Problem while Recording a Vinyl Record [SOLVED]

[JLeite]

Hello.
I'm using Ubuntu 16.04 and I'm new to Audacity.
While making my first recording of a vinyl record I noticed that some part of the sound was, I suppose, subtracted.
Please see attachment/picture.

Screenshot from 2016-08-30 00-19-50.png (171.58 KiB) Viewed 1080 times

What am I doing wrong?
Thank you.

[Gale Andrews]

How exactly are you connecting the turntable to the M-Audio? Is there a phono amplifier between the turntable and the M-Audio?

Is this the card you have http://www.m-audio.com/products/view/audiophile-2496?


Gale

[JLeite]

Thank you for your reply.
My turntable is connected to a Pro-Ject Phono Box MKII, which is connected to a Pro-Ject Pre Box, which is connected to my M-Audio Delta Audiophile 2496 sound card.
Yes, that sound card is the one I'm using.

[Gale Andrews]

Some waveforms are naturallly asymmetrical - horn solos are an example. What is the music and what does it sound like? Try recording another piece.

The peak levels are good - not too loud, not too quiet. You can use Effect > Amplify to make the recording louder.

The recording looks like dual mono (both channels the same). Is it supposed to be mono? Are you using a stereo cable to connect the equipment?

It possible the recording has DC offset but it does not look like it. You can upload a sample of audio for us to inspect if you are still concerned. See how to post an audio sample.


Gale

[JLeite]

The piece was from a not so official Jimi Hendrix recording, so the recording quality isn't very good.
Alternatively I've recorded a piece from another album but the problem remains.
And you're right, the stereo effect is gone I think, from the memories I have from this piece of music.
Yes, I'm using stereo cables to connect every component. Those cables that has two cables together with different colors.
http://www.mediafire.com/download/xrs26 ... _Witch.wav

[Gale Andrews]

I am not an expert in DC offset, but the track you posted is good stereo and according to the code at http://forum.audacityteam.org/viewtopic ... 93#p195693 when made mono, there is minimal and variable DC offset which would suggest to me that it's occurring naturally.

So unless someone wants to contradict me I don't think there is anything to be concerned about in that waveform.

If you think there is a problem you could experiment by swapping over the right and left ends of the cable or use an alternative output in your chain (you have not given details on exact connections you are using). Also check you have the moving magnet/moving coil switch set correctly on the Pro-Ject Phono Box.


Gale

[steve]

The piece was from a not so official Jimi Hendrix recording, so the recording quality isn't very good.
Alternatively I've recorded a piece from another album but the problem remains.

If it's only occurring with one record, or only with that piece of music, then I'd not worry about it.
It shouldn't be happening on all records. If it is, then something is not right and further testing will be required to locate the cause.

[Gale Andrews]

The piece was from a not so official Jimi Hendrix recording, so the recording quality isn't very good.
Alternatively I've recorded a piece from another album but the problem remains.

If it's only occurring with one record, or only with that piece of music, then I'd not worry about it.

The file posted online has the same asymmetrical waveform:

season_witch.png (20.42 KiB) Viewed 1065 times

but I don't believe it has any more than minimal variable offset. I can only see the variable offset if I amplify the result of your DC offset detection script. Without Amplify, the result appears to be a flat line.


Gale

[JLeite]

Greetings, again.
I've been away of this topic but I'm back now.
My initial problem remains, the graph seems to had suffer a haircut.
What could it be the problem?

[Gale Andrews]

My initial problem remains, the graph seems to had suffer a haircut.
What could it be the problem?

If you still have the bottom (negative) part of the waveform taller than the top (positive) part, please see the previous replies. Have you tried a different cable, using the correct moving magnet / moving coil setting on the Pro-Ject Phono Box, and checked the weight, tracking and wiring of the cartridge?

If the waveform is flat topped at the the top (+1) and bottom (-1), turn the recording level down.

If the problem is something else, please attach an image of the waveform or a WAV audio sample (2 MB maximum).


Gale