DAC AD1862: Almost THT, I2S input, NOS, R-2R

[diyiggy]

mostly the link to miro site page

 

[miro1360]

@Vavilen exactly as diyiggy mentionted, the first link contains almost every shortcut
here are configurations:

• without shift registers (direct drive by jlsounds) #2225
• with shift registers (normal I2S) #617

 

[crymen]

not only more dynamic, but I feel myself immerse into music with deep and clear bass.

Which DAC are you referring to? PCM1702?

 

[grunf]

@NIXIE62 @lcsaba @grunf
PCM1704 (used without digital filter) is very good DAC, I compared it for about 1 full year with the AD1862 (the same topology, the same power supplies, the same I/V). Every time I turned on the AD1862, I was somewhat more satisfied with the sound, PCM1704 sounds slightly colder to my taste
I would like to see the the new PCM1704 for $20 on mouser then i would buy it

I have never listened to PCM1702 or PCM1704 without a digital filter. At the time when they were popular, I was in the hi-fi trade and I heard a lot of players and dacs with them in combination with the PMD100 or PMD200. Krell and Wadia had these combinations and many other manufacturers in the lower price range and they generally played better than other combinations of dacs or filters.
Since those days, my obsession with BB dacs and PMD digital filters continues, even though I had NOS dac for many years so I would no longer go in that direction.
I tested NOS TDA1541A and PMD100+2*PCM1702 a long time ago, with the same power supply, passive I/V and tube output stage, the receiver in both cases was CS8414, and unfortunately that's where NOS TDA1541 lost the battle, since then I sold and donated the excess TDA1541A and I left only one from the first series.
As for the TDA1540 itself, I listened to it a couple of years ago and I had no complaints about the sound, on the contrary it was very analog but it still lacks the detail and precision of its bigger brother so maybe that's why the impression of deep bass.
The first picture is is from 2011 when I did the NOS TDA1541 vs PMD100+PCM1702 tests.
The second picture is the finished DAC from 2012, which was presented a couple of times at DIY audio gatherings and festivals.

 

[NIXIE62]

PMD-100 & 200 are also outdated and hard to find components. And the topic is mainly about non-oversampling DACs. If @miro1360 had followed that path in design, with PMDs, nothing would have come of this topic, nor would so many people have done so many devices and enjoyed it. This is so simple, a small child can assemble it.

 

[ra7]

Hey guys, I am nearing completion for the TDA build. Where can I get readymade connectors for the 4x2 data block? I tried a cursory search at Amazon but couldn’t zero in on it. Thanks in advance!

 

[miro1360]

@ra7 Something like this cheaply from aliexpress or also on amazon: https://www.aliexpress.com/item/32966292996.html
search like "arduino jumper wire breadboard dupont" ... different types (like female-female, male-female) and different lengths

 

[miro1360]

@grunf I can confirm that the PCM1704 NOS (and 1702) is better than TDA1541A, and also AD1862 is better than TDA1541A ... and TDA1540 is also better ... In my opinion the TDA1541A is overrated and overpriced
Anyway it is nice to have it in the vintage collection, it is like an old veteran - you won't race it, but you have it in the garage and sometimes you try its seats

 

[lcsaba]

@miro1360 Then TDA1541A is like my first car, the VW Beetle. I liked it very much. I would like to have one an listen the engine. It had really deep bass. It's true, not for racing, but I woul still drive it these days. Overpriced too, if you find one in good shape.

 

[Brijac]

@grunf I can confirm that the PCM1704 NOS (and 1702) is better than TDA1541A, and also AD1862 is better than TDA1541A ... and TDA1540 is also better ... In my opinion the TDA1541A is overrated and overpriced
Anyway it is nice to have it in the vintage collection, it is like an old veteran - you won't race it, but you have it in the garage and sometimes you try its seats

Miro, you need to redo your tda dac 😊 It cannot be made like the rest of these.

 

[diyiggy]

@grunf I can confirm that the PCM1704 NOS (and 1702) is better than TDA1541A, and also AD1862 is better than TDA1541A ... and TDA1540 is also better ... In my opinion the TDA1541A is overrated and overpriced
Anyway it is nice to have it in the vintage collection, it is like an old veteran - you won't race it, but you have it in the garage and sometimes you try its seats

*it's you hadn't listened the tda1541a in a sota layout yet, imho : it is quite a difficult dac chip toextract the best, as I said its bass performance are better than the tda1540, the mid is no question, the treble can be as good if not better than many, especially late taiwann and most of the time the loudspeaker here is tthe limit...

 

[sworder84]

Hi, guys. I decided to show the pre-final version of my Dac (AD1865). Last week I was added a third transformer but there are questions. The difference was noticeable with a separate feed of the opamps (12V) and now I split the feed with two trans. I can also power up the Jlsound (5V). Opamps is OPA604.
The case is not there yet. I wish there was something else to improve but I don't have idea
I like the sound a lot. I try to connect with Beaglebone as renderer but it works only with another Dac (through usb).
And photos

 

[miro1360]

TPA6120 Headphone Amplifier

TPA6120 is outstanding for audio use. It is a CFA topology and can drive any headphone to its full power
Volume control is logarithmic (best for headphones because the first half of the regulation is more precise, the second half is faster.
It contains relay for switching between headphone output or line output (output from DAC).
The amplifier is free of interference, noise or hum
TPA6120 chip is good for preamp, therefore this headphone amplifier can directly serve as preamplifier for any amp.
Potentiometer is mounted directly on the PCB and the whole headphone amplifier can be mounted on the side of DAC front panel.

• power supply voltage can be from +-5V up to +-15V
• R1/R2 (R6/R7) combination works as attenuator for the headphone amplifier; With default values the headphone output voltage is equal to the DAC output voltage; If double output voltage is needed then R1=100R and R6=100R, R2 and R7 are not installed
• gain can be set by adjusting R4(R9) (gain formula = 1 + (R4/R3))

Start with mounting TPA6120 - carefully solder all legs. Then solder the big hole from the bottom PCB with the TPA6120 package (this is important!)
Add all resistors, diode and relay. Capacitors and connectors can be mounted from the bottom (see pictures). Finally mount the potentiometer.

PCB size: 43 x 65 mm

BOM example:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=78477312e5

 

[diyiggy]

Smart little thing Miro. So it is swapping the buffer stage if exesting after the first I/V stage of the DAC board ? How about Cermet pot ?

thank you for sharing

 

[Vunce]

Neat board Miro.
I'm not interested in the HP function, but as a preamp with volume control. This could be included in the DAC chassis and drive an amplifier directly thus eliminating a stand alone preamplifier box. Or an all in one integrated amp..... lots of potential .

Thanks again for sharing with us!

 

[miro1360]

@diyiggy I am not sure if it is cermet or carbon, or something else, but the tap material is produced for audio ... it can be used along with the buffer, it is very fast CFA.
@Vunce It can work as a preamp with volume control All resistor values can be calculated for a desired output voltage

 

[NIXIE62]

Assembled and inserted the PCM56/AD1860 PCB into the DAC to try that as well. Electrolytic capacitors are Panasonic Low ESR, PP capacitors are Wima, I/V resistor Dale 2k7. So far I only have AD1856N-J for testing (PCM56 clones, used ones from ebay). Tried it with TL071, Burson V6 Classic and OPA1611. The best match is the OPA1611, and I believe the Burson V5 will be the best, but I don't have it at the moment. Compared to the DDDAC I can say the AD1856 is not in the same league. The sound is much softer, lacking a bit of detail. It might be better with the Burson V5. I'm still waiting for the AD1860 to arrive, I expect an improvement over the AD1856.

 

[NIXIE62]

Here are two pictures of PCM63 DAC measurements. The first is noise at the DAC output and the second is noise at the power supplies. Power supply noise exists on all lines, the same everywhere, on all power lines. The same noise is present on RAW DC as after the regulator. I think it's interference from the environment or from the laptop's power supply, and the box is plastic, so I don't have any protection. I didn't notice the oscillations of the regulator or I can't notice them.

 

[NIXIE62]

Sine signals at the output of the PCM63 DAC for various frequencies.

It was measured at a load of 20koma+390pF. It is the same with no load.

The output voltage in the range 20Hz-20KHz is about 2.13VRMS, very linear, say 2.12-2.14VRMS and equal for both channels.

The DAC has a frequency range of -3dB at 18kHz and -6dB at 20kHz when the input is 44.1kHz 16bit or 24bit

The DAC has a FR range of 0db at 20kHz when the input is 96kHz and 24bit or 16bit, I always listen to it above 88.2kHz

The DAC has a FR range of 0db at 1Hz.

All of the above is for PCM63 and Burson V6 Classic. With that Burson, there is also the largest DC offset at the output, around 20mV. With OPA1611 it is say 4-8mV.

The current output itself has DC offset plus the DC offset of the operational amplifier.

 

[NIXIE62]

Square signals at the output (24bit 192kHz). At fewer bits and lower frequencies, everything is of course much uglier.