[IDEA] Upgrading my DAC Hat

[doobster]

I've been running moOde 4.4 since 2018 and have been pretty happy with the quality of the audio I'm getting.  My setup is a Pi-2B with a HifiBerry DAC+ Pro hat (floating and powered by a linear power supply I built), going into a passive preamp with a stepped attenuator (which is sitting at 0 db - full volume, as volume is controlled by hardware in moOde), going into an ATI 1502 amp and feeding a pair of NHT 3.3 speakers.  I'm not an interconnect freak, so my RCAs were built by myself and are 1 foot from Pi to preamp and 2 feet to amp, and my speaker cables are just 12 gauge zip cords.

Recently I upgraded to 8.2.1 and am wondering if there are any better DACs available now.  Back in 2018, the HFB DAC+ Pro was a very good compromise between quality and cost, but are there better DAC hats that would be around $100?  Would they be considerably better than the HFB DAC I have now?  Would upgrading for Pi3 and 64bit do anything to sound quality?  I don't want to go to Pi4 because I don't want the fan, even if it's totally silent.

Thanks.

[HEGOM]

Hi doobster.

i have a PI4 fanless. The case is absolutely able to 'waste' heat and its working since years now. No problems at all.
PI4 has a better management of USB and i connected an external DAC.
I found a topping E50 and iam quite satisfied of results.

[the_bertrum]

I also run Pi4 without fans "enclosed" in plastic tubs that takeaway noodles came in. Heat is not an issue.

[TheOldPresbyope]

@doobster

There are a variety of passive heat dissipation techniques for the Pi4B that keep it from over-temperature throttling but adding a HAT to the board complicates life. The combination can get pretty toasty in tight quarters. I run one Pi4B in an Argon One case with no fan and a USB DAC. The case gets noticeably warmer than ambient but not unpleasantly so. Just now, at idle, the CPU temp is 39 Celsius in 21 C ambient air.

As for sound quality of different DACs, it’s so subjective I wouldn’t venture an opinion. Some people (me included) like amirm’s Audio Science Review site; others hate it as too focused on measurements. Nevertheless, I’d start there to collect a short list of ca $100 “recommended” DACs to consider.

Several years ago I bought a Khadas Tone Board v1 for about that price. It’s my only USB DAC and I’m quite satisfied with it. No case and no extra features such as a display at that price. If I were to get another DAC I’d probably consider the Topping offers.

Regards,
Kent

[DRONE7]

Everything @TheOldPresbyope said. :-)
Also running a Pi4 in an Argon One case and same result.

Home-brew DAC with DiyinHk usb receiver, multiple power supplies and ES9028 board.
https://www.diyinhk.com/shop/
https://www.mouser.com/ProductDetail/ESS...DeVw%3D%3D
https://www.diyaudio.com/community/threa...00.297610/

[hifinet]

If you have not heard nonoversampling DACs, I would recommend a trial. I think the oversampling filters in most modern delta sigma DACs cause significant problems. You can turn off the OS filters on your PCM5122 by upsampling to 32/384. SoX in Moode can do it, and does a better job than the internal OS filters.

The PCM1794 is well thought of, but only when the internal OS filters are turned off. Turn off internal OS filters, and your DAC will sound much better.

For less than $50 you can get an L1387 USB, which uses the TDA1387 DAC chip, an old Philips multibit DAC chip. This uses USB (or SPDIF) input and has RCA output, and even a built-in headphone amp. It is powered from USB. This will give you a flavor of nonoversampling (NOS).

My current DIY HAT uses a TDA1387 x 8 module (usually used as a plug in replacement for the famous and rare TDA1541). There is minimal parts count with two I/V resistors, three metal film 470R I2S resistors, two 10 uF coupling caps, one audio electrolytic cap, HAT proto board and RCA jacks. Cost can be less than $20. Construction time a few hours. Use the generic drivers in Moode. My build uses premium I/V resistors (naked bulk metal foil $10 each) and expensive, high quality film coupling caps. But, 1/4W AB carbon comp resistors sound excellent. The resistor value is critical. Inexpensive Silmic II sound very good as coupling caps. Recommend an audio quality electrolytic. This is probably the easiest to build DIY DAC. The TDA1387 not only sounds great, but is easy to use. I2S input straight from the RPi GPIO, single 5V supply from the GPIO, bitrates up to 384k.


TDA1387 x 8 module

[DRONE7]

Would you care to post a detailed build thread for that ?
I have an ancient Phillips cd-650 c/w TDA1541 and would be interested to reuse.

[chano22000]

I am personally very happy with the following hat board which is fully supported by moode (I2S and SPIF input selection - reconstruction filters selection)
AUDIOPHONICS DAC I-Sabre ES9038Q2M Raspberry Pi / I2S & SPDIF / PCM DSD USB-C Power Supply - Audiophonics

[hifinet]

Would you care to post a detailed build thread for that ?
I have an ancient Phillips cd-650 c/w TDA1541 and would be interested to reuse.

It will not work with the TDA1541, which is much more complicated and has greater parts and power supply requirements. On the TDA1387 x 8 module, of the 28 pins, only 7 pins are actually connected (I2S, V+, GND, Left out, Right out).

I can post the pictures of the top and bottom of the board for the TDA1387 x 8 module, if interested. It is very simple. The I/V conversion process is passive. There is no filter on the output. 

It is possible to use upsampling in Moode using SoX up to 384k, but I have found that the native bitrate always sounds better than the upsampled. I think this is due to innaccuracies with SoX, even with the highest quality settings.

When I had a PCM5122 DAC, similar to OP Doobster, I found the best sound quality could be obtained by SoX upsampling to 384kHz. This turns off internal chip oversampling filters. It does require an RPi 3 for stable operation. It might be worth getting a trial use of PGGB. It only does integer upsamples and I think the PCM5122 needs to see 384kHz sampling rate to turn of the internal OS filters. PGGB also needs a fairly powerful computer with a lot of RAM.

I have upsampled a few files using PGGB (performs a windowed sinc function) with over 100 million taps to 16/384, and I cannot hear a difference from the native bitrate file with the TDA1387 x 8 DAC.

The TDA1387 DAC is limited to 16 bits. It can play 24 bits, but truncates the least 8 significant bits. It still sounds great.

The TDA1387 is a very interesting design. The end of the multibit era. It uses continuous calibration of the five most significant bit current sources, so it has 32 current sources and one spare source. Philips multibit DACs are also unique in that they do not use resistors like the Burr Brown DACs, but use active devices to generate the currents.

[Tim Curtis]

Would you care to post a detailed build thread for that ?
I have an ancient Phillips cd-650 c/w TDA1541 and would be interested to reuse.

It will not work with the TDA1541, which is much more complicated and has greater parts and power supply requirements. On the TDA1387 x 8 module, of the 28 pins, only 7 pins are actually connected (I2S, V+, GND, Left out, Right out).

I can post the pictures of the top and bottom of the board for the TDA1387 x 8 module, if interested. It is very simple. The I/V conversion process is passive. There is no filter on the output. 

It is possible to use upsampling in Moode using SoX up to 384k, but I have found that the native bitrate always sounds better than the upsampled. I think this is due to innaccuracies with SoX, even with the highest quality settings.

I have upsampled a few files using PGGB with millions of taps to 16/384, and I cannot hear a difference from the native bitrate file.

The DAC is limited to 16 bits. It can play 24 bits, but truncates the least 8 significant bits. It still sounds great.

The TDA1387 is a very interesting design. The end of the multibit era. It uses continuous calibration of the five most significant bit current sources, so it has 32 current sources and one spare source. Philips multibit DACs are also unique in that they do not use resistors like the Burr Brown DACs, but use active devices to generate the currents.

The 1387 is legend for NOS designs when implemented well.

Consider offering some pre-built DAC boards. I'd definitely buy one.
Is it a HAT form factor?

-Tim