Old, Worn Vinyl

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Old, Worn Vinyl

Postby dave.daniells » Wed Jan 24, 2007 11:41 pm

During the last year, I've been scouring charity shops and friend's attics for old 45's, and am finding a lot of good stuff which is sometimes in very poor condition.

Some of the oldest, and I guess most played records tend to have a 'gritty' sound that no amount of cleaning diminishes. And they mostly have the greatest 'noise' during the loud sections. The waveform in these areas often has one channel where the waveform near to the peaks looks like they have been 'bitten'.

Now I know what to look for I find I can correct most of this distortion, but it takes forever on a peak-by-peak basis.

I suspect that a lot of the discs displaying this type of waveform have been played without replacing the stylus, and the worn stylus has widened the grooves, resulting in something like a 'rattle' when played with a good stylus.

Now a rattle is a dynamic phenomenon, and should reduce at lower speeds. So, in the last week, I've been experimenting with the speed-conversion feature of Wave Corrector. Poor discs are played at 33 1/3 RPM, and a speed conversion of 0.7407. It is early days yet, but my experience of 3 such discs seems to show a noticeably cleaner recording that makes it easier to spot and correct the remaining faults.

If any of the above sounds familiar, why not give it a try. I only wish I could see a way to use a similar technique to record my poorer LPs, but the turntable has no lower playback speed (though I might just try removing the pulley, and let the belt run on the smaller shaft diameter!)

Good Luck
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Postby Derek » Thu Jan 25, 2007 9:51 am

Yes, this is good advice. Tracking distortion will be reduced significantly as you reduce the tracking velocity. (This is why the distortion less at the start of a record compared to the end.)

Another technique to try with badly worn records is to use try a different size stylus and/or a different tracking weight. A larger stylus will track higher up the groove wall which will often be less worn.

Also, as noted above, distortion is always worse on the inner tracks of the record and for these tracks one channel is often worn more than the other. So, if it is a mono record, you could try just recording the good channel.
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Postby deeor2 » Thu Jan 25, 2007 8:42 pm

Although it is concerned with 78's http://www.videointerchange.com/vintage_78s.htm
gives some useful info on using wider and truncated styli. The latter are seriously expensive unless you are seriously into the music. :)
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Postby knighte » Mon Mar 12, 2007 11:55 pm

Hi Dave, you are a man after my own heart. I was wondering if you think a variac would work to slow down your turntable. I intend to try it myself when I get the time. I imagine a person would need a strobe and a "speed disc" to get it right, but even with experimentation one could get pretty close to the desired speed. If you don't have a variac, they can be pretty reasonable on Ebay if you are patient. Maybe just borrow one first. I know what you are talking about regarding rough sound from an LP. I use an ASRU from Symmetric Sound Systems (out of business) to smooth out my recordings. It does a very nice job, but it took me a while to realize to let the Wave Corrector do its work first and then use the analog filter. The a/b difference in the waveform is amazing. I just checked the free program Audacity, and in the menu under "Effect" that software can manipulate speed, tempo, and pitch. If you want to hear something interesting, change the tempo without changing the pitch. Perhaps adjusting your recording in this program first may help. I doubt it since the stylus is still rattling at the higher speed.
Here's wishing you luck in your endeavor.
Larry
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Postby citguy » Tue Mar 13, 2007 12:37 am

Hi Larry and Dave. I am not a fan of audacity BUT when it comes to changing pitch or speed it is a great program. I have taken tapes that were recorded at the old extended play speed on cassette and mixed with standard speed and made them all correct with audacity. You are right on here.
Stan
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Postby Ray Bell » Wed Mar 14, 2007 5:48 pm

Larry

I don't think you are likely to have much luck using a variac to slow your turntable speed. As far as I am aware there are 2 main systems used for turntable speed control and neither would respond well to the reduced supply voltage from a variac.

The first system is to use a 'synchronous' a.c. motor for which the rotation speed is locked to the incoming mains supply frequency as long as the motor has sufficient torque to drive the load. Dropping the voltage will reduce the available torque but not the speed until the torque is insufficient; at which point the motor 'slips' and the speed will drop but become unstable so wow and flutter will increase.

The second system uses a d.c. motor with a regulated supply generated from the mains input and possibly adjusted by feedback from a speed sensor. This system will give a constant speed until the mains voltage is reduced to the point where the control circuitry has too low a supply voltage to deliver the required output to the motor. Below this point the speed will drop but stability is again likely to be poor and the motor may even stop abruptly.

There is another issue to consider if you are successful in changing the turntable speed which is that of equalisation. Standard recordings are produced with a frequency response which is far from flat having both a treble boost (to improve high frequency signal to noise ratio) and a bass cut (to reduce the maximum travel of the stylus). The inverse frequency response must be accurately applied in the preamplifier to restore a flat response. If the turntable speed is changed then the frequencies of the playback signal will shift and the required characteristics of the preamplifier will also change. This can probably be compensated for by use of Wave Corrector's filters and may only be a subtle effect in any case but I thought I would mention it as I have not seen it discussed here.

Ray
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Postby dave.daniells » Fri Apr 20, 2007 5:35 pm

After trying playing 45's at LP speed, I was sufficiently pleased with the result to go one step further, and I've made a new motor pulley that gives me slightly over 16 RPM. Which has given me the chance to record LPs at reduced speed too.

As far as calibration goes, I simply took an old (swap) 45, and deliberately put a radial scratch on it. Recording with Wave Corrector and then testing the time between major faults gave me an accurate reading for the new rotational speed, and thus the speed correction factor to use in future.

It has proved only partly successful as far as my original aim. I am seeing less 'rattle' (if that is indeed what it is), but it has only reduced the volume range of the noise areas by a few db. So there are still a lot of corrections to be made. However, I have been really impressed with the smoothness of the waveforms obtained.

Before all this latest experimentation, I would often see waveforms that simply looked like saw-tooths, and it was hopeless trying to locate the faults and apply manual corrections. But now, the same discs produce smooth shapes where the faults are relatively easy to spot and correct.

Thanks for the responses and good luck to all of you who boldly go into the 'Vinyl Frontier'
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Postby citguy » Fri Apr 20, 2007 5:59 pm

Hi Dave. This raises a host of situations, especially with classical LPs that are reissues of older recordings especially European recordings. Many of these remasters were done at the wrong speed. European orchestras recorded at widely varying pitches in the first half of the twentieth century. Some reissues attempted to standardize the pitch at A=440 which was a mistake. One almost has to know the accepted pitch of the orchestra at the time of the original recording to get the playback speed correct. Some were below A+440 and some were above A=440. Being a musician, I have a digital tuning device which can determine the playback pitch of a recording during 'held chords'. Of course knowing the original pitch of the recording is more of an academic research project than most of us want to engage in. Even today, when my daughter ,who lives in England, performs in Germany or some other country on the continent, she sometimes finds it almost impossible to play at the addopted pitch of a given orchestra. In the old days, changing pitch equaled changing tempo but now with programs like 'Audacity' and others we can vary the pitch of wave files with out varying tempo and vary tempo without varying pitch (but just varying pitch alone could produce inaccurate tempos). Just some ramblings your comments brought to mind.
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Postscript

Postby dave.daniells » Thu Jun 07, 2007 2:56 am

It seems I was right in assuming the noise I heard was rattling of the stylus within the record grooves during periods of high amplitude, but wrong in thinking this was down to worn records.

Decades ago, I tried to find simple, non-destructive ways of cleaning records, and discovered that methylated spirit worked well to remove much of the debris, including skin oils from careless handling. And I still use it today. But I recently found a way to dramatically increase the effectiveness of this cleaning fluid.

I guess we will all be familiar with the 'playing wet or dry' debate - there are posts on this topic within this forum. Well, as I had been cleaning an old disc with meths, and had it to hand, I decided to try playing the disc with the record surface wetted with meths, applying more with a soft brush as it visibly evaporated. Initially, I could detect no difference in recording quality, but afterwards noticed a significant build-up of debris around the stylus.

Worried that this might be due to a worn stylus, I repeated the process with one fresh from the box, and got the same result, but with even more build-up round the stylus. It took a further 3 or 4 plays before the stylus remained clean. At this point it became obvious that most of the buzzing noise I had previously heard had vanished. And this was true whether the disc was played wet or dry.

There was still a sneaky suspicion that the sound was cleaner because this process had rubbed-off some of the vinyl peaks, but comparing the first and last recording showed the recording level had actually increased, resulting in a smaller normalisation correction being required.

It seems likely that an oil/dust mixture can harden over time and fill the bottom of the groove leading to the 'rattling' effect I observed some months ago. And while a simple meths wipe will take off relatively fresh, soft deposits, it doesn't touch the hardened accumulations. However the combination of meths, the locally high contact pressure under the stylus, and the mechanical movement of playing the disc DOES start to soften the crud.

To finish, let me say that a track to which I had previously made over 2000 manual corrections, once cleaned in this way, sounds seriously better, and only need a few hundred corrections.
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Postby knighte » Sat Jun 16, 2007 2:51 am

Greetings Dave,
I find your experiments fascinating and informative. Your success at improving the output of your turntable certainly deserves merit. The use of what you refer to as "meths" are along the same lines as solvents I have tried. I settled on trichlorotrifloroethane (good luck trying to find it now) as a final cleaner for my albums. This is used after the usual solutions that are the accepted norm. Using it as a "wet" play agent never occurred to me, although most of my albums are pretty clean. One other thing I have noticed that might be of interest is that the use of "anti-skating" affects the amplitude of impulse noise. If the tonearm is not in balance the stylus is exerting more force on one side of the groove thus making the tics or pops louder for whatever channel. I made three recordings of the same passage in order to observe this using Wave Corrector. If the tonearm is tracking right down the middle, the noise amplitudes are less, and there seems to be an overall smoother waveform.
Larry
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Recording at different speed and cleaning records

Postby mannie.gross » Sun Jun 24, 2007 2:32 am

Just a few observations and some questions:

I recall reading many years ago in a hifi magazine that it was inadvisable to use methylated spirits to clean records as the methylated spirits reacted with the plasticisers in the record and caused the grooves to deteriorate. From that time on I have never used anything other than water or specialized cleaning agents (such as Discwasher) to clean my LPs. However my original information may have been wrong. Does anyone have a definitive answer to the use of methylated spirits on vinyl records?

With respect to the RIAA equalization problem when recording records at a different speed from the original and compensating with Wave Corrector, does Wave Corrector also compensate for the RIAA equalization error?

Is it true that RIAA equalization was not used on 78 RPM records?

I have been toying with the idea transferring some old 78 RPM records to CD using Wave Corrector. (My old but still very good Thorens TD 125 Mark 2 turntable only plays 16, 33 and 45 RPM.) Therefore the RIAA equalization error issue is important.

Other than the RIAA equalization issue, it also occurs to me that slowing down the playing speed of the record has the advantage of effectively increasing the frequency response of the cartridge. However at the low end of the frequency response it would be a disadvantage as say a 20Hz signal would appear lower and the cartridge's response would drop off. This is hardly likely to be a problem for 78s but could be an issue for say classical hifi recordings at 33 RPM. Can anyone shed any light?

Regards,
Mannie
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Postby knighte » Sun Jun 24, 2007 12:59 pm

Greetings everybody,
While researching frequency response from lp's I happened across this site.

http://www.tnt-audio.com/accessories/mothmk2_e.html

This is a novel idea that makes a lot of sense, cleaning a lp in reverse rotation on a vacuum type cleaner. The author used a microscope to verify his findings. The site is a gold mine of excellent information. Also, here is an explanation for a magnetic cartridge that makes the reasons for the loss of high frequencies in a record groove understandable.

http://en.wikipedia.org/wiki/Magnetic_cartridge

I'm looking for more information on cleaning agents for vinyl, especially those that might do damage or shorten the life of an lp. Have you ever smelled the product from Last for record preservation?
Larry
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Re: Recording at different speed and cleaning records

Postby Derek » Mon Jun 25, 2007 8:33 am

mannie.gross wrote:With respect to the RIAA equalization problem when recording records at a different speed from the original and compensating with Wave Corrector, does Wave Corrector also compensate for the RIAA equalization error?

No it does not. Wave Corrector simply records what is presented at the input to the soundcard. After having made your recording, you can apply filters to compensate for the pre-equalisation of the original record. One of our tutorials describes how to use the graphic filter to create an RIAA equaliser characteristic. See http://www.wavecor.co.uk/tutorials/tapetocd.html#mozTocId156570
Is it true that RIAA equalization was not used on 78 RPM records?

You would need to adapt the filter slightly if the 78 was recorded using a different characteristic. However, in practice, you are unlikely to need much adjustment. The best approach is to try different settings and use your ears to decide what sounds optimum.

There are various websites that describe 78 equalisation. For example, see http://www.rfwilmut.clara.net/repro78/repro.html
Derek Higgins
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Postby mannie.gross » Mon Jun 25, 2007 9:24 pm

Hello Derek,

Because the signal to Wave Corrector has already been processed by the phono preamp, the RIAA equalization (in the preamp) will have been applied to the wrong (shifted) frequencies on an LP not played back at the correct speed. But no matter it should not be difficult to work out a filter to correct for this.

Thanks for the informative links.

Regards,
Mannie
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Postby Glenn » Mon Jul 02, 2007 7:13 pm

Hi Mannie,
you wrote
Does anyone have a definitive answer to the use of methylated spirits on vinyl records?

I don't have a definitve answer, just my two cents worth. This discussion I think should not be about what spirit to clean a record with but rather how to clean the record. While everyone is looking for the universal solvent that will restore their vinyl to like-new condition, no-one is considering what to do with the detritus released by the solvent. Most authorities recommend scrubbing the record with distilled water, using a vacuum to remove the dirt. I've tried this and it works very well.
Glenn
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