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DAC AD1862: Almost THT, I2S input, NOS, R-2R
DAC AD1862: Almost THT, I2S input, NOS, R-2R
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Old 7th May 2020, 01:32 AM   #1
miro1360 is online now miro1360  Europe
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Default DAC AD1862: Almost THT, I2S input, NOS, R-2R

AD1862 DAC is one of the best analog sounding DACs ever made:
- dynamics is perfect
- no digital fatigue for the ears
- just a pleasant analog sound
- nicer sound than PCM1704 on the same input, power supply and I/V
It was used in the most expensive premium players, whose production has been gradually replaced by economical delta-sigma devices.
This DAC easily beats many modern delta-sigma DACs from the expensive class, if not all of them

I designed a simple THT board in the way, that almost anyone can put it together.
There is a few SMD SOIC shift registers - easy to solder.

It has been built and tested by: (did I skip someone?)
chi0001, Vunce, pistollero, nano35 with update, Paddy Garcia + .2., happylistening, Ripster, galac - custom, Robin De Wolf, manniraj, RickRay


Gerber files are available for download. You can order the boards directly from a PCB manufacturer for a small price. The choice is up to you.
The PCB size is 90x75mm.

Tested PCB for download: =click= (the same PCB is in this first post - PCB in #1 == PCB in #81)
PCB version 1.3 - untested: #1278
PCB version 1.3 (pad) - untested: #1323
PCB version 1.3 - untested: #1351 (I2S header pins rearranged (not only) for PPY's ReClocker (#1330, #1333); 2 different I/V opamp packages: DIL08 and SO08) ... @Traktorist3d, @Vunce


Build notes:
VA: +12V and -12V analog power supply, a filtered regulator MC7812/MC7912 is fine (from OnSemi), or LM317/LM337; no UFO technology is needed; AD1862 has a precise internal voltage reference and internal converters are very sophisticated
VD: +5V and -5V digital power supply; again a filtered MC7805/MC7905 is fine
- you can try other power supplies at any time, write your comparison in the thread; read the thread for hints from other members
I2S: standard I2S (no Alien clocks, R-2R architecture is not sensitive to the pS jitter; or read and ask in the forum and share your own experience) ... there are many ready-made USB-I2S, RPi-I2S, bluetooth-I2S, spdif-I2S, toslink-I2S, MCU-I2S, xyz-I2S devices on the market ... I2S signal can be also sourced from your existing player (find out if there is the signal)
J1-J13: is 0R resistor, or a wire jumper. It can be used as an alternative input for separate power supplies for each channel (no significant advantage with separate channels).
R8, R9: this resistor sets the output voltage from I/V (L-OUT, R-OUT), 1k4==1.4Vp, 2k4==2.4Vp, 2k7==2.7Vp (2.7Vp==5.4Vp-p)
C15, C16, C25, C26: the exact values must be maintained (ratio 1:10), a high quality electrolyte (Nichicon UFG or UKZ), (or a tantalum can be installed), again your preferred choice
R4, R5, R6, R7, TR1, TR2: install only if the MSB trim adjustment will be performed, otherwise let it empty
C31, C36: this is SMD, everyone can solder SMD 1206, it should be a C0G type ... or use polypropylene (PP) THT cap (alternatively it can be omitted)
C37, C38 (C0G type), but let it empty, don't populate it, it was meant as a simple RC filter on the output (about 330kHz cut-off frequency), but it is better without, my AD1862 is without this filter ... someone tried a passive Bass-Boost? #684
@Vunce suggested a great inspiration to install some capacitors from the bottom. It can open a space on the PCB for future experiments (custom I/V boards), or as a way to deal with bigger capacitor packages. Check his build for more details: #141, #339, #525


Operational amplifier has a direct effect on the sound quality and is one of the key parameters of sound in any DAC. Get the opamp only from a trusted supplier, avoid fakes from china (post in the thread only results based on genuine opamps).
Alternatively any custom I/V can be connected (or a high quality audio transformer with ratio 1:10 .. 1:20, low input resistance).
Good genuine opamps, tested, which are not obsolete, in random order: LM6171, ADA4627, ADA4898-1, OPA828, AD797, AD711, OPA627 and much more are discussed in the thread.


Where to find AD1862 chips?
a) AD1862 is still available from eBay, aliexpress or other china stores. It comes as a genuine part, but could have been used before! (DAC chip is not easy to fake, they were often only remarked from a lower grade to a higher grade (N to N-J), sold out as a remaining stocks, or extracted from electronic waste, certainly not produced as a new chip). Read condition on the seller's ad: "Used" or "New".
When you buy such a chip, take a good look at whether it is new or shows signs of use:
- legs bent to round (not straight), very scratchy, corrosion, ...
- signs of abraded surface (remarked)
- remnants of old tin is the worst, because such a chip was extracted using heatgun and can be degraded
b) The last genuine seller of obsolete AD1862 chips is Rochester: Post #290 ... consider a group buy in your location due to a lower postage ... as a group supplier count with additional costs (customs duties, VAT, fee)
Group buys are taking place in the thread, read new posts and stay updated.
c) In old CD players: List ... find out if the chip is soldered or inserted into the socket and get the inserted one


Other shortcuts:
- @Mark Johnson created a nice power supply from LM317/337 + de-noiser + CRC, see his thread: VRDN ... @RickRay tested it with this DAC: #1224
- dual to single opamp adapter from @Vunce: #1140
- 192kHz is nicely playable with XMOS #1272
- how to connect and configure new version of JLSounds I2SoverUSB v.III, read from post #617; note that the configuration and connection without shift registers is different: #538 and configuration pins are described in the manual (don't be confused at this point, without shift registers it is more for testing purposes, you can still use shift registers with JLSounds in standard I2S configuration)
- @Ripster connected jlsounds over the raspberry usb (seems like any USB-I2S can be configured that way) #1373


My recommendation: Start cheap and continue with improvements later.

Don't forget to share your experience with other members in this thread, it is helpful.
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Attached Files
File Type: zip diyAudio_AD1862_DAC-rev1.1_2020-06-20_JLCPCB-Gerber.zip (625.7 KB, 104 views)

Last edited by miro1360; Today at 01:29 PM. Reason: update
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Old 7th May 2020, 01:39 AM   #2
miro1360 is online now miro1360  Europe
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Old 7th May 2020, 01:55 AM   #3
abraxalito is offline abraxalito  United Kingdom
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Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Have you listened to it without the 4n7s on the outputs of the OPA627s? I'm curious how they affect the SQ.
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Old 7th May 2020, 05:12 AM   #4
miro1360 is online now miro1360  Europe
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C37, C38 can be omitted, it is just a simple RC filter on the output (about 330kHz cut-off frequency), my AD1862 is without RC filter
if such a filter is not here after DAC, it will be present at any amplifier input (if not manually removed)
the sound is affected by the capacitor type, it is least affected by the type of PP and C0G (SMD) (they have the lowest THD of all capacitor types)

Last edited by miro1360; 7th May 2020 at 05:17 AM.
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Old 7th May 2020, 05:30 AM   #5
abraxalito is offline abraxalito  United Kingdom
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Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
I wasn't thinking about distortion caused by cap type (I assumed NP0). Rather loading on the opamp output at higher frequencies. Filters at the input of amps generally have higher valued Rs than 100ohm before shunt caps. And have lower values of caps (1n would be about the highest I've seen).
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Old 7th May 2020, 05:48 AM   #6
miro1360 is online now miro1360  Europe
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right, it has to be omitted, or the value with resistor can be changed easily for any combination
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Old 7th May 2020, 11:09 AM   #7
dewdrop is offline dewdrop  Singapore
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Subscribed!
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Old 7th May 2020, 11:59 AM   #8
juancho is offline juancho  United Kingdom
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Subscribed. But why not a nice tube output stage for this DAC instead of opamps?
David
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Old 7th May 2020, 03:31 PM   #9
miro1360 is online now miro1360  Europe
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there are many different tupe output stages, that's why I left the basic opamp with the possibility of Iout for any tube stage ... likewise, power supplies are not on the PCB because everyone prefers something different ... it is only a purely basic solution of the DAC module with endless expansion possibilities
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Old 7th May 2020, 04:18 PM   #10
juancho is offline juancho  United Kingdom
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Quote:
Originally Posted by miro1360 View Post
there are many different tupe output stages, that's why I left the basic opamp with the possibility of Iout for any tube stage ... likewise, power supplies are not on the PCB because everyone prefers something different ... it is only a purely basic solution of the DAC module with endless expansion possibilities
Fair enough! And thanks for the great work DAC AD1862: Almost THT, I2S input, NOS, R-2R
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