CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS

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Author Topic: Vintage R2R/multibit DAC Thread  (Read 12181 times)

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madaboutaudio

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Re: Vintage R2R/multibit DAC Thread
« Reply #60 on: July 20, 2015, 06:08:21 AM »

Agreed. PCM1702 and PCM63 > PCM1704.

Even Ken Ishiwata of Marantz shares the same view:

See 5:08 onwards

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lukeap69

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Re: Vintage R2R/multibit DAC Thread
« Reply #61 on: July 20, 2015, 09:14:22 AM »

Thanks for sharing.
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madaboutaudio

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Re: Vintage R2R/multibit DAC Thread
« Reply #62 on: July 30, 2015, 12:59:37 AM »

Interesting article with notes on sound quality changes on his mods:
https://sites.google.com/site/computeraudioorg/mdht-havana-dac-modifications

Quote (selected)
Upgrade Summary - Total 54 parts upgraded

-PCM56P-K grade chips x2 - classic NOS Dac sound and increased extension
-R-Core x1- increased impact and clarity across the spectrum
-Jupiter Caps x6- incredible lush textured sound but still clear presentation throughout
-ELNA Silmic and Silmic II x25 - electrolytic caps throughout - sound stage depth/width
-Shinkoh Tantalum resistors x6 - transformed the Dac into a different beast, now I can hear the harmonics of the tube. The music swings as it should, shimmer and sheen without glare. Shinkohs seem to remove the electronics from the music.
-Schottky Diodes x8- enhanced the character of the Shinkoh resistors a must have to get the full potential of Shinkoh
-Auricaps x5 -  improved texture throughout the frequency range
-Hi-Fi Tuning Supreme fuse x1- provided more energy and impact




Misc. Tweaks
Silver Power Cord with Furutech ends vs. a standard copper 12ga cord.  The Silver cord was a bit brighter and the copper cord gave more of an organic textural sound. Liked copper better.
Black Diamond Racing cones both ways, the low-end texture was gone and the high-end details stood out more. This took away the rich tubey character imo so I decided to go without the cones.
1.5" thick wood platform under gave me a nice solid foundation to the lows which seemed to enhance the low-end texture.
Small weight on top tightened up the sound throughout the spectrum a must try for everything imo just to listen for a benefit.
Removed caps [C5 and C25] which are only used for the "stability of the circuit under critical conditions" the sound became thin sounding so I put them both back. Edit: with the new r-core in place, removing these is a MUST, with them in place the sound is severely constrained.
Bypassed the fuse with a piece of copper solid core wire. Nice improvement with overall speed and impact, was too chicken to leave it in place and returned the fuse. I might put the wire back in place though.

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paras1te

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Re: Vintage R2R/multibit DAC Thread
« Reply #63 on: July 30, 2015, 08:59:11 AM »

Possibly Philips' last multi-bit DAC effort (TDA1387 and TDA1545, both same except the former is I2S and the latter is EIAJ) is a source of "hope" for multi-bit resurrection (at modest cost).

Not a bad DAC from my experience (Monica DAC from DIYParadise.com) ... but you need a very good output section!

That DAC is only 8-pin and SOIC sized, so no wonder its popular in DIY.

Philips made LOTS of them in the late 90s for use in certain SoundBlaster cards. Judging from eBay and Alibaba, the Chinese seem to have acquired a huge stash (you can buy a single chip for $2-3). (Chinese have huge DE-SOLDERING/DISASSEMBLY factories!)

Seems certain Chinese opportunists have already put out some ready-to-go D/As (USB, etc.) based on this now-ancient Philips chip.
 
Google "Eight parallel 8X TDA1387 Hifi DAC Hifi Decoder USB digital input " for some insight.
Note the use of MULTIPLE MULTI-BIT architecture ;)


$100-130 for most of these TDA1387-based D/As.
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BassDigger

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Re: Vintage R2R/multibit DAC Thread
« Reply #64 on: July 30, 2015, 02:25:06 PM »

Aha!! At last, I've stumbled upon a thread that reeeeally piques my interest.
I haven't read through it, yet. But I will be doing so (when I've the time). Oh yes, I will!!!

My addition:

Brand: Cambridge Audio
Model: DAC 3 (Original version, but heavily modified)
Year:...err...1989....I think. (Modified 2012)
Inputs: S/PDIF coaxial + dedicated SD card player multi-purpose I2S/power combi
Outputs: Original RCAs variable and fixed (never tried them) + New RCA outputs (from tube output stage)
Sample Rates: up to 48kHz
DAC chip: TDA1541S1 x 4

That's my 'baby'!
« Last Edit: August 17, 2015, 05:44:44 AM by BassDigger »
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paras1te

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Re: Vintage R2R/multibit DAC Thread
« Reply #65 on: August 29, 2015, 10:33:43 AM »

I don't understand the CONTEXT of this thread...

Is it about stand-alone D/A processors, or the DAC chip (IC) itself?

Context makes a difference because (e.g.) SPDIF is a pretty big hit (in the negative direction) in terms of sound quality.

Is there another thread of related topic(s) ... such as multibit/R2R vs. single-bit vs. Delta-Sigma?

It's not just a matter of multibit/R2R (DAC architecture) when it comes to that classic (vintage) device's digital-sound characteristic. Many of the heavy-hitters from those days (Meridian, Theta, Wadia, Krell, etc.) used their own DSP-based digital filters --that was a MAJOR selling point. In addition, of course, there was output section and PS/regulation. Etc.

Coming back to modern times -- roughly late 1990s, henceforth -- when D-S (off-the-shelf DAC chips) were SELECTIVELY being used by folks like Meridian (they used Cirrus D-S 439x series), one can't really nail down multibit/R2R wholesomeness/goodness on DAC architecture. Many of the modern "high-end" units from Meridian, Boulder, Linn use $3.00 D-S dacs (chips) -- "encapsulating" them with optimized topologies (digital filter/upsampling; I/V and output stage; PS and regulation; RF/EMI shielding). And YES: these modern high-enders -- as $$ as they are -- not only sound (subjectively) as good/better than best multibit Thetas and Mark-Levinsons and Sonic Frontiers from the '90, their MEASURED (objective) performance blows away the antiques.

Bottom line:
High-end audio is supported by folks that have "high-end" incomes--the gear in Stereophile and TAS. And its not like those folks don't know (or don't want) the best sound.
If multibit/R2R was as good as some tout it is (and/ or D-S was "so bad"), major high-enders -- like Meridian, who do have $$ and political power --  would have pressured the semiconductor industry at AD, TI/BB, Philips, Wolfson, et al. to either produce/stock (incl. new-old-stock) multibit/R2R or improve D-S. (see **) They seem to have done the latter as they all abandoned multibit/R2R. ESS -- by their own claims -- seem to have licked some of D-S' inherent "problems". The latest DAC (ICs), like the new ones from AKM, with very good implementation (that's important) should allow one to attic those heavy, hot-running R2R antiques ... of course, bored "audiophiles" with plenty o'$$ and time-to-kill on eBay or Audiogon will always find 'scuses to justify their "superior" (classic n' good)  devices ;) ***


** This is what happened in the early days of digital audio. The high-end community didn't like the sound of early CD players, so Philips, Sony, etc. improved their designs. Not just that but modders of OEM (Meridain, Mission, etc) further improved on the overall strategy. I.e., oversampling, better I/V + output filters, etc.
Similar thing kinda/sorta happened when MASH/Bitstream (i.e., early/mid 1990s single-bit) DACs were being used by the majors. (Not so good sounding, so DAC manufs. intro'd D-S).

*** Pressure from classic-obsessed fanboyz are what make those old absurd, polluting clunkers comin' back, time and again, into modern cinema ...



P.S. What about that Stax CD player or the M-L no. 30?
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BassDigger

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Re: Vintage R2R/multibit DAC Thread
« Reply #66 on: August 29, 2015, 11:17:27 AM »

I don't understand the CONTEXT of this thread...

Is it about stand-alone D/A processors, or the DAC chip (IC) itself?

 ahoy  Maybe you should read the first post. http://www.changstar.com/index.php/topic,2278.msg62421.html#msg62421  facepalm
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paras1te

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Re: Vintage R2R/multibit DAC Thread
« Reply #67 on: August 29, 2015, 12:15:17 PM »

ahoy  Maybe you should read the first post. http://www.changstar.com/index.php/topic,2278.msg62421.html#msg62421  facepalm
That was the FIRST post I read, toots ;)
it seems to suggest the stand-alone units (no source or xport). In this, the correct nomenclature to use is D/A processor ;)
The acronym "DAC" can refer to ... a chip or D/A section of a device or D/A processor.
This is gettin' anal, I know, but after going thru several pages in this thread, the thread-starter post loses its context ... not that that was anything 'pecial to start with ... and, then, you get to my whacky post above: and, henceforth, any sane person feels like they're in 'Nam ')
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madaboutaudio

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Re: Vintage R2R/multibit DAC Thread
« Reply #68 on: August 29, 2015, 02:07:06 PM »

Delta sigma was favoured over r2r dac not because it sounded better but because it was easier to manufacture:


http://www.head-fi.org/t/701900/schiit-happened-the-story-of-the-worlds-most-improbable-start-up/3045#post_10944447
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paras1te

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Re: Vintage R2R/multibit DAC Thread
« Reply #69 on: August 29, 2015, 04:16:29 PM »

IMPLEMENTATION is most important.
Use of D-S or R2R dac chips may be the lowest common denominator.
Just look under the hood of Gen.V, Wadia, Mark Levinson, Sonic Frontiers, Meridian, Krell, etc. There's a lotta tight PS regulation, bypassing, careful PCB layout, low-noise techniques. Probably much more so than any Schiit, or M-F or Cambridge or  NAD made today. (Yeah: A manuf . can use a good chunk of what the customer pays for (the end product) to tweak and polish. You simply can't do that at LHLab's or Schiit's or NADs price level. So if on eBay you pay little for vintage high-end R2R D/A processor, and it's working fine, you got yourself a nice device that may very well be better than much modern gear at the same $$. The problem is: how many folks get to hear MODERN high-$ Sigma-Delta, like that $15K Meridian, or $25k Boulder? )

My comment about modern DACs (DAC ICs) measuring better is a red herring -- it was meant to be. Recently looking at a classic Stereophile review from 1993 -- several CD players compared -- the best measuring (but worst sounding) was a Marantz Bitstream unit; the best sounding (MSB) was a souped up Philips OEM, using classic 80s-era multi/R2R SAA7220+TDA1541A.
I do have several multibit/R2R goodies in my possession. Most are OEM Philips CD player mods. And these do have super sound (better than any CDP, sound card, DAP or D/A processor in my collection that incorporate D-S, which are mostly mid-grade jobs like Asus Xonar sound cards or Oppo disc player).
That said, and as noted in the beginning, the multi/R2R jobs are quite tricked out: CD players with discrete-component I/V+output section, no less than 20 indiv. power regulators., outboard PSU, etc. Not unlike the situation w/the Gen.V (and similar vintage D/A processors that are generating interest again).

Hmm... I have a theory about that ... other than the boredom hypothesis noted earlier.

Say you're an audio geek, always searching for "great" sound. You spot a deal on eBay -- a classic multi/R2R -- and win the bid for several hundred $$. It ain't a very good processor by its original reputation, but because you've ALREADY spent your hard-earned $$ on it (not to mention the time/effort of bidding, unpacking, setting up for listening), you're prone to the Sunk Cost Fallacy:
https://en.wikipedia.org/wiki/Sunk_costs
Hey, it's not your fault -- it's evolution, meant for survival...man vs wild ... Bear Grylls.
IAC, I'm not sure classic multi/R2Rs were the only game in town BACK THEN...
Recall the Optimus CD3400 portable CDP from Radio Shack, made 1993-94. It STILL sounds and measures great, but it's DAC (chip) is 1-bit. It's not that it sound better/worse than my best R2R or best D-S ... it's a very different (euphonic) sound that some suites certain moods or music genres. Makes no sense, huh???
« Last Edit: August 30, 2015, 01:23:18 AM by paras1te »
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