No mention anywhere that the constant velocity sweep is only "linear" without RIAA?? Or is that the +-1.5dB?
Bill I hope I didn't lead you astray, the STR112 is the square wave, tracking, IM one. The STR120 is the 500-50k sweep one. They use up a whole side with L/R/Lat/Vert at three diameters.
The CH Precision LP is probably 1/2 speed mastered at 45 which would explain possibly its freedom from artifacts. Jan gave me a copy I assume he did not buy the $31,000 pre-amp it comes with.
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Bill, when you have some patience, I have located 2 brand new CH Precision disks.
Since I only need one, you can have the other one.
Hoe about that ?
Hans
Hans that would be wonderful as I can also shuttle that to LD as and when he can make use of it.
This what Chris Feickert replied concerning his Adjust+ LP.
The signal cut with a Neumann VMS80 and a SX74 cutter head had an accuracyof ±0.5 dB from 20 Hz up to 20 kHz. The signal used (pink noise) was generatedin 96 kHz / 24 Bit resolution with a frequency spectrum 20 to 20k and notabove.
Have you ever tried to measure what the LP cutter planted on the LP ?
Yes, we did. And what we found is, that the linearity of measuring frequency response with pink noise (and compensating the energy filtering 1/f applied)results in far superior results than using a linear sweep. Sweeps usually do use an attenuation of 20 dB at either 1 or 3.15 kHz. If not you would simply convert cutterhead and/or stylus to ashes...
Why do we get better accuracy without ringing in case of pink noise? Verysimple - sweeps are rund with constant velocity in terms of octave per second. This means that we do have way less bins to Fourier transform causing cancellation effects that finally show up as ringing. In case of pink noise you do have all frequencies at all time and the computing of the numbers is way superior with almost no cancellation effects...
Hope that helps and yours in service...
The signal cut with a Neumann VMS80 and a SX74 cutter head had an accuracyof ±0.5 dB from 20 Hz up to 20 kHz. The signal used (pink noise) was generatedin 96 kHz / 24 Bit resolution with a frequency spectrum 20 to 20k and notabove.
Have you ever tried to measure what the LP cutter planted on the LP ?
Yes, we did. And what we found is, that the linearity of measuring frequency response with pink noise (and compensating the energy filtering 1/f applied)results in far superior results than using a linear sweep. Sweeps usually do use an attenuation of 20 dB at either 1 or 3.15 kHz. If not you would simply convert cutterhead and/or stylus to ashes...
Why do we get better accuracy without ringing in case of pink noise? Verysimple - sweeps are rund with constant velocity in terms of octave per second. This means that we do have way less bins to Fourier transform causing cancellation effects that finally show up as ringing. In case of pink noise you do have all frequencies at all time and the computing of the numbers is way superior with almost no cancellation effects...
Hope that helps and yours in service...
That answer was simply why pink noise is better than a sweep (in their opinion). The artifact beyond 20k was not addressed. I tried the Omnidisk again and the 9k artifact is clearly audible at low RPM as a whistle in the blank channel that moves with the speed of rotation so it tracks the LP velocity and has nothing to do with the cart.
I'm beginning to feel like the time I found a USB sound card (from a major manufacturer) that played a 1k tone off of a reference test CD at 1.006k and no body knew what I was talking about or ever noticed.
This is very interesting though. And at least proves one thing, which is you can't trust most test records!
Can you imagine the blank stares if we gave this feedback after getting back test pressings from a DIY test LP?
That's exactly what CH Precision told me.
Cutting and pressing the disc had to be redone several times because the result was appalling at first.
I found the reaction from Chris Feickert quite open and positive.
He told what his intention was, pink noise just from 20hz to 20kHz within +/-0.5dB and that's exactly what's on the LP.
What's beyond is none of his worries.
Hans
Cutting and pressing the disc had to be redone several times because the result was appalling at first.
I found the reaction from Chris Feickert quite open and positive.
He told what his intention was, pink noise just from 20hz to 20kHz within +/-0.5dB and that's exactly what's on the LP.
What's beyond is none of his worries.
Hans
This is what I understand . That “linear” = No RIAA emphasis during cutting.
He isn't a nerd 😀
George
Continues the myth that a load on the output affects the mechanical action of the stylus. Also curious are some of the other claims about response. The traditional way is to use optical interference patterns of the groves and a microscope to look at the amplitude. That won't work for random noise. After dialing in the amplitude and velocity the RIAA is added but you can't check accuracy on an equalized record.
Another option might be a final audio optical turntable. It removes a lot of unknowns but adds a few of its own.
Here is more about the history of audio recording than most would ever want to know: http://sts.kahaku.go.jp/diversity/document/system/pdf/083_e.pdf Its somewhat Japan centric. The part about measuring record levels starts about page 50.
The CBS STR100 used a simple system that switched mechanically from constant amplitude to constant velocity at 500 Hz. Plot the unequalized output of the cartridge and a ruler will show the response. No EQ nonsense there. CBS Laboratories - Technical Series - Professional Test Record - Issue 3 (Vinyl, LP, Stereo) | Discogs
The link above has a good list of available test records and what they are about. Possibly the most boring playlist ever created.
The link above has a good list of available test records and what they are about. Possibly the most boring playlist ever created.
Not much there, they could just be referring to the damping of the L/C resonance.
Yes I have all (STR) on that list, some have equally bad artifacts.
Scott, how many dacs had you subsequently used to verify that the spinning CD outputs 1kHz exact? 😀
George
If you read the text its pretty clear they are talking about mechanical damping.
Does the associated preamp dial a pot to get flat response?
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