PCM1704 last of the R2R dac chips, today done discrete.

[georgehifi]

 

Stumbled on this Stereophile article on the pcm1704 when it was released in 1998 and only cost $12.95 each.

But announced in 2006 they were stopping manufacture of them in a year or so, because of high cost of laser trimming each microscopic R2R resistors to be in spec.

And so was born Delta Sigma (bitstream), cheap to make.

https://www.stereophile.com/news/10221/index.html

 

 

Today if you want to make a dac around them to get a NOS PCM1704 cost over $200 each, for genuine ones 

https://www.ebay.com.au/sch/i.html?_from=R40&_nkw=PCM1704-K&_sacat=0&LH_PrefLoc=2&_sop=16

 

Cheers George

 

 

Edited November 1, 2022 by georgehifi

[muon*]

What an investment it would have been to by a box of them in 98

 

Edit: I heard one of Clay's dacs using these chips but decked out with Duelund VSF caps ect', was very impressive.

Edited November 1, 2022 by muon*

[georgehifi]

4 hours ago, muon* said:

What an investment it would have been to by a box of them in 98

 

 

Better than any shares.

 

Cheers George

[frankn]

Isnt this what the Audio-GD HE-7 MK2
is based on?  

For who got love on PCM1704UK to order


(Regenerative power supply)

(Apply 8 pcs the most real like sound DA chip PCM1704UK)

Fully discrete real balanced  current transmition design.

2 pc ultra high frequency 90/98 MHz Accusilicon 318B femtosecond clocks provide synchronous clock for whole unit without PLL up-frequency .

32bit / PCM384K asynchronous transfer Amanero 384 apply the FPGA synchronous clock.

Both USB / HDMI have built in separate isolator and pure class A isolate power supply.

The whole digital circuit built with 1 pc FPGA and 3 pc CPLD programmable chipsets to separate the different configured circuits for avoid interrupt, data process in parallel mode. 

[georgehifi]

9 hours ago, frankn said:

Isnt this what the Audio-GD HE-7 MK2
is based on?  

 

Won't be long before KingWa will have change to going to discrete R2R, as those PCM1704's must be getting thin on the ground.

It'll be interesting if he does a non biased shootout between the two using the same dac, to which come out on top, as the R2R resistors today can be .000001% accuracy!!!, and no one really knows what the % accuracy the resistors inside the Texas Intruments  PCM1704's were laser trimmed down to in manufacture and they don't specify the accuracy.

And that will be the determining factor to what's going to sound better in the same dac.

 

Cheers George  

Edited November 3, 2022 by georgehifi

[frankn]

Hi George,

They already do, R-7HE MK2 ;

Design overview: 

        Fully discrete parts are used in a truly balanced current transmission design. 
        4 sets of fully discrete and independent DSD hardware decoders. 
        8 sets of fully discrete R-2R DA modules to form a two-channel balanced push-pull decoder. 
        2 top-notch Accusilicon TCXOs with frequencies of 90 and 98MHz provide synchronization for the whole unit, and they are applied to the playback of all data rates without PLL up-conversion. 
        32bit / 384K asynchronous Amanero USB interface synchronized with the FPGA. USB and HDMI modules equiped with galvanic isolators and fed by two groups of independent isolated power supplies, to avoid the mutual electrical contamination between USB and HDMI.
        Using the latest discrete servo stabilized power supply, whose performance is comparable to batteries after more than a year of calibration and optimization for each part of the circuit. 
The digital circuit uses these new discrete servo stabilized power supplies, while the clock and the analog circuits are still powered by pure class-A power supplies to achieve the best sound, as determined during listening tests.
        The digital circuits of the whole DAC are comprised of 1 FPGA and 7 CPLDs (both programmable devices), which allow separating the different functional circuits and preventing interference.
        The FPGA operates in the parallel data processing mode even at the fastest data rate, and supports firmware upgrades to improve sound quality when new and better design ideas are eventually found and implemented.

[georgehifi]

6 hours ago, frankn said:

 R-7HE MK2 ;

        8 sets of fully discrete R-2R DA modules to form a two-channel balanced push-pull decoder. 

 

Wow so he does do a discrete R2R

If they are the same topologies then that would be a good A/B between the (discrete R2R) R-7HE MK2  vs  HE-7 MK2 (8 x pcm1704K)

But he doesn't say what percentage resistors he uses in the R-HE7Mk2, only that there are .00001% resistors are available on the market.

 

PS: He did say this about the discrete R2R

Quote

"Productions and sales were not scheduled until we were fully satisfied with how realistic the sound was. The improvement is quite obvious compared to the previous generation.

Previous generation being PCM1704???? If so looks like Discrete wins out.

 

Quote

"We have successfully integrated the analog vinyl sound characteristics into this product, this being allowed optionally through the front panel."

If it's this. In the 60's stereo recordings sounded ok with vinyl, but cd off those masters were very ping pong left right sounding, and mimic'ing a vinyl cartridge channel separation, fixes cd to sound better.

I did the experiment years ago on the back of a cd player bleeding left and right to only have 30db channel separation instead of 120db and it made those early discs sound richer and better. At least the user can switch it out if that what it does.

 

 

Cheers George

Edited November 4, 2022 by georgehifi

[-Prince-]

On 01/11/2022 at 11:34 AM, muon* said:

Edit: I heard one of Clay's dacs using these chips but decked out with Duelund VSF caps ect', was very impressive.

Was its Clay's NOS PCM1704 DAC?

[pete_mac]

48 minutes ago, -Prince- said:

Was its Clay's NOS PCM1704 DAC?

 

The timeline pre-dates the Kompakt NOS DACs... I suspect it was a Lenehan PDX DAC, especially if it featured the enormous Duelund VSF output capacitors.

Edited February 16 by pete_mac

[MrBurns84]

the PCM1704 UK chip was the preferred one, but who knows how much these are today.  Shame though, these were used in the earlier models of the Audio-GD dacs, and i went through quite a few of them back in 2010-2013, should have kept them.

[pete_mac]

3 minutes ago, MrBurns84 said:

the PCM1704 UK chip was the preferred one, but who knows how much these are today.  Shame though, these were used in the earlier models of the Audio-GD dacs, and i went through quite a few of them back in 2010-2013, should have kept them.

 

Yes, likewise! I had four audio-gd DACs with the PCM1704UK chips:

 

DAC3SE

DAC-19

Ref 5

SA-1

 

 

[MrBurns84]

2 minutes ago, pete_mac said:

 

Yes, likewise! I had four audio-gd DACs with the PCM1704UK chips:

 

DAC3SE

DAC-19

Ref 5

SA-1

 

 

 @pete_mac  Mine were the Dac 3SE, Ref 7, Ref 7.1

[pete_mac]

43 minutes ago, MrBurns84 said:

 @pete_mac  Mine were the Dac 3SE, Ref 7, Ref 7.1

 

Very nice!

 

I heard a few of the 8 DAC chip models but they never made their way into my system. It seems there was an invisible barrier set at 4 chips!

[MrBurns84]

24 minutes ago, pete_mac said:

 

Very nice!

 

I heard a few of the 8 DAC chip models but they never made their way into my system. It seems there was an invisible barrier set at 4 chips!

The one i should have kept was the Ref 7.  That was the nicest of the lot.  

[Muscat]

1 hour ago, pete_mac said:

 

Yes, likewise! I had four audio-gd DACs with the PCM1704UK chips:

 

DAC3SE

DAC-19

Ref 5

SA-1

 

 

I'm still running the DAC-19 DSP and C2 as an office setup.  Never had to opportunity to hear further up the line but see them listed now and then and they're good buying used these days.

[MrBurns84]

1 hour ago, Muscat said:

I'm still running the DAC-19 DSP and C2 as an office setup.  Never had to opportunity to hear further up the line but see them listed now and then and they're good buying used these days.

Keep them and be happy.  I wish i did that with my Valab 1543 NOS dac bought back in 2009, here:

never invited friends over and just stayed happy.  This would have saved me $$$$$ over the last 16 years playing around with my gear.

Edited February 17 by MrBurns84

[pete_mac]

2 hours ago, Muscat said:

I'm still running the DAC-19 DSP and C2 as an office setup.  Never had to opportunity to hear further up the line but see them listed now and then and they're good buying used these days.

 

I loved my DAC-19 DSP - I bought it new, sold it, and then it popped up for sale and I bought it back! I added an Amanero384 USB board to it and it sounded great.

 

SOLD: FS: audio-gd DAC19DSP - PCM1704UK R2R chips and Amanero 384 USB conversion | Stereo, Home Cinema, Headphones Components

 

I modded my DAC3SE to the DSP1 V5 digital board too. That was a fun DAC, especially with the adjustable DSP and filter settings:

 

audio-gd DAC 3SE digital board upgrade | Digital Sources, DACs, and Computer Audio

 

 

 

Edited February 17 by pete_mac

[pete_mac]

41 minutes ago, MrBurns84 said:

Keep them and be happy.  I wish i did that with my Valab 1543 NOS dac bought back in 2009, here:

never invited friends over and just stayed happy.  This would have saved me $$$$$ over the last 16 years playing around with my gear.

 

Ah yes, the audio merry-go-round!

[Grizzly]

2 hours ago, pete_mac said:

 

Very nice!

 

I heard a few of the 8 DAC chip models but they never made their way into my system. It seems there was an invisible barrier set at 4 chips!

 

I had a Kenwood CDP some years back with 8x 1702 chips in it, and no balanced outputs!

[Muscat]

4 hours ago, MrBurns84 said:

Keep them and be happy.  I wish i did that with my Valab 1543 NOS dac bought back in 2009, here:

"Comparison is the thief of joy" surely applies to hifi.  My trick is not having any audio friends

 

[MrBurns84]

1 hour ago, Muscat said:

My trick is not having any audio friends

 

Or in my case, audio friends that have more disposable income than me...