Hi,
Have you ever seen the Electronics that come as standard with a VMS-80 or 82 Neumann Lathe (never mind the earlier VMS-70 and before)? Did you notice the digital delay they used, the tracing compensation pre-distorter and all the other jazz?
Even with careful calibration I doubt 1dB accuracy was possible to maintain from analogue input through the tracing simulator, the digital delays AD converter and DA converter with Filters and the cutting Amp's all the way to the cutting stylus 20Hz-20KHz.
The concept of "accuracy" in LP's is rather amusing to anyone who knows how an LP actually is cut.
I suspect the Lathe Stan Ricker has may be calibrated carefully to at least stick to 1dB (I believe he cuts a lot of the Audiophile Reissues), if we are all lucky.
John, I believe you know Stan, care to ask him?
Then buy CD.
AP2 works well. I also have made an iRIAA network which I verified against the AP2 as < 0.1dB.
I selected the cap's for my iRIAA using a precise LCR Meter, verified against a high precision (10 pcs parallel of 0.5% capacitors) reference cap. The resistors where 0.1% off the shelf.
I do...
Ciao T
Have you ever seen the Electronics that come as standard with a VMS-80 or 82 Neumann Lathe (never mind the earlier VMS-70 and before)? Did you notice the digital delay they used, the tracing compensation pre-distorter and all the other jazz?
Even with careful calibration I doubt 1dB accuracy was possible to maintain from analogue input through the tracing simulator, the digital delays AD converter and DA converter with Filters and the cutting Amp's all the way to the cutting stylus 20Hz-20KHz.
The concept of "accuracy" in LP's is rather amusing to anyone who knows how an LP actually is cut.
I suspect the Lathe Stan Ricker has may be calibrated carefully to at least stick to 1dB (I believe he cuts a lot of the Audiophile Reissues), if we are all lucky.
John, I believe you know Stan, care to ask him?
Then buy CD.
AP2 works well. I also have made an iRIAA network which I verified against the AP2 as < 0.1dB.
I selected the cap's for my iRIAA using a precise LCR Meter, verified against a high precision (10 pcs parallel of 0.5% capacitors) reference cap. The resistors where 0.1% off the shelf.
I do...
Ciao T
Hi,
Of course.
No, electrically cut 78's used EQ in the cutting Amp.
Europe used mostly "Bluehmlein", USA had a profusion. EQ on 78's is a subject that makes EQ on microgrove records seem trivial. Luckily (or not) few 78s survive in any viable condition.
Ciao T
Of course.
No, electrically cut 78's used EQ in the cutting Amp.
Europe used mostly "Bluehmlein", USA had a profusion. EQ on 78's is a subject that makes EQ on microgrove records seem trivial. Luckily (or not) few 78s survive in any viable condition.
Ciao T
A small intervening.
I found it on line (if it is the one you are referring to). Thanks for the info
http://www.bl.uk/reshelp/findhelprestype/sound/anaudio/analoguesoundrestoration.pdf
Good for pointing out common sense and realism while remaining polite (post #59)
Regards
George
I found it on line (if it is the one you are referring to). Thanks for the info
http://www.bl.uk/reshelp/findhelprestype/sound/anaudio/analoguesoundrestoration.pdf
Good for pointing out common sense and realism while remaining polite (post #59)
Regards
George
Hi,
This is the one. The BBC Sound Recording Archive became part of the British Library a while back. I did post the link in post 26, to the main page, the download link is a wee bit hard to find on that page.
BTW, the core turnovers needed to cover most (not all) curves are 50/70/100Hz, 400/500Hz and 1.59/2.12/3.18KHz. The 50Khz additional turnover is hotly debated.
The interactivity of the various EQ parts in common networks makes this hard to implement switchable (unless we switch whole network) makes this a little hard to implement. Using Split passive or passive/active EQ is much easier.
Ciao T
This is the one. The BBC Sound Recording Archive became part of the British Library a while back. I did post the link in post 26, to the main page, the download link is a wee bit hard to find on that page.
BTW, the core turnovers needed to cover most (not all) curves are 50/70/100Hz, 400/500Hz and 1.59/2.12/3.18KHz. The 50Khz additional turnover is hotly debated.
The interactivity of the various EQ parts in common networks makes this hard to implement switchable (unless we switch whole network) makes this a little hard to implement. Using Split passive or passive/active EQ is much easier.
Ciao T
Hi,
I have on occasion downloaded something (all deleted now), but I have bought huge amounts more and lined the pockets of the record industry executives (not the Musicians - few of them make real money from their recordings).
Ciao T
I have on occasion downloaded something (all deleted now), but I have bought huge amounts more and lined the pockets of the record industry executives (not the Musicians - few of them make real money from their recordings).
Ciao T
Hi,
Nope, it is quite straightforward, tinfoil cap's I only use for coupling, EQ is Silver Foil...
As I like to use several smaller value cap's in parallel (in part for availability of values, in part for the improved tolerance) so it is not all that onerous.
I managed with only a few extra components (over RIAA) and relay switches. I do not try to switch 23 different Networks, just modify the tree available turnovers by adjusting capacitor and resistor values.
Yes, the fun part is, the 23 happened by accident, not intent (I rather like RAW's writings, did you read Prometheus rising?).
By intent originally there where 22 curves (the acrostic significance of the number 22 should be obvious).
I suspect we are observing the much vaunted Illuminati law of the fives in action here...
(Law of the fives, as 23 -> 2+3 = 5, also using the most recent version of the english alphabet before the current [which included the lower case form of the long s] places the V for Latin numeral for 5 in the 23rd position...)
Ciao T
Nope, it is quite straightforward, tinfoil cap's I only use for coupling, EQ is Silver Foil...
As I like to use several smaller value cap's in parallel (in part for availability of values, in part for the improved tolerance) so it is not all that onerous.
I managed with only a few extra components (over RIAA) and relay switches. I do not try to switch 23 different Networks, just modify the tree available turnovers by adjusting capacitor and resistor values.
Yes, the fun part is, the 23 happened by accident, not intent (I rather like RAW's writings, did you read Prometheus rising?).
By intent originally there where 22 curves (the acrostic significance of the number 22 should be obvious).
I suspect we are observing the much vaunted Illuminati law of the fives in action here...
(Law of the fives, as 23 -> 2+3 = 5, also using the most recent version of the english alphabet before the current [which included the lower case form of the long s] places the V for Latin numeral for 5 in the 23rd position...)
Ciao T
I missed it. Sorry for the duplicated link.
On the topic what's the best way to measure the accuracy of the equalisation:
Sy, the cumulative inaccuracies arising from changing ranges at the multimeter and the signal generator is a problem that has to be considered.
For an diyer the use of a PC card and software producing a RIAA stage output curve which can be compared to a theoretical perfect RIAA look-up table is IMHO a better solution if such a work is done infrequently.
For more frequent testing, the use of a RIAA inverse network plus PC card and software producing a curve that has to be compared against a flat line is easier, faster and potentially more accurate.
It would be nice if anyone having access to an AP and a PC card/software could make FR measurements on a certain RIAA stage and compare the two, just to see the scale of discrepancies btn a professional measuring equipment and a diyer affordable set-up.
Regards
George
Empirically, I've found that, with a good AC meter and the use of a reference that has a common point on two scales. tight trimming is pretty straightforward. This was a technique that the late Allen Wright showed me a few years ago. I have a precision inverse RIAA (Lipshitz) which is useful for verification, but the meter is much easier to use for the trimming process.
A sound card (assuming at least a half decent one) should work fine, maybe even for watching curve changes in real time, I just haven't done it that way.
A sound card (assuming at least a half decent one) should work fine, maybe even for watching curve changes in real time, I just haven't done it that way.
Thanks Sy.
The “common point on two scales” is crucial.
Also the “good AC meter”.
You have mentioned somewhere the importance of using an analoque AC meter, in contrast to a digital one. I could not agree more.
The problem is that a good analoque AC meter is a rarity in our days.
Digital Ac meters have too limited a “flat” frequency response.
Whenever I buy a digital meter I have to “calibrate” it using what I have in my workshop. I produce a Voltage to Frequency table and chart with deviations relative to 1KHz. *PS
Then, when I use this instrument in practice, I have to compare against this chart. Excel spreadsheet helps but it is still a pain.
Regards
George
*PS: I check the consistency of those measurements in the passage of time. They are stable, if the instrument’s battery is OK
SY
It occured to me (I'm a bit slow) that you are refering to a home built one, like the one here:
Google ???????????? E?????? ??? http://www.electronics-circuits.com/schematics/instrumentation/attenuator-amp.png
Thorsten L,
The UK is still awash with 78's in pristine condition which very few people want and usually end up on the rubbish tip! I am mostly referring to 1920's to 40's-the earlier ones are less common and in usually poorer condition. They are quite robust as long as you don't sit on them and in general have faired rather better than many of the earliest LP's which were often thrashed by the heavy pickups of the time,the plastic materials being less wear resistant than the shellacs with their abrasive fillers.
The National Sound Archive in London have at various times published information on early recording systems. They claim that the early Western Electric amplifier had an essentially flat frequency response from 50 Hz to 5 kH and that the constant amplitude section of the recording characteristic is due to the changing reactance with frequency of the EM cutterhead itself.
The equalisation of electrical 78's is normally quite straightforward as in most cases there is no pre-emphasis. However acoustic records are an entirely different matter.....
The UK is still awash with 78's in pristine condition which very few people want and usually end up on the rubbish tip! I am mostly referring to 1920's to 40's-the earlier ones are less common and in usually poorer condition. They are quite robust as long as you don't sit on them and in general have faired rather better than many of the earliest LP's which were often thrashed by the heavy pickups of the time,the plastic materials being less wear resistant than the shellacs with their abrasive fillers.
The National Sound Archive in London have at various times published information on early recording systems. They claim that the early Western Electric amplifier had an essentially flat frequency response from 50 Hz to 5 kH and that the constant amplitude section of the recording characteristic is due to the changing reactance with frequency of the EM cutterhead itself.
The equalisation of electrical 78's is normally quite straightforward as in most cases there is no pre-emphasis. However acoustic records are an entirely different matter.....
For the few I have compared to LP versions, +-1 dB or so EQ was hardly the worst problem.
As for some other comments here, I don't find something like a gradual +-2 dB tone stack to ever make a recording "unlistenable" no matter where it's set.
Hi,
Well, most soundcards have significant measurable deviations in loopback.
I often use the EMU 1616m, but I know it has a drooping high end.
One might be able to ask the guys who write RMAA to include a anti RIAA (digitally) equalised version of the test signal, as well as an option to use a given set of measurements as calibration (removing at least the FR of the card from the measurement). It should not be too difficult.
Actually, AMR are users of RMAA Pro, maybe we can ask, if I remember, have too much time on my hand and all... Otherwise maybe someone reading here can ask...
Anyone with really good EQ software could also take an RMAA test signal dump and anti-RIAA equalise this and make it available to the community. This would also allow measurements, just not as easy as a direct RIAA EQ in software (like the AP2 does as well).
Then depending on the exact card 0dB @ 1KHz would be -20dbFs, if the soundcard is decent (e.g. EMU 1616m) even SNR & THD measurements, FFT spectrums of HD and so on would still be meaningful. An attenuator of 32dB would give 5mV "0dB", 52dB would give 0.5mV. So a resistor chain of 10R (MC cartridge simulation), 91R (for the MM Cartridge level) and 3K9 to the cardoutput for 2V @ 0dBfs sould be all that is needed.
Ciao T
Well, most soundcards have significant measurable deviations in loopback.
I often use the EMU 1616m, but I know it has a drooping high end.
One might be able to ask the guys who write RMAA to include a anti RIAA (digitally) equalised version of the test signal, as well as an option to use a given set of measurements as calibration (removing at least the FR of the card from the measurement). It should not be too difficult.
Actually, AMR are users of RMAA Pro, maybe we can ask, if I remember, have too much time on my hand and all... Otherwise maybe someone reading here can ask...
Anyone with really good EQ software could also take an RMAA test signal dump and anti-RIAA equalise this and make it available to the community. This would also allow measurements, just not as easy as a direct RIAA EQ in software (like the AP2 does as well).
Then depending on the exact card 0dB @ 1KHz would be -20dbFs, if the soundcard is decent (e.g. EMU 1616m) even SNR & THD measurements, FFT spectrums of HD and so on would still be meaningful. An attenuator of 32dB would give 5mV "0dB", 52dB would give 0.5mV. So a resistor chain of 10R (MC cartridge simulation), 91R (for the MM Cartridge level) and 3K9 to the cardoutput for 2V @ 0dBfs sould be all that is needed.
Ciao T
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