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Chip vs. discrete resistor R2R

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Posted on June 17, 2024 at 04:45:39
morricab
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 At the end of this chain of conversion technologies is something surprising: a DAC chip. Not just any DAC chip, but one that was an important step forward for digital audio when introduced-in 1998. It is Burr-Brown's PCM1704 R-2R ladder DAC chip, four per channel. Why do it this way instead of laying out an actual R-2R ladder with resistors, as several much cheaper, excellent-sounding Chinese imports do? I asked that. "The fact that it is a monolithic chip makes it both consistent and wonderfully accurate to work with, something that a discrete ladder cannot achieve even with the highest precision resistors," Cossy answered. He also wrote, "Even though it is an 'old' chip, it more than meets current requirements."

Quote from CH precision regarding using a chip R2R DAC vs. Discrete. I have found that the best R2R DACs have always used a chip rather than discrete resistors...those tend to sound "dry" to my ears.

I also found it interesting that CH uses an "old" R2R chip rather than an FPGA or sigma/delta solution.

 

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CH Precision DAC cheapest $36,000 to $127,000 (+!), posted on June 17, 2024 at 08:57:37
Jon L
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 add $25,000 if you want their external clock.

I miss those days when PCM1704 was introduced in 1998 at $12.95 :)

 

Yes, imagine the price if they had to design the DAC inside the fancy box, posted on June 17, 2024 at 10:00:25
13th Duke of Wymbourne
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 :)
Spline filtering and PCM1704, CH Precision must be Wadia fans. Back then, probably, no one thought you could make a discrete R-2R but that is not the case these days so you need a really good story to differentiate yourself from all the other commercial DAC-chip-in-box companies. Sounds like they should work more on that story.

I don't know the market price of new-old-stock PCM1704 chips but if that is $100 each and they are using four then that's adding ~ $1600 to the retail price.

 

RE: Yes, imagine the price if they had to design the DAC inside the fancy box, posted on June 18, 2024 at 01:23:52
morricab
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 You should check your history. Accuphase made a discrete 16bit and then later 20bit DAC back in the 1980s. Discrete DAC architecture is nothing new...probably making a resurgence due to lack of chip availability. I own an Ayon Skylla II, which uses the BB PCM1704 (4 of them) and Ayon switched to ESS and later AKM due to lack of availability of 1704s (seems CH has enough but how many $50K dacs get sold per year?).

https://audio-database.com/Accuphase-kensonic/etc/dc-81l.html

After that they switched to chips...the preferred one being the BB PCM63K (the DC91 DAC used like 16 per channel in their MMB configuration). At one time the BB PCM63 was about $70 per chip when Sigma/Deltas were like $2.

https://www.stereophile.com/content/accuphase-dp-90-cd-transport-dc-91-da-processor

The simple fact is this: A laser trimmed R2R IC like the BB PCM-1704 is MUCH higher precision than any discrete ladder DAC can possibly be with macro sized resistors. Same holds true for BB PCM63, AD 1865, TD1541 etc.

 

Adcom R2R BB63, posted on June 18, 2024 at 08:02:46
scriabin
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 Morricab - Are you stating that my Adcom GDA 600 will most likely outperform a Holo Audio May KTE (resistor ladder) when playing CD's? I have 2 Adcom's. Thank you.

 

RE: Yes, imagine the price if they had to design the DAC inside the fancy box, posted on June 18, 2024 at 12:12:20
13th Duke of Wymbourne
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 Now you mention it there was a company called UltraAnalog that made DAC modules, which contained discrete components. Maybe Accuphase used those? I think you are right that discrete DACs were made out of necessity before good monolithic DACs then faded away during the PCM63/1702/1074 era and are now back with us.

The claim that a laser-trimmed PCM1704 is MUCH higher precision should be tempered. Here is the linearity plot from Stereophile's measurement of a CH Precision C1.2 ($43k as reviewed in Jan 2023). This uses four DAC chips per channel (two paralleled for each phase).




We can see the linearity error starts to grow below -60dBFS (JA is more generous in saying -80dB). Compare that to the holo May DAC with a discrete R-2R DAC.



Here there is no linearity error until down to -120dBFS. This is up there with delta-sigma DACs and I don't know how Holo does it. You might find plots for PCM63/1702/1704 that are much better than CH Precision's implementation but even the best will not exceed the Holo May.

footnote for anyone who doesn't read graphs:
The blue lines represent the 'gain' of the DAC from input digital value along the bottom to the measured analog output voltage on the left axis. Both are scaled in dB with the top-right corner representing the max analog output voltage for the maximum input digital value. Ideally the blue line should be straight as it slopes down to the minimum values in the bottom left corner. The red line shows the slope of the blue line - the blue line should have a slope of 1 (= 0dB). The red line should be completely flat across the plot with a value of 0dB, where it is not 0dB indicates a linearity error in the DAC.

 

RE: Yes, imagine the price if they had to design the DAC inside the fancy box, posted on June 19, 2024 at 01:37:14
morricab
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 The ultraanalog used a 12 bit BAC for the last 12 bits. It used discrete for the first 8 bits.

For whatever reason, the CH is not the best linearity measurement I have seen for the PCM1704. Not that this has any correlation with sound quality whatsoever.

 

R-2R ladder DAC chips are still in production. , posted on June 19, 2024 at 16:59:50
AbeCollins
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 R-2R ladder DAC chips are still in production today with the same benefits you described in your post. "The fact that it is a monolithic chip makes it both consistent and wonderfully accurate to work with, something that a discrete ladder cannot achieve even with the highest precision resistors.."

One of many examples still in production today

Schiit uses these DAC chips or variants in some of their DACs.



 

I wouldn't bet on it. , posted on June 19, 2024 at 19:26:51
PaulN
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 The May attains signal-to-noise figures at the threshold of electron noise and has an effective resolution of more than 22 bits, neither of which the PCM63 can match.

 

RE: Adcom R2R BB63, posted on June 20, 2024 at 04:04:04
morricab
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 Technically probably not...sonically with cds I wouldn't be surprised if you prefer it.

 

RE: I wouldn't bet on it. , posted on June 20, 2024 at 04:04:47
morricab
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 And neither of which will dictate if he prefers the sound of it or not.

 

Anyone that didn't prefer , posted on June 20, 2024 at 15:53:31
PaulN
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 the May to an Adcom would be deaf. The May is a bespoke product like Ferrari and highly biased into class-A in the discrete output stage. While the Adcoms sounded pretty good in their day and offered HDCD decoding in their digital filter chip, they are more akin to a Hyundai. I have never heard a better DAC than the May and at it's level, the differences between products in minimal technically and mostly flavors of tuning.

 

RE: Anyone that didn't prefer , posted on June 21, 2024 at 05:36:23
morricab
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 Well, a friend of mine had their level 2 DAC (not the May but same tech) and it was destroyed by my Ayon DAC and a Lampizator Atlantic TRP2 DAC. Wasn't really close in terms of actual listening...sorry to point out the obvious but the measurements themselves don't mean much for how somethign sounds.

 

RE: R-2R ladder DAC chips are still in production. , posted on June 21, 2024 at 09:50:23
Dawnrazor
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 Yeah my dac has one of those chips. I heard it sounded bad though because it has terrible measurements.

Cut to razor sounding violins

 

" I heard it sounded bad though because it has terrible measurements", posted on June 21, 2024 at 11:30:52
Story
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 where did you hear that? Please answer this one...

more questions -

1. Did YOU just hear that it sounded bad from somewhere?

2. If so, then why did you buy it?

3. Give us a link about this R-2R DAC

4. Were the bad sound CD's you listened to victims of the Sound Wars?

5. Can you give us one CD where you thought it sounded pretty good?





 

"threshold of electron noise"? gimme a break !, posted on June 21, 2024 at 19:24:08
AbeCollins
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 "...attains signal-to-noise figures at the threshold of electron noise"

I'm not saying the May isn't special but come on....

"threshold of electron noise" matters not for HiFi but applicable to LNA for radio astronomy or medical instrumentation. Never seen Friis formulas applied to HiFi.



 

(I think he was trying to be sarcastic) [nt] ;-), posted on June 22, 2024 at 11:09:26
Chris from Lafayette
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there's too much Voom Voom here, posted on June 22, 2024 at 11:38:10
Story
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 keep it where it deserves to be



 

I was being intentionally hyperbolic..., posted on June 23, 2024 at 14:57:44
PaulN
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 to make a point. Its is a very, very, very quiet DAC, despite being a ladder DAC. I honestly don't think much about the specs, I just listen. But you are made aware when you do listen that the sound come out of inky blackness and the soundfield is incredibly coherent ans stable, both of which I would attribute to that S/N ratio.

 

Hard to tell as this is an audiophile forum ;-), posted on June 23, 2024 at 15:25:43
AbeCollins
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 nt


 

the measurements themselves don't mean much, posted on June 23, 2024 at 19:35:06
mitch2
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 "the measurements themselves don't mean much for how something sounds"

Owned a Tambaqui last year and still own the excellent measuring Benchmark DAC3 HGC. Sold the Tambaqui, and the Benchmark now sits in a box. I like the sound of my two Mojo Audio R2R DACs better. Those Mojo DACs use old AD-1862N (special Z version) chips and they only process up to 24/192 but to me they sound tonally rich and musically satisfying while the Tambaqui, which I characterized as sounding mostly perfect, just didn't provide the same level of enjoyment.

 

RE: " I heard it sounded bad though because it has terrible measurements", posted on June 24, 2024 at 14:47:00
Dawnrazor
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 Mostly ASR where they don't listen and just go by measurements. Chris was right I was being sarcastic...

1. Yeah I think I saw on ASR or some forum that it sounded bad because it measured bad.

2. I think I bought it way before the measurements. Guttenberg and A youtube reviewer I trust basically said that with an A/B with the Chord Dac, he preferred the Qutest to this dac, but always kept coming back to listen to this dac. He had a good analogy about an HDR photo and how it looks great but how they can also look unnatural. I liked the powersupply and output stages too. In addition, he ended up here because he got some Stax electrostatic phones. I have some electrostatic earbuds so I thought it would be a good match.

3. Here is a link to the measurement part of the dac review: https://www.stereophile.com/content/borderpatrol-digital-analogue-converter-se-measurements

4. I actually like the dac and I am fairly sure the music I listen is pretty much done before the loudness wars. Its mostly 80s stuff.

5. Most stuff really.

Cut to razor sounding violins

 

Guilty as charged!, posted on June 24, 2024 at 14:47:34
Dawnrazor
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 nt

Cut to razor sounding violins

 

Looks like the Voom Voom was actually the truth, posted on June 25, 2024 at 12:40:52
Chris from Lafayette
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 And I try to keep the truth where it deserves to be! ;-)

 

I already saw his answer *, posted on June 25, 2024 at 14:45:17
Story
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RE: Chip vs. discrete resistor R2R, posted on June 26, 2024 at 03:29:08
Terry
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 About 3 years ago, at a quite low period in my life (I had just lost my mother), I decided to invest in a new DAC. I read and watched lots of reviews and finally decided on the Holo Audio May KTE. This was going to be the single greatest expenditure in my audio system, for a single component, in my 45 years in the hobby. I was definitely nervous (am I crazy?).
At the time I was using a Monarchy M24 which used the Burr-Brown PCM 63 chip. I really liked this DAC and had never heard anything better in my system. (I'm sure psychologists would have some fun explaining why I decided to give up the M24 but I try to avoid dwelling on this subject).
Anyway, the May is definitely superior to the M24 in all respects and particularly when combined with HQPlayer. Nevertheless, I often wish I had held on to the M24 and spent that $5,000 on more useful projects (like buying more music).
Terry

 

LOL! Yeah - AFTER you posted your previous comment. . ., posted on June 26, 2024 at 14:36:52
Chris from Lafayette
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 . . . and tried to give him all sorts of grief. I mean, really, you should do some more study and contemplation of Daniel 5:27. ;-)

 

really...now? You need to pay attention better, posted on June 26, 2024 at 15:31:22
Story
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 we all make mistakes here at AA, and you do also. It's all one big melting pot.

What are you inhaling? Whippets?

I like Daniel, BTW. You should try to read up on Revelation



 

Yes we do all make mistakes, but you seem to try to avoid acknowledging your own, posted on June 26, 2024 at 23:52:16
Chris from Lafayette
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 Hence, my recommendation of the verse from the Book of Daniel, which seems to have escaped you.

But in any case, sure - I'm always up for reading drug-addled ancient hippie divinations, and I don't mind plowing through Revelation!

 

RE: the measurements themselves don't mean much, posted on June 28, 2024 at 02:48:39
morricab
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 Exactly! I have a friend with a Tambaqui and it just detaches me from the music.

My Ayon Skylla II DAC with BB PCM1704s and tube output stage sounds resolved, full and engaging.

 

RE: Chip vs. discrete resistor R2R, posted on June 28, 2024 at 02:53:08
morricab
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 I have a Monarchy M24 as well as my Ayon Skylla II DAC, which uses BB PCM1704 chips.

The Monarchy is a very musical machine and while it might be behind others in resolution, it is not behind in delivering music. i also find it's soundstage and image 3d are superior to most others. It's main weakness is a high output impedance, which means that it is not as compatible as other DACs. i suspect that those who haven't found it to sound stellar were not matching it properly to their preamp or integrated amp.

 

RE: Chip vs. discrete resistor R2R, posted on June 29, 2024 at 08:03:26
Leo loves music
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 What is your opinion on PCM1704 vs TDA1541?

 

RE: Chip vs. discrete resistor R2R, posted on July 1, 2024 at 07:31:00
morricab
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 Did a comparison recently where a friend brought over an ABBAS DAC from Ukraine that uses the TD1541 and all tube power supply and output stage vs. my Ayon Skylla 2 that has all tube power supply and tube output stage but uses the BB PCM1704K (2 per channel).

The take away, which might have a lot more to do with the analog stages rather than the DAC chips, is that Ayon is more "perfect" and the Abbas somewhat more rich and harmonic. Resolution is very good with both and bass was more potent with the Abbas (not that the Ayon is short in any way on bass). Soundstage was both deep and wide with 3d images for both but perhaps the Abbas was even more in that direction and more "wet" overall.

Suffice to say that I would not say resolution is lacking on either DAC and the TD1541 does not sound obsolete to me. I have also owned DACs with the 18 bit AD1865N and those also sound highly resolved and yet more grounded in sound like other top R2R dac chips.

 

RE: Chip vs. discrete resistor R2R, posted on July 1, 2024 at 08:37:34
Leo loves music
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 I agree with observation. I had the same feeling.

 

RE: Chip vs. discrete resistor R2R, posted on July 1, 2024 at 08:42:51
Leo loves music
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 Do you have more info for that ABBAS DAC?

 

RE: Chip vs. discrete resistor R2R, posted on July 4, 2024 at 00:45:42
morricab
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 Nothing beyond what's on their website.

 

RE: Chip vs. discrete resistor R2R, posted on July 4, 2024 at 03:14:58
Leo loves music
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 Do you have a link?

 

RE: Chip vs. discrete resistor R2R, posted on July 5, 2024 at 01:33:05
morricab
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 https://www.abbasaudio.com/en/productlist-dacs/

 

thanks. nt, posted on July 5, 2024 at 03:09:09
Leo loves music
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RE: Chip vs. discrete resistor R2R, posted on July 6, 2024 at 16:14:26
rogerh113
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 I think my R2R dac (VTL 20 bit) is noticeably more musical than the other dacs I have had and have.

It seems most dacs are delta sigma, and have been for some time. I have to wonder if the whole industry listening narrative has shifted to the importance of 'resolution', since delta sigma seems to be very good at that. Musicality seems difficult for delta sigma to achieve. I recently got a Lampizator G4L4 while I was repairing my VTL (who knows how long it would take me, if I could repair it at all). Tube rolling has definitely achieved a more musical capability, but it is still a bit lacking.

If your primary focus is resolution, then possibly r2r is a waste of time for you. Perhaps, however, if you hear a good r2r, with a tube output stage, in a well put together system, you might be quite surprised at the soul it has.

The taste of everyone is different - it is great there are choices to suit all....

 

RE: Chip vs. discrete resistor R2R, posted on July 7, 2024 at 19:39:53
AbeCollins
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I think the lack of resolution turned me away from two of the R2R DACs I had in my system. It always felt like I was missing something plus they were both a bit too smooth and 'polite' dynamically for my musical preferences.

Yup, everyone's taste is different.



 

RE: Chip vs. discrete resistor R2R, posted on July 13, 2024 at 00:49:49
morricab
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 Polite? If anything it's the exact opposite of what you state. It sigma/delta that has the smooth and lacking dynamic jump reputation .There is no lack of resolution on a DAC with a good 18-24 bit chip.

 

RE: Chip vs. discrete resistor R2R, posted on July 13, 2024 at 07:36:10
rogerh113
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 The D to A translation is going to have an impact on the content, some a lot less than others. If elements of the original source are lost in translation, then no amount of post processing can recover them.

From my experience, more 'soul' is lost in the delta sigma I have heard, rendering the music noticeably less musical. It just feels sterile.

I do not sense any real limitation with either R2R or delta sigma with regards to resolution - that might be more a factor of the rest of the system or the post processing in the DAC.

I do not equate sterility with increased resolution, so that may be a personal limitation.

 

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