IVX
Major Contributor
It was last year, I've got an idea to add to a DAC THD analyzer working on the same principle as APx555(analog notch filter +DSP and some "photoshop" to turn notched FFT plot to a normal view). The very first proto I made was on a mono PCB, and had unsolvable current loops problem(probably 6 and more layers would help). The second one I made the same like AP analyzers does 30 years i.e. mother PCB and small modules, daughter PCBs on it. That approach instantly eliminates current loops issues, in the result, inexpensive single ES9038Q2M shows SNR/Dynamic range -126/126db(A-weighted, actually, so far I've got -125.6db but I hope to tweak it up), and distortions level -130-135db + cleanest noise floor like a baby's tear!
Now a little about the analyzer. A normal analog notch filter for 1kHz should contain highly precise resistors and capacitors and at least two potentiometers to adjust F and Q as during production and calibration during exploitation as well. I moved a bit more parameters from analog to the digital domain to avoid such adjustment at all, and it works, hence, I can offer soon $100/pcs range PCB assembly 150x50mm with:
USB-C1 input 32/384 DSD256
USB-C2 for the power only
ES9038Q2M single or dual configuration(one or two DAC daughter PCBs use), ES9038Pro version also possible
XLRs balanced output 4VRMS
3.5mm jack unbalanced output 3.4VRMS, 300mA current, ready for >500mW@16ohm headphones, 330mW@32ohm
just in case 3.5mm jack has optical SPDIF in as well
Bluetooth Low Energy interface to control the analyzer, DSP, and ES9038Q2M registers by iOS/Android app. The app will allow you to see 20 harmonics(1kHz..20kHz) and adjust 2nd and 3rd harmonics levels and see that online at any particular load. If you like, you may minimize distortions for your few favorites cans and save it as presets. Or you can maximize 2nd harmonic up to .3% if you believe it makes tube-sound and so on. In other words, you have your own "AP analyzer" to see distortions up to -130db level, you don't need to visit that site anymore to see the mismatch of specs vs measurements
Also, I keeping the ability to use DSP for the audio as well. I had no such plans but our discord-channel guys asked me to use that option even if DSP has only 24/96 resolution. Almost for free about 100 parametric EQ, compressor itc.
A couple of plots with 1kHz and 12kHz FTT XLR output.
Video shows the DSP analyzer in action(0db corresponds -100db), THD measurement on the fly, and quite good matched with AP analyzer result. Noise floor first, next, no-load distortions, and 32ohm load in the end of the video.
Now a little about the analyzer. A normal analog notch filter for 1kHz should contain highly precise resistors and capacitors and at least two potentiometers to adjust F and Q as during production and calibration during exploitation as well. I moved a bit more parameters from analog to the digital domain to avoid such adjustment at all, and it works, hence, I can offer soon $100/pcs range PCB assembly 150x50mm with:
USB-C1 input 32/384 DSD256
USB-C2 for the power only
ES9038Q2M single or dual configuration(one or two DAC daughter PCBs use), ES9038Pro version also possible
XLRs balanced output 4VRMS
3.5mm jack unbalanced output 3.4VRMS, 300mA current, ready for >500mW@16ohm headphones, 330mW@32ohm
just in case 3.5mm jack has optical SPDIF in as well
Bluetooth Low Energy interface to control the analyzer, DSP, and ES9038Q2M registers by iOS/Android app. The app will allow you to see 20 harmonics(1kHz..20kHz) and adjust 2nd and 3rd harmonics levels and see that online at any particular load. If you like, you may minimize distortions for your few favorites cans and save it as presets. Or you can maximize 2nd harmonic up to .3% if you believe it makes tube-sound and so on. In other words, you have your own "AP analyzer" to see distortions up to -130db level, you don't need to visit that site anymore to see the mismatch of specs vs measurements
Also, I keeping the ability to use DSP for the audio as well. I had no such plans but our discord-channel guys asked me to use that option even if DSP has only 24/96 resolution. Almost for free about 100 parametric EQ, compressor itc.
A couple of plots with 1kHz and 12kHz FTT XLR output.
Video shows the DSP analyzer in action(0db corresponds -100db), THD measurement on the fly, and quite good matched with AP analyzer result. Noise floor first, next, no-load distortions, and 32ohm load in the end of the video.
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