SMSL DP3 un petit lecteur réseau surprenant et performant

[Poogo]

(05-02-2020, 08:30 PM)renan a écrit :

(05-02-2020, 08:14 PM)Poogo a écrit : The expansion of the stereo base in DP3 is done simply: the signal from the main channel with an 18dB level and an inverted signal is mixed into the opposite channel. An old trick, I have it in the 1979 Sanyo M9998 boombox. The problem with DP3 is that this effect is independent of frequency (it must be smaller at low frequencies) and there is strong distortion at the signal peaks (look at my oscillograms). In any case, I think that the player should give a clean, unprocessed signal at the output, and then you can do whatever you want with it.

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(05-02-2020, 07:58 PM)renan a écrit : So in fact you told Hiby and SMSL something they already know, if it was done on purpose...

If this is done on purpose - it should be able to enable / disable.
All the same, this is not a toy for $ 20.

What bring you do perform some measurements? what was your first impressions earing the DP3? what was the initial qualities highlighted for the DP3 in the russian forum? I'm curious about how it begun...

I am not a programmer and not a developer. At the very beginning, I was looking for a budget device that can play high-res audio over the network (all my files are located on two NAS). Of the options, there were only DP3 and a HiFiBerry clone (now I have both). I decided to buy DP3. I liked the sound, but distortion was heard on loud music. The first problem is a small font (I'm a bit blind). The second problem is the inaccessibility of the NAS through the HibyMusic application (I prefer convenience and am ready to sacrifice quality for convenience). I created a topic on our forum and found like-minded people with DP3. I unpacked the firmware and configured it for myself. Member of our forum with the nickname korobkoff recently drew attention to a problem with sound. I disassembled the application in DP3 and found the cause of the problem. It is treated by fixing just one byte, but I searched for this byte for a whole week. I gave a link to our forum, you can read there (google translator will help you). Just be careful with the firmware, on that forum there are versions that replace the bootloader and you can erase your bluetooth MAC address. Nothing terrible will happen, everything will work, but the MAC will be different (generally I advise you to write down your real BT-MAC address, it is visible in the About device menu).
The DP3 firmware that I post here (and on the manufacturer’s website) is safe, they do not replace the bootloader, and if something goes wrong it can always be fixed. In the post above, I wrote how to do this.
Also on our forum there are a lot of technical details on circuitry and repair of DP3.

I’ll add one more pic, this is the Crosstalk chart from original firmware obtained using the Right Mark Audio Analyzer program (excellent program and absolutely free (link)).

On the Сrosstalk graph on the line-out when playing the wave file by the player (white graph) and when playing the same file in DAC-mode (green graph). As you can see, there is no problem in DAC-mode. But when playing the file by the player itself, the problem is obvious (the normal crosstalk of a modern digital device must be <-70dB). This measurement was made by the member of our forum with the nickname korobokoff on the laptop’s built-in sound card, therefore it does not pretend to be accurate, but it reveals the problem.