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Author Topic: Vintage R2R/multibit DAC Thread  (Read 12176 times)

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jjacq

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Re: Vintage R2R/multibit DAC Thread
« Reply #50 on: May 18, 2015, 12:00:08 AM »
Hello guys, I'm quite new to r2r DACs and I just got a deal for an ADCOM GDA-700 for ~$270 in the mail right now. Let's hope it's a good match for my upcoming Liquid Carbon (or my current NFB 15.32) and the LCD-X.  :)p2

Brand: AdCom
Model: GDA-700
Year: Maybe 1996?
Inputs: AES/EBU, Optical, 2 Coax
Outputs: RCA and XLR
Sample Rates: 32/44.1/48 kHz
DAC chip: 2 Burr-Brown 1702
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Za Warudo

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Re: Vintage R2R/multibit DAC Thread
« Reply #51 on: May 30, 2015, 08:16:03 PM »
I bought an Angstrom 200 DAC/Preamp, designed by Mike Moffat.  Does any know what kind of chip this uses?  Is it R2R?
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AustinValentine

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Re: Vintage R2R/multibit DAC Thread
« Reply #52 on: May 30, 2015, 09:53:26 PM »
Quote from: Za Warudo on May 30, 2015, 08:16:03 PM
I bought an Angstrom 200 DAC/Preamp, designed by Mike Moffat.  Does any know what kind of chip this uses?  Is it R2R?

Nice pickup! I keep considering picking one up myself.

The setup of the Angstrom 200 is...well...a bit complex. It employs both R2R and Multi-Bit chips (DAC8143 & CS4328-KP).

It uses 6x daisy chained AD DAC8143 chips (http://www.analog.com/media/en/technical-documentation/data-sheets/DAC8143.pdf), which are 12-bit R2R. Then it uses 3x Crystal (Cirrus) CS4328-KP chips (http://www.wolumen53.com/pdf/CS4328-KP_Crystal.pdf), 18-bit /multibit Delta-Sigma.

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Za Warudo

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Re: Vintage R2R/multibit DAC Thread
« Reply #53 on: May 30, 2015, 11:53:01 PM »
Quote from: AustinValentine on May 30, 2015, 09:53:26 PM
Nice pickup! I keep considering picking one up myself.

The setup of the Angstrom 200 is...well...a bit complex. It employs both R2R and Multi-Bit chips (DAC8143 & CS4328-KP).

It uses 6x daisy chained AD DAC8143 chips (http://www.analog.com/media/en/technical-documentation/data-sheets/DAC8143.pdf), which are 12-bit R2R. Then it uses 3x Crystal (Cirrus) CS4328-KP chips (http://www.wolumen53.com/pdf/CS4328-KP_Crystal.pdf), 18-bit /multibit Delta-Sigma.




Interesting.  I wonder which of the chips it uses for just stereo DAC function instead of all of those chips for its DSP.  I'm going to keep it on to see if it benefits from warm up.
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kothganesh

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Re: Vintage R2R/multibit DAC Thread
« Reply #54 on: May 31, 2015, 02:06:56 AM »
Quote from: AustinValentine on May 30, 2015, 09:53:26 PM
Nice pickup! I keep considering picking one up myself.

The setup of the Angstrom 200 is...well...a bit complex. It employs both R2R and Multi-Bit chips (DAC8143 & CS4328-KP).

It uses 6x daisy chained AD DAC8143 chips (http://www.analog.com/media/en/technical-documentation/data-sheets/DAC8143.pdf), which are 12-bit R2R. Then it uses 3x Crystal (Cirrus) CS4328-KP chips (http://www.wolumen53.com/pdf/CS4328-KP_Crystal.pdf), 18-bit /multibit Delta-Sigma.



AV, meaning to ask you this...youmentionedthat some mods to the Adcom 600 really help. Do you know what they are? Thanks
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AustinValentine

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Re: Vintage R2R/multibit DAC Thread
« Reply #55 on: May 31, 2015, 02:40:27 AM »
Quote from: kothganesh on May 31, 2015, 02:06:56 AM
AV, meaning to ask you this...youmentionedthat some mods to the Adcom 600 really help. Do you know what they are? Thanks


Definitely! This thread from Polk Audio here covers all of the cap and opamp modifications. (The associated Audiokarma thread is here.)
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rb2015

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Re: Vintage R2R/multibit DAC Thread
« Reply #56 on: July 12, 2015, 02:19:28 PM »
I posted this over on another thread - but is might be better here:

Couple of DACs I've had success with:  The APL NWO and recently a heavily modded Lite DAC60.

Now the NWO is $20K+ but the Lite DAC60 with mods (most important Mundorf Supreme Silver/Gold/Oil coupling caps and better tubes '75 HG 6N23p are my favorites) - is very competitive.  Stock excellent for around $600 + another $500-$800 in mods outstanding!

A few features on the DAC60:

True R2R PCM1704K 24bit ladder DAC chips.
True (not an opamp buffer) 6922 tube output section
Separate PS for Analog and Digital Sections

Here is the thread I started on Headfi for the mods:
http://www.head-fi.org/t/740362/lite-dac60-pcm1704-r2r-tubed-dac-mod-project

This thing is sooo sweet sounding, yet detailed and resolving, extended tight bass and wide and deep sound stage.  The best is the rich natural tone - I listen to this for 8-10hrs a day in my office system.  Just captivating.  Better then any SS DAC I have heard yet.

Feeding it with a modded Melodius MX-U8 (Audio Sensibilities silver ref 1.5M RCA SPDIF), custom dedicated iCore 5 WIN7 Pro music server.
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rb2015

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Re: Vintage R2R/multibit DAC Thread
« Reply #57 on: July 12, 2015, 02:20:52 PM »
Some other good info on different DAC designs:

Here are some great articles that explains Resistor ladder DACs vs the sigma-delta and multi-bit newer designs.  All have issues.  The R2R's are very expensive and difficult to make, the S-D have major filtering issues and the Multi-bits have on silicon opamps.

http://www.mother-of-tone.com/conversion.htm
http://funwithaudio.blogspot.com/2012/01/today-in-electronics-everything-is-made.html

With the DAC60 you do give up a few things - like no I2S input, no DSD native processing (I use Foobar conversion to PCM), and limit to 96K sampling and 24 bit depth.  But how many folks have 192K - true Ultra Hi Res downloads?  Or true (not resampled) DSD files?

What you get is amazingly detailed and smooth sound.

Some of the very best DAC's use R2R ladder DACs - like Audio Note, Total DAC, MSB, Audio-gd (Master 7 - uses the same PCM1704 but twice as many), Zanden, etc...
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LarryHo

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Re: Vintage R2R/multibit DAC Thread
« Reply #58 on: July 16, 2015, 04:58:35 AM »
Find something has PCM1702 or PCM63 there. IT's classic.
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Marvey

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Re: Vintage R2R/multibit DAC Thread
« Reply #59 on: July 16, 2015, 05:30:26 AM »
Agreed. PCM1702 and PCM63 > PCM1704.
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