ProtoDAC TDA1387 X8 project

[jwchen119]

It's not a dead short, but a semiconductor voltage drop? It might vary with the type of meter, but with my DMM it beeps with a semiconductor and then shows voltage drop. With dead short, it beeps and then measures a resistance.

The other question I have with your module is that all the ceramic caps are the same size. Did they just use all 100nF caps to lower cost?

The seller has blank PCBs? I would like to get modules without the pins. That would make it easy to stack modules. I want to try 100R I/V resistors and four paralleled modules. I have removed pins and stacked two modules.

The TDA1387 X4 modules are back. The ones with the 1uF electrolytic pin 7 caps and 100nF film decoupling caps.

It looks like the seller is measuring resistance with 10k level. And the value shows 3 multiply by 10K to get 30K(Weird, should the pointer be on the far left if it is OL?)
All of the capacitor seems to be the same dimension, not sure about the capacitance value.
I'm not sure where to measure next, guess I should buy one blank PCB to measure by myself...

[hifinet]

See post #606. RPi 4 would not boot with the official Pi power supply. ProtoDAC doesn't use much current, but the 2000uF of the C3/C4 caps might result in the power supply going into protection mode at startup.

[jwchen119]

See post #606. RPi 4 would not boot with the official Pi power supply. ProtoDAC doesn't use much current, but the 2000uF of the C3/C4 caps might result in the power supply going into protection mode at startup.

I actually have 2 "old" TDA1387x8 modules bought from Taobao but it is making some noise, I have discussed with you via e-mail few month ago.
When I mentioned Pi is not booting, swap the module with the old one, then booted normally.
I have tried Pi4 official power supply and 5V/35W PSU by Meanwell but none will booting with these 3 new modules.
I believe the power supply itself is not the cause, but the module is.

With the proper modules, I can even boot the Pi with ProtoDAC from PC's 500mA USB-A port!
I'm using the Pi+ProtoDAC as "hardware" DRC machine.
By setting the Pi4 as USB gadget to receive the signal from digital source and process the convolution files with CamillaDSP, then output the analog by ProtoDAC.

[hifinet]

Ali listing says "replace TDA1541". That is definitely not the case with those modules. It's unfortunate that there are bad modules out there.Noisy ones from Taobao and some incompatible ones from Ali.

How do you "set Pi 4 as USB gadget"?

[gperpetuo]

Ali accepted to refund me so already dissoldered the caps. Still have the short. I think I'll remove all chips to try to better understand the issues

[jwchen119]

Ali listing says "replace TDA1541". That is definitely not the case with those modules. It's unfortunate that there are bad modules out there.Noisy ones from Taobao and some incompatible ones from Ali.

How do you "set Pi 4 as USB gadget"?

Guess what, the seller claim it's the direct replacement of TDA1541/TDA1541A.

Check here for the USB gadget or here
   
   

[hifinet]

Thanks for the links regarding USB gadget. There was a thread here about adding this functionality to Moode.

Personally I have no interest in Camilla DSP. No digital room correction except possibly in the subwoofer region or as a digital volume control. Much better to use room treatments and speaker positioning, with decent speakers.

The flexibility to use USB from a computer (probably with a USB isolator) would be nice .Many people are reluctant to use a digital audio system like Moode. Gadget mode can run on a Zero. Not sure how well this works compared to a dedicated USB to I2S device.

[jwchen119]

...

Personally I have no interest in Camilla DSP. No digital room correction except possibly in the subwoofer region or as a digital volume control. Much better to use room treatments and speaker positioning, with decent speakers.

...

Actually, before I came across REW and some high-quality, well-structured tutorials, I had the exact same thoughts as you. However, after giving it a try, my perspective on this new tool completely changed.
Focus on correcting only the frequencies below the Schroeder frequency, which are dominated by room mode, I achieved tighter, more powerful bass, clearer mids that weren't masked by low frequencies, and highs that emerged as bright as they should be.

You can easily confirm through measurements and simulations that adjusting speaker placement alone is almost never enough to solve resonances cause by the room mode.

CamillaDSP is a excellent tool to impelement multiple filters including FIR/IIR convulution engine, which means you can easily apply the target EQ export from REW.

[DRONE7]

@jwchen119 " high-quality, well-structured tutorials"

Links ? :-)

[hifinet]

Focus on correcting only the frequencies below the Schroeder frequency, which are dominated by room mode, I achieved tighter, more powerful bass, clearer mids that weren't masked by low frequencies, and highs that emerged as bright as they should be.

This does make sense. I will investigate, but I don't like equalization.

I currently have the speakers far away from walls. The equilateral triangle of speakers and listening position has been consistent in three different rooms. Trying to have the majority of sound direct. Then bass traps in the corners and absorption/diffusion for first reflections. It works very well., and the experience is very realistic. If reflections and room modes are a problem, the volume level is unrealistically loud. The only instruments that aren't realistic are concert bass drum (although it's pretty good on some recordings) and bass pedal organ. Those would be hard to achieve in a normal sized room.