I've got glass optical cable. Absolutely incredible improvement over few different plastic cables, one of which was daxx R05. I didn't expect that.
So I would rather keep optics there, and if DAC doesn't have optical input, it's much much easier to add led receiver on that side, instead of fighting with transformers, wires, signal shapes and so on...
So I would rather keep optics there, and if DAC doesn't have optical input, it's much much easier to add led receiver on that side, instead of fighting with transformers, wires, signal shapes and so on...
Ok,ok, ok....
So I tried it: In the DAC I bypass the pulse transformer, a 34C86 and go directly to the input of the CS8411. First trials make me believe that the sound improved. I have more space between instruments and more details. I will confirm after more listening.
On the scope the spdif square waves look better but have quite a bit of overshoot. I do not think that it is an issue. Feel free to comment on this.
So I tried it: In the DAC I bypass the pulse transformer, a 34C86 and go directly to the input of the CS8411. First trials make me believe that the sound improved. I have more space between instruments and more details. I will confirm after more listening.
On the scope the spdif square waves look better but have quite a bit of overshoot. I do not think that it is an issue. Feel free to comment on this.
Cool! That's exactly what I've heard when changed plastic optics to the glass one. More air, more details. I've been listening to my own vinyl rips that became more close to the vinyl itself with that change.
Obviously, ignoring optical transmission (especially transmitter and receiver parts) must be one more good step, in my case. You've done yours.
Obviously, ignoring optical transmission (especially transmitter and receiver parts) must be one more good step, in my case. You've done yours.
If I understand correctly, you bypassed the rectifier and switching part of the original AE power supply and applied 12V DC at a suitable point in the chain?
Can you provide some more details on your modification? Like where exactly on the AE power supply 12V DC should be applied?
Can you provide some more details on your modification? Like where exactly on the AE power supply 12V DC should be applied?
Hi Lucas,
You can indeed access the I2S signal on the AE. Basically you find it around the DAC.
On the french thread I started on Source de Passion a person has done it.
See the picture in this link:
http://clemmaster.free.fr/Airport_I2S.jpg
You can indeed access the I2S signal on the AE. Basically you find it around the DAC.
On the french thread I started on Source de Passion a person has done it.
See the picture in this link:
http://clemmaster.free.fr/Airport_I2S.jpg
Well, the DAC requires I2S, so ideally I2S is the way to go, if at all possible.
In order to use this AE, I will need:
Twisted Pear SPDIF to I2S module and
Twisted Pear Optical to SPDIF converter and
A small board with a missing chip from above modules, but required for this DAC.
All of that is more expensive and probably less ideal than the new Airport Express with I2S I should imagine. What do you think? My French isn't brilliant, but it seems to work. How well it works is still unclear I guess. Any ideas?
Many thanks
Lucas
In order to use this AE, I will need:
Twisted Pear SPDIF to I2S module and
Twisted Pear Optical to SPDIF converter and
A small board with a missing chip from above modules, but required for this DAC.
All of that is more expensive and probably less ideal than the new Airport Express with I2S I should imagine. What do you think? My French isn't brilliant, but it seems to work. How well it works is still unclear I guess. Any ideas?
Many thanks
Lucas
That sounds like a lot.
I don't think all of this is really necessary, though. The S/P-DIF signal can be taken off the PCM2704/5 (pins 5, 6) similarly to the picture above. So the Toslink converter isn't required.
Regarding the adaptation you're probably referring to the S/P-DIF receiver/multiplexer kit. This would of course be way overboard, cost wise. I suspect there are cheaper solutions on the market, especially considering that most of the TP kit's features aren't even required for your purpose.
There's even another possible attempt, untested but possible: circumventing the PCM2704 altogether and replacing it with a different USB DAC. The signal between processor and DAC inside the old AE is a vanilla USB 1.1 bus. There's no reason that a different DAC wouldn't work. Cheap USB DACs with I2C output can be had i.e. via ebay.
As for your DAC, it really has I2C input only?
Cheers,
Sebastian.
I don't think all of this is really necessary, though. The S/P-DIF signal can be taken off the PCM2704/5 (pins 5, 6) similarly to the picture above. So the Toslink converter isn't required.
Regarding the adaptation you're probably referring to the S/P-DIF receiver/multiplexer kit. This would of course be way overboard, cost wise. I suspect there are cheaper solutions on the market, especially considering that most of the TP kit's features aren't even required for your purpose.
There's even another possible attempt, untested but possible: circumventing the PCM2704 altogether and replacing it with a different USB DAC. The signal between processor and DAC inside the old AE is a vanilla USB 1.1 bus. There's no reason that a different DAC wouldn't work. Cheap USB DACs with I2C output can be had i.e. via ebay.
As for your DAC, it really has I2C input only?
Cheers,
Sebastian.
Hi Sebastian,
Thanks for the reply. I see you're right about the toslink converter - not necessary at all. I haven't found any good alternatives to the TP module, but I am excited about not needing it at all, and going direct to i2s.
Yes, my DAC I made myself. It is 2x Phillips TDA-1541a - the classic DAC chip. It cost a lot to make and has valve output stage (Lampizator design). It has only i2s input, but I also have a good USB to i2s module called Teralink X2 that I can use with it, but I want Wi-fi music streaming mostly, as there are 3x laptops in our house and it is much more practical for all of us to have Airport Express. I want to keep jitter down and signal purity as much as possible so going through SPDIF isn't ideal, if i2s is avaliable. Isn't buying the new Airport Express "n" (£50 on eBay) and tapping i2s from it easier and better than trying to swap a tiny robot-soldered chip inside my current Airport Express to get i2s?
Many thanks for all of your help?
Lucas
Thanks for the reply. I see you're right about the toslink converter - not necessary at all. I haven't found any good alternatives to the TP module, but I am excited about not needing it at all, and going direct to i2s.
Yes, my DAC I made myself. It is 2x Phillips TDA-1541a - the classic DAC chip. It cost a lot to make and has valve output stage (Lampizator design). It has only i2s input, but I also have a good USB to i2s module called Teralink X2 that I can use with it, but I want Wi-fi music streaming mostly, as there are 3x laptops in our house and it is much more practical for all of us to have Airport Express. I want to keep jitter down and signal purity as much as possible so going through SPDIF isn't ideal, if i2s is avaliable. Isn't buying the new Airport Express "n" (£50 on eBay) and tapping i2s from it easier and better than trying to swap a tiny robot-soldered chip inside my current Airport Express to get i2s?
Many thanks for all of your help?
Lucas
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I realise that I am making the assumption that signal purity will be improved by utilising i2s rather than SPDIF.
Perhaps that is wrong - I have been assuming that the i2s signal is turned into SPDIF signal, and that I can avoid this stage completely, helping signal purity, as i2s keeps signal and clock separate. Is this right?
Perhaps that is wrong - I have been assuming that the i2s signal is turned into SPDIF signal, and that I can avoid this stage completely, helping signal purity, as i2s keeps signal and clock separate. Is this right?
Great, why not do it directly.
Cut pins 8 and 9 off the PCM2704 and connect the USB input of your X2 to the solder pads on the PCB.
A USB cable is easy to understand, as is the pinout of the PCM2704.
Pin 6 (DGND) serves as ground reference, pin 7 is USB power (in case the X2 needs it).
As the X2 is class compliant , it should work when connected to the AE's internal USB lines.
Hi Sebastian.
That's astonishing news! Has this method ever been tested to work?
Given that I have spent a good €450 on this DAC (way over the top components and {German} design) and still don't have a case for it, would it make any sense, in terms of quality, to continue the idea to get the newer airport express anyway and use I2S from it? Would there be an improvement in signal quality there, due to simplification of signal processing?
That's astonishing news! Has this method ever been tested to work?
Given that I have spent a good €450 on this DAC (way over the top components and {German} design) and still don't have a case for it, would it make any sense, in terms of quality, to continue the idea to get the newer airport express anyway and use I2S from it? Would there be an improvement in signal quality there, due to simplification of signal processing?
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