Hello
I am using a P-1a and P-3a (modwright II) which both have the option of using an I2s input and ouput. The stock cable is not that good but no one seems to make a sensible priced replacement.
I have been able to source some 999 silver teflon coated wire and deicided to make my own replacement but I do not have any details of the pin conifguration. I think that only four pins were used and one is not but not certain.
I do remember that this may have been information already on the site and I have tried a number of searches using different words and names but have not been able to find anything.
If someone could either send me a link to the thread that has this or provide me with the details I would be very grateful .
I am using a P-1a and P-3a (modwright II) which both have the option of using an I2s input and ouput. The stock cable is not that good but no one seems to make a sensible priced replacement.
I have been able to source some 999 silver teflon coated wire and deicided to make my own replacement but I do not have any details of the pin conifguration. I think that only four pins were used and one is not but not certain.
I do remember that this may have been information already on the site and I have tried a number of searches using different words and names but have not been able to find anything.
If someone could either send me a link to the thread that has this or provide me with the details I would be very grateful .
Hi all
Thanks for those of you that have viewed this and appreciate it is a pretty specialist sort of thing. I have had a text from another contact and he has provided the following which I will list here in case anyone else needs the information .
PIN 1 : word clock
PIN 2 : bit clock
PIN 3 : audio data
PIN 4 : master clock
PIN 5 : not connected
Shield : circuit ground
This will most likely be one of those jobs that will be more fiddly than difficult but they are a real curse if you have large hands (and more pertinently fingers) . See there are some days when I wish I married a woman who can solder .
Thanks for those of you that have viewed this and appreciate it is a pretty specialist sort of thing. I have had a text from another contact and he has provided the following which I will list here in case anyone else needs the information .
PIN 1 : word clock
PIN 2 : bit clock
PIN 3 : audio data
PIN 4 : master clock
PIN 5 : not connected
Shield : circuit ground
This will most likely be one of those jobs that will be more fiddly than difficult but they are a real curse if you have large hands (and more pertinently fingers) . See there are some days when I wish I married a woman who can solder .
just use quality belden copper in PTFE ethernet cable with every signal wire paired with its own ground, you want tight coupling and consistent impedance in a cable like this and it should be as short as possible, no point going to the trouble of using i2s if you use a long cable, its got terrible noise immunity and no error correction, as its meant for short length of circuit board trace, not cables. better off doing spdif properly than screwing up i2s with some half way imitation of an expensive cable that is twisted and bonded by machine to control the impedance.
urgent please note
Please note that when making up this cable as per the advice given to me this cable did not work . I had checked that the wiring was all correct and that it was consistent .
I have now found after much searching the below picture which comes from another thread and this picture is supposed to have come from Perpetual Technology themselves .
This is the confirguration for the PT P-1a and P-3a units plus the Audio Alchemy units and for those units only. It would appear there is not standard cable configuration and these cable would not work with any other companies units such as Stello .
Please accept my apologies for getting this wrong but this was a genuine error .
Please note that when making up this cable as per the advice given to me this cable did not work . I had checked that the wiring was all correct and that it was consistent .
I have now found after much searching the below picture which comes from another thread and this picture is supposed to have come from Perpetual Technology themselves .
This is the confirguration for the PT P-1a and P-3a units plus the Audio Alchemy units and for those units only. It would appear there is not standard cable configuration and these cable would not work with any other companies units such as Stello .
Please accept my apologies for getting this wrong but this was a genuine error .
Attachments
Audio Alchemy I2S cables
Slightly off topic for those committed to making up their own cables, but for those looking to find the original Audio Alchemy I2S cables which are the recommended standard for PT kit (noting that they are likely to be of the same indifferent quality as bencat's original), you could try contacting:
Carrie Martinez
Silicon Salvage, Inc.(ebay sellers ssinc1500)
1500 N Dale Ave.
Anaheim, CA 92801
phone: 714-523-2425
fax: 714-523-2552
SS are selling them at $4.99 each but won't ship outside the USA. UK-based people may need to ask a friend in the US to take receipt for onward transmission....
I have bought three on the basis that I will have at least one right when I try cannibalising the wire! I guess it might be worth the investment in one for testing to ensure that you are working to the correct configuration.
For a higher quality bought cable, I think Bettercables still supplies them.
Best
Peter
Slightly off topic for those committed to making up their own cables, but for those looking to find the original Audio Alchemy I2S cables which are the recommended standard for PT kit (noting that they are likely to be of the same indifferent quality as bencat's original), you could try contacting:
Carrie Martinez
Silicon Salvage, Inc.(ebay sellers ssinc1500)
1500 N Dale Ave.
Anaheim, CA 92801
phone: 714-523-2425
fax: 714-523-2552
SS are selling them at $4.99 each but won't ship outside the USA. UK-based people may need to ask a friend in the US to take receipt for onward transmission....
I have bought three on the basis that I will have at least one right when I try cannibalising the wire! I guess it might be worth the investment in one for testing to ensure that you are working to the correct configuration.
For a higher quality bought cable, I think Bettercables still supplies them.
Best
Peter
I do not want to post this too soon as the original cable did not work due to me getting the pin configuration wrong as in the above thread. However I have been able to find a cable maker who will make up the 5Pin mini din for the I2S lead for PT equipment using 99.9% silver cable it is Achtung Audio on E-Bay .
I will confirm how this sounds and if it works once I have the cable reconfigured and will also confirm that the wiring as per my attached diagram does indeed work. I think this would be a viable and sensible cable with costs around £35 - £40 per 0.5 metre (try and keep this cable as short as possible this is not a proper protocol for use with cable but meant to travel only very short distances through pcb track between ic chips.)
I have the original PT cable and frankly it does not even begin to show the quality f this connection a good decent coaxial with proper 75 ohm cable will sound much better and a 110 ohm XLR will sound better again. I have a Kimber I2S and that shows a real quality difference over both of the above. I expect the silver cable to be better still.
As I say too early to say but thought it better to advise this now and save anyone who was thinking of getting the standard cables from the US. They may well end up costing more than they are worth. Would also mention for the record that Russ Andrews will make up a cable for you as well and this will be very good and about a similar cost to the Achtung cable. All I need to confirm now it that the pin configuration is as the diagram shows and anyone could order one from either of the above two or any other custom cable maker.
I will confirm how this sounds and if it works once I have the cable reconfigured and will also confirm that the wiring as per my attached diagram does indeed work. I think this would be a viable and sensible cable with costs around £35 - £40 per 0.5 metre (try and keep this cable as short as possible this is not a proper protocol for use with cable but meant to travel only very short distances through pcb track between ic chips.)
I have the original PT cable and frankly it does not even begin to show the quality f this connection a good decent coaxial with proper 75 ohm cable will sound much better and a 110 ohm XLR will sound better again. I have a Kimber I2S and that shows a real quality difference over both of the above. I expect the silver cable to be better still.
As I say too early to say but thought it better to advise this now and save anyone who was thinking of getting the standard cables from the US. They may well end up costing more than they are worth. Would also mention for the record that Russ Andrews will make up a cable for you as well and this will be very good and about a similar cost to the Achtung cable. All I need to confirm now it that the pin configuration is as the diagram shows and anyone could order one from either of the above two or any other custom cable maker.
Better quality I2S cable
I think Bencat's onto something and that a better quality cable is a good idea.
The cheap AA cable I found is nothing at all special and I am emphatically not recommending it. I mentioned the source of the AA cables simply to provide information, as AA stuff is becoming rarer and rarer, and any (correct) cable is better than none...
Whatever your views on silver cables and the "digits is digits and I use fuse wire/dental floss/old dental fillings to no sonic ill effect" arguments, presenting a proper impedance and making good connections seems worthwhile: in particular, decent shielding must be important and the mini DIN plugs AA and PT specified are fairly crappy at their best - and these AA cables are not much better than the freebies you get with cheap stereo components or computers pre-USB. Putting the question of what wire to one side, a good pair of Neutriks would make a far more secure and solid connection, for example.
Bencat's experiment is not going to break the bank (his cable will cost about a tenth of what Revelation Audio are charging for their bespoke cable, taking into account import duties and VAT) and he has offered to share his impressions with us.
I am awaiting the outcome of Bencat's experiment with interest. If negative, I suspect he will soldier on, still seeking to squeeze a bit more out of his kit some other way. If positive, we will have benefited from his research and those who are interested can then also order an extra wire with a pre-terminated end and an unterminated end and whip out their soldering irons and try to hook up the direct I2S connection from their CDPs, having, of course, digested and understood Kal's articles!
Peter
I think Bencat's onto something and that a better quality cable is a good idea.
The cheap AA cable I found is nothing at all special and I am emphatically not recommending it. I mentioned the source of the AA cables simply to provide information, as AA stuff is becoming rarer and rarer, and any (correct) cable is better than none...
Whatever your views on silver cables and the "digits is digits and I use fuse wire/dental floss/old dental fillings to no sonic ill effect" arguments, presenting a proper impedance and making good connections seems worthwhile: in particular, decent shielding must be important and the mini DIN plugs AA and PT specified are fairly crappy at their best - and these AA cables are not much better than the freebies you get with cheap stereo components or computers pre-USB. Putting the question of what wire to one side, a good pair of Neutriks would make a far more secure and solid connection, for example.
Bencat's experiment is not going to break the bank (his cable will cost about a tenth of what Revelation Audio are charging for their bespoke cable, taking into account import duties and VAT) and he has offered to share his impressions with us.
I am awaiting the outcome of Bencat's experiment with interest. If negative, I suspect he will soldier on, still seeking to squeeze a bit more out of his kit some other way. If positive, we will have benefited from his research and those who are interested can then also order an extra wire with a pre-terminated end and an unterminated end and whip out their soldering irons and try to hook up the direct I2S connection from their CDPs, having, of course, digested and understood Kal's articles!
Peter
Shielded CAT 5 perfect, signal in close proximity to its return path, impedance similar to the signal on the PCB. As Qusp stated. The impedance should match from the transmitter to the reciever. Otherwise you will degrade the signal and add jitter to the clock.
Silver, what is that going to do to the digital signal transmission.
Of course the only way you can revue the cables effect on the signals will be with scope shots and eye daigrams
DIGITAL is DIGITAL, read the two excellent books by Howard Johnson, they explain in great detail on how we can propogate digital signals down traces, along wires etc and still get the correct bit pattern.
Silver, what is that going to do to the digital signal transmission.
Of course the only way you can revue the cables effect on the signals will be with scope shots and eye daigrams
DIGITAL is DIGITAL, read the two excellent books by Howard Johnson, they explain in great detail on how we can propogate digital signals down traces, along wires etc and still get the correct bit pattern.
I am sorry but digital is not digital and the idea that you will get bit perfect copies is just is not convincing. Cat 5 cable sounds different to Cat 6 . To my ears in my system Cat 6 even if just replaced by 1 metre lengths sounds better. You can tell me and show me all the proofs that you want that this is impossible but the difference was not subtle and I am not going back to Cat 5.
With regard to this cable my idea is very simple Silver cable is a much more efficient and better conductor than copper the difference in cost is negligable so I went for the silver. I was going to consider getting the cable fitted with shield which is an option (£5 extra) but then companies are using Cat 6 cable to connect I2s and that has no shield so I decided to take a chance. Sadly not got the cable back yet so no update on the sound but I do promise that I will post what I think .
With digital, the slightly less resistance of silver vs copper is not realy taht relevant, what is is controlling the impedance of the path the signal travels down, and matching the driver to the line, with either series or parallel termination. In digital signal transmission the main area of concern is the brief interval of time when the signal changes, thats when all the excitement happens. This is the rise time of the signal and the length (electrical) of the trace to the reciever(s). get that part of the equation right and the rest will follow.
If digital is not digital, what is it? The whole point of the ever increasing world of digital data transmission is its reliability, it not affected by noise like analogue transmission, never mind the other benefits. At the end of the day the reciever will either register a 0 or a 1, no inbetweens, unlike analogue that may register a slight change in voltage due to PCB or Cable effects.
Everything else digital we use every day seems to work quite well...why is audio repreduction so flawed in the digital domain, not saying it is perfect, but is it as bad as made out.
I use a couple of squeezeboxes unmodified through a mismatch of amps and speakers, in different rooms, but it all sounds good to me, better than wearing out CD's trying to get them in the player, is it better sound quality ( I have a dedicated music server, basic, big disk, runs SB server) or is it the ease of finding a CD and enjoying the music!
If digital is not digital, what is it? The whole point of the ever increasing world of digital data transmission is its reliability, it not affected by noise like analogue transmission, never mind the other benefits. At the end of the day the reciever will either register a 0 or a 1, no inbetweens, unlike analogue that may register a slight change in voltage due to PCB or Cable effects.
Everything else digital we use every day seems to work quite well...why is audio repreduction so flawed in the digital domain, not saying it is perfect, but is it as bad as made out.
I use a couple of squeezeboxes unmodified through a mismatch of amps and speakers, in different rooms, but it all sounds good to me, better than wearing out CD's trying to get them in the player, is it better sound quality ( I have a dedicated music server, basic, big disk, runs SB server) or is it the ease of finding a CD and enjoying the music!
Marce
Please excuse me as my technical knowledge is not anyhting like as good as it should be but the digital is either 0 or 1 is not correct either I have been reading a huge number of articles on this at various sites dealing with computer audio and others and the problem is that while the information is only 1 or 0 the bit word is quite long combination of these words and the digital system is designed to accept certain words with minor (?) errors and then recalculate them to make up what it thinks was sent orginally.
I think we have to accept that digital is not perfect and is subject to errors and these errors are small enough to be accepted and not have the item just cut out but they are not the same. If all digital was as it should be then various Dac,s Streamers and other items would not all sound different. I know there are people who say they do not sound different and I am sure they state this becasue they do not hear any difference I wish I was like them then I could just buy the best I can afford and play music . But I can hear differences and soem of them are not subtle . To date I have heard almost the whole range of Nait equipment and find them all not to my tastes I have no idea why they are well designed well made and lots of people are fervent in their admiration. Yet they leave me with an empty feeling that just wants to turn the music off for they do not image and they are just too relentless .
I wish I had the real technical knowledge to understand and argue my case from a real engineering point of view but I can not . I also think there is much in this field that is not fully understood as well by those who do have the technical skill so I would suggest that we accept that we will have differing views on this because of my inability and ignorace in being able to explain what I hear.
Please excuse me as my technical knowledge is not anyhting like as good as it should be but the digital is either 0 or 1 is not correct either I have been reading a huge number of articles on this at various sites dealing with computer audio and others and the problem is that while the information is only 1 or 0 the bit word is quite long combination of these words and the digital system is designed to accept certain words with minor (?) errors and then recalculate them to make up what it thinks was sent orginally.
I think we have to accept that digital is not perfect and is subject to errors and these errors are small enough to be accepted and not have the item just cut out but they are not the same. If all digital was as it should be then various Dac,s Streamers and other items would not all sound different. I know there are people who say they do not sound different and I am sure they state this becasue they do not hear any difference I wish I was like them then I could just buy the best I can afford and play music . But I can hear differences and soem of them are not subtle . To date I have heard almost the whole range of Nait equipment and find them all not to my tastes I have no idea why they are well designed well made and lots of people are fervent in their admiration. Yet they leave me with an empty feeling that just wants to turn the music off for they do not image and they are just too relentless .
I wish I had the real technical knowledge to understand and argue my case from a real engineering point of view but I can not . I also think there is much in this field that is not fully understood as well by those who do have the technical skill so I would suggest that we accept that we will have differing views on this because of my inability and ignorace in being able to explain what I hear.
Digital is 1s and 0s, look up how digital works, sorry but I have spent nearly 3 decades laying PCBs out and working in design teams for a whole range of projects from the mundane to highly technical. i also now do a lot of high speed routing and training for PCB designers in high speed digital layout and using the tools for such, and its all geared to transporting bits and getting from a to b intact and at the right time.
The early days od CD's and digital in music was quite problematic, hence Reed Solomon correction code, and the Audio belief in digital being flawed probably comes from this. And a lot of the early problems were the reading of the disk. These days and for many years digital (while not foolproof) has enough checking systems to ensure that the digital data transmission is perfect from a to b, otherwise so many things would not work, the internet for one.
i am not disputing any sound differences that may occur with different equipement, but digital data transmission is well understood by those working in the field, and even mundane products have to work and work reliably these days, never mind life critical applications, where failure is not an option.
The early days od CD's and digital in music was quite problematic, hence Reed Solomon correction code, and the Audio belief in digital being flawed probably comes from this. And a lot of the early problems were the reading of the disk. These days and for many years digital (while not foolproof) has enough checking systems to ensure that the digital data transmission is perfect from a to b, otherwise so many things would not work, the internet for one.
i am not disputing any sound differences that may occur with different equipement, but digital data transmission is well understood by those working in the field, and even mundane products have to work and work reliably these days, never mind life critical applications, where failure is not an option.
@marce - you don't get the concept of whishfull thinking?
One's brain can imagine things just based on what wishes/desires are firing the synapsis... Like the conviction that silver would sound better than copper for digital transmission lines - it would sound "better" to somebody that really, really wants to be that way
One's brain can imagine things just based on what wishes/desires are firing the synapsis... Like the conviction that silver would sound better than copper for digital transmission lines - it would sound "better" to somebody that really, really wants to be that way
I know thats why I work in an engineering disipline...and probably why it took 2+ years and many cabinets (and different drivers)before I was finaly happy with some OB speakers (and why I dont MOD digital).
Even if I thought I was percieving a difference I would have to prove it to my self with measurements and then it would have to be repeatable
With I2S (and I2C) personaly I would be wary of taking it off board, having done numerous boards with Ti codecs (TPS320, TVS320 etc) and other devices, layout and impedance control can be critical, and matching the drivers output to the layout and number of devices on the local bus is critical.
I dont think moders who are not involved with the day to day design of digital (and analogue) circuitry realise the intense level of development that goes into such designs. They want to spend a week simulating and laying out a JTAG clocks to a multi device board to see how **** retentitive you have to be with digital, or building models of scope probes for the simulation software, so you can match the simulations to the viewed waveform (often distorted by the loading of the probe).
The only time I use silver plated copper wire (instead of tinned) is for certain applications that require a better temp rating etc, but these aint commercial designs.
Even if I thought I was percieving a difference I would have to prove it to my self with measurements
and then it would have to be repeatableWith I2S (and I2C) personaly I would be wary of taking it off board, having done numerous boards with Ti codecs (TPS320, TVS320 etc) and other devices, layout and impedance control can be critical, and matching the drivers output to the layout and number of devices on the local bus is critical.
I dont think moders who are not involved with the day to day design of digital (and analogue) circuitry realise the intense level of development that goes into such designs. They want to spend a week simulating and laying out a JTAG clocks to a multi device board to see how **** retentitive you have to be with digital, or building models of scope probes for the simulation software, so you can match the simulations to the viewed waveform (often distorted by the loading of the probe).
The only time I use silver plated copper wire (instead of tinned) is for certain applications that require a better temp rating etc, but these aint commercial designs.
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It depends. You need to be specific about what and how you are cabling things together. Sometimes digital is pass/fail, other times it can carry analog noise that may or may not have some unwanted side effect. Same for connectors: If sending clock signals, which are at some level analog in time, then a little connector corrosion can affect jitter, and so on. Again, you have to be specific about exactly what you are doing with wires and cables. It can also matter how you solder, route wires, wire length, characteristic impedance, etc.
In the case of I2S inputs on commercial dacs, IIUC they use LVDS signaling, and they include an MCLK signal. In that case then, yes, there could be effects arising in various places along the signal flow. Cabling could potentially be one such place. Can you post clear, hi res pics of your work? What specific cable are you using, and how long is it?
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Reading though the thread regarding the particular connector used in this case, if its really a DIN connector with one ground for all the signals, that's not good. Basically, it would mean the whole scheme is junk. Any cable might sound different from any other cable, since no cable could be technically correct at the frequencies involved.