Very Interesting Frank, thank you as adds another data point
Having slept on the problem I just wanted to clarify that,
1. To devinylise Flat reponse on L and R is the target and if some compromises on L-R flatness are required that is an acceptable tradeoff
2. L-R attenuation only needs to be about 20dB.
But I realised I am missing two data points
A. What is the level of L-R compared to the rest of the signal.
B. Where would this go in the signal chain and would it require heroic overload margins
Having slept on the problem I just wanted to clarify that,
1. To devinylise Flat reponse on L and R is the target and if some compromises on L-R flatness are required that is an acceptable tradeoff
2. L-R attenuation only needs to be about 20dB.
But I realised I am missing two data points
A. What is the level of L-R compared to the rest of the signal.
B. Where would this go in the signal chain and would it require heroic overload margins
The Vinyliser starts here!
The basic structure I plan is:
1) White noise source
2) Pinkening or reddening filter as required to accentuate VLF noise.
3) Resonance peaking filter around 7 Hz to simulate arm/cartridge resonance.
4) Level control and inverter to give two anti-phase signals.
I think that should be a reasonable first attempt.
The B&K document suggests otherwise. Look at Fig 4 and Fig 10, peaking very much 5 - 10 Hz. Fig 10b also shows motor rumble at 25 Hz, but are we convinced that it is out of phase? Seems likely it could be partly in and partly out, and anti-phase cancellation will be of doubtful use.
What is not planned for The Vinyliser? The addition of:
Distortion (many ways to do this- mostly 2nd and 3rd required, I assume)
Clicks (a series of pulse generators timed to record rotation speed)
Groove noise (adding more wideband noise is very simple)
Interchannel cross talk (pretty much the opposite of The Devinyliser)
Wow and flutter (this would require a variable digital delay)
Distortion (many ways to do this- mostly 2nd and 3rd required, I assume)
Clicks (a series of pulse generators timed to record rotation speed)
Groove noise (adding more wideband noise is very simple)
Interchannel cross talk (pretty much the opposite of The Devinyliser)
Wow and flutter (this would require a variable digital delay)
Having abandoned vinyl decades ago, I had forgotten all I ever knew about arm/cart resonance. A bit of Googlage brought up the following useful references.
Resonance frequency
Resonance Frequency
Adjust+ Part II
Ortofon says "the acceptable range is 7 to 12 Hz, whereas 10 Hz is recommended" and the other links generally agree.
Resonance frequency
Resonance Frequency
Adjust+ Part II
Ortofon says "the acceptable range is 7 to 12 Hz, whereas 10 Hz is recommended" and the other links generally agree.
Pretty much on-topic, I'd say, as it must have a big effect on the amplitude of our anti-phase signals. Here is an AES paper on it; it's behind a paywall and I haven't read it myself:
AES E-Library Dynamic Damping of Stylus Compliance/Tone-Arm Resonance
But how many people use arm-damping these days?
Pages 12 and 15. Figure 35 on page 15 I need to look at more as on first inspection it gives a different picture from the rest of the document when you take arm resonances into account. Or I am misreading, which is more likely!
Edit: my bad Fig 35 is acoustic feedback resonances, which although may be pertinent to the overall 'experience' can at least be dealt with.
Edit: my bad Fig 35 is acoustic feedback resonances, which although may be pertinent to the overall 'experience' can at least be dealt with.
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B&K Page 12 suggests that an arm resonance of 13 - 18 Hz could provide mechanical filtering of subsonics, but this seems more like a recommendation for the future than a description of the present.
Fig 35 is the resonant modes of a speaker->turntable setup, and while 27.5 Hz is mentioned, that is surely too high for arm resonance. Perhaps the first overtone?
It looks to me as if 5 - 13 Hz is a good range to target.
Fig 35 is the resonant modes of a speaker->turntable setup, and while 27.5 Hz is mentioned, that is surely too high for arm resonance. Perhaps the first overtone?
It looks to me as if 5 - 13 Hz is a good range to target.
Oddly been trying to find time today to start a thread on just that to prevent too much OT breaking out here. So far have failed
Yes, that seems a good idea, I'd contribute to that thread. I hold the firm opinion that most conventional wisdom that survived as lore is plain wrong, well not optimal or even self-consistent. But it would be OT here and the thread would disappear into the weeds: a separate thread would be interesting.Oddly been trying to find time today to start a thread on just that to prevent too much OT breaking out here. So far have failed
I think the on-topic aspect is how much of the c 7Hz headshell wobble finds its way into out-of-phase L-R modulation of either amplitude or frequency in programme material. I'm still thinking about that ! The headshell wobbles in 2 dimensions, following a sort of lissajous figure shape with a major period c 7Hz or whatever it may be. Pretty much all 2D vectors get covered then, including pure vertical and pure lateral and all paths in between. At the moment I don't think there is AM modulation of programme. There is certainly FM, and also baseband noise at 7Hz. Dunno, still thinking !
Otherwise, I think the pseudo-ambience is more likely to be due to rumble/roar random noise in the 30-200Hz range, rather than c 7Hz headshell wobble.
The Emu 16m series chips and analog design are essentially what is inside the Creative Soundblaster Elite Pro. Ebay. Extremely nice conversion in something that says "soundblaster" Funny but true. There are more examples including some older pro usb cards.
I hate commenting on things I actually know something about however I feel compelled to mentiin Fyi, we have been using a vst plugin called "The Grundgelizer" in hip hop production for at least a decade settings include broadband noise, two types of distortion, wow, flutter, tics, pops, record speed and bandwidth restriction. However no phasing or antiphase are included.
I seem to recall there was once an arm where only the headshell pivoted up and down, the actual arm moving in the horizontal plane only.
I imagine that would have a radical effect on the arm resonance frequency, possibly at the cost of worse wow & flutter.
Can anyone point me to the product?
I imagine that would have a radical effect on the arm resonance frequency, possibly at the cost of worse wow & flutter.
Can anyone point me to the product?
Are you thinking of the Dynavector DV series of arms?
Dynavector DV 507 Manual - Bi-Axis Inertia Controlled Dynamic-Balance Type Tonearm - Vinyl Engine
jeff
Dynavector DV 507 Manual - Bi-Axis Inertia Controlled Dynamic-Balance Type Tonearm - Vinyl Engine
jeff
We had this thing in our audio store. The arm is exactly as described, headshell is all the moves up and down:
http://digilander.libero.it/bellocaddo/turntables/saturn.jpg
http://digilander.libero.it/bellocaddo/turntables/saturn.jpg
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