Still need to explain the same result with the Adjust +, in fact if someone could run it with a carefully set up line contact stylus it would be interesting.
Scott,
A bit easier for the eye as the previous merger, this image shows the 33 1/3 merger for your Cart and my line contact stylus, 3x60um, and only the pink noise channel.
Does this answer any question ?
Hans
Attachments
May I carefully mention that it looks as if your termination Cap is too large, causing the bump at 13kHz ?
Hans
It's a Grado, I believe the 13kHz comes for free with each one. Cap loading doesn't change things much as L is very low.
Bill knows there is no L/C resonance it's Joe's "careful" design. As to your other plot you could have a resonance masking part of the issue as you can see it tracks pretty well as the frequency goes up. How about 45RPM? I don't think there is definitive evidence of simple geometric stylus issues yet.
Another confounder occurred to me this morning, the crest factor of the noise. They are not the same LP to LP and this confuses the issue because the tracks are recorded to an RMS value but the peaks (which with RIAA pre-emphasis would be the highs) vary by several dB.
We are still taking data, for one LP (even being -6dB in level), to have no visible evidence of an issue is still hard to believe.
Scott, I'm sorry that it's most likely just me, but I have no idea what you mean with the resonance masking of the issue.
What resonance and what issue are you referring to where it is hard to believe that we still have no visible evidence ??
Evidence of what ?
So before recording 45rpm, I would like to understand what we are looking for, avoiding some Babylonian confusion.
I fully agree that there is no evidence at all of geometric issues of styli, our Carts have little in common, but I thought we were trying to find a well behaving pink source as a first step.
You mentioned the wish for someone to play the Adjust+ LP with a line contact stylus and here it was with my input.
We were both averaging some 100 spectra, doesn't this significantly reduce the rms value per frequency bin, making the crest factor variation LP to LP much less important ?
Hans
P.S. Could you kindly react to my question regarding the details of the Swiss Precision LP ?
I have sent Chris Feickert an email, in which I have asked him how exactly the pink noise spectrum should look like up to 50 kHz.
Hope he reacts.
Hans
Hope he reacts.
Hans
33/45 rpm won't affect stylus-groove geometry. But it does affect the mapping of programme level and slew rate onto groove angle and curvature.
A shallower angle maps onto higher programme level. So the net effect of playing back a record with levels intended for 33 at 45 is to make it harder to track.
But this has little to do with the effect at issue which is v interesting. Levels get small for pink noise above 20kHz without RIAA emphasis. LD
A shallower angle maps onto higher programme level. So the net effect of playing back a record with levels intended for 33 at 45 is to make it harder to track.
But this has little to do with the effect at issue which is v interesting. Levels get small for pink noise above 20kHz without RIAA emphasis. LD
Yes I am surprised at how well the 33/45 artifacts map by simple frequency translation and how different the LP's look, possibly 33/45 is not enough difference to see the non-geometric effects?
Hans your plot has a bump right around the same place how do you know it's not a resonance in response, remember it's rms averaging so only 10dB or so more signal will bury the other.
In a non-linear system superposition does not apply the crest factor matters because the geometric component of the tracing distortion is a power law with level. If you pass multiple tones tones through a low order non-linear transfer function the phases (i.e. crest factor) matter to the distortion generated.
I certainly don't know the cause of the bump. One way to find out might be to look at individual non averaged spectra.
Alternatively, playing at 45rpm would show the bump at the same frequency if it were a Cart resonance.
In your case this bump moved upwards when going to 45 rpm, so IMO there is a strong indication that the bump is LP related, also because the CH Precision didn't show a bump at all at this spot.
In the meantime I'll await the answer from Chris Feickert to his Adjust+ Lp.
Hans
Contact radius of stylus doesn't alter tracing geometry when one runs the same record at 33 or 45 rpm. It does change the surface tribology but that is a dark science. Do not open the box...……
LD
LD
My bizzaro experiment for the week. I spun the Adjust + LP by hand down to 3 RPM or so and the crosstalk was still there, in fact it was clearly audible at low RPM. A quick look at the grooves with my USB microscope seemed to confirm there was a signal in the channel that was supposed to be blank.
Attachments
The convex area from 200Hz to 2kHz conforms completely to the deformation by the RRiaa, now applied at points lying 10 times lower.
When corrected for this effect, the curve is straight and going down with 3dB/oct as it should.
This proves once more that the bump, now between 2.5kHz and 3kHz is LP related.
So I won't spend anymore time on the Adjust+ LP and wait for the CH Precision LP.
Hans
New (?) test LP from Ortofon with Frequency Sweep 800 Hz – 50 kHz. Log. 28 sec. Linear cut (constant velocity amplitude) 800 – 20000 Hz ±1,5 dB
Ortofon Test Record
George
Ortofon Test Record
George
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