RF Attenuators = Jitter Reducers

[DaveK]

Hi Fran,
Thanks for that, it's nice to know that others hear similar results.
I don't vist here very often 'cos the atmosphere I often find to be mildly toxic and unwelcoming of anything other than the general opinion of what I would describe as 'the usual suspects'. Frankly I don't give a s--t about whether anyone thinks I'm deluded or deaf or both - they may well be right . My intention in posting was to add my findings to the general pool of knowledge or delusion, depending on how closed your mind is.
Anyone interested enough to put it to the test will form their own conclusion, whatever that might be (and if my post encourages one or more to do so I would be happy). Anyone not open minded enough to risk shattering their firmly held theoretical beliefs is beyond any assistance I can render and the only sufferers are they themselves - their problem, not mine. I can only report on what I find.
If it carries any weight I would add that my background is in engineering, including a spell in a very well respected research laboratory, and I was educated (a long time ago) to post graduate level so I am reasonably experienced in A to B trials and the confirmation of findings. Just put it to the test and see for yourself. The concensus of theoretical opinion is that the bumble bee cannot fly but the bumble bee decided to try it for himself .
Cheers,
Dave.

 

[sendler]

Everyone's problem

Hi Fran,
Anyone not open minded enough to risk shattering their firmly held theoretical beliefs is beyond any assistance I can render and the only sufferers are they themselves - their problem, not mine.

Unfortunately, the momentum of discussion always shifts to the "All (fill in the blank) sounds the same" crowd. I feel sorry for the newbies to the hobby that constantly get their brains washed over by this. Listening is still more sensitive than measurement. The hatred of sighted listening was built up in the 90's to challenge the dishonest marketing of the swelling High End. And rightly so. The price gouging is ridiculous. Now, the internet is mature and we have diy as a great alternative to High End Audio. It is time to let up on the constant hammering of the subjectivists that contribute freely all over these forums with nothing financial to gain.

 

[SY]

Why are the FFT tests held to a higher standard than the listening tests?
.

They're not being held to any standard whatsoever. The spectra are being criticized on the basis of a completely incorrect and misleading "analysis" disguised as a diatribe, with a wildly inaccurate claim that a -120dB noise floor of the spectrum of a DUT and a -135dB noise floor of the test instrument somehow magically become 13 bits of resolution.

The people with a financial or personal interest are either seizing on it because they don't know any better (which is a pity for people trying to sell into that market- emptor should be very caveat) or, if they do actually know better, dishonesty. I don't see a third alternative, but you being a nicer person than I am might be able to point one out. The trolls seize on it because, like Aesop's scorpion, they can't help it, it's their nature.

Actual engineers who are familiar with measurement theory are staying far away, as they should.

As for listening tests, there have been none. Zero. Fun afternoons with buddies, perhaps, but no tests.

edit: My bad- the noise floor of the DUT was at -125dB, not -120dB.

 

[jkeny]

Thanks to Dave, Fran & Sendler for following the intent I had in starting this thread - to try it, experiment & report the findings (there are others on other sites !)- maybe those with an enquiring mind can learn something. The close minded one's are irrelevant as DaveK correctly identified

Anyone not open minded enough to risk shattering their firmly held theoretical beliefs is beyond any assistance I can render and the only sufferers are they themselves - their problem, not mine. I can only report on what I find.

 

[wakibaki]

Listening is still more sensitive than measurement.

Basically now we're down to an argument between subjectivists and engineers.

There's jkeny, who wants a test, which kind of makes him an engineer, but he only wants it to show what he claims, which makes him a salesman, and a self-publicist. So we can discount him, he's an interested party.

Then there are a bunch of other people out there, trolls, some of whom claim that they are engineers and can demonstrate what jkeny claims, but they have various reasons why they can't or won't post the evidence. Principally ThorstenL and Joseph K. They just love an argument. Nothing suits them better than if they can score a point (as they see it) but whether it's relevant or not, they don't care. They're interested only in making themselves look good by their own standards, which principally consists of making other people look bad, and in this category I include stormsonic and abraxalito. So we can discount them, they're acting out of self-interest too.

Then there are the subjectivists. They insist that their ears are better than any instrument (devilish device) and that controlled listening test (which would be acceptable to the engineers) is unnecessary. They can hear the difference, and the possibility that they might be mistaken is zero. They take themselves seriously, but nobody else does. A favourite anthem of theirs is that anybody who disagrees with them has a 'closed mind', conveniently ignoring the fact that the engineers keep calling for evidence, and they keep ignoring such as is available. They have no conception of what is meant by evidence. Anybody that is so convinced that they can't be wrong is a flake, so we can discount them.

Then there are the engineers. They remain open to being convinced either by instrumented test or controlled listening test. They're prepared to hear arguments regarding flaws in their tests, but they insist that anyone advancing such arguments should produce their own evidence to support their case. They, and people like them, are responsible for inventing hi-fi in the first place.

Big mistake. We should have kept it to ourselves.

w

 

[Spartacus]

Note to self: don't feed the monkeys

 

[Badge]

ah, another thread weighted down with doubters and irrelevant comments. I have read as much as I could stomach and then ordered a attenuator to try myself. Thanks for jumping into the fire Jkeny.

 

[DaveK]

WakiBaki, I had told myself that I would not post here again until I had further to report on my personal tests but I can not let your post pass without responding.
I take it from your last quip that you regard yourself as an engineer - you may well be the only one on here that does. What pontificating c**p!! What engineer rubbishes someone elses results when they have no knowledge of the tests concerned and the only 'evidence' they have is their own pre-conceived convictions based on their own very personal interpretation of the theory.
You invite posters who have personal experience of what the attenuation does to post the evidence - if you, as an experienced audio engineer, can tell me how I post evidence of what I and others hear with our own ears then I will be pleased to do it. You are asking for the impossible and you know it, but what is worse is that you try to use the inability to share our hearing experience as evidence that we do not experience anything and that we are all deluded or worse. This is a very un-engineering response IMHO, but as you infer that you are a true audiophile engineer I will give your opinion the respect it so wholeheartedly deserves, and I suspect others may well do the same.
As they say in many 'fields', if you ain't tried it, don't knock it. What is it that prevents you from trying it? - surely not the expense, which doesn't leave us with many understandable alternatives. Still, as you know you're right I guess there's no point in considering alternative viewpoints is there?
Over and out.
Dave.

 

[wakibaki]

It's odd, really, for some people it's enough that the only evidence available shows that something doesn't work for them to want one.

w

 

[DaveK]

It's odd, really, for some people it's enough that the only evidence available shows that something doesn't work for them to want one.

w

Just my opinion but never was a signature more appropriate.
Dave.

 

[planet10]

Come on guys, lets keep it civil.

dave

 

[jan.didden]

[snip]You invite posters who have personal experience of what the attenuation does to post the evidence - if you, as an experienced audio engineer, can tell me how I post evidence of what I and others hear with our own ears then I will be pleased to do it. [snip]Dave.

Dave, that's an easy one - just do a controlled subjective listening test. We'll have our proof one way or another.

jan didden

 

[wakibaki]

DaveK

Why don't you take a look at my blog on common emitter amplifier design? Or have a look through my other posts. You'll find a number of examples of original circuits I've posted.

Subjects range from SS power supply design, microprocessor hardware and code thru RF matching and tube preamps.

http://www.diyaudio.com/forums/power-supplies/176646-electronic-fuse-3.html#post2357249

http://www.diyaudio.com/forums/construction-tips/172590-led-uv-lightbox-inkjet-stencils-smt-pic-16f887-bcd-code.html

http://www.diyaudio.com/forums/solid-state/165549-intresting-design-problem-20mhz-200v-pkpk-200x-gain-3.html

http://www.diyaudio.com/forums/tubes-valves/137834-dual-supply.html#post1736450


So I believe you have 5 posts, 4 of them in this thread?

w

 

[godfrey]

As for listening tests, there have been none. Zero. Fun afternoons with buddies, perhaps, but no tests.

This sounds to me like it was a pretty good blind listening test:

... He was interested enough in the subject to make me a pair of his excellent 'home brew' co-ax cables, one with a 10db attenuator hidden in one end and the other one without the attenuator but otherwise technically and cosmetically identical apart from different coloured identification bands.
[snip]
I tried these cables alternately in my system between HiFace and heavily mod'd Beresford 7520 DAC (mod'd up to Caiman spec for those that are familiar with this range of DACs). I was very surprised to hear a clearly audible preference for one of these cables and reported such to the friend who made them within 45 minutes of starting the test. He was interested but otherwise said nothing. I listened for 24 hours, on and off, and the longer I listened the more confirmed my original opinion was. I was very relieved to have it confirmed that the cable I preferred was the attenuated one...

 

[godfrey]

Dave, that's an easy one - just do a controlled subjective listening test.

He already did.

 

[SY]

This sounds to me like it was a pretty good blind listening test:

Yet it isn't. 50% chance, single trial with coaching from the cable guy, is not exactly persuasive.

 

[jan.didden]

Yet it isn't. 50% chance, single trial with coaching from the cable guy, is not exactly persuasive.

Exactly. I said "a controlled subjective listening test".
I find it curious that we require from SY and his kind a fully documented, scrutinised technical test description including calibrated test equipment, characterizing of the DUTs etc, while anecdotal subjective listening tests of which we know almost next to nothing and 'executed' by those with an obvious interest should be considered as THE TRVTH (tm).

jan didden

 

[wakibaki]

He already did.

Yeah, and there's every chance, as I have pointed out already, that if he did detect a difference, that he actually expressed a preference for increased jittter. This is why solo listening should not be given any weight in the absence of instrumented test.

For pity's sake THINK for a moment before jumping in with both feet. We're trying to come to a scientific conclusion here.

!!!

w

 

[godfrey]

@SY:
Hey, a sample of one is a big step up from zero!
Just need some more like that.

 

[DaveK]

Dave, that's an easy one - just do a controlled subjective listening test. We'll have our proof one way or another.

jan didden

Hi Jan,
I'm not being thick, I genuinely am new to this so I have no real idea of what a contolled subjective listening test is, let alone how to conduct one . In my naive way I thought that's what I'd done. The cables were provided to me by another person who gave me no information about them other than one had a blue tag and one had a yellow tag. We have never met in person and he was at least 100km away from me at all times and no communication took place between us other than what is mentioned below. The listening tests were conducted by me alone in my own home with kit I am very familiar with.
Test 1 consisted of a listening session consisting of 3 tracks, one orchestral, one female vocal and one electronic, with the existing setup to give me a current bench mark, test 2 involved repacing the coax cable linking HiFace and DAC with one of the trial cables and listening to the same three tracks and test 3 involved replacing the first trial cable with the second one and listening to the same three tracks. My first impression placed my original cable between the two trial cables in terms of the SQ I was hearing and the best cable was so obviously better to my ears with my set up that within 45 minutes of starting the test I registered with the guy who made the cable what my initial opinion was and why. Other than saying "That's interesting" he made no further comment. I continued to repeat tests 2 and 3 with different tracks for a couple of hours that evening and again at intervals the next day. The result was that my I became even more convinced that my original opinion was validated, the difference was so obvious it was a 'no brainer' as they say. I reported my confirmed opinion to the friend who made the cables and he confirmed that the cable I preferred, tagged blue, was the 10db attenuated one.
Subject to me confirming his permission I am quite happy to put anyone in direct communication with the guy who made the cables - he is/was a Moderator on another very popular audio forum so his word may carry more weight than mine. Neither of us have any connection with or have ever met John Kenny - the only reason that I did the listening tests is that I am the only one with a HiFace of any description and I asked my more knowledgeable friend for his opinion on John's suggestion that such attenuation wouls improve the SQ from a HiFace/DAC combination. My friend was initially sceptical but open minded enough to volunteer to make the test cables so that I could undertake a 'blind' listenig test for myself. The rest is history as they say - we have absolutely no axe to grind in reporting my findings.
Jan, if you care to PM me with an outline of what you would consider to be a controlled subjective listenig test (if the above doesn't qualify), if it is within my capability I'm willing to have a go.
Over to you.
Dave.