Music Server with Improved Apple Airport Express - Page 2

glt · 17th March 2009, 05:14 PM

Yeah, I tap the USB and feed a PCM2707. Also there is a thread on diyhifi.org on using external clock for PCM270X. Seems jitter is determined by internal PLL of the chip...

glt · 17th March 2009, 05:17 PM

Here is a reference to convert spdif from the PCM to AES
http://www.rane.com/note149.html

cdfr · 21st March 2009, 02:25 PM

Thanks glt. I took time to shoot a new picture.
I reduced the clock path an filtered more the clock AC-DC supply. Seems to be improving the sound. Difficult without a scope to tell for sure. Ears are subjective

cdfr · 5th April 2009, 10:51 AM

I completed the last planned modification (Phase 2). Creating an AES/EBU compatible Digital Output.

Basically this consisted in by passing the digital optical output of the AE and soldering directly on the pin 5 of the PCM2705 a cap and pulse transformer 75:110 Ohm.
This resulted in another improvement in sound quality when connected to my DAC.
After spending sometime listening to this last mod, I believe that the customised AE is now on par with my Studer D730 (used as a drive on the same DAC).
Not better (unfortunately) but equivalent, which is already a very good result since the Studer was a great CD player/drive and that the AE is cheaper, and gives the convenience of streaming audio from hard drive.

In summary:
A stock AE (802.11g) with:
- 1) improved power supply
- 2) Electrical digital output (pseudo AES/EBU in this case)
- 3) Improved clock

is equivalent to what used to be a very good drive with a CDM mechanic.

cdfr · 19th July 2009, 08:21 PM

I just tried a new Airport Express change. I kept the two stage regulated power supply, but instead of feeding with rectifier/transformer, I used a car battery 12V 50Ah.
The change seems quite dramatic, the treble seems clearer and the bass tighter. At one point I actually wondered if I had less bass, but I think it is just less confused.

Has any body experience with DAc or preamp driven by batteries. What improvement did you notice?

cdfr · 27th March 2010, 03:19 PM

After modifying the Apple Airport Express 802.11g, I modified the Apple Airport Express 802.11n

Reports were saying the the AE N was much better. Indeed the stock version was already very good and superior to the G version.
Instead of a TI USB DAC, this version actually uses a Broadcom processor with (I think) an integrated 24/96 DAC.
All the voltages are 3.3v instead of 5v & 3.3v.
This N version is what is used in the db system ZardoZ, La rosita and the Micromega Air Stream.
I described (in franch) the modification I made on the homecinema-fr forum.

Basically I made 3x 3.3v supplies with LM317 & a pre-regulation stage, with a 12v battery as the source to remove all noise.
This combination with my Studer DAC beats my previous combination with a CD player as a source.

Has any one tried to perform changes to the AE?
What results have you gotten?
What changes did you do?

qusp · 28th March 2010, 03:45 PM

very interested in trying this out, I have plenty of spare reg PCBs that would be suitable for this. some SMD discrete super regulators and will have some spare salas/iko shunts

cdfr · 28th March 2010, 06:12 PM

Let me know, how it goes. I am very pleased with the results, but as usual I am looking for more

With the pre-regulator & LM 317 I think I am getting more than 80db ripple rejection on the supply.
There might be changes worth while to do on the AE itself, but would need more knowlege of the schematic.

promitheus · 28th March 2010, 10:05 PM

great work!
can the new AE handle 96KHz/24bit?
Can you get that from itunes?

cdfr · 29th March 2010, 05:23 PM

Thanks Promitheus. I am very happy with the results.

Technically the new AE does support 24/96 (I read the broadcom spec), however Apple has not enabled it with the SW flashed or Airfoil, so it is currently limited to 16/44.1 .
Itunes does support 24/96.

5th April 2009, 10:51 AM	#14
cdfr diyAudio Member Join Date: Jan 2005 Location: Seattle	Yet an another update of this project. I completed the last planned modification (Phase 2). Creating an AES/EBU compatible Digital Output. Basically this consisted in by passing the digital optical output of the AE and soldering directly on the pin 5 of the PCM2705 a cap and pulse transformer 75:110 Ohm. This resulted in another improvement in sound quality when connected to my DAC. After spending sometime listening to this last mod, I believe that the customised AE is now on par with my Studer D730 (used as a drive on the same DAC). Not better (unfortunately) but equivalent, which is already a very good result since the Studer was a great CD player/drive and that the AE is cheaper, and gives the convenience of streaming audio from hard drive. In summary: A stock AE (802.11g) with: - 1) improved power supply - 2) Electrical digital output (pseudo AES/EBU in this case) - 3) Improved clock is equivalent to what used to be a very good drive with a CDM mechanic.

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17th March 2009, 05:14 PM	#11
glt diyAudio Member Join Date: Oct 2004	Yeah, I tap the USB and feed a PCM2707. Also there is a thread on diyhifi.org on using external clock for PCM270X. Seems jitter is determined by internal PLL of the chip...

17th March 2009, 05:17 PM	#12
glt diyAudio Member Join Date: Oct 2004	Here is a reference to convert spdif from the PCM to AES http://www.rane.com/note149.html

19th July 2009, 08:21 PM	#15
cdfr diyAudio Member Join Date: Jan 2005 Location: Seattle	I just tried a new Airport Express change. I kept the two stage regulated power supply, but instead of feeding with rectifier/transformer, I used a car battery 12V 50Ah. The change seems quite dramatic, the treble seems clearer and the bass tighter. At one point I actually wondered if I had less bass, but I think it is just less confused. Has any body experience with DAc or preamp driven by batteries. What improvement did you notice?

27th March 2010, 03:19 PM	#16
cdfr diyAudio Member Join Date: Jan 2005 Location: Seattle	After modifying the Apple Airport Express 802.11g, I modified the Apple Airport Express 802.11n Reports were saying the the AE N was much better. Indeed the stock version was already very good and superior to the G version. Instead of a TI USB DAC, this version actually uses a Broadcom processor with (I think) an integrated 24/96 DAC. All the voltages are 3.3v instead of 5v & 3.3v. This N version is what is used in the db system ZardoZ, La rosita and the Micromega Air Stream. I described (in franch) the modification I made on the homecinema-fr forum. Basically I made 3x 3.3v supplies with LM317 & a pre-regulation stage, with a 12v battery as the source to remove all noise. This combination with my Studer DAC beats my previous combination with a CD player as a source. Has any one tried to perform changes to the AE? What results have you gotten? What changes did you do?

28th March 2010, 03:45 PM	#17
qusp is choosing a less facetious title... diyAudio Member Join Date: Oct 2009 Location: Brisbane, Australia	very interested in trying this out, I have plenty of spare reg PCBs that would be suitable for this. some SMD discrete super regulators and will have some spare salas/iko shunts

28th March 2010, 06:12 PM	#18
cdfr diyAudio Member Join Date: Jan 2005 Location: Seattle	Let me know, how it goes. I am very pleased with the results, but as usual I am looking for more With the pre-regulator & LM 317 I think I am getting more than 80db ripple rejection on the supply. There might be changes worth while to do on the AE itself, but would need more knowlege of the schematic.

28th March 2010, 10:05 PM	#19
promitheus diyAudio Member Join Date: Jan 2001 Location: Germany	great work! can the new AE handle 96KHz/24bit? Can you get that from itunes?

29th March 2010, 05:23 PM	#20
cdfr diyAudio Member Join Date: Jan 2005 Location: Seattle	Thanks Promitheus. I am very happy with the results. Technically the new AE does support 24/96 (I read the broadcom spec), however Apple has not enabled it with the SW flashed or Airfoil, so it is currently limited to 16/44.1 . Itunes does support 24/96.