[audioengr]

I finally tore into the AirPort Express, literally.  It is completely glued shut, so it is a chore to get inside.  What I found is simply amazing.  It reminds me of my days at Intel corp.  This design is superb! And there is so much packed inside such a small box.  Dont know how they can sell this for $129.  Here is a photo of the parts:


These boards all have 0402-sized SMT parts, so the rework is touchy at best.  Usually only machines install this stuff.  The audio output board utilizes the TI PCM 2705, which uses a 12 MHz clock.  This is available in Superclock, assuming the voltages are correct, and I will fix this if they are not.  Unfortunately according to the specs, it only handles 48 kHz sample rates maximum, so this will not pass 24/96 like the Transit will.  I have not figured-out a way to make iTunes player upsample to 24/96 anyway.

Next step is to start modding it. I will keep you posted here.

[audioengr]

First mods:

1) improved power delivery and signal paths
2) replaced the S/PDIF Toslink with a S/PDIF coax interface
3) added short S/PDIF coax cable and Bullet Plug connector

The mods definitely improve the performance over the Toslink.  It is almost on-par with the USB Expressway now.

Comparison of the USB Offramp and the AE apples to apples, using iTunes player and same format - Apple Lossless, I found that the USB Offramp was more focused and clear sounding.  Less reverberant - probably due to less jitter or different jitter spectrum.  The USB Offramp does have a modded Superclock2 and probably a quieter power supply.

Next thing is to mount the AE in a plastic box and add a Superclock.  Superclock typically needs at least 9V to operate.  Not sure if the power supply in the AE will have this.  It appears to supply 3 or 4 voltages from the switching power supply.  May require an external power source.

[SuperDad]

Hi Steve:
Glad you jumped on this so quickly.  I'll be very interested in the further results of you mods on the AE.  When you rebox it, be sure to retest the Wifi functioning since that is sort of the whole point for the device's existance.

Pardon my ignorance (and curiosity), but when turning the Toslink output into a coax, do you have to add any chips or components, or do you just attach a cable prior to the optical driver?

Thanks for your pioneering efforts.  I'll spread the word.
Best,
Alex
@Hovland

[audioengr]

Hi Steve:
Glad you jumped on this so quickly.  I'll be very interested in the further results of you mods on the AE.  When you rebox it, be sure to retest the Wifi functioning since that is sort of the whole point for the device's existance.

Pardon my ignorance (and curiosity), but when turning the Toslink output into a coax, do you have to add any chips or components, or do you just attach a cable prior to the optical driver?

Thanks for your pioneering efforts.  I'll spread the word.
Best,
Alex
@Hovland

The WIFI will function as before.

Yes, I have to add quite a few components to create the coax output, and it requires tuning as well.

[SuperDad]

You 'da man!
I can herdly wait.

Are your going to CES in January?
Cheers,
AJC

[audioengr]

You 'da man!
I can herdly wait.

Are your going to CES in January?
Cheers,
AJC

Of course, but I will be at THE show at the St. Tropez suite 1203.

[dc_guy]

Any new info on the modded Airport Express?

[audioengr]

Any new info on the modded Airport Express?

Nothing yet.  I have been buried in Off-Ramp orders and other mods.  I have one here to mod for a customer and I now have the Superclock to go into it...Just need to find the time.

Steve N.

[Wadek]

hi,
I'm a newbie on this forum. I opened yesterday my Aiport express Borne and I want to modify it.
Does someone have the service manual with the schematics of the circuitry?

1/ I would like to replace the clock and I have to remove it + 2 caps which I can't locate. Could someone help me?
2/ I also want to add a spdif output circuitry but it's very difficult to locate, where to plug in my modification because there are only CMS components.
3/ For an external power supply, does someone have any experience, which he could share?
I know, there are one 5V / 1A and one 3,3V power supply. Considering the PCM2705 data sheet, the 5V is for the power supply bus and 3,3V for the "external loop". (I guess)
But I guess, the 5V does also feed the Wifi circuitry, doesn't it?

Thanks for any help
 

Wadek

[audioengr]

hi,
I'm a newbie on this forum. I opened yesterday my Aiport express Borne and I want to modify it.
Does someone have the service manual with the schematics of the circuitry?

1/ I would like to replace the clock and I have to remove it + 2 caps which I can't locate. Could someone help me?
2/ I also want to add a spdif output circuitry but it's very difficult to locate, where to plug in my modification because there are only CMS components.
3/ For an external power supply, does someone have any experience, which he could share?
I know, there are one 5V / 1A and one 3,3V power supply. Considering the PCM2705 data sheet, the 5V is for the power supply bus and 3,3V for the "external loop". (I guess)
But I guess, the 5V does also feed the Wifi circuitry, doesn't it?

Thanks for any help
 

Wadek

Wadek - I dont mod these anymore because I just add my Pace-Car reclocker to the AE now.  The Pace-Car is a much better performing solution than trying to make the AE sound good by modding it.  The PCM2705 is not great, even driven with a Superclock.  It is a fairly jittery device.

If you want a completely modded AE, I have one, but it only has I2S output.  I sold these for $1500 when I was making them, but I would let this go for $400, slightly more than the cost of the Superclock in there.  It has a complete chassis and separate power supply and AC adapter (or can be 12V SLA battery).

If you interface the I2S to your DAC, this will be even better than S/PDIF.  It will drive Perpetual P-3A, and Northstar 192 directly.

Steve N.

[Wadek]

Well,
I must think about it. Thank you. 
I don't have much money at the moment, that's why I was searching for a solution at about max. 300$. If I must add a spdif or a I2S + shiping costs (France)... I'll be upon 600$.
Would your solution have 24/96 capability? You atually only use the first board of the AE (Wifi...) and then add your own receiver/DAC, don't you?
How to add a I2S input to my DAC which is a counterpoint DA-10 with CS 8414 receiver, which don't have I2S direct input capability I think (?)
Or could I add a SPDIF output out of the chip you use, which is not the best solution but perhaps the cheapest for the moment?

Wadek

[audioengr]

Well,
I must think about it. Thank you. 
I don't have much money at the moment, that's why I was searching for a solution at about max. 300$. If I must add a spdif or a I2S + shiping costs (France)... I'll be upon 600$.
Would your solution have 24/96 capability?

No, the AE only does 44.1.

You actually only use the first board of the AE (Wifi...) and then add your own receiver/DAC, don't you?

Correct, you need a DAC.

How to add a I2S input to my DAC which is a counterpoint DA-10 with CS 8414 receiver, which don't have I2S direct input capability I think (?)

If you dont have the engineering experience or know someone who does, then do not attempt it.

Or could I add a SPDIF output out of the chip you use, which is not the best solution but perhaps the cheapest for the moment?

Changing this particular unit to S/PDIF output would be very ugly.  It is fairly technical to add S/PDIF properly to an AE.

[Wadek]

Well,
I must think about it. Thank you. 
I don't have much money at the moment, that's why I was searching for a solution at about max. 300$. If I must add a spdif or a I2S + shiping costs (France)... I'll be upon 600$.
Would your solution have 24/96 capability?

No, the AE only does 44.1.

You actually only use the first board of the AE (Wifi...) and then add your own receiver/DAC, don't you?

Correct, you need a DAC.

How to add a I2S input to my DAC which is a counterpoint DA-10 with CS 8414 receiver, which don't have I2S direct input capability I think (?)

If you dont have the engineering experience or know someone who does, then do not attempt it.

Or could I add a SPDIF output out of the chip you use, which is not the best solution but perhaps the cheapest for the moment?

Changing this particular unit to S/PDIF output would be very ugly.  It is fairly technical to add S/PDIF properly to an AE.

Thank you for advices. I don't have indeed the knowledge to do it.

One point: I didn't express myself clear concerning the board and DAC: You write that the PCM 2705 is pretty jittery. So I thought you would have replaced the complete Audio section of the AE (including the PCM 2705) through your own circuitry built around another chip with no jitter or the possibility to kill it and with 24/96 capability (what the PCM 2704 or 2705 does not have.)
I wrote "receiver/DAC" meaning a chip like the PCM 2705 (which also has a DAC)

THank you

Wadek

[audioengr]

Well,
I must think about it. Thank you. 
I don't have much money at the moment, that's why I was searching for a solution at about max. 300$. If I must add a spdif or a I2S + shiping costs (France)... I'll be upon 600$.
Would your solution have 24/96 capability?

No, the AE only does 44.1.

You actually only use the first board of the AE (Wifi...) and then add your own receiver/DAC, don't you?

Correct, you need a DAC.

How to add a I2S input to my DAC which is a counterpoint DA-10 with CS 8414 receiver, which don't have I2S direct input capability I think (?)

If you dont have the engineering experience or know someone who does, then do not attempt it.

Or could I add a SPDIF output out of the chip you use, which is not the best solution but perhaps the cheapest for the moment?

Changing this particular unit to S/PDIF output would be very ugly.  It is fairly technical to add S/PDIF properly to an AE.

Thank you for advices. I don't have indeed the knowledge to do it.

One point: I didn't express myself clear concerning the board and DAC: You write that the PCM 2705 is pretty jittery. So I thought you would have replaced the complete Audio section of the AE (including the PCM 2705) through your own circuitry built around another chip with no jitter or the possibility to kill it and with 24/96 capability (what the PCM 2704 or 2705 does not have.)
I wrote "receiver/DAC" meaning a chip like the PCM 2705 (which also has a DAC)

THank you

Wadek

To replace the PCM2705 inside the AE is a major redesign.  It would have to involve Apple Computer designers.  Non-trivial, and includes new firmware for their embedded CPU etc..

It is much simpler just to add a Pace-Car to a stock AE, and the result is superior.

Steve N.

[juanitox]

  for information , the new airport express n don(t have the burbrown PCM2705
inside but a new audio chip from MARVEL.