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Pro-Ject Pre Box S2 digital DAC

Discussion in 'audio' started by miero, May 9, 2017.

  1. youreffer

    youreffer Member

    - the screensaver on the gadget screen is supplemented by an indication of the type of connection and sampling frequency,
    - USB logo changes from red to white
    - on the display of the gadget displays the sampling frequency set in the operating system (correctly displayed),
     
  2. youreffer

    youreffer Member

    - the win 64 bit 1909 operating system correctly connects the device itself from the moment the initial boot is completed (approximately 3 seconds after power is supplied), but the relay that connects the RCA outputs does not immediately work in the device.
     
  3. youreffer

    youreffer Member

    The response time of the relay (connecting the outputs of the RCA) varies from 5 minutes (if you turn it on after an hour of inactivity without power) to 5-6 seconds (if you turn off the external power for a second when the device is fully operational)
    Inside the device are 15 polymer capacitors of 1000 mf at 6.3 volts manufactured by Lelon. As I understand it, these capacitors do not hold the previously received charge, and when idle, they are discharged to a level that does not allow you to immediately connect relay contacts when the device is turned on again. And only after they are recharged for the specified time (up to five minutes - with a 5 volt 1 A power supply) does the relay connect RCA contacts.
    How true are my thoughts?
     
  4. skanderborg

    skanderborg Member

    Hi youreffer,
    my device behaves differently. The relay clicks immediately after the initial boot is completed. That's the right function, I think. The capacitors are electrolytic 1000 uF, not 1000 mF. They are mostly filter capacitors of the power supply. Your device apparently has a timing circuit fault, I think. But repair without a schematic will probably be difficult. If your device is still under warranty, contact your dealer.
     
  5. youreffer

    youreffer Member

    Hi, skanderborg!
    Thank you for your help.
    Be sure to contact the seller soon, the gadget is still under warranty.
    As I understand it, the service manual is hard to find.
     
  6. skanderborg

    skanderborg Member

    Hi,
    Pro-ject's support for this product is very poor. The service manual will be really hard to find. It would help if someone had at least a schematic. Some time ago, I sent a firmware error message to the Pro-ject, but it went unanswered. I'm afraid it won't be possible to get a service manual from the Pro-ject.
     
  7. youreffer

    youreffer Member

    Hi,skanderborg!
    You were right about a timing circuit fault.
    But there are two news.
    First news: I tried connecting PreBox to different USB ports of the laptop - and on one of the four ports - PreBox S2 digital starts immediately within one second of the time the power was turned on - regardless of the time when there was no power until this moment. But only on the headphone jack6. This is good news.
    And the second news: with this connection to the USB port, the output of the RCA gadget is still connected after a long time - as before - from 5 minutes to several seconds (depending on the time the voltage was removed from the external power supply).
    Perhaps the reason for this phenomenon is that the gadget is connected by the outputs of the RCA to the Exelia XK-009 cassette deck, which has an input impedance of about 67 kOhm, and PreBox just does not understand that the cassette deck is connected.
     
  8. skanderborg

    skanderborg Member

    Hi youreffer,
    1/ The switching time does not depend on the load impedance at the RCA outputs. When I connect a load of 100 Ohm or 10 MOhm, switching time is the same.
    2/ I measured the current consumption of the device. I measured 0.38A (idle) and 0.43A (during playback signal 1 kHz sine 0dBFS, load 300 Ohm).
    But the current peaks during the boot sequence are higher. If the USB current rating is not sufficient, the boot sequence will not work properly!
    Before you contact the dealer, test your device on another computer, preferably on a USB 3.0 (USB 3.0 has a higher current rating than USB 2.0).
    Let me know the result.
     
  9. youreffer

    youreffer Member

    Hi,skanderborg!
    Thank you for your help!
    I tried to connect the gadget to another laptop with USB 3, I checked several USB AB cables, but I didn’t get any changes in the gadget’s operation: the jack6 headphone connects instantly in 1-3 seconds; the relay connecting the output of the RCA (connection to Excelia deck), as before, only works after 5 minutes or less, but certainly not quickly.
    Replacing the power supply with a more powerful one (5 volts, current 3 amperes) also did not change the relay response time: the relay turns on the RCA outputs after a long time.
    + examle of work gadget 1khz https://yadi.sk/d/QWQC0qgTEZ6zzQ
     
  10. skanderborg

    skanderborg Member

    Hi yourreffer,
    the timing circuit fault is thus confirmed, I think.
    Your 1kHz example is OK, other circuits work correctly.

    For interest, my measurement (some time ago) is here:

    https://drive.google.com/open?id=1UF0D4MhoammtRlbmUxfZsj8rffrHQvqT
    https://drive.google.com/open?id=1T6_s-83dOhchpR5XpT1K0ihGu-T7xvZz
    https://drive.google.com/open?id=1CB0IBpBJ2alRFZPvYp-Ivrfk3V5kS8W2

    Last picture shows firmware bug, but Pro-ject did not fix the error.
     
  11. youreffer

    youreffer Member

    Hi,skanderborg!
    I conducted tests of the effect of filters on the original signal.
    The original signal is a square wave with a frequency of 1 kHz, a duty cycle of 1: 1
    https://yadi.sk/i/odElOEUcseC7gQ
    original meandr 500 hz

    Results Pre Box S2 digital filters:

    https://yadi.sk/i/RVvFL4nWlhzoDA
    optimal transient

    https://yadi.sk/i/esDMbtKpeGKWcQ
    fast rollof

    https://yadi.sk/i/wUC_VPPiD1HpeA
    slow rollof

    https://yadi.sk/i/ebwhmEwUuji_OQ
    minimum phase fast

    https://yadi.sk/i/Td4MtbkpqvjG3w
    minimum phase slow

    https://yadi.sk/i/NWo5sA3s2NbI9w
    linear apodizing

    https://yadi.sk/i/tOy3zyy6XOTGzw
    hybrid filter

    https://yadi.sk/i/4Dysee0T2UnGTg
    brickwall filter
    IMHO = brickwall filter is best!
    Perhaps this is useful to you in using the gadget
     
    Last edited: Apr 25, 2020
  12. skanderborg

    skanderborg Member

    Hi youreffer,
    thanks for the results of your measurements. Very representative. What measuring device (or software) do you use? I measured the spectral response for white noise (fs = 44.1 kHz, 0 dBFS peak) and my result is here: https://drive.google.com/open?id=1_gGqSLDcO-MhbMSiEZprBKePEWXIobco
    Some time ago, I measured the spectral response for PCM vs DSD (for comparison) and result is here: https://drive.google.com/file/d/1Xy4REoJwc4m0YH45GKCx3xqv77mz21Ha/view
    I have a lot of PCM and DSD recordings and in my subjective impression PCM sounds cleaner and "airier" than DSD. (Tested on Pre box S2D and Sennheiser DH600 headphones).
    Do you have any experience in this?
     
  13. youreffer

    youreffer Member



    Hi, skanderborg!
    I am using the following equipment:
    source - Asus N56JN laptop windows 10 64 bit 1909
    test file - 48 khz\16 bit https://yadi.sk/d/R2wBE4ndwenKUw
    Programm for playing a file - foobar2000 ver 1.4.8 , asio mode, output level in foobar2000 = minus 4db, without sound modification modules
    Output sounds level mixer in the windows operating system = 80 out of 100 ; output mode = 16 bit 48 khz
    Gadget settings:
    - connection = USB
    - signal level in the PreBox S2 digital = 0 (maximum)
    - Distortion - Off
    -Signal Type - User
    - filter - brickwall

    Recording equipment -
    Laptop ASUS ZENBOOK UX52VS windows 10 64 bit 1909
    - ADC Olivin2 (from Alex Torres) = 24bit\ 96 kHz
    - ADC channel recording level in windows = 75 out of 100
    - recording program - Audacity version 2.3.3
    - File Analysis Program - Cool Ed Pro

    Sound
    -Sennheiser HD569 used or DIATONE 77EXV+ DENON PMA 915R (spec
    https://www.hifihouse.de/hifi-gebraucht/denon-pma-915r/ = it has 4 amplifiers (separate output amplifiers of medium and high frequencies and a separate low-frequency amplifier - like the Yamaha A2000))

    The results of the comparison
    -brickwall your https://yadi.sk/i/RKEFsc0EUvudRg
    -my result brickwall for white noise https://yadi.sk/i/gp61jqekS_p-mw
    In my opinion, the results are quite similar.

    In my opinion, the coolest sound format- MQA 352khz
    I am a conservative :) - digital audio stream from program TIDAL i submit to the Pre Box S2 , and then record sound on a cassette (cassette deck Exelia 009), listen to the final result in the recording process . Recording on tape subtly changes the sound and it becomes more physical, felt like the presence of the performer in my room.
     
  14. skanderborg

    skanderborg Member

    Hi youreffer,
    thanks for the detailed description - very good equipment.
    I am "older boy", too. 25 years ago I had a tape recorder Akai GX620 and today I regret selling it. The sound of the tape recorder had its charm.
    If you need high quality measuring signals, look here: https://www.wavtones.com/functiongenerator.php
    I bought the "pro" version (15 USD) and I am very satisfied.
     
    Del monaco likes this.
  15. Del monaco

    Del monaco Del Monaco

    I kept my tape deck.Still sounds charming.
     
  16. skanderborg

    skanderborg Member

    Hi youreffer,
    I tested "Cool Edit Pro" on my laptop with windows 10 1909 64 bit but failed. On a virtual windows XP system it works normally.
    It works for you on Windows 10?
    Do I have something wrong in the system setup or do i need to install some other extensions?
    Thanks for the reply.
     
  17. youreffer

    youreffer Member

    Hi, skanderborg!
    I am using Windows 10 64 bit now.
    Installation history of Сool Edit Pro - previously i used Windows 7 64 bit license - installed Cool Edit Pro usually -then i was updated Windows to 8.1 license - updated Windows to Windows 10 64 bit license -the program works normally.
    Versions
    https://yadi.sk/d/-egDe1mt_V48Ew
     
  18. skanderborg

    skanderborg Member

    Hi youreffer,
    everything is already OK. In windows 1909 it was necessary to set the program's compatibility with windows XP SP3 and everything is already working.
    Thanks.
    Were you able to solve your Pre box S2D switching problem?
     
  19. youreffer

    youreffer Member

    Hi,skanderborg!

    Thanks for the help and support.

    Unfortunately, until now, the issue of the delay in connecting the relay outputs of the RCA in the gadget has not been resolved - the manufacturer’s support and regional support received all the necessary technical details from me, but they did not provide a solution.

    On the other hand, guaranteed after 5 minutes after turning on the gadget works perfectly.
    I can imagine that Pre Box S2 digital is assembled on lamps ... :)
     
  20. skanderborg

    skanderborg Member

    Hi youreffer,
    support is generally bad (in the style "pay and go to hell"). Perhaps some information could be provided by JohnW, who posted occasionally on this forum. He is the designer of PB S2D.
    But I have one more idea. It could also be a software glitch.
    You can try the following:
    1/ Download Device Firmware Update Utility (Windows) [zip] and Firmware v2.12 [zip] here: https://www.project-audio.com/en/product/pre-box-s2-digital/
    2/ Try reloading the firmware.
    Let me know the result, please.
     

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