My immediate worry for now is how to get the expected results from the clock, and adding the phase 2 (AES 110 Ohm output).Fans are used to move air in and out of your Apple product to help cool it. If you find pictures of the new AE 802.11n, let me know I am interested to find out more. This is the same model as the AE I am using (i.e. Keep me posted on your progress.įor the pictures I refer you this link: >I plan on tapping the USB inteface an feed that to a PCM2707, thus bypassing the internal USB to SPDIF (at least that was how the old AE was configured)Ĭdfr: Ok so if I understood you well, instead of the std pcm2705 of the AE 802.11g you want to put a pcm2707 which can deliver I2S. How easy was to remove the casing?Ĭdfr: Not very hard with a dremel, but you have to be careful not to go too deep.Ĭdfr: Yes you basically destroy the casing since it is welded. So far the CD drive (Studer D730) is still a far better source. May be the input wire is too long? I used a separate transformer, rectifier and a 1000uf cap just for this clock which is then regulated with a low noise regulation circuit (150db ripple). I cannot compare with phase 1 anymore but it seems worse, still better than the original AE but. I am not sure why but removing the built in crystal and replacing it with a low jitter clock (10ps 1ppm suposedly as good as tent's clock) has not provided any positive results. This turns out to be a big disappointment so far. All in all much better than the original. It gave a sound with more detail, more subjective dynamic and wider soundstage. The results were very good on both analog output and surprisingly on the digital output. I just wanted to post some updates on this project. There is a lot of buzz on this rosita and db system modified AE: However the newer ones support 802.11n and use a Marvel chip, not sure of their capabilities but supposedly better. The AE I have which is a 802.11g version has the 2705 so as you said limited to 16/44.1. I do not think it will work well.Īpparently itunes does not resample PC or Mac. Your idea of the Teddyreg seemed appealing, but I read that it is for small current. I don't have a link handy just google it. You can find plenty of explanations on how to do that. I cut it with a dremel at the seam between the 2 half. Schematic A which I think is a Sultzer could be better but I am not sure how to calculate the values for 3.3 & 5v as well as not sure if it can wistand 12.A draw.įrom looking at the forum, Jung redulator would be even better but there again the complexity increases and I could not find if actually i works for 3.3v. But true it does not change the fact that the LM317 will provide at best 80db ripple rejection. If the regulator input is less noisy than its output should be a bit better. I made sense to me on the "Garbage in, Garbage out" principle. What I read was that the pre-regulator with the zener would actually help reducing the noise. I'd appreciate if anybody can confirm that my calculations are correct. I have included the schematic in attachment. Rv1 Variable 1KOhm 1/4 Watt (Set at 386 Ohm) Rv1 Variable 1KOhm 1/4 Watt (Set at 706 Ohm) So here are the values that I have calculated: 1 secondary will be used for the 5v 0.7A and the other for 3.3v 1.21A. I plan to use a 30VA Transformer with 2x 9v on the secondary. If I understand correctly the schematic B, the transistor is a pre-regulation stage then the IC1 is the regulator. I think I am going to try schematic B as I think I was able to calculate the right values. What reference of transistor should I use? Can any of those schematics with a LM317 and a transistor handle up to 1.2A with 3.3V and 0.7A with 5V? I am looking for something more advanced than the std LM317, and I found the two schematics in old magazines (LED): This stock power supply is noisy and a quiet one should improve a lot the Analog and dig out. 3) Improve the clock (Apparently without trying to make any publicity Selectronic has a good clock)įrom what I can gather the AE I have 802.11g has a power switching power supply that can deliver 5V 0.7A and 3.3V 1.2A. 2) convert the optical output to a SPDIF coax or AES/EBU output (the PCM2705 has SPDIF output) My objective is to use the AE Dig output to High end dac (Studer D424) and I can envison a project in 3 phases: The modification seems related to the Power supply, the clock and some caps or dig output of the pcm 2705. For instance Apertura Rosita is a modified Airport express ( ). On the web you can find that the Apple Airport Express has been used apparently very successfully to work as a High End wifi audio source. This is a project to improve the Apple Airport express as an Audio Source. I'd like some advice on building a quiet power supply that could deliver 1.2A in 3.3v and 0.7A in 5v.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |