IPB

Welcome Guest ( Log In | Register )

Vinyl Ripping Problem: What Are These Lines in My Spectral?
greinedo
post Jan 28 2009, 16:49
Post #1





Group: Members
Posts: 6
Joined: 28-January 09
Member No.: 66341



Hi folks,

I recently purchased a new Pro-Ject Debut III turntable along with a Pro-Ject PhonoBox II for the purposes of vinyl ripping. Overall I am in love with the setup. Everything sounds great!

I am having a problem with ripping though. In all my recording I have done, I have visible lines at 19k and 38k.



I initially thought the lines I am seeing were a slight hum I could hear while listening in headphones. I brought the table back to Needle Doctor where they checked it out and asured me the slight hum was normal. (It goes away when music plays).

My question is this: What exactly could these lines be? It shows up in any recording I make, even if a record is not spinning on the table. Dead silence even has the lines:



The card I was using was a very poor Soundblaster X-Fi Xtreme (lol) Gamer. I figured this was the weak link in my system so I upgraded to a E-Mu 0202.

Is there a chance that these lines are created by my soundcard?

What else could this be?

Go to the top of the page
+Quote Post
 
Start new topic
Replies (1 - 24)
pdq
post Jan 28 2009, 17:09
Post #2





Group: Members
Posts: 3442
Joined: 1-September 05
From: SE Pennsylvania
Member No.: 24233



19 kHz and 38 kHz are frequencies that you find in FM radio broadcasts.
Go to the top of the page
+Quote Post
greinedo
post Jan 28 2009, 17:14
Post #3





Group: Members
Posts: 6
Joined: 28-January 09
Member No.: 66341



QUOTE (pdq @ Jan 28 2009, 10:09) *
19 kHz and 38 kHz are frequencies that you find in FM radio broadcasts.


I have heard that before as well....

but why do I have FM Radio Broadcast frequencies in my spectral? I don't have an FM transmitter sitting around nearby and these vinyl I am ripping were not FM radio sourced.
Go to the top of the page
+Quote Post
Canar
post Jan 28 2009, 18:02
Post #4





Group: Super Moderator
Posts: 3372
Joined: 26-July 02
From: To:
Member No.: 2796



The lines are there to convince you to brickwall the recording at 18kHz. tongue.gif Have you tried using shielded cables to connect your equipment? Something's picking up that pilot tone from the radio... You don't need much.

This post has been edited by Canar: Jan 28 2009, 18:04


--------------------
You cannot ABX the rustling of jimmies.
No mouse? No problem.
Go to the top of the page
+Quote Post
Soap
post Jan 28 2009, 18:41
Post #5





Group: Members
Posts: 1016
Joined: 19-November 06
Member No.: 37767



Canar,
Your sig appears to need updating. These appear to be 32 bit rips.

This post has been edited by Soap: Jan 28 2009, 18:42


--------------------
Creature of habit.
Go to the top of the page
+Quote Post
greinedo
post Jan 28 2009, 18:54
Post #6





Group: Members
Posts: 6
Joined: 28-January 09
Member No.: 66341



QUOTE (Soap @ Jan 28 2009, 11:41) *
Canar,
Your sig appears to need updating. These appear to be 32 bit rips.


Trying to rip 24/96 smile.gif

I'll have to possible try shielded cables.

Are these AudioQuest GSnake cabled shielded? This is what I am using right now

http://www.needledoctor.com/Audioquest-G-S...amp;category=92

I don't know why vinyl rippers in large cities aren't ALL getting these FM signals (if thats what it is). To my knowledge i'm not near any radio towers...Strange
Go to the top of the page
+Quote Post
pawelq
post Jan 28 2009, 19:14
Post #7





Group: Members
Posts: 541
Joined: 20-December 05
From: Springfield, VA
Member No.: 26522



I doubt you can get 19 kHz directly from FM signal.

Which of the soundcards did you use when you got the lines? This is not clear to me.

Do lines show up on every LP?

Can you try a different turntable and preamp?


--------------------
Ceterum censeo, there should be an "%is_stop_after_current%".
Go to the top of the page
+Quote Post
greinedo
post Jan 28 2009, 19:22
Post #8





Group: Members
Posts: 6
Joined: 28-January 09
Member No.: 66341



QUOTE (pawelq @ Jan 28 2009, 12:14) *
I doubt you can get 19 kHz directly from FM signal.

Which of the soundcards did you use when you got the lines? This is not clear to me.

Do lines show up on every LP?

Can you try a different turntable and preamp?


The spectrals are from the P.O.S Soundblaster internal card. I have a E-Mu 0202 on the way in the mail.

I'm worred that the E-Mu 0202 will arrive and I will STILL have the 19khz signal when I record with it, even though I was assured by Needle Doctor that it wasn't my TT OR Preamp. I guess this is a way to find out for sure!

When I get home from work I will try the PC in the basement to see if I can reproduce the issue. If it is there, then I know for certain it is TT/PreAmp/
Go to the top of the page
+Quote Post
pdq
post Jan 28 2009, 20:05
Post #9





Group: Members
Posts: 3442
Joined: 1-September 05
From: SE Pennsylvania
Member No.: 24233



If you unplug the cable, or plug in a cable with nothing on the other end, do you still see these frequencies?
Go to the top of the page
+Quote Post
Axon
post Jan 28 2009, 20:16
Post #10





Group: Members (Donating)
Posts: 1985
Joined: 4-January 04
From: Austin, TX
Member No.: 10933



It might also be from a power supply near the phono cables (or in the worst case, in the phono power supply). It's not unheard of for the switch frequency to be in the 20khz range, although in my experience with Dell laptop power supplies, they will also throw all kinds of other harmonics out in the 1-20k range.
Go to the top of the page
+Quote Post
Juha
post Jan 28 2009, 22:26
Post #11





Group: Members
Posts: 478
Joined: 14-February 07
From: EU-FIN
Member No.: 40610



QUOTE (greinedo @ Jan 28 2009, 22:22) *
...

The spectrals are from the P.O.S Soundblaster internal card. I have a E-Mu 0202 on the way in the mail.

I'm worred that the E-Mu 0202 will arrive and I will STILL have the 19khz signal when I record with it, even though I was assured by Needle Doctor that it wasn't my TT OR Preamp. I guess this is a way to find out for sure!

When I get home from work I will try the PC in the basement to see if I can reproduce the issue. If it is there, then I know for certain it is TT/PreAmp/


I think it's there w/ 0202 as well.

I had this issue w/ E-MU 0404 USB ... @ ~33.578kHz (actually it didn't showed up with Audigy2 PCI card) ... IIRC, it was Cable Modem connection (someone suggested horizontal refresh rate for a HDTV signal ... yes, I had my TV set near the PC at that moment). After moving the PC/E-MU package few meters from these possible culprits it isn't disturbing anymore.

19kHz is a pilot signal for FM radio broadcast as mentioned already so this could be the culprit in your case ... 38 kHz looks like just an octave (sub signal) for that. 38kHz is used w/ IR devices as well (maybe TV remote control, etc.) but, as the "main" frequency is 19kHz in your case ...


Juha

This post has been edited by Juha: Jan 28 2009, 22:31
Go to the top of the page
+Quote Post
pdq
post Jan 28 2009, 22:47
Post #12





Group: Members
Posts: 3442
Joined: 1-September 05
From: SE Pennsylvania
Member No.: 24233



An FM receiver takes the 19 kHz pilot signal and doubles it to generate the missing 38 kHz part of the L-R signal, so unless you are picking up interference from an FM receiver, the FM station itself doesn't broadcast a 38 kHz signel.

Or it could be completely coincidental and have nothing at all to do with FM
Go to the top of the page
+Quote Post
Rotareneg
post Jan 29 2009, 02:46
Post #13





Group: Members
Posts: 194
Joined: 18-March 05
From: Non-Euclidean
Member No.: 20701



Many things in and around a computer can generate RF in that range. CRT horizontal scanning and LCD backlight inverters are two obvious examples that are outside the computer itself. You might try turning off all unessential electronics (including the monitor and any TVs) while making the recording.
Go to the top of the page
+Quote Post
greinedo
post Jan 29 2009, 03:28
Post #14





Group: Members
Posts: 6
Joined: 28-January 09
Member No.: 66341



I have completed some additional testing and troubleshooting and have some interesting results that have kind of boggled my mind. I can't really make sense of what these spectrals are telling me...

Here is the spectral of just silence with only a cable plugged into the line in of the soundcard. The lines are faint, but I def. see the signal at 19 khz and the harmonic at 38 khz.



What confuses me is this bit. Here is what the spectral looks like with ONLY the preamp hooked up (also recording silence). Preamp is on with the OUT running to the soundcard. Nothing is plugged into the IN of the *PREAMP* (EDIT). Notice the complete lack of the 19 khz/38 khz singal.



Finally, I connect the tonearm leads from the turntable into the IN of the preamp. The signal has returned, this time much louder...And to further complicate things: THE TURNTABLE IS UNPLUGGED FROM A POWER SOURCE (the spectral when it is plugged in is the same)



What the hell does this tell me exactly?? I think the soundcard (weakest part of the system) may be to blame for this as is evident from the spectral with just a cord connected to the line in. I would believe that if I would've seen the 19khz signal on the spectral of the cord plugged into the preamp (without anything in the IN of the preamp). Is that even a correct assumption?

What would the much more well defined lines with the turntable plugged into the IN of the preamp indicate? The turntable spectrals look the same regardless of whether it is plugged in or not plugged in when I record 'silence'

Hope my confused ramblings make sense to someone!
Go to the top of the page
+Quote Post
Axon
post Jan 29 2009, 03:36
Post #15





Group: Members (Donating)
Posts: 1985
Joined: 4-January 04
From: Austin, TX
Member No.: 10933



Seems pretty easy to interpret to me. It means the turntable circuit is picking up the noise, not the sound card or the preamp (or anything in between).
Go to the top of the page
+Quote Post
greinedo
post Jan 29 2009, 03:41
Post #16





Group: Members
Posts: 6
Joined: 28-January 09
Member No.: 66341



QUOTE (Axon @ Jan 28 2009, 20:36) *
Seems pretty easy to interpret to me. It means the turntable circuit is picking up the noise, not the sound card or the preamp (or anything in between).


Axon,

Do you believe that there is something inherently wrong with the turntable ) or is it merely picking up the noise from something external from the system (like a power supply on the PC, flourescent lights, etc)? Is the turntable at fault here?
Go to the top of the page
+Quote Post
Axon
post Jan 29 2009, 03:51
Post #17





Group: Members (Donating)
Posts: 1985
Joined: 4-January 04
From: Austin, TX
Member No.: 10933



I wouldn't say there's anything "faulty" with it. Cartridges pick up electromagnetic signals. It's what they do. Turntable cables are unbalanced poorly-driven things that are extremely susceptible to interference. That said, there are some clearly superior designs for each with better noise rejection than others, and some designs are really just bad, but you can't draw any conclusions without additional info.

I'd first try shorting out the cartridge leads and check the noise levels, to see if the cart is picking it up. If that doesn't work, try plugging in some really small length of RCA cable into both inputs of the preamp. Whichever change causes a significant difference will identify the likely source of the noise.

From there, go back to your original setup and physically unplug nearby electronics until you've turned something off that makes the problem go away. From there, your options are either to separate the table from that device by a longer distance, or to try a different component that has improved noise rejection.
Go to the top of the page
+Quote Post
Axon
post Jan 29 2009, 03:52
Post #18





Group: Members (Donating)
Posts: 1985
Joined: 4-January 04
From: Austin, TX
Member No.: 10933



Also, check the noise levels with the turntable both turned off and turned on.
Go to the top of the page
+Quote Post
Axon
post Jan 29 2009, 03:53
Post #19





Group: Members (Donating)
Posts: 1985
Joined: 4-January 04
From: Austin, TX
Member No.: 10933



Also, it really helps if you have a real spectrum-style plot, instead of a spectrogram to look at these things. If your software doesn't have it, use Audacity.
Go to the top of the page
+Quote Post
Glenn Gundlach
post Jan 29 2009, 03:57
Post #20





Group: Members
Posts: 372
Joined: 19-April 08
From: LA
Member No.: 52914



QUOTE (greinedo @ Jan 28 2009, 18:28) *
I have completed some additional testing and troubleshooting and have some interesting results that have kind of boggled my mind. I can't really make sense of what these spectrals are telling me...

Here is the spectral of just silence with only a cable plugged into the line in of the soundcard. The lines are faint, but I def. see the signal at 19 khz and the harmonic at 38 khz.



What confuses me is this bit. Here is what the spectral looks like with ONLY the preamp hooked up (also recording silence). Preamp is on with the OUT running to the soundcard. Nothing is plugged into the IN of the *PREAMP* (EDIT). Notice the complete lack of the 19 khz/38 khz singal.



Finally, I connect the tonearm leads from the turntable into the IN of the preamp. The signal has returned, this time much louder...And to further complicate things: THE TURNTABLE IS UNPLUGGED FROM A POWER SOURCE (the spectral when it is plugged in is the same)



What the hell does this tell me exactly?? I think the soundcard (weakest part of the system) may be to blame for this as is evident from the spectral with just a cord connected to the line in. I would believe that if I would've seen the 19khz signal on the spectral of the cord plugged into the preamp (without anything in the IN of the preamp). Is that even a correct assumption?

What would the much more well defined lines with the turntable plugged into the IN of the preamp indicate? The turntable spectrals look the same regardless of whether it is plugged in or not plugged in when I record 'silence'

Hope my confused ramblings make sense to someone!


With no power on the turntable, does the 'noise' change character as you move the stylus toward the inside (end) of the disc ? If it's magneticly induced it will change vs the position of the cartridge. There is also the possibility that the inductance / capacitance of the system is interacting with the preamp which shouldn't but could be oscillating. A strategically place ferrite bead on the input lead where the wires connect to the preamp PCB can reduce external interference pick up with no adverse effects.

The ferrite fix is for folks in high RF fields like near broadcast transmitters. Keep in mind that for FM or TV, the field strength is often lower very near the tower due to the 'focus' of the multi-element antennas providing the Effective Radiated Power (ERP) gain. The maximum field intensity for those is a mile or 2 distant from the tower and then reduces following the inverse square law. AM field strength is maximum near the tower(s) and follows the inverse square law as you move away.

G
Go to the top of the page
+Quote Post
pdq
post Jan 29 2009, 14:03
Post #21





Group: Members
Posts: 3442
Joined: 1-September 05
From: SE Pennsylvania
Member No.: 24233



The difference between just the cable vs. cable plugged into the preamp is easy to explain. With the preamp disconnected you have only the high input impedance of the sound card, so you are more sensitive to noise pickup. The preamp has a low impedance so it attenuates any noise pickup and the noise becomes much smaller. So far there is nothing to say whether the noise is coming from inside or outside of the computer.

The increase in noise when you plug the turntable into the preamp says that the noise is definitely being picked up outside of the computer, but doesn't prove that the computer, or the monitor, or some other device associated with the computer isn't the source, but since the turntable was unplugged you have ruled out any circuitry inside of it.

I would set up to display a live spectrum of the signal from the sound card, then start moving things around to see if anything affects the strength of the signal you are seeing.
Go to the top of the page
+Quote Post
Arnold B. Kruege...
post Jan 30 2009, 03:12
Post #22





Group: Members
Posts: 4247
Joined: 29-October 08
From: USA, 48236
Member No.: 61311



QUOTE (greinedo @ Jan 28 2009, 10:49) *
Hi folks,

I recently purchased a new Pro-Ject Debut III turntable along with a Pro-Ject PhonoBox II for the purposes of vinyl ripping. Overall I am in love with the setup. Everything sounds great!

I am having a problem with ripping though. In all my recording I have done, I have visible lines at 19k and 38k.


Probable cause is pickup of EMI by the phono cartrdige from either a nearby FM stereo receiver or radio station, or a switchmode power supply for a PC or display (CRT or LCD).

QUOTE
The card I was using was a very poor Soundblaster X-Fi Xtreme (lol) Gamer. I figured this was the weak link in my system so I upgraded to a E-Mu 0202.


Sorry man, but the SB X-fi is not all that bad. The EMu is a better audio interface, but like I said, neither audio interface is the problem.


QUOTE
Is there a chance that these lines are created by my soundcard?


Slim and none.

QUOTE
What else could this be?


Probable cause is pickup of EMI by the phono cartrdige from either a nearby FM stereo receiver or radio station, or a switchmode power supply for a PC or display (CRT or LCD).

BTW, the spectral view is OK, but a standard dB amplitude versus log frequency display can be easier to interpret
Go to the top of the page
+Quote Post
charliemcdo
post Jan 30 2009, 04:41
Post #23





Group: Members
Posts: 19
Joined: 30-September 06
From: Torrance, CA
Member No.: 35774



I may have missed reading it in this thread, but does your Pro-Ject turntable have a ground wire, and is it connected to a ground terminal on the preamp?
Go to the top of the page
+Quote Post
Redoubts
post Jan 30 2009, 05:15
Post #24





Group: Members
Posts: 11
Joined: 7-August 07
From: Cambridge, MA
Member No.: 45983



If you want to try some ad hoc shielding, you can build a Faraday's Cage out of some mesh, and wrap your recording device with it.


--------------------
<null>
Go to the top of the page
+Quote Post
2Bdecided
post Jan 30 2009, 11:55
Post #25


ReplayGain developer


Group: Developer
Posts: 5259
Joined: 5-November 01
From: Yorkshire, UK
Member No.: 409



Start moving things around. Get the turntable as far from the PC as possible. Turn it through 90 degrees. etc etc. You're just checking for the interference - it doesn't have to be properly supported to play a record, so this testing should be fairly quick and easy.

Measurements / recordings with things disconnected can be misleading - e.g. the "faulty" part can appear different with no input impedance, and hence not show the fault.

Check grounding / earthing of everything.

Cheers,
David.
Go to the top of the page
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 23rd November 2014 - 05:59