John Curl's Blowtorch preamplifier part III

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With the greatest respect, I have a Topping D10 and it is immaculately built. People of stuff and hear what just isn’t there. I mean, I just look at what this thing looks like after bring modded and think about the clock noise, EMI etc and tell me it performs better - by ear or on a test set?

I never said anything about it's build but did mention that it measured immaculately (based on currently accepted standard measurements)

As I said, I haven't tried the mod suggested but it is a simple change to the power supply at the PLL_AVDD pin which was stated to make the biggest audible difference - not the rest of the mods seen in the pic.

I suggested this might be an alternative & good base for evaluating audibility Vs measurements as the device is well built & measures well - all that has to be ascertained is, does the mod to power at XMOS PLL_AVDD pin make an audible difference?

I will do the mod & report back if anyone is interested?
 
I suggested this might be an alternative & good base for evaluating audibility Vs measurements as the device is well built & measures well - all that has to be ascertained is, does the mod to power at XMOS PLL_AVDD pin make an audible difference?

I will do the mod & report back if anyone is interested?

What matters more is if there is a measurable difference. Unless you are arranging a no peeking test.
 
Did you watch Uri Geller on the Tonight Show, quite a performance. I guess Johnny "cheated" by farkleing all the magician's props before the show. :rofl:

Performance artists, like SY, operate by the same technique magicians use - by directing attention to what they want the audience to focus on not what is important. SY's 'tests' were similarly circumscribed to those tests that would support his worldview, not a scientific endeavour for 'truth' (whatever that might be?).
 
“Yes, as the system 'dials in' as you say new sounds can appear as if by magic. ”

The only systems that dial in are ones that perhaps need a few minutes for bias to stabilize or tubes to heat up.

In my not too inconsiderable listening experience, it’s your brain<>ear system that tunes in. I’ve heard systems that were initially very aurally unpleasant but after a few days, sounded great.

In another life, I was in the military and would go away for 3 months. I remember coming back from the bush and my system would sound absolutely fantastic for a few days before it returned to sounding good. As far as I know, there wasn’t any communication going on between the electrons flowing around my gear and my commanding officers.

I do wish folks around here would accept that the stuff they hear (here’s looking at at you Dan,mmerill, et al) is generated for the most part between their ears. You can’t hear -80 dB distortion products (ie below music peaks) but you sure as hell imagine you can.
 
What matters more is if there is a measurable difference. Unless you are arranging a no peeking test.

I believe the point is that standard measurements are not showing what can be audible

Forgive me if I haven't followed this vein in the thread but wasn't Mark's offer to do with something which is audibly noticeable but according to many here, measures way below the threshold of audibility.

I already gave ABX results for audibility of -90dB differences which some here denied should be audible
 
Good to learn new words. But as a teacher once said to me, people who are good communicators use straightforward language, the use of needless and / or unusual words tends to indicate someone trying to impress or confound.

... string goop theory .... to go with quantum bybee theory...
Theory may be the wrong word.....

Ok, how about ‘hypothesis’?

😀
 
.........
I do wish folks around here would accept that the stuff they hear (here’s looking at at you Dan,mmerill, et al) is generated for the most part between their ears. You can’t hear -80 dB distortion products (ie below music peaks) but you sure as hell imagine you can.

I gave an example of ABX results which showed that two files were audibly differentiated & the only measurable difference found between them was at 90dB

Did you miss this or simply just deny it's existence?
 
Why do people forget that using things like Reaper to learn the differences in sounds is totally on the palette for testing. The process of testing BEGINS with educating the ear and mind to the sounds you are trying to differentiate. That is not only allowed, but called for.

Then, after you think you can differentiate the sounds, take the bloody ABX test. p=0.95, yah, I really can hear it! p=0.5, oops, try again. p<0.4, you're listening to the wrong thing!

Cheers
Alan
 
-90dB and -120dB are very different levels. 30dB different in fact. difference between possibly audibly and 'your having a giraffe mate'

Yes, but see Bonsai's claim above - he adamantly claims -80dB is inaudible
So he is demonstrably wrong, for a start

But the focus on this -120dB measurement was already pointed out as possibly being a focus on a misleading measurement - that it might well be just an indicator of an underlying difference that is not currently being measured
 
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In another life, I was in the military and would go away for 3 months. I remember coming back from the bush and my system would sound absolutely fantastic for a few days before it returned to sounding good. As far as I know, there wasn’t any communication going on between the electrons flowing around my gear and my commanding officers.

1001+ :up: I have a policy of never ever listening to music in the background. For me, listening to music is the final act of the artists original musical intent, and what the music is played on is of little consequence. The fact that my play back sounds incredible is of no relevance at all. That it could sound better is something for tomorrow to think about. Today is now, and I am content.

tapestryofsound
 
mmerrrill: I have tried, but you add zero to the discussion other than obfuscation. I have no option but to ignore you now. Please let the grownups discuss this.

What you are really trying to say is "stick to my set of defined measurements & don't ever question them" - you call it obfuscation - I call it a full consideration of what's presented.

I understand & it is a neat attempt at confining the discussion to only the terms/measurements that you guys want defined when what is actually being said is that the "terms/measurements that you guys want defined" may well be lacking in their revealatory ability of what is audible
 
Because getting people organized around here is like trying to herd cats.

Well, people are calling me from time to time: rude, stubborn, *** orifice, cynical, big mouth, etc... Set aside these attributes don't bother me (this is the Internet after all, and some times I can even see why people think so through the monitor glass) why am I never called "delusional" or "crook"?
 
I have a proposal for measuring (or more accurately, presenting) distortion values - I've mentioned it before, but I just took a few minutes to make it a little more formal. I'll split this into two posts and put the proposal in the second one.

I could ABX files which were supposed to have a difference in THD. The problem was, the THD was very low that it wouldn't make sense if human could perceive it, so my conclusion was that 'it was not the THD being perceived'.


Around 5 years later I 'found out' that what I thought a THD was not really THD, it just sounded like distortion. Mark to me was just suggesting that we shouldn't make a test for THD but for other suspected mechanisms instead, such as IMD.
As I think PMA was saying, THD and IMD are actually pretty closely related. if something "sounds worse" and measurement indicates it has higher THD, I would presume that it also has higher IMD.
Sometimes I'm curious too. When an amp is 0.002% (THD), then we change the input coupling cap from ERO MKT 1.5uF to Solen MKP 1.5uF, what will happen to the amp that make it audibly difference (as claimed by many people)? Was it imagination? I don't think so as I could even passed ABX of such test. For anyone curious, this should be a simple test to set up (also with Dan's Goop), I don't understand why some people seemed to be so afraid of.
I don't know that anyone is "afraid of" investigating such, but as an engineer myself, I can see where technical people can be dismissive, thinking "oh, that component in that location can't possibly make any difference."

But there could indeed be an audible difference between these capacitors. It would be good to know other things, such as the model amplifier, and especially its input circuit to evaluate its input impedance. This would give the low-frequency cutoff with that value capacitor. While we're at it, each capacitor's value should be measured to within 1 percent - if one's value is too far off, it would add suspicion that the different value is what makes it sound different. Combined with the amp's input impedance, these should have cutoff well below 20 Hz where there could be "no practical difference" but it's always good to know exact (or within a few percent) values of these things.
That's it, many people say "distortion" and do not think about non-linear distortion in fact, and they do not know what it is, just do not understand what they are speaking about. Then, they state that "distortion of -120dB might be audible" and similar nonsense is often declared. Same people are unable to tell -40dB distortion (nonlinear quadratic or cubic distortion) in an ABX DBT, which was shown in several threads. So first, correct terms should be used. Second, some objective evidence other than "I heard it". This discussion will last forever, with no output other than anecdotal stories about audibility of -120dB distortion, that lies far below audibility threshold.
The mention of quadratic and cubic distortion (which I presume meaning running on parts of the curve that generate mainly low harmonics) reminds me of a totally different circuit used in some music synthesizers, a "wavefolder." Each stage of this doesn't just clip at a diode threshold, but INVERTS the signal above the threshold. Running a signal through several stages produces humongous amounts of higher harmonics. Signals put into this should be VERY audible when added at -40dB to the original, and surely audible at much lower levels. This not in any sense a realistic distortion, but I thought it an interesting idea.
And please do not say "THD" being perceived. THD is a number. You speak about non-linear distortion, system non-linearity, which does not care how you call it. THD, IMD is just a different way how to try to evaluate a non-linearity, one and same non-linearity.
I agree, again THD and IMD are each composite numbers made from many individual measurements of a complex signal.

(continued response and proposal in next post)
 
So please clarify ABX is OK now for subtle differentiation or is this not considered subtle?

I knew this would come up & most likely from you, too. So here we go again, for the umpteenth time

One of the big problem I have always maintained with Foobar ABX is that it has no controls (something you have struggled with greatly in the past & I presume still do?). These controls would allow for an evaluation of the test's sensitivity, but more importantly the exact problem I stated to Syn08 - there is no way that his nocebo bias is revealed in a blind test without such controls.

So we have no way of knowing if a null result is because there is genuinely no audible difference to be heard or the participant's lack of training, their nocebo bias, etc. caused them to be 'deaf' to the differences - look at this guy (Ultmusicsnob) training & lack of prior beliefs about what is audible - he is purely an experimentalist without an agenda. He has other ABX positive test results which I linked to previously & in those tests he listens for a totally different audible cue. Even in these set of jitter audibility tests, he changes what he is listening to as the level of jitter changes (these are pre-prepared files with injected jitter done by someone else). It takes effort & flexibility to do such blind tests as well as stamina & curiosity plus a belief in one's hearing - all of these characteristics are lacking in most people on forums who do Foobar ABX tests - they expect that subtle audible differences will slap them in the face & be obvious - not so!

So, yes a null Foobar ABX result really leaves a lot of questions unanswered

The Foobar ABX test is totally geared towards removing sighted/knowledge & the bias that can be caused by this knowledge.

So when a participant gets a positive ABX result what do you then glean from this?

I hope this answers your dilemma about where I stand on Foobar ABX tests as you seem not to have grasped all this which has been said in the past?

And of course what was measured was carefully scrutinized or does that only matter when the test gives a null result?
You would need to read the thread I linked to in order to evaluate for yourself the files - as I said the jitter is generated at various levels by someone technically adept - I'm sure you can evaluate the measurements yourself?
 
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