I finally have proven to myself Bits are Bits and the SqueezeBox 3 (no mods) transmits every last one of them. I was discouraged to hear folks talking about Linear vs Switching power supplies, changing caps and who knows what else. The standard SqueezeBox 3 transmits (over SPDIF) perfectly. What really got me was the Coax vs TosLink debate. I have, as many of you have, had done a sanity check with a DTS CD. But some folks argue that DTS may have error correction (or recovery to smooth over errors) even if the pipeline isnt perfect. So it wasnt proof enough for some.
To test I generated a simple 200 Hz sine at max amplitude in MatLab. Then sampled this at 44.1Khz for exactly 2 seconds and saved it to wave file. I did this because it was important I knew exactly when it started and ended. I then played this on the SqueezeBox 3. The simple max amplitude sine wave does not have to be any more complex. It measured the full dynamic range and a good many levels in between (441). The hardware does not care what order the data is (i.e. how many simultaneous frequencies) the DACs, crossovers and speakers worry about that. I could just as easily used complex music. But I would have had to add markers to help line things up for comparing. I may do this in the future for grins. I chose 200 Hz so I could hear it on my PC speaker working in MatLab. Recording this was a bit of chore. I went through 5 USB SPDIF input/output devices (2 of them twice) before I was happy. Folks at guitar center hate me. I tried a Fast Track Pro, EMU 0404 and Audigy 2 PCMCIA, Fast Track Pro again and finally the EMU 0404 again. You must use ASIO (or similar) drivers to get data bit perfectly in and out of the PC. What was nice with the EMU is it came with tons of software including WaveLab Lite which was the perfect tool for this. Most ASIO software are multi-track Recorder/Mixers that dont mind resampling or normalizing. The folks that sell WaveLab invented ASIO. To test the softer I actually managed to loop a DTS Track through SqueezeBox 3, into EMU 0404, into WaveLab (in monitor mode) back out the EMU 0404 and into the Meridian. Without skipping a beat. I could record the stream at will and then play it back. I needed this base line before looking at bits in the MatLab generated waveform. Then I finally recorded my MatLab waveform out of the squeezebox and saved it to disk. Question was, was it bit for bit, sample for sample the same. I had to edit the recorded waveform down to the exact samples I started with. This was tedious but fairly easy to confirm and do in WaveLab. Then I read it back in MatLab and plotted the difference between the two vectors. And they were ZERO. In fact the files were so close (even the headers) I was able to diff then with FC/b in Windows (FileCompare in Binary). For grins and Im sure this has been done before. I burned the waveform and ripped it to see if anything was lost there as well. Header were different and I could not diff them with FC. So I used MatLab and they were the same. So if youre hooked up with SPDIF you can do no more perfectly than a standard squeezebox 3. If you want 24/96 or need good analog then you may consider mods or a transporter. Oh yeah I recorded off the Coax. -- mswlogo ------------------------------------------------------------------------ mswlogo's Profile: http://forums.slimdevices.com/member.php?userid=9090 View this thread: http://forums.slimdevices.com/showthread.php?t=34292
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