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Re: [softrock40] Re: USB Soundcard (minimal size)

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  • Rajiv Dewan, N2RD
    I ordered the build yourself kit for the USB AD/DC and will report back the group. Raj, N2RD -- Rajiv Dewan, N2RD n2rd@arrl.net FN13fc --
    Message 1 of 54 , Apr 2, 2007
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      I ordered the build yourself kit for the USB AD/DC and will report back the group.
      Raj, N2RD


      Rajiv Dewan, N2RD




      On Apr 2, 2007, at 9:10 AM, RAY wrote:

      Perhaps my language is a little too harsh, It isn't too shabby but 89db
      dynamic range could be better, in the real world we may not see the 89db may
      be 84- 86 db) and SNR is a little off for range of the SOFTROCK. but again
      for the price it is unbeatable. Unfortunately I do not own one so I can
      not measure real performance. I didn't mean to scare folks off the device -
      just saying not to expect to be a one-on-one hot USB device that competes
      with newer boards. But as you point out for low end laptops it is probably
      the most cost-effective solution, especially since you can do stereo IN/OUT.
      If you don't mind doing a few Xtals to get back the range it should be fine.
      Let us know what you see when you get one online. I will probably order one
      just to play with it, certainly is cheap enough. Good luck it will be
      interesting to see one in the application with SOFTROCK. The other side of
      the story is I like the pin profile for Homebrew mounting.

      73, Ray, N0FY
      ----- Original Message -----
      From: Edson Pereira
      To: softrock40@yahoogroups.com
      Sent: Monday, April 02, 2007 6:06 AM
      Subject: [softrock40] Re: USB Soundcard (minimal size)
      What specs do you think would cripple the Softrock? The chip does
      indeed has a 48 kHz sampling rate limit, but that is the maximum one
      can have on a full-duplex 12 Mbps USB. With all the limitations, I
      find that the PCM2900 has better quality than most of the 16-bits
      sound cards.
      -- Edson, pu1jte, n1vtn

      --- In softrock40@yahoogroups.com, "RAY" <WA2HVI@...> wrote:
      > IMHO: I just came from the spec sheet and from all appearance this
      chip will
      > cripple a softrock receiver in a few ways - yes it is minimal and a
      lot I/C
      > for the buck for its size but also minimal in performance. Perhaps I
      > missed something on the spec sheet - I would love to be wrong. It
      is a nice
      > stereo chip.
      > 73, Ray, N0FY

      > Thanks Ignacio, I just ordered two built units to play with. Any
      > idea on Linux support?
      > Terry
      > --- In softrock40@yahoogroups.com, Ignacio Cembreros <eb4apl@>
      > wrote:
      > >
      > > Terry wrote:
      > > >
      > > > Hello Tom,
      > > > Have you played with the PCM2900 to see how well it works with
      > > > SoftRocks? Are there appropriate drivers for Windows XP and/or
      > Linux?
      > > >
      > > > VERY INTERESTING....
      > > >
      > > > I ran into a reference to an article in Nuts and Volts from June
      > 2005
      > > > that has a board available for $25-35 that incorporates this chip,
      > > > and was wondering it this setup would be good for laptop softrock
      > > > use. I presently use either the Audigy 2 ZS PCMCIA, or an Extigy.

    • Terry
      ... a year ... so I can ... affects the ... components, ... should be ... the ... the ... the ... and ... done ... that ... codec. I ... in the ... affacted
      Message 54 of 54 , Jul 31, 2007
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        --- In softrock40@yahoogroups.com, Ignacio Cembreros <eb4apl@...>
        > Guido wrote:
        > >
        > > On 7/30/07, *Ignacio Cembreros* <eb4apl@...
        > > <mailto:eb4apl@...>> wrote:
        > >
        > > Terry, Guido et all.
        > >
        > > I bought the same kit mentioned in Nuts and Volts, more than
        a year
        > > ago. Finally I found the kit documentation in digital format
        so I can
        > > describe the problems I had.
        > >
        > > The picture has an error, a swapped resistor pair, which
        affects the
        > > balance. If you have followed the picture for placing the
        > > like me, you swapped R11 and R13. R11 should be 6k8 and R13
        should be
        > > 3k9 and they must be located as per the silkscreen, not per
        > > picture.
        > >
        > > Another error is in the PCB itself which doesn't agree with
        > > schematic and is related to the supply method. This affects
        > > performance, according to TI.
        > >
        > > My solution is to cut the trace which goes from C2 to a via
        > > finally
        > > to U3 pins 8,9 and 27; do it just after C2 and solder a wire
        > > jumper from
        > > C2 (or C1) to R9 (VBUS in the schematic). All this rework is
        > > in the
        > > bottom side of the card.
        > >
        > > As you can see, both problems can be easily fixed, and after
        > > I use
        > > this mini card for demos with an SR40 with reasonable results.
        > >
        > > 73 de Ignacio, EB4APL
        > >
        > >
        > > Hello Ignacio,
        > >
        > > Thanks for reporting about your experience with the PCM2900
        codec. I
        > > have no access to the Nuts and Volts schematic, but presume the
        > > circuit is not different than the typical circuits as published
        in the
        > > datasheet [1] ? Could you indicate which of the components
        > > the performance?
        > Guido,
        > I was referring to a PCB layout error in the Nuts and Volts kit
        > not in the schematic which is close to the TI evaluation boards,
        > minor variations.. If you are interested in the schematics and the
        > description, let me know it and I will send it directly to you.
        > According to TI, the circuit can be powered from the internal
        > or an external one. The use of the internal regulator affects
        > negatively to the harmonic distortion and maybe the noise, I don't
        > the application notes here but are on the TI site. So TI
        recommends to
        > use a cheap external regulator, except for very cost sensitive low
        > applications.
        > --
        > 73 de Ignacio, EB4APL
        Thank you for the above information. I checked my ADDA board, and it
        has both the problems you mentioned above. I purchased the assembled
        units, not the kits, but the resistors were wrong anyway.

        I ahve made both the changes you outlined above, and will test the
        board for improvements. It certainly cannot be worse that the board
        originally performed!!

        It will likely be a week before I can test it, as I have some travel

        Thank you again for highlighting the two problems above. I do not
        have the original Nuts & Volts article. I have only the schematic
        that came with the board, and the TI datasheet.

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