Re J. Walton's "Pickups: The Key to Hi-Fi". I'd be pleased to loan the book to anyone willing to scan it and make it available online for us.
It's a small book -- like a lurid paperback novel
-- 12.5 cm x 18.5 cm, 106 pp. It's printed in four signatures (sections), perfect bound (pages glued at spine). It's all B&W (except cover); the paper has slightly yellowed from age. (My copy is the second edition, 1968.)
I only ask that the book be returned in reasonable condition. I.e.., as a bound book, not loose pages.
It's a small book -- like a lurid paperback novel
-- 12.5 cm x 18.5 cm, 106 pp. It's printed in four signatures (sections), perfect bound (pages glued at spine). It's all B&W (except cover); the paper has slightly yellowed from age. (My copy is the second edition, 1968.) I only ask that the book be returned in reasonable condition. I.e.., as a bound book, not loose pages.
The book is available here.
https://www.amazon.com/gp/offer-listing/B0000CMO8A/ref=dp_olp_used_mbc?ie=UTF8&condition=used
also here at UK
https://www.amazon.co.uk/Pick-ups-key-hi-fi-John-Walton/dp/B0000CMO8A
Regards
https://www.amazon.com/gp/offer-listing/B0000CMO8A/ref=dp_olp_used_mbc?ie=UTF8&condition=used
also here at UK
https://www.amazon.co.uk/Pick-ups-key-hi-fi-John-Walton/dp/B0000CMO8A
Regards
Just started to look at George's HFN 300Hz +12dB, +14dB, +16dB and +18dB files. Very interesting to look at the extremes of force/trackability in this test.
This visual is very interesting, I think. It shows just the right channel at the onset of mistracking @ +18dB. One can see the location at which the stylus stops following the groove locus, and follows a chaotic path before resuming. This is, unsurprisingly I suppose, near the peak of programme sine level, which corresponds to near the zero crossing of physical groove shape where angle (velocity) is high, curvature (acceleration) is near zero and displacement is near zero. At this point, force opposing stylus movement is dominantly from suspension damping and stylus-groove friction, and the balance of forces downwards and upwards is near zero.
But just look at how much variation there is from cycle to cycle in terms of mistracking onset point and the consequent behaviour..........! Is this evidence of variation in friction force, perchance ?
And, for this test including the 2.5g 300Hz previously analysed, the physical zero crossing location of the sine groove shape must be the area of maximum force, so if flex happens that is where to look, methinks.
LD
This visual is very interesting, I think. It shows just the right channel at the onset of mistracking @ +18dB. One can see the location at which the stylus stops following the groove locus, and follows a chaotic path before resuming. This is, unsurprisingly I suppose, near the peak of programme sine level, which corresponds to near the zero crossing of physical groove shape where angle (velocity) is high, curvature (acceleration) is near zero and displacement is near zero. At this point, force opposing stylus movement is dominantly from suspension damping and stylus-groove friction, and the balance of forces downwards and upwards is near zero.
But just look at how much variation there is from cycle to cycle in terms of mistracking onset point and the consequent behaviour..........! Is this evidence of variation in friction force, perchance ?
And, for this test including the 2.5g 300Hz previously analysed, the physical zero crossing location of the sine groove shape must be the area of maximum force, so if flex happens that is where to look, methinks.
LD
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Here's another interesting visual from George's 300Hz HFN tests, this one overlays the +12dB waveform with the +18dB waveform, normalised for level.
One can see that an effect of the extra +6dB is to make the waveshape more triangular: effectively slew rate has been limited. This seems to fit with odd-harmonic correlations seen in George's relax tests.
I think it's now possible to see and deduce what might be physically happening in the difference between these tests. At +18dB the stylus takes a longer path perhaps by riding up a groove wall when forces become high, until at some point the balance is impossible and it mistracks for a moment.
It's also possible that something flexes, rather than stylus rides up the groove wall. If that were vinyl indentation, the stylus path would become shorter, and slew rate would increase - but the opposite happens ! If the cantilever flexed, on the other hand, the generator at the far end would perceive a slower slew rate, which is consistent with what is observed.
So, perhaps this is differential evidence that, in this high force test, cantilever flex is possibly indirectly observed rather than vinyl indentation? Or that neither happens, rather the stylus rides a groove wall to find a longer path when force is strong, which I prefer I think.
LD
One can see that an effect of the extra +6dB is to make the waveshape more triangular: effectively slew rate has been limited. This seems to fit with odd-harmonic correlations seen in George's relax tests.
I think it's now possible to see and deduce what might be physically happening in the difference between these tests. At +18dB the stylus takes a longer path perhaps by riding up a groove wall when forces become high, until at some point the balance is impossible and it mistracks for a moment.
It's also possible that something flexes, rather than stylus rides up the groove wall. If that were vinyl indentation, the stylus path would become shorter, and slew rate would increase - but the opposite happens ! If the cantilever flexed, on the other hand, the generator at the far end would perceive a slower slew rate, which is consistent with what is observed.
So, perhaps this is differential evidence that, in this high force test, cantilever flex is possibly indirectly observed rather than vinyl indentation? Or that neither happens, rather the stylus rides a groove wall to find a longer path when force is strong, which I prefer I think.
LD
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Pano, I believe so, no problem. If you PM a snail mail address we can try.
billshurv Cool. I have ordered the uk copy. Happy for it to be split for scanning
Apologies if I came across as a hardass
I was thinking that mutilation of a scholarly book as equivalent to sacrifice of a phono cartridge. However, if in the interest of science . . .
Maybe we'll let Bill mutilate his copy before we abuse yours.
Good software will give you a nice raster image of the scan, plus run OCR and place that text under the image. Best of both worlds, looks original but with search and copy possibilities.
Lucky thank you for looking into these recordings. Very nice presentation.
When you want to visualize the actions and reactions that occur during playback of this extreme track, you want to isolate the events in time.
In the +18dB recording, the waveform peaks at 700ms.
The first few waveforms between 700ms and 706ms show what you are investigating at the very front end before the cartridge body, head shell, arm, arm base ect (*) start to return vibrations back to the cantilever fulcrum
Past the 706ms, waveform remains at the same amplitude but the visible distortion increases and moves a bit across the waveform. This is one of the indications of the returned vibration energy.
The waveform remains at the plateau peak up to 16s 408ms, then it starts dropping.
Notice how the distortion at the waveform is visible many ms after waveform reduces in amplitude , actually it is visible till 16s 438ms. This is another indication of the delayed vibrations coming back, dying out gradually.
Note that there was great care in modding and adjusting this pick-up system, that’s why what you see (at least in the +18dB recording) is a bit unique i.e. very mild distortion.
(*) and possibly vibrations from the vinyl bulk too.
George
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Lucky, could the longer path trace be attributed to simple tracing error (pinch effect) at these extreme modulation levels?
On a tangent (pun intended): LD rightfully emphasizes the role of groove wall slope. I’m thinking this explains the sudden onset of extreme “shattering” distortion encountered during modulation peaks. The downward VTF resolves into two components, each instantaneously normal to a groove wall. For small excursions (low slope), VTF components are nearly parallel with the direction of modulation and proper stylus-groove contact is maintained. However, during the zero crossing of a large modulation (large slope) the VTF components (still normal to groove walls) diverge from the direction of modulation. Thus a smaller VTF fraction is available to maintain tracing contact, while simultaneously a larger tracing force is needed to overcome stylus damping. As modulation level (slope) increases distortion rises gradually until contact is suddenly lost.
“Shattering” mistracking is most likely with large groove slopes, e.g. high modulation velocity and low linear groove speed (inner record diameters). The Shure papers emphasize need for low stylus damping at midrange frequencies to maximize midrange trackability. In my experience, female vocals are most prone to shatter. Lightly-damped pickups such as Deccas and Grados are noted for their vocal reproduction.
Well, in theory for a mono 300Hz sine waveshape as we have here, pinch effect should force a stylus up symmetrically at both grooveshape zero crossing points, and VTF should push symmetrically down at both peaks. So pinch effect fundamental should be at 600Hz, and stylus motion should be vertical. That's easy to see by extracting vertical signal from L-R channels, of course.
However, a quick look at the vertical signal (L-R) and lateral signal (L+R) in the time domain shows no such thing here. There's a whole peak missing at one of the zero crossing points, so it is very asymmetric across test tone cycle......suggesting the stylus isn't moving much vertically at one of the groove zero crossing points, where it should/must!?
I'm sure there's enough here to work out why, but it makes my head hurt right now ! Explanations ?
Yes if VTF is to be kept low, as was Shure's formula. But low damping has penalty in cart-arm stability, and hence pitch stability of course.
LD
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Re the x150 playback test.
Due to the large amount of data (2.66GB) and the 2GB limit of the free Dropbox account, I’ve uploaded only the first three folders. There is a total of 90 wav recordings in these three folders
Stanton 1-30
https://www.dropbox.com/sh/io43uq3aqo0uydv/AADEr_2w2bZ50C07G9LLIpGNa?dl=0
Stanton 31-60
https://www.dropbox.com/sh/6f7ezfk7e3qlypb/AAAHEPpT32P5OEb1ucjqUl4ya?dl=0
Stanton 61-90
https://www.dropbox.com/sh/yk5pgha81pa8bov/AAAIdojbHuki6Z7sTdBKZq3Za?dl=0
Please inform me if you can download and open the individual wav files from each folder.
If the upload is functionally OK, these three folders will remain there for two days.
I will remove them after these two days for to upload the rest Stanton recordings plus the control Shure recordings plus the documentation of the test.
George
Due to the large amount of data (2.66GB) and the 2GB limit of the free Dropbox account, I’ve uploaded only the first three folders. There is a total of 90 wav recordings in these three folders
Stanton 1-30
https://www.dropbox.com/sh/io43uq3aqo0uydv/AADEr_2w2bZ50C07G9LLIpGNa?dl=0
Stanton 31-60
https://www.dropbox.com/sh/6f7ezfk7e3qlypb/AAAHEPpT32P5OEb1ucjqUl4ya?dl=0
Stanton 61-90
https://www.dropbox.com/sh/yk5pgha81pa8bov/AAAIdojbHuki6Z7sTdBKZq3Za?dl=0
Please inform me if you can download and open the individual wav files from each folder.
If the upload is functionally OK, these three folders will remain there for two days.
I will remove them after these two days for to upload the rest Stanton recordings plus the control Shure recordings plus the documentation of the test.
George
Thank you Michael. The editing SW I use doesn’t support flac files and I am a bit hesitant to convert wav to flac or do a compression.
But this is secondary.
The main issue is if the individual audio files can be downloaded through the Dropbox links of the folder that contains 30 audio files, which I have provided or do I have to get and provide a link for each individual audio file?
The good news is that all the individual wav files are downloadable.
I checked on another PC that does not share my Dropbox account.
So, if anyone is interested on this x150 plays test, please download these 90 wav files. After about 36 hours there will be replaced by the rest of the test files.
George