[autovelocity]

Hello everyone,
 
I just received my "BRAND NEW" Benchmark DAC1 PRE last Friday.
 
My immediate thought about the performance/quality of the built in headphone amp is that it's marginally better than the analog output on the back of my XFI PCIe sound card. (I am using HD-650 headphones). 
 
Next for the disturbing part which I will have a talk with Benchmark on Monday.
 
I opened up the DAC1 PRE to have a peek at its PCB design, and right away I noticed the 2 main power capacitors were bulged.
This indicates possible over voltage/ripple or excessive heat damage (although I couldn't detect excessive heat by using an infrared thermometer), and it's always a sign of poor quality and future reliability problems. (This should have NEVER left the Benchmark Media assembly room)
 
The capacitors they use are Panasonic, and I have verified the specs with the Panasonic manufacturer data sheet.
The spec sheet states the Length of the capacitor is 16.50mm and +0.5mm for tolerance (tolerance is the part where the cap can expand from heat and still operate within limits).
 
I have measured both the capacitors length with a high-end Mitutoyo digital caliper to find out the height of the bulged capacitor and it came to ~18.00mm. This is far from the allowable tolerances specified by Panasonic.
 
Whatever has caused the capacitors tops to expand/bulge is ringing the alarms. This unit costs $1600 US and quality control like this UNACCEPTABLE. I am not impressed with Benchmark.
 
Also, i noticed a small scratch on the side of the unit.
 
 
Pictures of the capacitors can be seen here --> http://img685.imageshack.us/gal.php?g=img3155q.jpg
A more obvious image of the capacitors at fault --> http://img257.imageshack.us/f/bulgedcapacitors.jpg
 

 

[Nonpoint]

Sorry to hear that auto.  I have the HDR and have been quite impressed with the unit after having a number of higher priced dacs.  However, I have not compared the HPA2 to other external headphone amps.  I appreciate your initial observations.  I assume you are going to return the unit for a new one?

 

[autovelocity]

Hi,
 
For sure, this unit is getting returned.
 
Can you please open up your HDR and carefully inspect the capacitors across the whole board? (post pictures too from angles like I have)
 
I am curious to see if mine is just a bad apple, or this happens across all DAC1 models since they use the same capacitors. (if I see the same on your HDR, then I suspect a design flaw)
 
Thanks

 

 

[Nonpoint]

I will take a look and post.

 

[autovelocity]

Nonpoint:
 
I couldnt reply to your other private message because apparently I went over the limit of 2 private messages per day!
 
Anyways, I will post it here
 
 
 
Essentially that is correct. The lifespan is greatly reduced.
And I dont think anyone would be very happy to find out they just blew 1600$+ on a poorly engineered product.
 
Have a look here at failing/bad capacitors -->  http://www.youtube.com/watch?v=oDGjWOabJ2E

 

[Rdr. Seraphim]

This reminds me of Apple's bulging caps in the original iMac PPC series, the G5. They were Panasonic caps too. Apple replaced a whole bunch of motherboards. IMHO, definitely have that one looked at! It will mean reliability issues in the future, and maybe SQ too (depending on where in the circuit it resides). 

 

[autovelocity]

Seraphim:
 
Im currently talking to Rory Rall from Benchmark and this is what he had to say:
 
 
"We are examining this further but I was informed that they believed this to be normal and they have looked like this for years as they have been supplied by the factory. But we'll get back with you. In the meantime, enjoy."
 
 
I have asked him for pictures of other DAC1 USB/PRE/HDR boards so I can see for myself. Even though I know for a FACT capacitors are never bulged like this from the factory. (and if they do come this way from the factory, they are faulty to begin with)

 

[Rdr. Seraphim]

Some of the iMac caps actually started leaking... Never seen a cap that was "normal" or supposed to be like that! Maybe some of the other DAC1 owners would be willing to open up their cases and take a look. Do you have pictures? How much bulging we talking about? 

 

[autovelocity]

I do have the pictures, its posted in my first post.. Check the imageshack weblink.
 
 
Also, I got another response from Benchmark just now, but just after I almost believed them, I got a reply from DigiKey with pictures of the standalone capacitors and they are flat.
 
Here is what John Siau said:
[size=11pt]We have been using these Panasonic capacitors for many years.  We use them because of their performance and reliability.  The larger case sizes always show the bulging that you have observed.  Panasonic assured us that this is normal when we first sampled these parts about 8 years ago.  At that time, we discussed this very issue with Panasonic because it seemed so unusual.   Domed tops are entirely normal in the larger case sizes in this Panasonic family.  We have never seen any that were flat.[/size]
[size=11pt] [/size]
[size=11pt]If you were to request samples of these caps directly from Panasonic, they would be identical to the ones in your DAC1 PRE.  Unfortunately, the manufacturer’s mechanical drawing is slightly incorrect.  As you are probably aware, dimensional errors are very common in electrical component drawings. I would be glad to send you a new capacitor for comparison.[/size]
 
 
But then right after, I got the pictures of the standalone capacitors from Digikey

 
As you can see, the brand new capacitors they sell are perfectly FLAT. Who am I going to believe?
 
Then I received another picture from Benchmark themselves to prove their caps are bulged as well, and its normal.
 
This is getting conflicting.. You be the judge

 

[Rdr. Seraphim]

Duh! I'm not used to seeing domed caps like that. And they do look different than the pic's from Digikey. I'd document your findings and keep listening. If anything goes awry, you have the email thread in your hip pocket.  
 
Now the question is SQ... Keep familiarizing yourself to the DAC's signature and see if it's to your liking. 

 

[shane55]

I have opened mine (DAC1-PRE) a few times to make adjustments and have never noticed anything strangs... but then again, I really wasn't looking for cap bulge.
 
I'll try to remember to look at it tonight or this weekend...Very interesting.
 
shane

 

[Nonpoint]

Took some quick shots....
 

 

[autovelocity]

Nonpoint:
 
It appears your capacitors are bulging as well.
 
I've also emailed Panasonic to verify if indeed these 50V 1000uF 8J9J batch capacitors did indeed come bulged.
It's also possible that specific batch stamped 8J9J came that way, and newer ones don't, since the ones at DigiKey don't look that way.
 
Either way, I'll find out for sure and if they really did come manufactured this way, and if they have, it would be a first time for me to see something like this.
 
Thank you for the pictures.
 

 

[shane55]

Here are mine.
 

 

 
 

 
Hope this helps... whichever way you go. But I dunno... to me it doesn't seem like much to worry about.
 
shane

 

[amb]

Not a DAC1-PRE, but an older DAC1 here, and the caps are only slightly domed (not nearly as pronounced as the pics above).  It's been running almost 24x7 for several years now with no problem.  FWIW.