Re: Deja Vu
Hi Fred,
if you click on "click to enlarge" in the link, the schematic is quite legible.
I agree on the bandwith issue.
But a I2S direct interface between transport and DAC sounds MUCH better. Funny thing is, well you won't find it funny but Jocko does, the same mistakes are made here by the industry.
Audio Alchemy and Perpetual Technologies use a 5-pin mini Din Jack, North Star a RJ45 . The cable isn't even properly terminated in the Audio Alchemy.
How about this $169 cable?:
http://www.revelationaudiolabs.com/_wsn/page2.html
Fred Dieckmann said:
Hi Fred,
if you click on "click to enlarge" in the link, the schematic is quite legible.
I agree on the bandwith issue.
But a I2S direct interface between transport and DAC sounds MUCH better. Funny thing is, well you won't find it funny but Jocko does, the same mistakes are made here by the industry.
Audio Alchemy and Perpetual Technologies use a 5-pin mini Din Jack, North Star a RJ45 . The cable isn't even properly terminated in the Audio Alchemy.
How about this $169 cable?:
http://www.revelationaudiolabs.com/_wsn/page2.html
Been There Done That
'if you click on "click to enlarge" in the link, the schematic is quite legible."
I did...... its not. Want me to ask you to guess capacitor values from it?
I built IIS cables too. It does not sound better than SPDIF done right. It sounds better than the Audio Alcamy SPDIF interface, which was the worth I ever heard or measured. You can't transformer couple it and it transfers a lot of RF between Transport and DAC (or worse yet the DTI Pro, audio's worst RF generator.) It is unterminated on either end and uses an awful connector. The cables I built contained 3 pieces of minature coax and were a nightmare to build. People loved them as much as I hated building them. They have to be VERY short to sound any
where close to good. Mine were the minimum lenth I could make them .
Ever wonder why practically no one other than AA used it?
'if you click on "click to enlarge" in the link, the schematic is quite legible."
I did...... its not. Want me to ask you to guess capacitor values from it?
I built IIS cables too. It does not sound better than SPDIF done right. It sounds better than the Audio Alcamy SPDIF interface, which was the worth I ever heard or measured. You can't transformer couple it and it transfers a lot of RF between Transport and DAC (or worse yet the DTI Pro, audio's worst RF generator.) It is unterminated on either end and uses an awful connector. The cables I built contained 3 pieces of minature coax and were a nightmare to build. People loved them as much as I hated building them. They have to be VERY short to sound any
where close to good. Mine were the minimum lenth I could make them .
Ever wonder why practically no one other than AA used it?
ideal SPDIF interface?
The "feline" link posted previously is mandatory reading. There is a lot more to the SPDIF interface than meets the eye. From what I can work out from that thread to minimise any distortion caused on the SPDIF interface:
1) Use this circuit from Fred at the transport as it is easy to retrofit and uses a transformer for isolation like the Schott 67125450 (if your SPDIF source does not have a decent transmitter or isolation transformer): transport end
2) Use the receiver part of this circuit from Elso which has a differential input into the CS8412: DAC end
I dont see a reason why the OPA603 is necessary in Elso's circuit for the receiver. Any reason why the simpler circuit in 1) won't do the same job?
Would it be wise to add a cap on the input of the AD8561 on the receiver to ensure no DC is applied to the transport transformer? Would it also be possible to use another Schott transformer to replace the AD8561 as it can provide differential input to the CS8412?
To avoid ground loop current between the transport and the DAC would it make sense to only ground the 75 ohm coax at the DAC end?
Have I missed anything else that is needed to ensure the SPDIF interface does not cause problems?
(lots of questions here, but there are people on this thread with more experience than me and I'm keen to learn).
Regards,
Dean
The "feline" link posted previously is mandatory reading. There is a lot more to the SPDIF interface than meets the eye. From what I can work out from that thread to minimise any distortion caused on the SPDIF interface:
1) Use this circuit from Fred at the transport as it is easy to retrofit and uses a transformer for isolation like the Schott 67125450 (if your SPDIF source does not have a decent transmitter or isolation transformer): transport end
2) Use the receiver part of this circuit from Elso which has a differential input into the CS8412: DAC end
I dont see a reason why the OPA603 is necessary in Elso's circuit for the receiver. Any reason why the simpler circuit in 1) won't do the same job?
Would it be wise to add a cap on the input of the AD8561 on the receiver to ensure no DC is applied to the transport transformer? Would it also be possible to use another Schott transformer to replace the AD8561 as it can provide differential input to the CS8412?
To avoid ground loop current between the transport and the DAC would it make sense to only ground the 75 ohm coax at the DAC end?
Have I missed anything else that is needed to ensure the SPDIF interface does not cause problems?
(lots of questions here, but there are people on this thread with more experience than me and I'm keen to learn).
Regards,
Dean
Re: I2S short connection
Hi deanbob,
Yes very short would be better but is most unpractical.
If you use only a simple buffer like 74HC125 or no buffer at all the connection has to be very short. I see ringing on the WS and rounding off of the Bitclock with 50cm (two feet) leads.
You simply can not pipe around digital signals using simple leads. Please see Horowitz and Hill, the Art of Electonrics, Chapter 9, digital signals and long lines.
My plans are to use coax for each signal and terminate the coax correctly at the receivers end.
I will start with something simple like a 2N4401 driving the cable. Hopefully I get enough level at the DAC end to directly drive the TDA1543 or a 74HC125.
I also delved into the issue of line drivers and receivers like SN75173, SN75175, SN 75172, SN 75170, SN75123, SN75124. Interestingly all the line receivers use a Schmitt trigger.
deandob said:
Hi deanbob,
Yes very short would be better but is most unpractical.
If you use only a simple buffer like 74HC125 or no buffer at all the connection has to be very short. I see ringing on the WS and rounding off of the Bitclock with 50cm (two feet) leads.
You simply can not pipe around digital signals using simple leads. Please see Horowitz and Hill, the Art of Electonrics, Chapter 9, digital signals and long lines.
My plans are to use coax for each signal and terminate the coax correctly at the receivers end.
I will start with something simple like a 2N4401 driving the cable. Hopefully I get enough level at the DAC end to directly drive the TDA1543 or a 74HC125.
I also delved into the issue of line drivers and receivers like SN75173, SN75175, SN 75172, SN 75170, SN75123, SN75124. Interestingly all the line receivers use a Schmitt trigger.
Re: ideal SPDIF interface?
Hi Dean,
First where is the feline link?. Please provide a clickable link.
Fred and Jocko did not convince me that a transformer is necessary. I tried my transformerless interface in the Sony CDPX33ES, the Philips CD650 and CD931. I all cases it worked flawlessly. I only have a problem with my digital satellite receiver Philips DSR2000. Probably I have here a groundnoise problem. This tuner has a switched mode powersupply. The transformer brings the solution here. Necessary at the DAC end as I don't want to violate the warranty.
When I compare the following signal flows, I know which way to go:
SPDIF: [SAA7310]-> [PCF2705P] ->[74VHC04]->[OPA603]-> [AD8561]->[CS8412]->[TDA1543]
or I2S:
[SAA7310]->[74HC125]-> [TDA1543]
Signals for the latter can be best picked up at the inputs of the PCF2705P as this is a DIL IC (SAA7310 is a SMD part). You can solder the wires to the IC at the component side.
pin 1= WS
pin 2 = BCLK
pin 3 = DATA
deandob said:
Hi Dean,
First where is the feline link?. Please provide a clickable link.
Fred and Jocko did not convince me that a transformer is necessary. I tried my transformerless interface in the Sony CDPX33ES, the Philips CD650 and CD931. I all cases it worked flawlessly. I only have a problem with my digital satellite receiver Philips DSR2000. Probably I have here a groundnoise problem. This tuner has a switched mode powersupply. The transformer brings the solution here. Necessary at the DAC end as I don't want to violate the warranty.
When I compare the following signal flows, I know which way to go:
SPDIF: [SAA7310]-> [PCF2705P] ->[74VHC04]->[OPA603]-> [AD8561]->[CS8412]->[TDA1543]
or I2S:
[SAA7310]->[74HC125]-> [TDA1543]
Signals for the latter can be best picked up at the inputs of the PCF2705P as this is a DIL IC (SAA7310 is a SMD part). You can solder the wires to the IC at the component side.
pin 1= WS
pin 2 = BCLK
pin 3 = DATA
TDA1541 S2
I received my TDA1541A S2 chip from Elib the other day, and it looks like the real thing, identical to the one Peter Daniels received (link to pic at the start of this thread). I also have the normal version but have not had a chance to set it up & compare sound differences. I doubt if the S2 and crowns were added afterwards because the font, size, color, thickness and alignment of the text is perfect, and there is no sign of tampering with the face of the chip (eg. sanding). The S2 & crowns look to be screenprinted at the same time as the normal screenprint, which is different from the pics of the S1's posted on this board that are obviously printed on afterwards. Elib's S2 chip comes from a Taiwanese factory which is different to the normal TDA1541 chips which may explain why the S2 markings are not added afterwards.
I doubt that there is enough of a market for TDA1541 S2 chips that someone would go to the bother of doing a very good copy of the screenprinting, even though it can be done, eg. look at the "copy watches" sold in Asian markets which are done very well but they sell many thousands of these each year.
I'm fairly sure that this chip is the genuine article, mostly because the screenprinting looks to be original from the factory.
Elib can be a little slow at responding to email, but he answered all my questions and posted the chips pretty quickly after I sent the money with courteous service.
More info here TDA1541 fake
Regards,
Dean
I received my TDA1541A S2 chip from Elib the other day, and it looks like the real thing, identical to the one Peter Daniels received (link to pic at the start of this thread). I also have the normal version but have not had a chance to set it up & compare sound differences. I doubt if the S2 and crowns were added afterwards because the font, size, color, thickness and alignment of the text is perfect, and there is no sign of tampering with the face of the chip (eg. sanding). The S2 & crowns look to be screenprinted at the same time as the normal screenprint, which is different from the pics of the S1's posted on this board that are obviously printed on afterwards. Elib's S2 chip comes from a Taiwanese factory which is different to the normal TDA1541 chips which may explain why the S2 markings are not added afterwards.
I doubt that there is enough of a market for TDA1541 S2 chips that someone would go to the bother of doing a very good copy of the screenprinting, even though it can be done, eg. look at the "copy watches" sold in Asian markets which are done very well but they sell many thousands of these each year.
I'm fairly sure that this chip is the genuine article, mostly because the screenprinting looks to be original from the factory.
Elib can be a little slow at responding to email, but he answered all my questions and posted the chips pretty quickly after I sent the money with courteous service.
More info here TDA1541 fake
Regards,
Dean
feline link
Elso,
Regarding the feline link, I was referring to the thread about SPDIF that also talked about fat cats & beer drinking dogs
Here is the thread: SPDIF, cats and dogs
Regarding the transformer, wouldn't it be mandatory to avoid ground links between the different units? As SPDIF is a sensitive interface, having ground currents and noise travelling between the source and receiver must surely be avoided?
Regards,
Dean
Elso,
Regarding the feline link, I was referring to the thread about SPDIF that also talked about fat cats & beer drinking dogs
Here is the thread: SPDIF, cats and dogs
Regarding the transformer, wouldn't it be mandatory to avoid ground links between the different units? As SPDIF is a sensitive interface, having ground currents and noise travelling between the source and receiver must surely be avoided?
Regards,
Dean
rbroer said:Well,
Elib suddenly stopped emailing me; I've got two outstanding emails, but it seems he doesn't want my money.
And he was emailing me to convince me to order
For now I'll still assume he's out of town for some vacation.
Hi Rudolf,
Sorry to be late. 1st oct is our National Day, and we have a 3days' holiday. just send an email to you.
i can ensure all my s2's are from the same batch, in fact i got them in the original box.
regards,
Wang
Re: feline link
Thanks.
I already explained that the transformer can be usefull with my digital satellite tuner.
With the Scientific Conversion transformer I did not observe a decrease in soundquality in CD replay.
Hi Dean,deandob said:Elso,
Regarding the feline link, I was referring to the thread about SPDIF that also talked about fat cats & beer drinking dogs
Here is the thread: SPDIF, cats and dogs
Regarding the transformer, wouldn't it be mandatory to avoid ground links between the different units? As SPDIF is a sensitive interface, having ground currents and noise travelling between the source and receiver must surely be avoided?
Regards,
Dean
Thanks.
I already explained that the transformer can be usefull with my digital satellite tuner.
With the Scientific Conversion transformer I did not observe a decrease in soundquality in CD replay.
Hello all,
I got a pair of TDA1541a S2 chips from Elib. He was courteous and replied all my emails. The chips look geniune to me (not that I am an expert on this!) They were well packed within the tube with antistatic wrapping. There was minor problem in shipping, mainly because noone was at home during office hour for the delivery. He faxed and emailed to me just to make sure everything was alright.
I am in no way connected to Elib, just a satisfied customer.
Johnny
I got a pair of TDA1541a S2 chips from Elib. He was courteous and replied all my emails. The chips look geniune to me (not that I am an expert on this!) They were well packed within the tube with antistatic wrapping. There was minor problem in shipping, mainly because noone was at home during office hour for the delivery. He faxed and emailed to me just to make sure everything was alright.
I am in no way connected to Elib, just a satisfied customer.
Johnny
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