Vinyl to CD Tutorial Part 1. Recording Vinyl on a PC
- 1. Introduction
- 2. Equipment needed
- 3. Turntable/ Pickup Arm
- 4. Pickup Cartridge
- 5. Stylus Maintenance
- 6. Record Cleaning
- 7. Pre-Amplifier
- 8. Interconnecting Equipment
- 9. Test Recordings
- 10. The Recording Chain
- 11. A/D Conversion
- 12. Setting the Record Level
- 13. Channel Alignment
- A turntable and pickup arm fitted with a good quality cartridge and stylus.
- A Pre-Amplifier with RIAA equalisation.
- Interconnecting cables.
Most moving coil cartridges have a very low output voltage (~200 microvolts) and are supplied with a step-up transformer or a low noise amplifier to match the level (~10 millivolts) of a typical magnetic cartridge. Some modern moving coil cartridges are so called ‘high output’ and do not need a transformer or amplifier.
A very small number of magnetic cartridges (eg Decca ffss) should not be used with a ferrous turntable because the strong magnetic field of the cartridge will be attracted downward causing serious damage to the cartridge.
Crystal/ceramic cartridges require special equalisation and will not produce the high quality output obtainable from a typical magnetic cartridge. For these reasons they are not recommended.
Before playing each side of a record, always clean the stylus using a fine (camel hair) brush soaked in alcohol (IPA). Gently blow it dry before use. Only move brush from back to front (ie in the direction of record movement), NEVER from front to back or from side to side. High compliance cartridges, in particular, are very easily damaged so extreme care should be taken when cleaning your stylus.
When the side has finished playing, inspect the stylus for contamination. If the contamination is significant, you should consider re-recording part or all of the side. Only in this way will optimum results be maintained.
Your stylus should be regularly checked for wear as a worn stylus will permanently damage your records.
If your records have not been played for some years, dirt may have become ingrained in the grooves. In such cases, the record should be played at least once before recording. This will help remove dirt remaining in the groove and allow you to inspect the stylus to confirm the absence of contamination. If playing the record reveals high levels of background noise, or if the stylus becomes repeatedly clogged with dirt after playing, the record should be deep cleaned.
Deep cleaning involves covering the surface of the record with a mixture of alcohol and distilled water and then scrubbing and vacuum drying to remove all traces of residue. This task is accomplished using a ‘Keith Monks’ or similar specialist machine. A number of record/hi-fi shops will provide this service for a small charge. The results are usually dramatic.
A pre-amplifier must be used to amplify the low level signal from the pickup to a suitable level (~1volt) for a multimedia PC soundcard. Also, the pre-amplifier must provide the correct equalisation (RIAA) to ensure a flat frequency response from the record.
Some hi-fi systems integrate the pre- and power amplifiers into a single unit. In this case, it will usually be possible to utilise the output intended for tape recording to feed the soundcard.
It is very important not to drive too high a signal level into the PC soundcard. Otherwise, clipping distortion will occur. For this reason, your pre-amplifier should ideally have an adjustable output level. If your output level is fixed, then you will need to use the gain control in the Windows mixer applet to adjust your recording level. See Part 2 of the tutorial for a description of setting the recording level correctly.
Ensure that all connectors are of good quality and that they all are seated correctly. Poorly fitting connectors are a frequent source of noise and sometimes hum.
Even when everything is interconnected properly, it is still possible for low levels of hum to be present due to poor earthing or multiple earth paths. During initial auditioning, you should satisfy yourself that your recording set up is not introducing any hum. If you find there is some hum present, then you will need to carefully check all connectors. If this does not cure the problem, you may find removing the power supply earth from one or other item is effective. Note, if you do this, you should ensure that your personal safety is not compromised.
In some cases, you can make a test recording to your hard disk, for example to verify that the sound card is not being driven too hard and causing overload distortion. In other cases however, you will need to actually burn a CD in order to verify that all is well. For example, this is necessary to ensure that your left and right channels are not reversed. For these test recordings it is very useful to be able to use CD-R/W’s rather than CD-R’s. Unfortunately, CD-R/W’s will not play on the majority of audio CD Players. Therefore, if you use CD-R/W’s you may be restricted to auditioning the end results using the speaker system attached to your PC. In most cases this will be adequate but if your speakers are not of a good enough quality, you should consider using a pair of good quality headphones for these pre-mastering tests.
Because the A/D converter only uses a finite number of steps, it is important that the analogue signal is presented at an appropriate amplitude if optimum results are to be achieved. If the signal is too small, the higher order bits will never be turned on and thus you may end up with only a 12 or 13 bit recording. Conversely, if the signal is too large, the A/D converter will be unable to assign a value to some samples because they are outside its range of possible values. In this case digital clipping occurs which is a severe form of distortion.
Usually when recording, the sound level should be adjusted so that the loudest sections peak in the -3 to 0 section of the bar graphs. However, some sound cards with poor analogue front ends have a tendency to exhibit audio distortion at levels somewhat below this. In such cases, it is best to record at a lower level and then to digitally adjust the level after recording. (this is known as ‘normalising’) The best way to ensure an optimum recording level is to do some test recordings before burning any CD-R’s. In this way, you can discover the appropriate recording level for your particular hardware components.
With most sound cards, you can adjust the recording level using the Windows ‘Volume Control’ (mixer) applet or any replacement applet which may be supplied with the card. The applet controls digital attenuators and switches which are built into your soundcard. Note that some sound cards do not have the hardware to support all features and you may find that some controls are inoperative.
If your hardware pre-amplifier incorporates an output level control, you should use this in preference to the Windows applet control. In this case, set the applet control to maximum and adjust the recording level using the control on your pre-amplifier.
The Windows applet is selected by double clicking on the ‘Volume’ icon in the system tray. If the icon is not there, select Programs/Accessories/Entertainment/Volume Control. Having opened the applet, select Options/Properties and then select ‘Adjust Volume For - Recording". Then make sure that the ‘Line’ check box is checked. This enables a volume control for the soundcard Line Input. Now check the ‘select’ check box under the ‘Line’ volume slider. If necessary, you can use the slider to set the recording level.
Now, open your recording program and adjust your recording level to a suitable level as indicated on the program’s level meters.