Because I am interested in concrete values, how well these LDRs are matched/matchable, etc. See my earlier questions.
Extra points for also measuring the current through each LDR at your settings. 😉
I would guess that the bulk of LDR attenuators are passive ones where matching is crucial.
I do not like to repeat myself, but this could account for some of the differences that people say they hear.
Don't worry, people here will understand that it would be just a single data point.
I understood that the first time you posted it. Nothing is difficult about that.
With THD+N being roughly in the range of -60 dB +/- 20 dB, with 2.45Vrms input signal, and this could shift in either direction depending on the particular LDRs "selected" as well as the specific circuit. Are we on the same page here?
Btw, there were some comments about potentiometers a couple of pages back. The Silonex app note says regarding distortion: "LDRs: medium -> good", "potentiometers: very good". Even VCAs are described as "good".
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I'm not, as you put it, lobbing grenades at EEs so no need for the macho stuff. What I'm criticising is the cod psychology one encounters throughout the audio milieu, some of it, as here, from EEs. You're not seriously suggesting that the "psychology" points made here have merit?
Many EEs demonstrate an admirable grasp of the complexity of the empirical investigation of perception and steer clear of cheap "experiments" and assumptions. Some of them used to post here. These, days, not so much.
I readily agree that the design of psychological experiments is often flawed though, in fairness, I no longer follow the scene. What I'm less sure of is that because psychologists struggle with a difficult discipline it somehow follows that EEs can be excused knowing about any of it before spouting off. Have you ever e.g. read an EE write of the need for control groups and procedures, subject selection, data analysis etc etc and etc before telling us about "expectation bias" (always biased in favour of the writer's own expectations) or people being deluded or whatever? All of which is year 1 undergrad stuff. OTOH, the many EEs who do understand what's involved rightly decline to indulge in the cod psychology. I respect that, as I do their work in their specialised field.
That said, when I do read this or that of contemporary psychology, I'm often struck by how little seems to have changed in the years since I graduated in the subject. However, you imply (I'd agree) that the informed criticism typically comes from other psychologists. What's wrong with that?
I guess I'm failing to see what was so controversial about the psychology discussion--it's running the usual "your measurements don't cover what I hear" vs "the measurements are generally far more sensitive than human hearing". Yes, it's a trite argument of strawmen built up and burnt down time and again; and all parties tend to contain elements of truth, but your comments come across overly derisive of EE's (or, more generalizable, to technically-oriented folk) rather than critical of all parties (either everyone or no one should be excused before spouting off, discipline irrespective).
Perhaps I find it more annoying than you when someone claims their impression (uncontrolled in all the ways you describe) as an absolute truth. If my reading of Toole/Floyd and of different sample rates/compression algorithms is at all correct, the trend I see is that we humans aren't as good at hearing things as we'd like to think. Certainly makes me give an incredulous stink eye to anyone making wild claims about changes which, to first order, seem to be in the -60 dB or smaller range.
Apropos nothing, I wish I knew more of your 1st year Psych students who understood good experimental control. 🙂 (Most of the senior undergrad engineers I teach don't do that well, in spite of the hundreds of hours of labs we put them through)
Absolutely nothing wrong with internal criticism--we're in agreement here. The "rest of us" aren't in as good a position to make that criticism, so governing from within (done right) is probably the best path forward. Not sure how much has changed, but it's refreshing hearing the field (among many others) talk about going back and validating old studies.
Perhaps I find it more annoying than you when someone claims their impression (uncontrolled in all the ways you describe) as an absolute truth. If my reading of Toole/Floyd and of different sample rates/compression algorithms is at all correct, the trend I see is that we humans aren't as good at hearing things as we'd like to think. Certainly makes me give an incredulous stink eye to anyone making wild claims about changes which, to first order, seem to be in the -60 dB or smaller range.
Apropos nothing, I wish I knew more of your 1st year Psych students who understood good experimental control. 🙂 (Most of the senior undergrad engineers I teach don't do that well, in spite of the hundreds of hours of labs we put them through)
Absolutely nothing wrong with internal criticism--we're in agreement here. The "rest of us" aren't in as good a position to make that criticism, so governing from within (done right) is probably the best path forward. Not sure how much has changed, but it's refreshing hearing the field (among many others) talk about going back and validating old studies.
Cheap "experiments" like those anecdotal comparisons and wrong assumptions like LDRs being more linear (see earlier discussion in this thread)?
Full ACK, but I would say that any scientifically literate person and especially skeptical persons would steer clear of that.
Default position, null hypothesis. 'nuff said.
Thanks for an interesting reply. I did not intend to be overly derisive of anyone but there are regulars on DIY-Audio who seem to presume it's OK to belittle non-techies with cod psychology rather than explain technicalities in terms the non-technical will understand. I'm not critical because they're EEs but because there's something of the bully about them.
I took the OP as an enthusiatic response to a pleasing purchase that, in a more tolerant milireu, would have been noted as such. It wasn't.
I don't know of Toole/Floyd. I'm intrigued - I'll take a look.
As psychology undergrads, we were not taught about experimental design and control, we had it drummed into us by otherwise perfectly decent people. Given the non-linear, fuzzy nature of the subject, that was understandable though the practice is not, sadly, universal. I was too poor at maths to stick with experimental psychology and never aspired to but I remain half a century later indebted for the grounding.
OP here. Yes I was initially quite enthusiastic when I heard the described differences in the music that I listen to on a daily and regular basis. I merely described what I heard and made no pretensions that my findings were universal to everyone using an LDR attenuator. Unfortunately some have taken my words as being that.
I never felt the need to write, "this was in my audio system and may not be the same in yours", as I felt that that was obvious. All such audio comparisons, as I did, are always limited to the context in which they are done, meaning the audio system, room, etc. That is usually understood, or so I thought.
I feel that the differences I heard were due to the LDR attenuator, for obvious reasons. I didn't then, nor do I now, know why the LDR should have let the orchestral climaxes be louder or the low bass in many recordings be better.
As time passes I will have the opportunity to do a similar comparison of the LDR unit with a different stepped attenuator in passive mode, a preamp with that same stepped attenuator, and an Alps potentiometer in passive mode. Audio system will have the same player and amp, but different speakers and room. When that happens I'm sure I will be back with a short report.
As long as you are willing to entertain the possibility that the loud passages actually ARE louder.
To cap what I have been trying to get across:
-In real practical terms, the input voltage (which is dynamically varying in a music signal) will be divided between the Source's output impedance, the series LDR and the shunt LDR; Like my example with modern power amps the shunt LDR gets the least of the input voltage (meaning least distortion too); This LDR shunt's voltage drop and its distortion are what's generally passed on to the next stage -the power amp's input
-As Mr. Pass found out the series LDR and the shunt LDR's distortions subtract, where equilibrium is when series LDR = shunt LDR at -6dB; As a bonus my power amps are rated 20dB (x10) voltage gain so I spend my loud listening levels mostly at -6dB attenuation on 89dB/W speakers
-Distortion only peaks during peaks in music signal which is probably 1 to 5% of recorded music; 95% reside in "The Valley Where Music Lives", referring to Mr. Pass's distortion graphs which is 0.5V or less and which I expect to be 0.0035%(-89dB) to 0.025%(-72dB) distortion; Of note also is how at different attenuation levels the distortion curves all converge at the bottom of the valley!
-Recorded music of different genres that I have sampled as an album's peak voltage had ranged from -7dB to -3dB below the reference 2Vrms
-My hope is everyone gets to try and decide if these distortion figures are audible or if it's even worth to hurl insults amongst yourselves
Lastly, sometimes I get up with a start to look at my instruments and double-check if I'm on the correct wavelength...
I'll be on my way now to the Constellation Scorpius, in the neighborhood of Antares. Cheerio!
Well what do you know, as soon as I write something there quickly is someone who didn't hear anything telling me I didn't hear anything different and made it all up.
Really, that's what I said? There must be a language barrier. I said yes they sounded louder, no problem, entertain the possibility that they actually WERE louder. I don't get the adamant insistence that LDR's must be doing something that can't be quantified by ordinary diligent engineering. Minds open on both sides.
I gather from Nelson's write up LDR's can act like a (very?) mild volume expander under the right circumstances.
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Hm, well I took it that you were questioning what I wrote with that capital letter "ARE". Apparently you meant something different, or else I wrote poorly in my post. I'll take the blame for writing poorly.
At the risk of further poor writing I will write exactly how I heard things at the time it all happened as I remember it clearly, although I admit that memory is what it is...........
The comparison was done primarily with one orchestral piece, a new Penatone set of Tchaikovsky symphonies and shorter pieces. I used Romeo and Juliet as it's not too long at 24 minutes, has good dynamic range, and sounds very good like every other piece in the set. At first go with the stepped attenuator, everything sounded great and as music had sounded for a long time with my system. This then was my reference sound for the comparison. Any differences were from that.
I then swapped out the stepped attenuator for the new LDR unit. Everything sounded great and about the same. I did notice that the climaxes seemed a bit louder than earlier with the stepped attenuator, but nothing earth shattering. However with repeated listenings to this piece, and others, I sensed that most all orchestral climaxes were louder and I was taking more notice of the them. I also began to hear the heavy percussion hits of tympany and bass drum with more authority than with the stepped attenuator. This all was a noticeable difference that I took note of and was impressed by.
At the time of this comparison I was living in a small apartment and don't like the music to be too loud, for the neighbors sake. Thus I found myself repeatedly turning the sound down a bit from the loud climaxes. I hadn't done this before unless I had had the music just too loud.
I make no pretense to any of this being in any way scientific or anything. It's just my observations. And single observations such as mine can often vary from other single observations and other reasonings as well.
I've read enough in this thread from measurement charts and observations of other's and I do seem to be a little at odds with some of that. Well to me that's just how it is and doesn't bother me.
My only insistence on LDR's has been that the described changes were when I swapped the LDR unit in, so that's the correlation that I use. I know full well that correlations cannot always be trusted and that there might be other factors. Nonetheless, the only system change was the attenuator swapping.
I look forward to my next round of observations.
Perhaps I find it more annoying than you when someone claims their impression (uncontrolled in all the ways you describe) as an absolute truth. If my reading of Toole/Floyd and of different sample rates/compression algorithms is at all correct, the trend I see is that we humans aren't as good at hearing things as we'd like to think. Certainly makes me give an incredulous stink eye to anyone making wild claims about changes which, to first order, seem to be in the -60 dB or smaller range.
While that's generally true I find it's peoples attitude toward listening is weather or not they hear things, I used to have a friend that was a not concerned about just sitting and listening, but I've turned him into a (God forbid) audiophile, he did not realize what he was missing by active listening, so it knowing what to listen for. Girls in general are perfectly content to listen to their favorite song on a 2" rotted out car speaker.
I was at RAMF in Denver this year and Audio Precision had an interesting clinic,
and the rep gave a demonstration, they had some nice monitors (QSC) and he play the same track with each sequence.
He had a switcher box that allowed purely added 2nd harmonic distortion, then 3rd order, and then a transfer function to simulate (tim) distortion, like you would find in a badly biased bp transistor amp. Each participant (about 35) was asked to raise their hand when the distortion became to objectionable.(eyes closed but regardless we could not see what the rep. was doing.) I don't remember the value of the 3rd order, but the scary thing was most people did not raise their hand until 2nd order hit 33%! TIM distortion was ear bleeding at 1%.
While that's generally true I find it's peoples attitude toward listening is weather or not they hear things, I used to have a friend that was a not concerned about just sitting and listening, but I've turned him into a (God forbid) audiophile, he did not realize what he was missing by active listening, so it knowing what to listen for. Girls in general are perfectly content to listen to their favorite song on a 2" rotted out car speaker.
I was at RAMF in Denver this year and Audio Precision had an interesting clinic,
and the rep gave a demonstration, they had some nice monitors (QSC) and he play the same track with each sequence.
He had a switcher box that allowed purely added 2nd harmonic distortion, then 3rd order, and then a transfer function to simulate (tim) distortion, like you would find in a badly biased bp transistor amp. Each participant (about 35) was asked to raise their hand when the distortion became to objectionable.(eyes closed but regardless we could not see what the rep. was doing.) I don't remember the value of the 3rd order, but the scary thing was most people did not raise their hand until 2nd order hit 33%! TIM distortion was ear bleeding at 1%.
Apologies on coming across so defensive as well. Floyd and Toole's work is pretty good stuff, definitely worth the read.
Why did you do such a horrible thing?! 😛 Interesting anecdote about the distortion test. I think BWaslo's sousa test led me in a similar direction. Hopefully still all fun and games at the end of the day.
That's why I say just plain THD might be a red herring, a 1 or 2dB dynamic range expansion maybe not. All the input to output signal non-idealities have not been quantified by a long shot.
Since your post followed mine I assume you were writing in response to my post. Please tell me where I wrote, implied, or claimed, that my listening observations were anything other than listening observations of my audio system.
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No, as he corrects in the next post, that was a quoted reply to me.
Also, I didn't find your OP at all bothersome, lest you worry. 🙂
Are the references to Toole/Floyd references to two people, or is it meant to refer to Floyd Toole of Harman.
No, that's me being utterly all elbows (many apologies). Sean Olive's work and Floyd Toole's work. Sorry about that!