Burr Brown PCM1702...K, U-K, U, P, J ???

[audio39]

I'm in the final phase of securing a DAC I've wanted for some time that uses 4 PCM1702 20-dip chips per channel.

So, I'm a mechanical guy, and all this digital stuff is giving me a headache.

I have found that the manufacturer used the PCM1702, whereas some companies used the PCM1702U, others the PCM1702J, and I could type for a while, but what is the difference between the chips.

I found some original prices on the net that seem to indicate that the K, U-K, and the U were more expensive - does this equate to better SNR? Is it an indicator of better QA techniques and mean that these chips are better matched?

Thanks in advance.

 

[korben69]

Hi Audio39

Some hints there : http://www.ti.com/lit/ds/symlink/pcm1702.pdf
Maybe the answer is here... 😉

 

[audio39]

I've been through all of that data but it is just not clear to me.

My first interpretation of that data lead me to conclude that the "U" and the "K" marked chips would provide better SNR...but after looking at all the data I could find, well, it seemed less clear.

 

[audio39]

Ok, so the "U" indicates that the chip is 20 pin. The "J" and the "K" are grade marks.

But there are a few others...I have found the "L" and others.

So is the "K" the top of the heap, and if so, what does that mean...better SNR??

 

[stephensank]

The U means surface mount package. The grade marks are none, J and K, from least to best, and refers to how percisely they are calibrated in laser trimming. The datasheet does specify the differences in the performance data.

 

[erin]

In the datasheet the K grade chip is meant to have a red dot by pin 10.
Did Burr Brown ever print "K" on the chip?

I see a lot of chips for sale online that have "K" printed on them but no red dot.
Are these just regular chips sold as K grade?

 

[kazap]

Red dots on PCM1702 are rare- but are they from BB or a more recent addition? Are both these fake or only one?

 

[erin]

I suppose the chips will work. Its just a question of k grade or regular grade.

 

[kazap]

I suppose the chips will work. Its just a question of k grade or regular grade.

Good point. Theres little to lose. The chip on the right has a red dot in the right place and a date code that's believable too. Its also believable the SOIC PCM1702 are in abundance on the surplus market as manufacturers mainly seemed to use the DIP PCM1702 in commercial quantities.

 

[tiefbassuebertr]

in the attachments various imprints of PCM1702.
Are there the risk of fakes ?
Where is a trusted delivery source resp. ordering address ?

 

[Duo]

I'm looking for these as well, for the repair of a customer's Wadia 27 DAC.

The DAC has a combination of PCM1702U-J and PCM1702U-K chips with their outputs in parallel. The failed chip is a -J part (white dot).

Naturally these are seriously obsolete now and all I see are what appear to be knock-off variants. Hopefully it is possible to find a real one these days!

 

[Duo]

I snapped a photo of the original ICs in this DAC. The paint spots are more centered on the chip rather than sitting right near pin 10. EDIT: The crusty mess on the chips is the adhesive from the copper foil which I've peeled away for inspection.

 

[mterbekke]

Rochester has those, you'd have to contact them for the exact type they have. Cheaper than I thought:
Rochester Electronics (en-US)
: Part PCM1702

Another good place is chip1stop.com
All via RFQ, but a lot of choice, even K-versions.
Search result of Pcm1702 | Mail order site of electronic parts / semiconductor - chip one stop

 

[HpW]

@Duo & @mterbekke did you get any PCM1702 even in higher grade as K

 

[jtgofish]

I have A Krell KAV 300CD converted into a USB DAC using Ian Canada boards.That uses 1702 chips and a massive SS output stage.That is the best sounding DAC I have used.I also have an Accuphase DC61 DAC that uses 6 pairs of them which also sounds excellent.

 

[HpW]

@jtgofish "Ian Canada boards.That uses 1702 chips" where did you get those from, hopefully no fake 😉

 

[jtgofish]

The Ian Canada bits were for the USB input conversion.The 1702s were already there.

 

[HpW]

Ok, I understand now.

Do you have any detailed pictures of your Accuphase DC 61 & PCM1702U chips.

Not clear what grade are used none/J/K

as https://www.dutchaudioclassics.nl/the_complete_d_a_dac_converter_list/#A shows only the amount of used DAC chips.

Thank you

Hp

 

[jean-paul]

Taobao and Aliexpress sellers sell real original relabelled desolderded unused new recycled ones with only slight usage marks. Of course only the K version with the red dot. As Mr. Yuxinyuan stated:”customer king”.

https://www.taobao.com/list/item/7319198726.htm?from=redirectFromAutoCallApp

After the TDA1541A trade success they found a new market to serve the demanding but slightly delayed western audiophile customers with highest quality revenue.

 

[bohrok2610]

Not clear what grade are used none/J/K

Denon used non-documented L grade which in my measurements is similar to K grade.