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? LP to PC noise artifacts problem

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January 4, 2005 8:14:28 AM

Archived from groups: rec.audio.tech (More info?)

This isn't normal hiss and pop (I'm using a KLH TNE for that).

My current gear is an old Technics SK-1300 direct drive with a new Audio
Technca AT440ML/OCC cartridge.

My problem is that when I transfer to my computer, there's a pulse added
once every revolution of the turntable. It's not noticeable in louder
passages, but is really annoying with quieter material.

I don't hear this through my computer speakers, but when I play it back
on my CD player, it sounds a bit like a typewriter.

I have a photo of the sound at http://dude.pawluk.com/

Can anyone determine the cause? Is it fixable, or do I simply need a
new turntable? The LPs aren't warped, so that's not it.

Or is it in the LP, and my gear somehow amplifies it? I ask because the
occasional track, or sometimes channel, comes through without this weird
noise.

Thanks.
Anonymous
January 4, 2005 8:44:28 AM

Archived from groups: rec.audio.tech (More info?)

>My problem is that when I transfer to my computer, there's a pulse added
>once every revolution of the turntable. It's not noticeable in louder
>passages, but is really annoying with quieter material.
>
>I don't hear this through my computer speakers, but when I play it back
>on my CD player, it sounds a bit like a typewriter.
>
>I have a photo of the sound at http://dude.pawluk.com/
>
>Can anyone determine the cause? Is it fixable, or do I simply need a
>new turntable? The LPs aren't warped, so that's not it.
>
>Or is it in the LP, and my gear somehow amplifies it? I ask because the
>occasional track, or sometimes channel, comes through without this weird
>noise.

If it occurs on multiple LPs, then it can't be in the LP.

The fact that it occurs once per revolution means that the turntable
itself is (99.9%-certainly) the culprit. My guess is that something
on the bottom side of the platter is rubbing against, or striking
something else, and that this is exciting vibrations in the platter
which are travelling through the LP and being picked up by the stylus.
It's also possible that the vibrations are being coupled from the
point of impact, back through the chassis, into the tonearm, and out
to the cartridge and stylus.

In either case, the important thing is to figure out what's causing
the rubbing or impact, and fix it. It might be something sticking
down from the platter - possibly a stick-on label which has come
loose? It might be that some obstruction has gotten into the
direct-drive motor assembly, or there might be some sort of damage to
the platter's spindle which is scraping inside the main bearing. It
might even be something as simple as a lack of proper lubrication in
the bearing, due to the age of the 'table.

The problem may be simple enough to be fixable easily and
inexpensively, or might be the result of damage to parts which are no
longer available. In the latter case, replacing the 'table may be
less expensive... a simple, quiet belt-drive model might be a good
choice for LP->CD transcription use.

--
Dave Platt <dplatt@radagast.org> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
Anonymous
January 4, 2005 8:44:29 AM

Archived from groups: rec.audio.tech (More info?)

"Dave Platt" <dplatt@radagast.org> wrote in message
news:10tkb9s50us9j09@corp.supernews.com...
> >My problem is that when I transfer to my computer, there's a pulse added
>>once every revolution of the turntable. It's not noticeable in louder
>>passages, but is really annoying with quieter material.
>>
>>I don't hear this through my computer speakers, but when I play it back
>>on my CD player, it sounds a bit like a typewriter.
>>
>>I have a photo of the sound at http://dude.pawluk.com/
>>
>>Can anyone determine the cause? Is it fixable, or do I simply need a
>>new turntable? The LPs aren't warped, so that's not it.
>>
>>Or is it in the LP, and my gear somehow amplifies it? I ask because the
>>occasional track, or sometimes channel, comes through without this weird
>>noise.
>
> If it occurs on multiple LPs, then it can't be in the LP.
>
> The fact that it occurs once per revolution means that the turntable
> itself is (99.9%-certainly) the culprit. My guess is that something
> on the bottom side of the platter is rubbing against, or striking
> something else, and that this is exciting vibrations in the platter
> which are travelling through the LP and being picked up by the stylus.
> It's also possible that the vibrations are being coupled from the
> point of impact, back through the chassis, into the tonearm, and out
> to the cartridge and stylus.
>
> In either case, the important thing is to figure out what's causing
> the rubbing or impact, and fix it. It might be something sticking
> down from the platter - possibly a stick-on label which has come
> loose? It might be that some obstruction has gotten into the
> direct-drive motor assembly, or there might be some sort of damage to
> the platter's spindle which is scraping inside the main bearing. It
> might even be something as simple as a lack of proper lubrication in
> the bearing, due to the age of the 'table.
>
> The problem may be simple enough to be fixable easily and
> inexpensively, or might be the result of damage to parts which are no
> longer available. In the latter case, replacing the 'table may be
> less expensive... a simple, quiet belt-drive model might be a good
> choice for LP->CD transcription use.
>
> --
> Dave Platt

I would add that if it is audible, one should probably see the artifact in
the strobe pattern once each revolution.

Mark Z.
Related resources
Anonymous
January 4, 2005 1:22:13 PM

Archived from groups: rec.audio.tech (More info?)

On Tue, 04 Jan 2005 05:44:28 -0000, dplatt@radagast.org (Dave Platt)
wrote:

>The fact that it occurs once per revolution means that the turntable
>itself is (99.9%-certainly) the culprit. My guess is that something
>on the bottom side of the platter is rubbing against, or striking
>something else, and that this is exciting vibrations in the platter
>which are travelling through the LP and being picked up by the stylus.

The waveform picture isn't typical of mechanical noise.
Anonymous
January 4, 2005 8:05:28 PM

Archived from groups: rec.audio.tech (More info?)

On Tue, 04 Jan 2005 10:22:13 +0000, Laurence Payne
<l@laurenceDELETEpayne.freeserve.co.uk> wrote:

>On Tue, 04 Jan 2005 05:44:28 -0000, dplatt@radagast.org (Dave Platt)
>wrote:
>
>>The fact that it occurs once per revolution means that the turntable
>>itself is (99.9%-certainly) the culprit. My guess is that something
>>on the bottom side of the platter is rubbing against, or striking
>>something else, and that this is exciting vibrations in the platter
>>which are travelling through the LP and being picked up by the stylus.
>
>The waveform picture isn't typical of mechanical noise.

Certainly not on a direct-drive table - it may be a problem with
'hunting' in the speed-control servo. On a belt-drive, you'd suspect a
cyclic friction problem causing a 'twang' in the belt.

--

Stewart Pinkerton | Music is Art - Audio is Engineering
Anonymous
January 4, 2005 10:26:37 PM

Archived from groups: rec.audio.tech (More info?)

Anti-spam wrote:

> Looking at the waveforms, what I seem to have is a 433 Hz carrier
> frequency that's amplitude-modulated at 33-1/3 rpm.

You seem to be confused between rpm and Hz.
That high frequency wave looks like 10Hz or so.

Try some more tests:

With the turntable stationary, lower the arm onto an old record.
Check the output while stomping about on the floor or tapping the
plinth to see what resonates at 10Hz or so.

Does the turntable play at 45rpm? Try that and see what happens.

--
Eiron.
Anonymous
January 4, 2005 10:26:38 PM

Archived from groups: rec.audio.tech (More info?)

04 Jan 2005 11:26 AM Eiron wrote:
> You seem to be confused between ...

Geez, where was my head - the high frequency in the envelope is around
7-1/2 Hz.

Stomping on the floor, tapping the platform the TT is on had no effect.
The computer is about 4 feet away from the TT.

At 45 RPM, the modulations are still there, but there are only about 10
of the high frequency waves inside each (instead of about 13). The
higher frequency is still about 7-1/2 Hz.

And I'm still totally mystified.
Anonymous
January 5, 2005 5:56:18 AM

Archived from groups: rec.audio.tech (More info?)

^ <surf@ctant.com> writes:
> [...]
> I have a photo of the sound at http://dude.pawluk.com/

Could you by any chance post the actual .wav file there as well?
Just a short clip (5 seconds?) would be great.
--
% Randy Yates % "Though you ride on the wheels of tomorrow,
%% Fuquay-Varina, NC % you still wander the fields of your
%%% 919-577-9882 % sorrow."
%%%% <yates@ieee.org> % '21st Century Man', *Time*, ELO
http://home.earthlink.net/~yatescr
Anonymous
January 5, 2005 7:32:58 AM

Archived from groups: rec.audio.tech (More info?)

^ <surf@ctant.com> writes:

> This isn't normal hiss and pop (I'm using a KLH TNE for that).
>
> My current gear is an old Technics SK-1300 direct drive with a new Audio
> Technca AT440ML/OCC cartridge.
>
> My problem is that when I transfer to my computer, there's a pulse added
> once every revolution of the turntable. It's not noticeable in louder
> passages, but is really annoying with quieter material.
>
> I don't hear this through my computer speakers, but when I play it back
> on my CD player, it sounds a bit like a typewriter.
>
> I have a photo of the sound at http://dude.pawluk.com/
>
> Can anyone determine the cause? Is it fixable, or do I simply need a
> new turntable? The LPs aren't warped, so that's not it.
>
> Or is it in the LP, and my gear somehow amplifies it? I ask because the
> occasional track, or sometimes channel, comes through without this weird
> noise.
>
> Thanks.

Here's an idea: You say the record isn't warped, but no record is
perfectly flat, and since the amplitude is low, what you're seeing
IS a warp. You don't hear it over your computer speakers because
they have no low-frequency response and most of this energy is
in the lower frequencies, and you hear it on the CD player since
you're (presumably) playing that on a bigger, better stereo
system.

If that doesn't sound like it, please put the wave file (or mp3
or whatever) up on your site.
--
% Randy Yates % "Midnight, on the water...
%% Fuquay-Varina, NC % I saw... the ocean's daughter."
%%% 919-577-9882 % 'Can't Get It Out Of My Head'
%%%% <yates@ieee.org> % *El Dorado*, Electric Light Orchestra
http://home.earthlink.net/~yatescr
Anonymous
January 5, 2005 9:39:39 AM

Archived from groups: rec.audio.tech (More info?)

On Tue, 04 Jan 2005 19:24:16 -0800, Anti-spam <nosp@m.com> wrote:

>04 Jan 2005 11:26 AM Eiron wrote:
> > You seem to be confused between ...
>
>Geez, where was my head - the high frequency in the envelope is around
>7-1/2 Hz.
>
>Stomping on the floor, tapping the platform the TT is on had no effect.
> The computer is about 4 feet away from the TT.
>
>At 45 RPM, the modulations are still there, but there are only about 10
>of the high frequency waves inside each (instead of about 13). The
>higher frequency is still about 7-1/2 Hz.
>
>And I'm still totally mystified.

That sounds awfully like the main arm/cartridge resonance, but
seriously underdamped in this case. With a heavy arm and a
high-compliance cartridge, you could certainly get a 7.5Hz resonance,
but it seems to be continuously excited, which is odd.

--

Stewart Pinkerton | Music is Art - Audio is Engineering
Anonymous
January 5, 2005 1:17:36 PM

Archived from groups: rec.audio.tech (More info?)

You're right about the speakers and hearing the artifact, but the same
waveform is inserted into other LPs indentically and I find it hard to
believe they're all warped precisely the same way :-)

I've uploaded a sample as WAV and AIFF files, clipped to 30 seconds/5
meg to make downloading easier (and you wouldn't want ot hear much of
Mayall's singing on this cut anyhow).

Teh link is http://dude.pawluk.com/

Thanks.



Randy Yates wrote:
> Here's an idea: You say the record isn't warped, but no record is
> perfectly flat, and since the amplitude is low, what you're seeing
> IS a warp. You don't hear it over your computer speakers because
> they have no low-frequency response and most of this energy is
> in the lower frequencies, and you hear it on the CD player since
> you're (presumably) playing that on a bigger, better stereo
> system.
Anonymous
January 5, 2005 1:18:59 PM

Archived from groups: rec.audio.tech (More info?)

Stewart Pinkerton wrote:
> but it seems to be continuously excited, which is odd.

Yes indeed.
Anonymous
January 5, 2005 10:09:37 PM

Archived from groups: rec.audio.tech (More info?)

> > You seem to be confused between ...
>
>Geez, where was my head - the high frequency in the envelope is around
>7-1/2 Hz.

Aha.

This suggests to me that the waves you are observing on the scope are
a secondary effect... they're the result of a low-frequency mechanical
resonance (perhaps the platter suspension, perhaps the tonearm /
cartridge compliance resonance). Such low-frequency signals are not
going to be audible by themselves.

My guess is that you do have some sort of mechanical obstruction which
is snagging the platter once per revolution. Each time this happens,
the platter is jolted... this causes the low-frequency wobbling you
observe on the scope, and the higher-frequency sound created by the
impact is being carried through the platter and picked up by the
stylus to create the "typewriter-like" sound that you hear.

If you run a spectrogram on the leading edge of each 7.5 Hz set, I
suspect that you'll see that there's a brief burst of higher-frequency
noise included.

>Stomping on the floor, tapping the platform the TT is on had no effect.
> The computer is about 4 feet away from the TT.
>
>At 45 RPM, the modulations are still there, but there are only about 10
>of the high frequency waves inside each (instead of about 13). The
>higher frequency is still about 7-1/2 Hz.

10 cycles at 7.5 Hz would be 1.3 seconds, which is the period of a 45
RPM rotation. Apparently the low-frequency oscillation isn't having
time to damp down all the way before the next impulse re-excites it.

--
Dave Platt <dplatt@radagast.org> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
Anonymous
January 5, 2005 10:09:38 PM

Archived from groups: rec.audio.tech (More info?)

Dave Platt wrote:
> Aha.
> My guess is that you do have some sort of mechanical obstruction which
> is snagging the platter once per revolution. Each time this happens,
> the platter is jolted... this causes the low-frequency wobbling you
> observe on the scope, and the higher-frequency sound created by the
> impact is being carried through the platter and picked up by the
> stylus to create the "typewriter-like" sound that you hear.

Thanks, this sounds reasonable so I guess it's time to take the TT apart
and see what's going on.

And thanks to all of you, I really appreciate the feedback.
Anonymous
January 6, 2005 4:05:25 AM

Archived from groups: rec.audio.tech (More info?)

dplatt@radagast.org (Dave Platt) writes:

>> > You seem to be confused between ...
>>
>>Geez, where was my head - the high frequency in the envelope is around
>>7-1/2 Hz.
>
> Aha.
>
> This suggests to me that the waves you are observing on the scope are
> a secondary effect... they're the result of a low-frequency mechanical
> resonance (perhaps the platter suspension, perhaps the tonearm /
> cartridge compliance resonance). Such low-frequency signals are not
> going to be audible by themselves.
>
> My guess is that you do have some sort of mechanical obstruction which
> is snagging the platter once per revolution. Each time this happens,
> the platter is jolted... this causes the low-frequency wobbling you
> observe on the scope, and the higher-frequency sound created by the
> impact is being carried through the platter and picked up by the
> stylus to create the "typewriter-like" sound that you hear.
>
> If you run a spectrogram on the leading edge of each 7.5 Hz set, I
> suspect that you'll see that there's a brief burst of higher-frequency
> noise included.
>
>>Stomping on the floor, tapping the platform the TT is on had no effect.
>> The computer is about 4 feet away from the TT.
>>
>>At 45 RPM, the modulations are still there, but there are only about 10
>>of the high frequency waves inside each (instead of about 13). The
>>higher frequency is still about 7-1/2 Hz.
>
> 10 cycles at 7.5 Hz would be 1.3 seconds, which is the period of a 45
> RPM rotation. Apparently the low-frequency oscillation isn't having
> time to damp down all the way before the next impulse re-excites it.

A respectable conjecture, but now that I've seen the waveform, I don't
think that's it.

This thing is huge, peaking at more than half-scale (i.e., less than
6 dB below full-scale). If it were mechanical, there'd be frequency
modulation of the audio (if the offsets were planar) or the needle
would jump around (if the offsets were axial).

My guess is that you've got some sort of low-frequency electronic
feedback loop, possibly independent of the PC. If your preamp/receiver
has a rumble filter in it, it's possible this has been present a long
time but masked.

Intriguing.
--
% Randy Yates % "With time with what you've learned,
%% Fuquay-Varina, NC % they'll kiss the ground you walk
%%% 919-577-9882 % upon."
%%%% <yates@ieee.org> % '21st Century Man', *Time*, ELO
http://home.earthlink.net/~yatescr
Anonymous
January 6, 2005 5:54:45 AM

Archived from groups: rec.audio.tech (More info?)

Ding! It's a hole-centering problem. The high-frequency oscillation is your
tonearm's natural radial resonant frequency.
--
% Randy Yates % "Maybe one day I'll feel her cold embrace,
%% Fuquay-Varina, NC % and kiss her interface,
%%% 919-577-9882 % til then, I'll leave her alone."
%%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO
http://home.earthlink.net/~yatescr
Anonymous
January 6, 2005 5:54:46 AM

Archived from groups: rec.audio.tech (More info?)

Randy Yates wrote:
> Ding! It's a hole-centering problem. The high-frequency oscillation is your
> tonearm's natural radial resonant frequency.

Is there any way for me to get rid of that with the equipment I have, an
adjustment I can make or some sort of
'tone-arm-natural-radial-frequency-damper'?

The SL-1300 arm doesn't look too replaceable, so my other option appears
to be a turntable with a
less-tone-arm-natural-radial-frequency-susceptible tone arm.

Any suggestions, remembering that all I want to do is digitize some LPs
then get outta here without spending a bundle :-)

Thanks.
Anonymous
January 6, 2005 7:58:15 AM

Archived from groups: rec.audio.tech (More info?)

"Anti-spam" <nosp@m.com> wrote in message news:N73Dd.99$fC1.25@fe04.lga...
> Randy Yates wrote:
>> Ding! It's a hole-centering problem. The high-frequency oscillation is
>> your
>> tonearm's natural radial resonant frequency.
>
> Is there any way for me to get rid of that with the equipment I have, an
> adjustment I can make or some sort of
> 'tone-arm-natural-radial-frequency-damper'?
>
> The SL-1300 arm doesn't look too replaceable, so my other option appears
> to be a turntable with a
> less-tone-arm-natural-radial-frequency-susceptible tone arm.
>
> Any suggestions, remembering that all I want to do is digitize some LPs
> then get outta here without spending a bundle :-)

I couldn't load the picture you posted, but it certainly seems like the
solution should be obvious without having to resort to a lot of esoteric
solutions. Tonearm/cartridge resonance is usually only a big problem when
there's a big warp in the record, or if the platter is wobbling, or the unit
is being struck or shaken. Or when playing the Telarc recording of
Tchaikovsky's 1812 Overture.

If the hole-centering problem, referred to above, is what I think it is, I
should think tonearm resonance would be the least of your worries. The "wow"
factor would be unbearable. Direct-drive turntables are pretty simple,
mechanically, and should not be making any noise as severe as you describe
if working properly, regardless of tonearm resonance. This sounds as though
it's much more severe than anything I've ever seen from a tonearm/pickup
compatibility problem.

Does the platter turn freely and quietly when the unit is turned off? Have
you lifted the platter off to see if any foreign object has gotten lodged
between the motor windings and the magnet assembly? Is the thrust bearing
still present? If not, the platter will sit too low, and probably scrape on
the deck. A drop of heavy machine oil on the spindle might be a good idea if
it hasn't had any for a decade or two.

You might have a cartridge alignment problem. When a record is playing, is
the stylus the only object touching the record (from the top)? Or does the
cartridge body occasionally scrape the record's surface? Is the tracking
force set correctly?

We used to have a bunch of these at a radio station I worked at, and they
were not at all temperamental. Just some thoughts...
Anonymous
January 6, 2005 9:08:34 AM

Archived from groups: rec.audio.tech (More info?)

>Ding!

If correct, I AM inpressed. I don't remember though if it only did it on
the one record. After reading your reply Randy, I was thinking about the
OP's jpg. Seems to me that anything which made more of a "tick" rather than
a "rub" against the platter might create artifact like that seen.

Mark Z.


"Randy Yates" <yates@ieee.org> wrote in message
news:3bxfqnbk.fsf@ieee.org...
> Ding! It's a hole-centering problem. The high-frequency oscillation is
> your
> tonearm's natural radial resonant frequency.
> --
> % Randy Yates % "Maybe one day I'll feel her cold
> embrace,
> %% Fuquay-Varina, NC % and kiss her
> interface,
> %%% 919-577-9882 % til then, I'll leave her
> alone."
> %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO
> http://home.earthlink.net/~yatescr
Anonymous
January 6, 2005 12:21:32 PM

Archived from groups: rec.audio.tech (More info?)

Karl Uppiano wrote:
> "Anti-spam" <nosp@m.com> wrote in message news:N73Dd.99$fC1.25@fe04.lga...
>
>>Randy Yates wrote:
>>
>>>Ding! It's a hole-centering problem. The high-frequency oscillation is
>>>your
>>>tonearm's natural radial resonant frequency.
>>
>>Is there any way for me to get rid of that with the equipment I have, an
>>adjustment I can make or some sort of
>>'tone-arm-natural-radial-frequency-damper'?
>>
>>The SL-1300 arm doesn't look too replaceable, so my other option appears
>>to be a turntable with a
>>less-tone-arm-natural-radial-frequency-susceptible tone arm.
>>
>>Any suggestions, remembering that all I want to do is digitize some LPs
>>then get outta here without spending a bundle :-)
>
>
> I couldn't load the picture you posted, but it certainly seems like the
> solution should be obvious without having to resort to a lot of esoteric
> solutions. Tonearm/cartridge resonance is usually only a big problem when
> there's a big warp in the record, or if the platter is wobbling, or the unit
> is being struck or shaken. Or when playing the Telarc recording of
> Tchaikovsky's 1812 Overture.
>
> If the hole-centering problem, referred to above, is what I think it is, I
> should think tonearm resonance would be the least of your worries. The "wow"
> factor would be unbearable. Direct-drive turntables are pretty simple,
> mechanically, and should not be making any noise as severe as you describe
> if working properly, regardless of tonearm resonance. This sounds as though
> Does the platter turn freely and quietly when the unit is turned off? Have
> you lifted the platter off to see if any foreign object has gotten lodged
> between the motor windings and the magnet assembly? Is the thrust bearing
> still present? If not, the platter will sit too low, and probably scrape on
> the deck. A drop of heavy machine oil on the spindle might be a good idea if
> it hasn't had any for a decade or two.

It's all fine. I took the platter off, too, and there are no signs of
rubbing, no objects.

I did put a drop of light machine oil on the bearing and there's no
difference.

> You might have a cartridge alignment problem. When a record is playing, is
> the stylus the only object touching the record (from the top)? Or does the
> cartridge body occasionally scrape the record's surface? Is the tracking
> force set correctly?

No, yes, not even close, absolutely and the cartridge rides like a dream.
Anonymous
January 6, 2005 12:22:20 PM

Archived from groups: rec.audio.tech (More info?)

> If correct, I AM inpressed. I don't remember though if it only did it on
> the one record.

Multiple records in varying degrees.
Anonymous
January 6, 2005 1:51:34 PM

Archived from groups: rec.audio.tech (More info?)

"Mark D. Zacharias" <mzacharias@yis.us> writes:

> >Ding!
>
> If correct,

Yeah, well that's TBD!

> I AM inpressed.

Don't be until it's proven, because I could (again) be WRONG.

> I don't remember though if it only did it on the one record. After
> reading your reply Randy, I was thinking about the OP's jpg. Seems
> to me that anything which made more of a "tick" rather than a "rub"
> against the platter might create artifact like that seen.

Yes, I take your point. I too realized after posting that a spindle
offset would not have so much of an impulsive shape. So again I'm
baffled.

Note that in my bafflement I'm assuming the OP was intelligent enough
and observant enough to see if there were obvious physical defects on
the vinyl such as a warped groove and thus am assuming there are no
such defects.

--RY



>
> Mark Z.
>
>
> "Randy Yates" <yates@ieee.org> wrote in message
> news:3bxfqnbk.fsf@ieee.org...
> > Ding! It's a hole-centering problem. The high-frequency oscillation is
> > your
> > tonearm's natural radial resonant frequency.
> > --
> > % Randy Yates % "Maybe one day I'll feel her cold
> > embrace,
> > %% Fuquay-Varina, NC % and kiss her
> > interface,
> > %%% 919-577-9882 % til then, I'll leave her
> > alone."
> > %%%% <yates@ieee.org> % 'Yours Truly, 2095', *Time*, ELO
> > http://home.earthlink.net/~yatescr
>
>

--
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
randy.yates@sonyericsson.com, 919-472-1124
Anonymous
January 6, 2005 1:53:42 PM

Archived from groups: rec.audio.tech (More info?)

Karl, I'm with you - after posting I again realized the hole-centering
theory is probably wrong.

--RY

"Karl Uppiano" <karl.uppiano@verizon.net> writes:

> "Anti-spam" <nosp@m.com> wrote in message news:N73Dd.99$fC1.25@fe04.lga...
> > Randy Yates wrote:
> >> Ding! It's a hole-centering problem. The high-frequency oscillation is
> >> your
> >> tonearm's natural radial resonant frequency.
> >
> > Is there any way for me to get rid of that with the equipment I have, an
> > adjustment I can make or some sort of
> > 'tone-arm-natural-radial-frequency-damper'?
> >
> > The SL-1300 arm doesn't look too replaceable, so my other option appears
> > to be a turntable with a
> > less-tone-arm-natural-radial-frequency-susceptible tone arm.
> >
> > Any suggestions, remembering that all I want to do is digitize some LPs
> > then get outta here without spending a bundle :-)
>
> I couldn't load the picture you posted, but it certainly seems like the
> solution should be obvious without having to resort to a lot of esoteric
> solutions. Tonearm/cartridge resonance is usually only a big problem when
> there's a big warp in the record, or if the platter is wobbling, or the unit
> is being struck or shaken. Or when playing the Telarc recording of
> Tchaikovsky's 1812 Overture.
>
> If the hole-centering problem, referred to above, is what I think it is, I
> should think tonearm resonance would be the least of your worries. The "wow"
> factor would be unbearable. Direct-drive turntables are pretty simple,
> mechanically, and should not be making any noise as severe as you describe
> if working properly, regardless of tonearm resonance. This sounds as though
> it's much more severe than anything I've ever seen from a tonearm/pickup
> compatibility problem.
>
> Does the platter turn freely and quietly when the unit is turned off? Have
> you lifted the platter off to see if any foreign object has gotten lodged
> between the motor windings and the magnet assembly? Is the thrust bearing
> still present? If not, the platter will sit too low, and probably scrape on
> the deck. A drop of heavy machine oil on the spindle might be a good idea if
> it hasn't had any for a decade or two.
>
> You might have a cartridge alignment problem. When a record is playing, is
> the stylus the only object touching the record (from the top)? Or does the
> cartridge body occasionally scrape the record's surface? Is the tracking
> force set correctly?
>
> We used to have a bunch of these at a radio station I worked at, and they
> were not at all temperamental. Just some thoughts...
>
>

--
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
randy.yates@sonyericsson.com, 919-472-1124
Anonymous
January 6, 2005 1:56:34 PM

Archived from groups: rec.audio.tech (More info?)

Do you have an email address I can use to communicate with you directly?

--RY


Anti-spam <nosp@m.com> writes:

> Randy Yates wrote:
> > Ding! It's a hole-centering problem. The high-frequency oscillation is your
> > tonearm's natural radial resonant frequency.
>
>
> Is there any way for me to get rid of that with the equipment I have,
> an adjustment I can make or some sort of
> 'tone-arm-natural-radial-frequency-damper'?
>
>
> The SL-1300 arm doesn't look too replaceable, so my other option
> appears to be a turntable with a
> less-tone-arm-natural-radial-frequency-susceptible tone arm.
>
>
> Any suggestions, remembering that all I want to do is digitize some
> LPs then get outta here without spending a bundle :-)
>
>
> Thanks.

--
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
randy.yates@sonyericsson.com, 919-472-1124
Anonymous
January 6, 2005 1:56:35 PM

Archived from groups: rec.audio.tech (More info?)

Randy Yates wrote:
> Do you have an email address I can use to communicate with you directly?

"dude" and that's at "tude.com" (hate spam).

However, your eccentric hole theory may be right.

I just tried a quieter LP (Julian Bream plays Bach). The artifact is
still there at the beginning, although not quite as strong. It's also
worse in the left channel than in the right, unlike with the Mayall
record. The artifact essentially disappears by 6 minutes into the
record. I can see it since I know what I'm looking for, but can't hear
it on the better playback system. 12 minutes into the LP it's almost
invisible in the waveform, too. Side thrust from an off-center hole
would do that, wouldn't it - more force at the larger distance from the
center?

I also tried changing the tracking force, doubling it from the
recommended "optimal" 1.25 g, but this had no effect.

And the funny thing is that I never heard this when I played the LPs
directly 15 years ago so maybe there is something else ...
Anonymous
January 6, 2005 3:32:01 PM

Archived from groups: rec.audio.tech (More info?)

Anti-spam <nosp@m.com> writes:

> > If correct, I AM inpressed. I don't remember though if it only did
> > it on the one record.
>
>
> Multiple records in varying degrees.

Exactly how are you interfacing the TT's L/R outputs to your
soundcard?
--
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
randy.yates@sonyericsson.com, 919-472-1124
Anonymous
January 6, 2005 3:32:02 PM

Archived from groups: rec.audio.tech (More info?)

Randy Yates wrote:
> Exactly how are you interfacing the TT's L/R outputs to your
> soundcard?

I run through a Radio Shack preamp, and have tried two ways from there.

My normal setup is through a KLH Transient Noise Eliminator, then a
Vidicraft switcher then on to the sound input on my Macintosh.

Being a suspicious soul, I tried going directly to the computer from the
preamp but this made no difference whatsoever.

The turntable also gets it's power from computer back-up power supply
that eliminates noise, but bypassing this also had no effect.

Surely it couldn't be that cheap Radio Shack box, could it?
Anonymous
January 6, 2005 10:28:15 PM

Archived from groups: rec.audio.tech (More info?)

> No, yes, not even close, absolutely and the cartridge rides like a dream.

Hmmm... If tonearm resonance is the issue, you should clearly see
"gyrations" of the cartridge with respect to the stylus as it tracks the
record.
Anonymous
January 7, 2005 12:54:41 AM

Archived from groups: rec.audio.tech (More info?)

Karl Uppiano wrote:

>>No, yes, not even close, absolutely and the cartridge rides like a dream.
>
>
> Hmmm... If tonearm resonance is the issue, you should clearly see
> "gyrations" of the cartridge with respect to the stylus as it tracks the
> record.

How about making a fluid damper from blu-tak, paperclips and honey?

Why does the problem disappear after 6 minutes?
Is the arm or its wires catching on something at certain positions?

--
Eiron.
Anonymous
January 7, 2005 12:54:42 AM

Archived from groups: rec.audio.tech (More info?)

Eiron wrote:
> Why does the problem disappear after 6 minutes?
> Is the arm or its wires catching on something at certain positions?

The amplitude of the pulse just gets lower and lower as the arm moves
toward the center, which seems reasonable if it is being caused by an
off-center hole. The "throwing arm" is longer at the edge of the
platter, gets shorter as you move in.

Nothing is catching on anything.
Anonymous
January 7, 2005 1:50:48 AM

Archived from groups: rec.audio.tech (More info?)

"Anti-spam" <nosp@m.com> wrote in message news:fCiDd.281$cj5.135@fe04.lga...
> Eiron wrote:
>> Why does the problem disappear after 6 minutes?
>> Is the arm or its wires catching on something at certain positions?
>
> The amplitude of the pulse just gets lower and lower as the arm moves
> toward the center, which seems reasonable if it is being caused by an
> off-center hole. The "throwing arm" is longer at the edge of the platter,
> gets shorter as you move in.
>
> Nothing is catching on anything.

What off-center hole are we talking about? Because I can practically
guarantee a record with an off-center hole will produce unbearable wow long
before it begins to excite enough cartridge/tonearm resonance to be a
problem. Not every record would exhibit this defect, either. Furthermore,
this type of defect would not change with radius.

If we're talking about a loose, worn platter spindle (motor shaft), the
platter might wobble, causing a periodic "clunk-clunk-clunk". The motion
would be mostly vertical, producing out-of-phase noise between the two
channels. The "throwing arm" would get shorter with radius in this case. It
wouldn't be exactly at the rotational frequency, though. Heavy oil or grease
might help a bit, as I suggested earlier.

I'm wondering if the noise is being caused by an impending failure in the
motor drive electronics. At this age, the motor drive electronics could be
failing. If power supply bypass capacitors were starting to go, you might
end up with a once-per-revolution pop or click induced into the phono pickup
wiring, or even through the power or ground cable (the green or black
tonearm ground wire *is* attached to the preamp, right?). Is the noise
present when the platter is rotating, but with the tonearm in "cue"?
Anonymous
January 7, 2005 1:52:08 AM

Archived from groups: rec.audio.tech (More info?)

>> Why does the problem disappear after 6 minutes?
>> Is the arm or its wires catching on something at certain positions?
>
>The amplitude of the pulse just gets lower and lower as the arm moves
>toward the center, which seems reasonable if it is being caused by an
>off-center hole. The "throwing arm" is longer at the edge of the
>platter, gets shorter as you move in.
>
>Nothing is catching on anything.

Another possibility... perhaps the 'table has a loose spindle bearing,
and the platter is able to rock or wobble as it turns? That might
produce results similar to an off-center hole in the LP, but would
affect multiple LPs.

An off-center hole could cause (or excite) the low-frequency
oscillations in the suspension or arm/stylus system, but I have
difficulty seeing how an off-center hole could cause an audible
typerwriter-like "tick" sound in the audio.

A loose bearing, with a platter that wobbles with its rotation and
then actually rocks from side to side, might do both?

Another possibility to consider is that there might be some defect in
the direct-drive servo speed-tracking system. Servo-drive 'tables
sometimes have a speed sensor, which tracks the rotation rate of the
platter by optical or magnetic means. If there were damage to
whatever optical or magnetic marking is being sensed, the servo
controller might try to make a sudden change in the platter's rotation
speed once per revolution.

--
Dave Platt <dplatt@radagast.org> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
Anonymous
January 7, 2005 1:42:20 PM

Archived from groups: rec.audio.tech (More info?)

Thanks to you all for trying to help solve my problem.

I finally gave up and am simply processing the weird signal with software.

I'm running a piece of Mac software called the Hyper Engine with a
module called Ray Gun Pro. This has what seems to be a pretty good
"rumble" filter, a low cut filter. I set the cut frequency to 20 Hz and
ran my tracks through it with pretty good results.

A further benefit is that it also has a noise/click/pop/hiss filter that
I set at a mild setting to remove the last of the hiss and pops that
my KLH TNE hardware didn't get during the transfer.

More than acceptable to me (although my ears aren't what they used to be
:-).

I'd still, some day, like to find out what is causing the problem, though.

Thanks again,all.
!