with volume pot for using it with notebook. You know how bad the volume control on notebook can be...


Edited by akgfan - 4/26/13 at 12:16pm
post #641 of 674

A nother Pup DAC is alive. 

It took me about 6h to build. Since I had zero experience I was postponing the constuction as far as possible in order to get decent equipment.

It's hard to believe but here in germany it is close to impossible for a starving student like me to buy german made tools for a decent price.

I ended up ebaying used stuff and ordered the most from the US. Even Weller tips and Felder flux I had to get from overseas.

The first batch wasn't supplied with the OPA2836. It was a pain to get a sample from TI.

I'm very glad that my first smd project worked out all fine. 

On the first startup there was a strange popping sound on the left channel and a few scratching noises like a needle on vinyl.

I blame the moist in the opa, I will give it a few days to dry and burn in.

All the measurements where fine exept for the 4.5V which is a stable 4.75V. I hope this wont kill my puppy.

I replaced some caps with FR-type Panasonics with higher capacitance or a lower voltage rating for lower ESR.

I could have gone for a larger Nichicon C22. But I love the Panas, so I stayed with the provided one.

With my Ultimate Ears triple.fi I couldn't test really the SQ properly because my stepped ladder attenuator isn't finished yet.

IEMs are far too sensitve furthermore I don't like software volume control.

From what I could hear the puppy is at least on par with my rockboxed Sandisk clip zip playing FLACs.

Many thanks to cobalmute and tomb for this great kit. I can't attach any pictures atm. Maybe later.

 

Cheers!

post #642 of 674
Quote:
Originally Posted by Blanko View Post

A nother Pup DAC is alive. 

It took me about 6h to build. Since I had zero experience I was postponing the constuction as far as possible in order to get decent equipment.

It's hard to believe but here in germany it is close to impossible for a starving student like me to buy german made tools for a decent price.

I ended up ebaying used stuff and ordered the most from the US. Even Weller tips and Felder flux I had to get from overseas.

The first batch wasn't supplied with the OPA2836. It was a pain to get a sample from TI.

I'm very glad that my first smd project worked out all fine. 

On the first startup there was a strange popping sound on the left channel and a few scratching noises like a needle on vinyl.

I blame the moist in the opa, I will give it a few days to dry and burn in.

All the measurements where fine exept for the 4.5V which is a stable 4.75V. I hope this wont kill my puppy.

I replaced some caps with FR-type Panasonics with higher capacitance or a lower voltage rating for lower ESR.

I could have gone for a larger Nichicon C22. But I love the Panas, so I stayed with the provided one.

With my Ultimate Ears triple.fi I couldn't test really the SQ properly because my stepped ladder attenuator isn't finished yet.

IEMs are far too sensitve furthermore I don't like software volume control.

From what I could hear the puppy is at least on par with my rockboxed Sandisk clip zip playing FLACs.

Many thanks to cobalmute and tomb for this great kit. I can't attach any pictures atm. Maybe later.

 

Cheers!

Sounds great!

 

A few comments:

1.  Yes, the OPA2836 is so superior, there's no question it should be the standard for the pupDAC.  That's why I decided to include it in the kits later than yours - despite all expenses at my cost.  To be honest, I had already invested in the LM6643 at high volume, when we discovered that the OPA2835 was essentially superior.  That's why the first kits inclued the LMH chip for free in addition to the OPA2835. wink.gif  As time went on, I discovered that the OPA2836 was stable in the pupDAC - probably because cobaltmute re-designed the PCB and put the critical resistors on the bottom of the PCB.  Also, I think TI used the OPA2835 as a prototype and when they were satisfied with the design, they went all out with the next chip - the OPA2836.

 

2. There's nothing wrong in experimenting with upgrades of through-hole electrolytic caps.  Just make sure that they are truly superior to the excellent selections that cobaltmute has already provided.  I've built 4 using a Nichicon UHN 1500uf 6.3V cap as C22 and upgrading the C26/C27 caps to Panasonic FM's instead of FC's.  Keep in mind that these changes are really just in the margins, but the results are at least equivalent, if not slightly better.  The kit still offers an almost optimum selection of parts, but the thing to take from this is that the design is flexible and can be upgraded, if desired.

 

3. The 4.75V is what I register on my pupDACs, too.

 

4. If you used the OPA2836, put it out in the hot sun to ensure that any moisture has been cooked out of the chip.wink.gif

post #643 of 674

As promised a picture. To be honest I'm quite proud of my first smd hand soldering job.

 

http://imageshack.us/photo/my-images/560/p1000190jx.jpg/

post #644 of 674
Quote:
Originally Posted by Blanko View Post

As promised a picture. To be honest I'm quite proud of my first smd hand soldering job.

 

http://imageshack.us/photo/my-images/560/p1000190jx.jpg/

If that's your first, you should be very proud!  It looks like excellent work!

post #645 of 674

Thanks for the compliment tomb. I use a Weller WTCPS with a 60° 3mm wide bevel tip. I solder at 310° C.

The flux I used in large amounts is a FSW-32 "solderoil" from Felder. Solder wire is a 0.5 mm Sn60Pb38Cu2.

I really took all the time I needed for construction. In my oppinion preparation is the most important thing.

I read a lot about soldering techniques. watched videos and talked with professionals. I guess I learned quite a lot from the mistakes others made.

Luckily they shared their issues on the forums so their strugle wasn't in vain, because others can avoid those mistakes.

 

The PCB and chips are clean and dry now. I had them in the oven for one hour at 50° C.

When no music is playing the pup is dead silent. 

Since I have a real crappy DMM I couldn't measure the output DC offset. But everything is working superb so I dont have concerns about this.

 

The sound the pup delivers is stunning with my AKG K420. I don't own better head phones. The only comparison I have are my UE triple.fi 10 for portable use.

Ofcourse the K420 are no match for them but I have never heared them perform better. 

 

Later the pup's purpose is to feed a battery powered TA2021b amp hooked up to a raspberry Pi running xbmc in order to play some FLAC files from the network. 

Still need to build some high efficiency fullrange speakers. Everything is meant to be a very low power consumption system, which is small and portable. 

 

Cheers!


Edited by Blanko - 5/12/13 at 11:10am
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