The nearest thing I know of is mine; see:
The Wireless World Archive
I have just added the Macaulay and Lawson circuits at the very bottom of the page.
The Wireless World Archive: rumble filters
Sorry, meant to do that yesterday, but "...events, dear boy, events!"
A good discussion of the problem, including what happens if you have a signal on only one channel.
A number of us here could easily do the anti-phase, rumble filtering in software and post the files somewhere. Obviously the playback would be digital, but it might lead some listening tests.
It's not difficult in audio software to do the LF out of phase cancellation, or to add in LF of of a certain flavor.
This can be done to rips from CD and recordings of vinyl. Anyone interested?
(I'm on the road for work, but might be able to do a bit while traveling.)
It's not difficult in audio software to do the LF out of phase cancellation, or to add in LF of of a certain flavor.
This can be done to rips from CD and recordings of vinyl. Anyone interested?
(I'm on the road for work, but might be able to do a bit while traveling.)
The sim was not sound. I screwed up, getting a sign wrong, and I now owe Mr Macauly a humble apology for disrespecting his design.
The step in the gain for in-phase signals is -0.55dB below 100 Hz
The gain for anti-phase signals is actually only +1.2dB at 140 Hz, and below this it decreases ar 6dB/octave, much like the Langvad circuit.
So, apologies to Mr Macaulay, in the unlikely event that you are watching. (But you were still wrong about crossover distortion)
Mistakes were made. Time to move on.
@Pano: Agreed, all I need now is to work out best way to ri p some vinyl as never done it before (despite being on my todo list since about 2000). I proved last night I can do some basic Munging in Audacity which should be good enough to at least show an effect (and allow me to do some OT analysis over if CD has a greater amount of Antiphase than dirty vinyl.).
@Douglas: Reading both the WW circuits, they start from the assumption that rumble is vertical. I'm having trouble with that idea for bearing induced noise, although makes sense for warps and crud in the grooves the wiki entry is hardly the greatest piece of research https://en.wikipedia.org/wiki/Rumble_(noise) and references Macaulay! I realise rumble definitions are OT but not sure if anyone has looked at magnitudes in each plane. I know Scott Wurcer was commenting on the very significant infrasonic energy he was seeing when researching his Linear Audio article although by 10-12Hz do we care anymore?
@Douglas: Reading both the WW circuits, they start from the assumption that rumble is vertical. I'm having trouble with that idea for bearing induced noise, although makes sense for warps and crud in the grooves the wiki entry is hardly the greatest piece of research https://en.wikipedia.org/wiki/Rumble_(noise) and references Macaulay! I realise rumble definitions are OT but not sure if anyone has looked at magnitudes in each plane. I know Scott Wurcer was commenting on the very significant infrasonic energy he was seeing when researching his Linear Audio article although by 10-12Hz do we care anymore?
Well, the 10-12Hz stuff is probably the cart/arm resonance which is in fact a single resonant system in 2 planes, not isolated vertical and lateral planes. This means that displacement of the arm results mostly in a resonant system which has content at 10-12Hz in both vertical and lateral planes, sort of following a lissajous type path. It's inevitable that this content will be strong in the subsonic range, but is usually filtered by the preamp at least to an extent.billshurv;4574094@Douglas: Reading both the WW circuits said:
Bearing rumble isn't confined to vertical plane either to any extent, IME.
Warp/platter levelling runout is by far the biggest contributor to vertical signal error, but at vlf and attenuated by the mechanics of cart/arm suspension system.
Spectrum analysis of my noisy old Rek-o-kut still showed 10Hz to be the strongest level. Rumble was below that in amplitude
Here's a question I've never managed to get a definitive answer to. Just how 'good' is microgroove stereo disc recording? In other words, 1) what is the best unweighted SNR one can expect; 2) how flat is the frequency response at inside and outside diameters; 3) what about power bandwidth, can you record 20kHz at 7cm/sec; 4)what is typical THD at 7cm/sec, or however 'standard operating level' might be defined, at inside and outside diameters; 5) ditto on IMD. Figure using the best Neumann lathe and head, and the best turntable/cartridge combination you can find. Come up with some numbers. I'll bet they don't look all that good.
I just don't understand how vinyl can be considered 'better' than a lossless, linear digital recording, even an old fashioned 44.1/16 one. Tell me what contemporary recorded works are mixed and mastered in analog and then ruined when transferred to Red Book CD standards.
Try this: Rip a vinyl disc to a CD and A/B them. Can you hear a difference? I doubt it. But, cut a lacquer from a CD and A/B those. I'll bet you hear a difference there.
Film sound tracks used to be recorded optically... I'm not talking about the optical track on a release print, but how sound was recorded on the sound stage in the old days. When full-coat magnetic film recorders replaced the optical ones, old-time recordists did not like the new sound, it just didn't sound 'right.' There was similar inertia in broadcast as well, mag tape just didn't have the same sound as a 16" transcription. We get used to, and comfortable with, certain distortions and other quality-limiting mechanisms. "Golden ear" audiophiles should spend some time listening to a live performance and compare recordings to that!
I just don't understand how vinyl can be considered 'better' than a lossless, linear digital recording, even an old fashioned 44.1/16 one. Tell me what contemporary recorded works are mixed and mastered in analog and then ruined when transferred to Red Book CD standards.
Try this: Rip a vinyl disc to a CD and A/B them. Can you hear a difference? I doubt it. But, cut a lacquer from a CD and A/B those. I'll bet you hear a difference there.
Film sound tracks used to be recorded optically... I'm not talking about the optical track on a release print, but how sound was recorded on the sound stage in the old days. When full-coat magnetic film recorders replaced the optical ones, old-time recordists did not like the new sound, it just didn't sound 'right.' There was similar inertia in broadcast as well, mag tape just didn't have the same sound as a 16" transcription. We get used to, and comfortable with, certain distortions and other quality-limiting mechanisms. "Golden ear" audiophiles should spend some time listening to a live performance and compare recordings to that!
When I worked in the HiFi business it was my experience that it was easier to sell someone a new cartridge or turntable than to convince them to engage that switch.
Just to take you back to something I said. An analogue tape cut on a modified Scully lathe sounds so similar as to be not easy to believe. If the idea put forward here is right the LP cut should sound better than the Master tape. You will have to take my word for it they sound the same. A SACD transfer did not. It sounded lighter. As the company wanted to sell both they were not doing a worse CD to win a point. The monitoring was via high grade domestic hi fi. With the greatest of respect gentlemen and ladies you need to do this test. Much of what you think is fact is not. That's like me writng a book about Austrailia when I have never been there. Doubtless I can get 90% of it right.
If you doubt how the RIAA changes sound please build my inverse RIAA. As all the phase shifts must resolve to zero ( we hope ) we can only be left with distortion being higher and bandwidth lower. The transformation for anyone who hasn't tried it is not subtle. I would have to suggest it is the larger factor.
I may have missed the point about the out of phase material at LF. As far as I can see when I play mono records on a Lyra mono pick up it is sometimes the best sound I have ever heard. Even stereo LP's work well on this pick up ( I think it's point 7 and not 1 thou, too late as I tried it ). I suspect Jonathan Carr who designed it and is a DIY. member will not join this debate?
If you doubt how the RIAA changes sound please build my inverse RIAA. As all the phase shifts must resolve to zero ( we hope ) we can only be left with distortion being higher and bandwidth lower. The transformation for anyone who hasn't tried it is not subtle. I would have to suggest it is the larger factor.
I may have missed the point about the out of phase material at LF. As far as I can see when I play mono records on a Lyra mono pick up it is sometimes the best sound I have ever heard. Even stereo LP's work well on this pick up ( I think it's point 7 and not 1 thou, too late as I tried it ). I suspect Jonathan Carr who designed it and is a DIY. member will not join this debate?
How is a tape 'cut' on a lathe ?
The hypothesis is that out of phase lf noise can provide pseudo ambience for vinyl, and that this can be euphonic and not on the master tape nor digital transcriptions of it.
It's simple AB to get it to sound right. Some will have told you a black art is employed where the skill of the engineer in his head arrives at a result. You will have further been told a CD made from this master will not work. This is not true. The cutting master can be exactly what the engineer wants the LP to sound like. He like us can not live with too much guessing. Now the black art will come in. Choices make the cut possible. One you and I might never learn. One is not to burst through to the previous section. The next is to make sure you nearly do. Swarf on the cut drives me bonkers. You know it can get out of control.
Seeing as this mastertape ( cutting mix down ) sounds great to me I see no reason to think the CD shouldn't be identical. After that it is matters of taste.
Being happy with most digital I question how well CD works. Nothing else. Could it be to make a CD is slightly harder than it should be? I fully understand the hypothisis but think it might be false. The cut being played in near enough real time sounds exactly like the master. The master is exactly what we call LP sound when it is tape.
I will go further. If this out of phase quality is important at all, it possibly is something we should avoid. My mono test seem to say it's a red herring. I very serriously take rumble as a possible enhancement. Owning turtables near the state of the art I suspect rumble is not helpful. I can not say if that is true as some is always on the disc. Vibrato is a well known musical enhancement ( not always liked ). It is reasonable to think rumble is the quality we hear. The mastertape will have no real rumble ( we hope ). It sounds remarkably like the LP if you get my point.
LP is making a comeback. I think I might have helped that as I have never given up liking it and have a very big mouth. CD to me is like my mother chooses me a wife. Yes my mum might know best. Doesn't make me like the girl. I want a naughty girl is it ?
Seeing as this mastertape ( cutting mix down ) sounds great to me I see no reason to think the CD shouldn't be identical. After that it is matters of taste.
Being happy with most digital I question how well CD works. Nothing else. Could it be to make a CD is slightly harder than it should be? I fully understand the hypothisis but think it might be false. The cut being played in near enough real time sounds exactly like the master. The master is exactly what we call LP sound when it is tape.
I will go further. If this out of phase quality is important at all, it possibly is something we should avoid. My mono test seem to say it's a red herring. I very serriously take rumble as a possible enhancement. Owning turtables near the state of the art I suspect rumble is not helpful. I can not say if that is true as some is always on the disc. Vibrato is a well known musical enhancement ( not always liked ). It is reasonable to think rumble is the quality we hear. The mastertape will have no real rumble ( we hope ). It sounds remarkably like the LP if you get my point.
LP is making a comeback. I think I might have helped that as I have never given up liking it and have a very big mouth. CD to me is like my mother chooses me a wife. Yes my mum might know best. Doesn't make me like the girl. I want a naughty girl is it ?
I wanted to add one thing for balance. This is me guessing so please allow for that. Having never been at the cutting of a digital master to LP session I can only give you what I hear from the products. No LP I can think of sounded better than the CD if that CD was DDD. Some sound nicely compressed perhaps when LP? That isn't to say I like DDD best of all.
This again might prove LP does not add anything of importance to enhance the sound. The one small advantage the LP might have is over a cheap CD player. Some DVD players as CD players have excellent sound yet cost £80. To be honest most cheap turntables are not as good if excluding secondhand buys. That being as it is, they both are not studio quality.
Given DDD or AAA if you like, AAA is the one I like. I think this a very important point as I do not universally prefer LP. If fact what I prefer came to an end in 1983. It lives on like steam railways.
If anyone doubts LP quality try this Louis Armstrong. I seem to remember it's well before 1960.
Louis Armstrong - Satchmo Plays King Oliver (Vinyl, LP, Album) at Discogs
This again might prove LP does not add anything of importance to enhance the sound. The one small advantage the LP might have is over a cheap CD player. Some DVD players as CD players have excellent sound yet cost £80. To be honest most cheap turntables are not as good if excluding secondhand buys. That being as it is, they both are not studio quality.
Given DDD or AAA if you like, AAA is the one I like. I think this a very important point as I do not universally prefer LP. If fact what I prefer came to an end in 1983. It lives on like steam railways.
If anyone doubts LP quality try this Louis Armstrong. I seem to remember it's well before 1960.
Louis Armstrong - Satchmo Plays King Oliver (Vinyl, LP, Album) at Discogs
Vertical disturbances is what this thread is all about, because they are, I'm sure, much greater than anything coming from the bearing, and have the potential to be much aggravated by the low-frequency resonance of pickup arm mass and stylus compliance. It's a great pity that article says nothing about the frequencies and levels to be expected.
On the contrary, they are at the heart of it.
Now the digital sruff is OT.
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Douglas and all,
over the years I have collected well recorded audio samples from most of the well respected high end TTs, and have several dozen of them to hand. They are short stereo recordings of 3150Hz sine tone from various test records, and were made by various 3rd parties and posted on various forums over the years.
In the past I have used these test clips to analyse pitch stability, via FM demodulation and analysis of the 3150Hz test tone. This is another aspect to LF noise, but let's park it for now.
These stereo clips in wav or flac format are effectively silent below 3kHz or so, and so it strikes me as a ready made source of rumble spectra from many of the well known and loved TTs.
If we can define a method, I'm happy to analyse a few for vertical/lateral noise and post the results. Before I get stuck in, suggestions are invited for method, and what we might wish to see presented? I'll be using Audacity, BTW.
over the years I have collected well recorded audio samples from most of the well respected high end TTs, and have several dozen of them to hand. They are short stereo recordings of 3150Hz sine tone from various test records, and were made by various 3rd parties and posted on various forums over the years.
In the past I have used these test clips to analyse pitch stability, via FM demodulation and analysis of the 3150Hz test tone. This is another aspect to LF noise, but let's park it for now.
These stereo clips in wav or flac format are effectively silent below 3kHz or so, and so it strikes me as a ready made source of rumble spectra from many of the well known and loved TTs.
If we can define a method, I'm happy to analyse a few for vertical/lateral noise and post the results. Before I get stuck in, suggestions are invited for method, and what we might wish to see presented? I'll be using Audacity, BTW.
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I would have been 100 % happy to buy into the rumble story except my best sounding turntables are -78 dB weighted and -75 db weighted. The conflict in my mind is the discs will have rumble so I haven't disproved the theory.
The reduction in rumble ( if torque is high ) seems to make the sound of the mastertape more obvious. That is a clean sound for want of a better word. It is also more dynamic in a " yes please I like that" way. Not in the CD " where is it "way.
One thing in the motor I designed was a reduction to near zero of vertical bearing noise. That noise is very like white noise of the dirtier kind ( it is chaotic noise ), it can be seen on tests. We then have 100 Hz and about 23 Hz which looks like text book drawings of AM modulation. The work for this done by Greenwich University ( big thanks ).
The cutting lathe I mentioned was fitted with a modified Technics SP10 to replace the Scully motor. People who know the SP10 will realise it is a very low rumble design. I have found on faster pace cuts I am not convinced the SP10 can do the job. On Belefonte it's just excellent. The older recordings seem to have simple microphone positioning some would call Blumlein. These seem to be more important than if LP very often.
I more than anyone would say that proves nothing as it's my hearing verses others. I might seek an accurate sound over a well liked sound. The interesting thing which I never questioned before is that I prefer very low rumble records and turntables. Anyone who hears my system seems to like the sound and says " vinyl is better ". I upset many by mostly playing CD's these days. What I haven't said to them is I inherited a pile that might take years to get through. They think I have been buying CD's!
The reduction in rumble ( if torque is high ) seems to make the sound of the mastertape more obvious. That is a clean sound for want of a better word. It is also more dynamic in a " yes please I like that" way. Not in the CD " where is it "way.
One thing in the motor I designed was a reduction to near zero of vertical bearing noise. That noise is very like white noise of the dirtier kind ( it is chaotic noise ), it can be seen on tests. We then have 100 Hz and about 23 Hz which looks like text book drawings of AM modulation. The work for this done by Greenwich University ( big thanks ).
The cutting lathe I mentioned was fitted with a modified Technics SP10 to replace the Scully motor. People who know the SP10 will realise it is a very low rumble design. I have found on faster pace cuts I am not convinced the SP10 can do the job. On Belefonte it's just excellent. The older recordings seem to have simple microphone positioning some would call Blumlein. These seem to be more important than if LP very often.
I more than anyone would say that proves nothing as it's my hearing verses others. I might seek an accurate sound over a well liked sound. The interesting thing which I never questioned before is that I prefer very low rumble records and turntables. Anyone who hears my system seems to like the sound and says " vinyl is better ". I upset many by mostly playing CD's these days. What I haven't said to them is I inherited a pile that might take years to get through. They think I have been buying CD's!
What does the spectrum look like?
I've seen just a few examples on DIY, and this is typical:
Above is comparison of 16bit 44.1kHz treatment of master v rip of vinyl. The tracks are provided by PMA in his thread: http://www.diyaudio.com/forums/ever...-you-prefer-cd-vinyl-version.html#post4347337
It is obvious which plots are for vinyl and for cd.
Turn table fundamental results in intense spectrum of harmonics do to combination of off center disk with tone arm and cantilever resonances.
For me, describing this as rumble or low frequency noise, then thinking about adding suitable out-of-phase low-frequency noise will result in a listener preference for the processed track over the original is that it is not going to happen.
Obviously the stylus tip motion is modulated by the complex spectrum it is exposed to. This leads to modulation of stylus contact force. Tracking force changes can be very audible. Even with tracking force apparently optimized, surface noise becomes modulated with low frequency spectrum.
So with sub-sonic filter the brain is still receiving information that most likely cause groups of neurons to fire at some very low frequencies. The perceptual possibilities are vast.
In my prior post I used Cool Edit to generate spectrum picture. Too really see low frequency behavior of vinyl records, a very big FFT needs to be used, or down sample the ripped track to get better resolution with smaller FFT.
In picture, sample rate was changed from 44.1kHz to 882Hz, at low rate 65k FFT spans about 74 seconds.
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