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Topic: Vinyl silence (Read 8274 times) previous topic - next topic
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Vinyl silence

After listening to Pio2001's rather excellent vinyl recordings I'm rather stumped as to why mine are so poor. Along with some significant cracks/pops on absolutely pristine vinyl, I think I'm seeing a far higher noise floor than I should, given the equipment and the sample involved.

Attached is 10 seconds of silence between the tracks "LCC" (1) and "Ipacial Section" (2) of the US release of Autechre's Untilted. This is only the third time this disc has ever been played, and I only bought the album last May. Recording chain is Music Hall MMF-5 -> TCC TC-750 preamp with upgraded power supply -> RME DIGI96/8 PAD -> MAGIX Samplitude V6 Master. Recording was done at 24 bits 96khz and downmixed to 16/44 with foobar. Recording peak was roughly -15dbFS. The recording level was normalized to the peak level of the entire side of the record, and there were no pops on the record that caused that peak to increase significantly, so the peak amplitude of this signal is representative of the final noise floor of my rips.

So far I can clearly hear several issues, all of which I'm unsure how to proceed on:
  • Notable 60hz hum + harmonics. My preamp had stupidly huge amounts of this without the turntable turned on, but all of it disappeared when I swapped in a regulated power supply. No idea if this is coming from the preamp, the turntable or the recording.
  • Rumble peaks around 10hz after subjecting the entire rip to an FFT. I'm guessing I should just forget about fixing this in hardware and just figure out a good rumble filter strategy in software.
  • Some other lowish frequency noise that is dominant in the left channel. Dunno what to really think of this. I doubt it is due to a warped disc as this one has a warp in the low millimeters. In general, I think my recordings have a good bit more pops in the left channel.
  • Low level crackling/popping. Dunno if this is due to small amounts of dust accumulating on the disc, static, or what.
This record had been wet-cleaned immediately prior to recording, but the veracity of that cleaning process is, to put it mildly, suspect. I'll be doing more recordings after tweaking my system more to see how it changes.

Any explanations, suggestions and pointers are gladly welcome.

Vinyl silence

Reply #1 –
Sorry, got it wrong.   
Nov schmoz kapop.

Vinyl silence

Reply #2 –
My kneejerk reaction is that either your turntable sucks, your needle sucks, or both. But then again, I know very little about your set-up, so this is merely conjecture.

Vinyl silence

Reply #3 –
The noise of this sample seems pretty high but normalizing just gets in the way of  trying to figure it out. If you amplified the recording by 15dB, maybe it isn't too abnormally high after all.

You can get some insight to your system by doing things one step at a time.

First unplug everything from your soundcard and record its noise floor. If you don't have software to fully analyze everything, record twenty-five seconds or so, then select five seconds a few seconds before the recording's end. Save that five seconds as your sample. This more involved procedure probably isn't necessary, but sometimes soundcards have an initial settling time that I have seen last as long as 15 seconds after start of recording. This way, if you don't know for sure, you can be more certain your data isn't contaminated by unstable conditions.

Next plug the phono preamp output into the soundcard with nothing plugged into the preamp and make another recording. If you then short the preamp's input you will probably get different results and these latter are more characteristics of what the preamp contributes under actual use.

Go next with the TT plugged into the preamp, with its grounding wire attached. You can compare TT turned off with TT turned on. You can make another recording with the platter turning but without the stylus on an LP.

Finally you can record between track silence or the unmodulated grooves of a test LP. You need to compare this final recording as-is with your other recordings, not normalized or otherwise modified.

Just to give you some kind of reference point, the difference I get with the last step, full system, no LP vs with LP is about 24dB for the album I'm correctly working on. That is, the noise floor for the TT is -80dB RMS Average (CoolEdit Statistics)  and this fairly beat-up LP reads -57dB RMS Average.

You may be able to improve on your system by fixing it, if something isn't right, or replacing with better components. You can improve on the LP contribution only by properly cleaning the stylus and the LP -- until you have it in the computer.

On your sample I reduced the level by 15dB with a rumble filter. You won't hear much of that directly, but it represents a goodly amount of wasted amplifier power and some potential signal interaction.

Running a notch filter for the hum improved the level by 3dB, and that is definitely hearable. I did not spend much time tuning the filter for optimum results and I applied it equally to both channels.

Many 50s and early 60s LP have quite a bit of hum. In my experience such hum is most often not equal on the two channels, so best results are obtained by doing them separately. A  channel difference can also come from differences in you components' power supplies or from less than optimum wiring. The big 120 Hz peak on your sample is close enough to the same on both channels, but the 60Hz component is much more pronounced in the right channel.

Vinyl silence

Reply #4 –
I'll make some recordings tonight in different configurations: sound card with nothing plugged into it, then cabled to preamp with preamp turned off, then preamp turned on, then turntable turned on, then actually spinning the disc, all unnormalized. IIRC, the noise floor with the preamp off is about 100db and 78db with it on. (These are amplitude peaks and not RMS peaks.)

Is 60hz hum ever an issue with albums produced and mastered in 2005?

The MMF5 is a moderately expensive turntable. I did buy it used from a dealer, but he swore up and down that it was in excellent operating condition. The previous owner bought it new from him and used it for 9 months. I've put the needle under a microscope and couldn't find anything obviously wrong with it.

Vinyl silence

Reply #5 –
andy you mention doing recordings with nothing else pluged in, when i record stuf i usually plug my headphones (sennheiser hd-570's) into the soundcard to monitor it as i dont have any pc speakers. will this affect the quality? im still using my audigy though as i cant decide which new card to get so that probably does more damage than pluging in my headphones 

Vinyl silence

Reply #6 –
The "doing recordings with nothing else pluged in" is just to determine the soundcard's noise floor. It really only means no input. Using the output should not effect noise the system makes, but of course you could experiment by making recordings both ways.

I don't know what "amplitude peaks and not RMS peaks" means. Are you saying you have no way to measure except by watching VU meter displays? If that is so I guess you just have to do the best you can. Do you have software to make any kind of frequency analysis or otherwise determine what may be responsible for observed differences?

Vinyl silence

Reply #7 –
Quote
  • Notable 60hz hum + harmonics. My preamp had stupidly huge amounts of this without the turntable turned on, but all of it disappeared when I swapped in a regulated power supply. No idea if this is coming from the preamp, the turntable or the recording.[a href="index.php?act=findpost&pid=330306"][{POST_SNAPBACK}][/a]


To my ears, this is the only defect in your recording.
It can come from the ground wire of the turntable not being attached to the ground pin on the phono input (but usually, it sounds quite different), or from the turntable conception.
I had a Luxman direct drive turntable which made exactly the same noise as yours when I moved the cartridge above the engine, without playing any record. Diferent cartridge may pick more or less noise, but the problem is with the turntable.

Quote
  • Rumble peaks around 10hz after subjecting the entire rip to an FFT. I'm guessing I should just forget about fixing this in hardware and just figure out a good rumble filter strategy in software.[a href="index.php?act=findpost&pid=330306"][{POST_SNAPBACK}][/a]


This is normal and causes me no problem as it is not audible. I leave it as it is. Just make sure to use short fade-in/out and the ends of your recording, because abruptly stopping this waveform will cause an audible click.

Quote
  • Some other lowish frequency noise that is dominant in the left channel. Dunno what to really think of this. I doubt it is due to a warped disc as this one has a warp in the low millimeters. In general, I think my recordings have a good bit more pops in the left channel.[a href="index.php?act=findpost&pid=330306"][{POST_SNAPBACK}][/a]


I can't see nor hear it.

Quote
  • Low level crackling/popping. Dunno if this is due to small amounts of dust accumulating on the disc, static, or what.
    [a href="index.php?act=findpost&pid=330306"][{POST_SNAPBACK}][/a]


Hey ! This is a vinyl !
Vinyls that don't click are very rare. This is perfectly normal.

I once posted samples of vinyl background noise, but I had to remove them because my webspace is full, and my upload rights on Hydrogenaudio are full too. My webspace should increase soon, but I have to call my ISP again for this to be effective.
 

Vinyl silence

Reply #8 –
I think that I know what you mean with the "lowish frequency noise that is dominant in the left channel". It is the "rattling" sound that is quite in phase opposition in the two channels isn't it ?

I regret to tell you that this might have been caused by the wet cleaning ! When you have a brand new record, never put your fingers on it, and use only a carbon fiber brush in order to remove dust, before playback.

I think that any use of a felt brush, or soft cloth can introduce a rattling surface noise. I've got a Stanton cleaning kit for vinyl, and I've noticed that the use of the felt brush produces this kind of noise in the record. This must only be used on records that have been spoiled with moisty dust or fingerprints.

I've never experimented with recording a vinyl before and after brushing. So my conclusion might be influenced by their visible effect on CDs. The carbon fiber brush is the only thing that I managed to use on a brand new CD to remove dust without producing any scratch visible under any angle of vision. Any other brush I tried immediately produces thin scratches visible when the light hits them perpendicularly.

Vinyl silence

Reply #9 –
You might be right on the wet cleaning bit. The exact method I used was as follows: I protected the label and submerged the entire album in a mix of distilled water, dish soap and isopropyl alcohol (I didn't bother figuring out the exact mix). I brushed the record with a blue cloth-covered sponge advertised for safe record cleaning. After letting the disc sit and get washed for a few minutes, I rinsed off the record with Brita-purified tap water (!) and then I let it dry for a couple hours in a clean dishwasher before recording it. I figured that adequately rinsing the records with distilled water would require a stupidly large amount of the stuff - like 10+ gallons - and I only cleaned about 5 of my records that night.

Needless to say, the odds of me doing something severely bad to my records in this process are rather high. Especially since I now see pale, faint white streaks on the grooves of this album. But I need to start somewhere with figuring out how to clean my records, and the kitchen sink method is in fact advocated by more than a few people. I don't consider these records priceless as long as a couple of them ever get damaged due to bad practice at a time - and moreover, I recorded all the albums before I cleaned them as well, using only a carbon fiber brush for cleaning. I'll get a clip of the silence pre-cleaning uploaded tonight.

I've also ordered a HiFi News Test Record, which has an unmodulated groove on it. That should also prove useful for figuring out my noise level.

Vinyl silence

Reply #10 –
Brita-purified tap water or any water contains MANY inpurities. Put some on a sufrace mount PCB and you get conduction and dead components.
Isopropynol is very pure and not too expensive. Perhaps a bath of that would be better, if re-used. Maplin (UK) sell litres for about £10. I admit i know nothing about vinyl, but cleaning in any water and leaving to dry will leave many particles.  Get a clean piece of glass, or a cd, sprinkle the water on, let it dry, and check it in the light or a scope, i bet theres dry residue, its inavoidable with water.

Of course wether this applies to records OR audability, I don't know.

Kristian

Vinyl silence

Reply #11 –
The water here seems soft enough. I easily get plenty of suds with soap or detergent. However, running some experiments one day, I found that it leaves hard, very difficult to remove deposits if allowed to dry (on my glass microscope slides). Once dried, the deposits do not re-dissolve in water (or in two different acid mineral removers I tried).  Those deposits would interact unpleasantly with a stylus.

Properly filtered water does not leave such deposits. Properly filtered means reverse osmosis or distilled, or at least some process that removes minerals. Carbon filters remove organics, not dissolved minerals.

There are a variety of approaches to proper vinyl cleaning. There is quite a bit of instruction and discussion on the web. Not all of it is terribly reasonable, but there is much good information. This web page has the best instructions for general cleaning. http://discdoc.com/ Of course, he hopes to sell you his products, which are quite good, but the technique does not require them for decent results. Vacuuming away the rinse is still better, I believe, but you can still do a good job without that expense.

There are a number of less expensive brushes that can do a reasonable wet cleaning job. Those LAST sells are the least expensive targeted brushes and are pretty good. There are inexpensive paint trim applicators with fuzzy pads in a plastic holder that are just the right size for a regular sized LP. They work quite well.

The general consensus is there is material from the manufacturing process on new disks and said material is not conducive to keeping the LP in the best condition (read scouring powder). High power microscopes can be, and have been, used to observe the surface and grooves, so pure speculation about whether something is there or not, or whether it can be cleaned away or not, is not necessary.

Speaking of microscopes, I think something on the other side of 1000X is required to really see normal stylus wear -- plus some insight about what to look for.

Vinyl silence

Reply #12 –
New set of samples. This time everything is unnormalized.

Download noise-comparison.zip from http://briefcase.yahoo.com/bc/richard.toll...case.yahoo.com/
  • sound-card-cable-silence-out.ape: Cables wired out of sound card to preamp, preamp not turned on. Equivalet to the recording with the cables unplugged.
  • sound-card-preamp-silence-out.ape: Preamp turned on.
  • sound-card-tt-silence.ape: Preamp and turntable turned on, needle not dropped.
  • autechre-untilted-side1-take4-silence-out.ape: 4th needle drop of this side, same track location as the earlier sample.
  • autechre-untilted-side1-take4-music-out.ape: First 10 seconds of music immediately after said silence. This selection is effectively the peak amplitude of this track.
The state of the record itself is not much different than before. There was a chance the record was still slightly wet when I played it before and everything is definitely dry now. I did replace the mat on my MMF5 with a supposedly antistatic mat (that works through "corona discharge"! woot).

A couple things stand out:
  • There is a definite crackle that is directly tied to the preamp.
  • Turning the turntable on measurably worsens the noise, even if nothing is playing.

EDIT: Yahoo Briefcase sucks.

Vinyl silence

Reply #13 –
Quote
I don't know what "amplitude peaks and not RMS peaks" means. Are you saying you have no way to measure except by watching VU meter displays? If that is so I guess you just have to do the best you can. Do you have software to make any kind of frequency analysis or otherwise determine what may be responsible for observed differences?
[a href="index.php?act=findpost&pid=330456"][{POST_SNAPBACK}][/a]

Right. Unless there's an RMS meter already in Audacity (Nyquist?) then I'll need to roll my own.

Quote
To my ears, this is the only defect in your recording.
It can come from the ground wire of the turntable not being attached to the ground pin on the phono input (but usually, it sounds quite different), or from the turntable conception.
I had a Luxman direct drive turntable which made exactly the same noise as yours when I moved the cartridge above the engine, without playing any record. Diferent cartridge may pick more or less noise, but the problem is with the turntable.

Near as I can tell, the grounding wire on the turntable is plugged in. There's a very small chance it doesn't work and there's an open circuit somewhere. I did try a tweak suggested for reducing static pops, which was to ground the plinth bearing assembly, but that didn't help anything. There's also a very small chance I just have crappy power noise rejection; I'm plugging the turntable right into the wall outlet. I may be able to test this by plugging it into my UPS, knocking the UPS power offline and figuring out what the PSRR really is. Would that be worth pursuing?

As far as cleaning goes.. I'm pretty much resigning myself to the fact that I need to get a vacuum cleaner. I have too many vintage LPs (200+) to ever seriously clean all of them. I suspect the KAB EV-1 ($150 ish) will definitely suit me the best, plus a moderately decent cleaner like LAST.

As far as removing the deposits goes: Vinegar is commonly recommended to clear out deposits in coffee pots, etc. Has that ever been known to work? Would it be useful to heat up/boil the vinegar before using it, or would that just leach the stabilizers out faster?

Vinyl silence

Reply #14 –
Another set of samples. These ones attempt to show the differences that accumulated between the 1st and 3rd needle drops, between which occured the aforementioned wet cleaning, several carbon brush cleanings, and IIRC a small tracking force increase (perhaps from 1.8 to 2.0g). Note that I had already normalized these recordings, so to equalize the volumes, I normalized the silent tracks against the next 60 seconds of music (no crackling occured in that interval). Assuming that no gross changes in response occured, these track peaks should be consistent through needle drops.

Download cleaning-comparison.zip from http://briefcase.yahoo.com/bc/richard.toll...case.yahoo.com/

autechre-take1-silence.wav: Same part of silence as before
autechre-take1-music.wav: Should be roughly the same section of music as before
autechre-take3-silence.wav
autechre-take3-music.wav

Vinyl silence

Reply #15 –
I can't download it. The URL seems to lead to nothing.

Vinyl silence

Reply #16 –
Alas, I have 750 megs of space on Yahoo! Briefcase and it's next to impossible to get downloads out of it without releasing a personal email address. Screw it, I don't even use that address anyway. URLs updated.