solderdude
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Post by solderdude on Sept 20, 2013 10:41:35 GMT
Ah... I removed my analog rant as I assumed you were talking about analog cables. In your reply it wasn't clear you spoke of digital cables only about I/C's.
Well... here is the problem with me testing digital cables.... I can NOT test the digital cable as I would ALSO need YOUR DAC and YOUR source. The tests would be similar to those performed by Archimago. For the same reason it would be hard to conclude that his results with digital cables will always yield similar results as it depends on the DAC mostly. It is completely pointless to ship just the cables as they will measure differently in the frequency area where it is used and the effects that MAY have will depend mostly on the used DAC. Some will view this as 'chickening out' but I would REALLY need the whole system so the 'challenge' is pointless.
Another problem is you cannot AB digital cables directly as you can with analog as no bits should be missing while switching by punsihment of drop-outs and muted signals. There are smply NO affordable mechanical switches that can do that.
As explained it is all about proper termination and insensitivity of the DAC itself to (all kinds of) jitter as well as the source (albeit in a lesser degree unless the SPDIF out is really crappy)
IF there are very noticeable differences then these are caused by your DAC having crappy jitter rejection (IF it is caused by jitter) and it is more than likely another DAC will NOT react in a similar way. These differences could be caused by reflections or level differences upsetting the PLL in your DAC. If both were RF cables I would be very skeptic though.
To ME your test is not very valid for the same simple reasons I have had 'discussions' in another forum. The test is done SIGHTED and regardless of how trained one is and thinks expectation bias works it won't be admissable as 'technical proven evidence' by any technician.
A test you could very easily do yourself is to have someone ELSE change the cable where you do not know which cable is tried. You and the cable swapper need to keep a log. IF those logs shows a solid relation you should look out for/try a different DAC or keep using the 'better' cable.
A really blind test would be far more convincing than a sighted test if enough statistical relevant samples are used (cable swaps). Only when such a test is performed you can speak MORE of 'facts', with sighted test one simply can NOT. Most are not willing to do that or go though all the trouble for various reasons.
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Dave
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Post by Dave on Sept 20, 2013 11:50:33 GMT
Hi Frans, I will try very hard to avoid using the word "chicken" as I know that you are not so devious or protective of your firmly held beliefs. Mike might take a different view but I am only interested in whether there is any difference in the sound emanating from cable 'A' compared with cable 'B'. If there is in your system(s) and in mine then the cable is most likely responsible for that difference. If there is not, then my system is most likely responsible. I know how Mike has 'tweaked the cable and I have 'tweaked' other digital cables with 'stuff' provided by Mike and in each case it was possible to tweak the sound to make it better or worse, no exceptions. In each case there was an optimum level of tweak which differed with each cable and remained the same, irrespective of where in the system it was placed. So I repeat: will you humour an old man and test my two digital cables in any set up you choose and see if you can hear any difference in the sound resulting from them? Leave aside any explanation why you may or may not hear any difference, just a simple, "Any difference, yes or no?". The only proviso is that you listen before you 'test it to death' and you post your 'warts and all' different or not different findings on here - I have no doubts about you tweaking the result to suit your firmly held views. Well? Dave.
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Post by solderdude on Sept 20, 2013 13:02:35 GMT
I do not have an SPDIF DAC and either use FiiO X3 (24/192 WAV max) or USB DAC's (have 3), in all cases coax can not be used. The only way Mike can 'tweak' them is by adding 'networks' in the plugs, simple or complex. The cable is NOT the one having 'a sound', it may or may not have some influence on the transmitted eyepattern which in turn may or may not influence the performance of a DAC and ONLY in the field of 'timing', a misinterpreted bits will not lead to a change of sound but in other problems that do not reveal itself in that way. Mike can very easily make scope shots of both cables which would show IF the eyepattern differs. If it doe not then really nothing actually changes. Willing to bet he has already done this. A scope may 'load' that cable incorrect BUT this does not matter when showing differences. These measurement would only be 'telling' if performed with actual signals. your remark 'irrespective of where in the system it was placed' is intriguing as the cable can only be placed between source and DAC, unless you mean the 'tweak' (which would be a network of sorts). I sure hope the tweaks did not consist of stones, diamonds, rubber sticky feet or sanitary pads though. Here is the thing.. I could connect the cables and listen but I do not trust my ears, certainly not combined with the eyes. I could do it 'blind' IF I had a jitter sensitive DAC with SPDIF input though. rather I would rely on tests and measurements showing differences in jitter or do 'audio nulling' tests which would be more conclusive. Till this day I have not seen anyone claiming differences that has also shown differences to exist in a measurable way and if there were Hydrogen forum would be plastered with them in a great effort to find out why. Of course one can be of the opinion hydrogen people would rather die than admit it is possible after all but I am convinced IF they found soomething that measured different every one of them would want to be the first showing this and resolving it.
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Dave
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Post by Dave on Sept 20, 2013 14:14:04 GMT
Hi Frans, I guess I should have made my statement a little clearer but I realise I am already open to accusations of suffering from 'verbal diarrhoea' so tried to be brief . Regarding your statement "your remark 'irrespective of where in the system it was placed' is intriguing as the cable can only be placed between source and DAC, unless you mean the 'tweak' (which would be a network of sorts). I sure hope the tweaks did not consist of stones, diamonds, rubber sticky feet or sanitary pads though. ", what I meant was that I have a few sources and DAC's so I could conduct a variety of test with different combinations of source, cable and DAC. In each case, when the cable was the only change the same cable always gave the best results. I can also assure you that there were no "stones, diamonds, rubber sticky feet or sanitary pads though", used or otherwise . I do know what there is and it is something you would recognise and can measure. As you well know, I am way out of my depth here, technically but my ears, although far from perfect, are very capable of distinguishing between so noticeable a difference between two cables. Being out of my depth I am going to leave further discussion on this subject to Mike, who knows what he is talking about, unlike me . BTW, FWIW, do I hear a slight echo of clucking in the far distance? . Cheers, Dave. EDIT: Frans, you may find post No. 59 on here interesting: - theartofsound.net/forum/showthread.php?27980-Digital-Cable-Lengths-and-Other-Stuff/page3If I understood any of it myself I may be able to suggest why . Dave..
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solderdude
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Post by solderdude on Sept 20, 2013 14:35:36 GMT
All I can say is:
A: it is not obviously NOT the cable but the circuit used (the tweak), even when a tweak is build into a cable. B: If you hear it with various sources DAC's I would scream .... BLIND.... test it BLIND and 'document' the test. Invite people have them test it blind as well, have the signals verified by measurements an publish it.
HOW does the sound improve and HOW could that be verified (other than blind) is the next step.
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Dave
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Post by Dave on Sept 20, 2013 15:07:28 GMT
Frans, I'm not trying to be super-funny but all I can say is that the difference was so obvious to me that a blind test was totally unnecessary, believe me . Of course the 'difference' was caused by the tweak and I thought this was obvious from square one - the basic cables were identical in every way (except for the coloured insulation tape at one end of each for identification purposes) - same length of the same cable, same connectors soldered into the same place by the same guy at the same time using the same solder and I'm not aware of any theories about the colour of any insulation tape involved having any effect on the sound (joke ). My point is that it would appear that it is possible to improve the SQ in any system using a digital/SPDIF cable by applying a simple tweak. The teak is relatively inexpensive, variable for optimum results and easy to install and uninstall, IMHO a no-brainer for someone with a suitable system and an open and enquiring mind. Just a couple of further points: - 1) I have no first hand knowledge but reading between the lines of Mike's recent posts it sounds to me as if he has now taken his theory a stage further so my remarks apply only to my experiences with the first 'beta' cables 2) you might find it interesting to follow the link added as an EDIT to my immediate previous post. All in the best spirit of this forum . Dave.
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solderdude
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Post by solderdude on Sept 20, 2013 15:13:06 GMT
I'm not trying to be super-funny but all I can say is that the difference was so obvious to me that a blind test was totally unnecessary, believe me I have heard that one before !! All kidding aside... for those that like to experiment making an attenuator (a lot of SPDIF signals may actually be a bit too 'loud' if not terminated properly or are not complying to standards here a basic schematic that will attenuate and lower reflections considerably as a reflection (which is a small percentage of the original signal and only the higher frequencies(edges) in general) need to travel back to the source, reflect a percentage there and travel back and 'alter'the original waveform: If you make a better 'load' the reflection will be less, that reflection will be attenuated while travelling back, reflect less due to better matching of impedance and that smaller reflection will be attenuated one more. So in essence the reflections will be less IF the matching wasn't good to begin with AND the reflection will be attenuated 3x more than the original signal which is only attenuated 1x. Basic circuit. the secret sauce is in the calculation of the correct values which will depend on: output impedance of the source, load impedance of the receiver, signal strength of the source, optimal signal strength at the receiving side. Good luck. Here is a good site to start tinkering in that area. calculator: n9zia.ampr.org/att_pad.main.cgiexamples: www.qsl.net/n9zia/wireless/pics/att_pads.pngcable reflection tester: www.qsl.net/n9zia/wireless/pics/tdr.pngwww.qsl.net/n9zia/wireless/appendixF.html#4
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Dave
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Post by Dave on Sept 20, 2013 15:25:49 GMT
I have heard that one before !! Frans, I regard that remark as being borderline unfriendly but I don't think it was intended that way so I'm relaxed about it. I prefer that response to believing that you think I (and anyone else who might have tried the tweak - don't know if anyone else did - Mike?) am a self deluding idiot. If you insist on denying any possibility of what I distinctly heard, repeatedly, was in fact there to be clearly heard whilst at the same time refusing to try it for yourself or get someone else to give their opinion I guess this discussion is drawing to an end. How about me sending the cables down to Ian to see what he finds? Ian? Cheers, Dave.
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solderdude
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Post by solderdude on Sept 20, 2013 15:43:38 GMT
It was not intended as being unfriendly nor to portray anyone that hears something as an idiot.
Why not save on shipping costs and run the risk of other peoples gears and ears not being 'sensitive' to this change (attenuatorr ?) and simply re-test but now blind. Just to humor me....
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Dave
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Post by Dave on Sept 20, 2013 16:32:12 GMT
Imovable object .... irresistible force. Pity all such discussions founder on this same rock, innnit, and I include myself in that criticism. I'm out now and will leave others to continue the discussion but, if I can find the original cables they are available to any open minded ( ) and keen eared member to try. Remember the only criteria for me is whether the two cables give different sounds in an otherwise identical set up and if so, which one sounds best to the tester's ears. It would also be interesting, to me at least, to hear how each compares with what the tester replaced them with. Mike on the other hand might have slightly different requests. My prime candidates for this test would be Ian and Javier 'cos I know Frans respects their opinions on such things but any member is invited to express interest. Cheers, Dave.
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Mike
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Post by Mike on Sept 20, 2013 17:50:37 GMT
Hi Chaps,
Just to confirm; these 'tweaks' that Dave refers to are RF attenuators in the exact configuration that Frans has detailed above. I sent Dave a selection of different values to play with but we didn't really get any further thanks to my sabbatical.
*NOTE* I don't take any credit for this idea of using RF attenuators, as far as I remember (it must be about 2 years ago) a chap called John Kenny (I think?) introduced my to the idea via Dave. I think he was doing something with a hiFace?
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solderdude
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Post by solderdude on Sept 20, 2013 18:15:30 GMT
John was indeed playing with these attenuators and had screenshots of scope pictures. He might even chime in when he reads his name.
There is also a 'T' damper (this is called a 'pi' filter) which could be used.
John noticed the eyepattern was cleaner. IMHO a slightly cleaner signal (high and low levels) won't create 'better sounding' bits. a slightly different or more jittery '0 point' combined with an interface or receiver and or PLL DAC circuit the result may be less 'jittery'. Unfortunately I have never seen J-test plots or other convincing evidence that indicate that the clock frequency of the DAC output is actually improved.
That would have been VERY easy to do for those who know what they are doing and may have made their case.
Also I don't remember seeing much of it since, including in other fora.
Nice experiment, I hope John chimes in with his findings and research on this subject.
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Mike
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Post by Mike on Sept 20, 2013 18:26:25 GMT
John was indeed playing with these attenuators and had screenshots of scope pictures. He might even chime in when he reads his name. There is also a 'T' damper (this is called a 'pi' filter) which could be used. John noticed the eyepattern was cleaner. IMHO a slightly cleaner signal (high and low levels) won't create 'better sounding' bits. a slightly different or more jittery '0 point' combined with an interface or receiver and or PLL DAC circuit the result may be less 'jittery'. Unfortunately I have never seen J-test plots or other convincing evidence that indicate that the clock frequency of the DAC output is actually improved. That would have been VERY easy to do for those who know what they are doing and may have made their case. Also I don't remember seeing much of it since, including in other fora. Nice experiment, I hope John chimes in with his findings and research on this subject. Me too!
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Mike
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Post by Mike on Sept 20, 2013 19:05:53 GMT
Anyway, are we (pretty much) agreed that cable length (within reason) 'should' make negligible difference to the 'sound' of a digital interconnect? Assuming, of course, that the cable used isn't utter crap and is at least fit for purpose? Incidentally, (if anyone's interested?) I don't actually use an 'RF cable' such as RG59 etc. It's a coax designed for high speed digital transmission in the telecommunication industry. There was some chatter about silly priced SPIDF cables over on AoS many years ago and I just sort of thought; "hang on a minute, I can do this for *MUCH* less money", and had a go. A few guys tried what I came up with (for about £10).... and all hell broke loose! So here I am still making the damn things!
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Dave
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Post by Dave on Sept 20, 2013 19:21:46 GMT
Just to update Mike's last post but one, I did indeed add attenuation to a wide variety of SPDIF cables (I think I mentioned this above somewhere ? ) and found in each case that, to my ears and for whatever reason, it was possible to add attenuators to the cable until the optimum point was reached, after which the improvement went rapidly backwards and very soon I got silence. You guys may be able to explain the phenomenum technically and confirm that it does or does not surprise you or interest you - either way, I don't give a toss, all I am saying is that some level of attenuation to SPDIF cables seems to improve (to my ears) the resulting sound. As they say about other things , don't knock it if you haven't tried it - what have you got to lose? Go on, try it and you may be surprised . Dave.
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