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Interfacing PC Sound System to Analog Devices

 

Section 7-9-0:
  1. Interfacing PC Sound System to Analog Devices (Author ~ Jack, aka Fireberd)
  2. Ripping Vinyl to CD (Care of ~ Nick)

 

 

 

7-9-1: Interfacing PC Sound System to Analog Devices (Author ~ Jack, aka Fireberd)

 

INTERFACING THE PC SOUND SYSTEM TO ANALOG DEVICES

By Fireberd

Many questions arise on how to connect the PC sound to an external stereo system and connecting an external audio device (tape, record player, etc) to the PC. The basic analog connections are the same in any PC, whether it has the on-board (built on the motherboard) or a separate sound card such as a SoundBlaster, Turtle Beach or some other brand of sound card.

All modern PC’s have, at a minimum, a "Speaker out", "Line Out", "Line In" and "Microphone input". Some have the speaker connections labeled "speaker 1" and "speaker 2" or "front speaker" and "rear speaker" but it is still basically the four connections listed.

In almost all cases the I/O jacks are color coded:

"Mic" = Pink (red)

"Line In" = Blue

"Speaker" (also Line 1 or front speaker) = Green

"Line Out" (also Line 2 or rear speaker or speaker 2) = Black.

The audio I/O jacks are all 1/8" (3.5mm) stereo jacks. The Mic input is not stereo but uses the "ring" on the stereo plug to provide a DC voltage to the "computer microphone" which is a condenser type microphone that requires the DC voltage to operate.

 

Jacks and connectors on the Sound Blaster Live! card

SB sound card

 

Two Speaker Configuration:

Speaker Mode is set to 2 Speaker in the Main tab of the Santa Cruz Control Panel.

This configuration allows you to keep both your stereo speakers and headphones connected all the time, without the hassle of reaching around the back of your computer and plugging and unplugging cables. The headphones can also be set to play the emulated rear channel audio in games with 3D audio capability.

  1.   Connecting the PC audio to an external source such as a stereo system. Connection is made from the "Line out" of the PC audio to a low level input on the stereo system, such as an "aux in", "CD in", etc (not the turntable in). Use a cable with a 1/8" stereo plug on one end and the proper connector(s) for your stereo system (usually RCA phono plugs). Keep the length of the cable as short as possible and at a maximum of 20 feet. Over 20 ft and you could get signal loss and frequency (fidelity) loss. Only use shielded audio cables, do not use "speaker" cables that are unshielded.

 

Recording Audio

This section covers hooking your stereo to record your LPs and cassettes, and recording from a microphone.

To Record From Your Stereo

CAUTION: DO NOT CONNECT THE SPEAKER OR SPEAKER OUTPUTS OF YOUR STEREO TO THE PC, THIS IS A HGH SIGNAL LEVEL AND MAY DAMAGE YOUR PC’S SOUND SYSTEM.

There are several steps to record audio from your stereo:

Let's go through them step by step.

Locating the Right Inputs and Outputs

Nearly every stereo has at least one stereo pair of outputs (we'll call them jacks from here on out) you can use for recording. They usually are RCA jacks (the standard type used to connect your stereo components). RCA jacks look like this:

RCAoutput.jpg (9650 bytes)

To Locate the Right Stereo Outputs

RCA jacks are always color coded in white and red, or black and red. Red is always the right channel.

Select one of the following RCA jacks, located on your stereo's receiver (the component that has the volume and tuning controls). Any of these are acceptable for sending signal to your PC:

 

To Locate the Correct Computer Inputs

Look at your sound card. It is located in the back of your PC. It probably has three 1/8 inch jacks, two inputs and an output. Look for the input labeled Line In. If you have a "professional" sound card, it has 1/4 inch inputs, and you should look for a pair of inputs labeled Line Inputs or Analog Inputs. Consult your sound card's documentation if you cannot identify a line in jack.

Getting the Right Cables and Adaptors

Once you have determined what your stereo's outputs and your sound card's inputs look like, you are ready to get the cables/adaptors to connect them. Use the following procedure to get your cables/adaptors.

To Find the Correct Cables and Adaptors

If you have an 1/8 inch input on your computer's sound card, you need the following:

If you have a pair of 1/4 inch inputs on your computer's sound card, you need the following:

 

To Connect Your Stereo to Your Computer

  1. Plug the cables into the RCA jacks you have chosen to use on your stereo.
  2. Plug the other end of the RCA cables into the RCA end of the Y-adaptor or RCA-to-1/4 inch adaptors.
  3. Plug the 1/8" end of the adaptor or the pair of 1/4 inch plugs into the sound card's input jacks.

 

To Set the Recording Levels

  1. Click the Record button to open the Recording Options dialog.
  2. Play the source material on your stereo.
  3. Watch the meter. Peaks should pass the OK mark, but not reach the end of the meter.
  4. Adjust the Windows mixer, and if necessary, your stereo's volume level, until the levels are right.

 

Adjusting the Windows Mixer

The Windows Mixer controls the volume levels of your sound card inputs, and it also can mute any input or output.

To Open the Windows Mixer

Click the Open Windows Mixer button at the bottom of the Recording Help dialog.

The Windows Mixer looks like this:

winmixer.jpg (17082 bytes)

When you open the Windows Mixer it may be labeled Play Control or Recording Control. We want to see the Recording Controls.

To view the Recording Controls:

  1. Click the Options menu and select Properties.
  2. The Properties dialog appears.

    mixerprop.jpg (15150 bytes)
  3. In the Adjust Volume For section of the Properties dialog, select the Recording radio button.
  4. In the Show the Following Volume Controls section, the Line-in and Microphone options should be checked. If they are not, check them.
  5. Click OK.
  6. The Recording Controls now appear in the Windows Mixer.
  7. Check the input you want to use, either Line In or Microphone.

Selecting an input:

Unless you are using a microphone, you should use the Line In. If you are using a Microphone, use the Microphone input. Make sure you are selecting the input that you are connected to. If you are unsure which input to select, consult your sound card's documentation.

Recording to the PC. The above details general information on recording. Specific recording depends on the program you use to actually get the analog data "recorded" (stored) on the PC. You should not record direct to a CD, any problem with the recording procedure, either the analog signal or some interruption in the CD burning process and the CD will be ruined and you will have to start over. By "recording" to the hard drive first allows you to only recover (redo) a small portion if there are problems. Additionally, audio should be stored on the hard drive as a wav file, not some compressed format such as MP3. If the purpose of recording to the hard drive is for recording to a CD in the "standard" CDDA format (the format for standard audio CD’s) the wav produces the best fidelity.

Actual procedures for "recording" from an analog source in the various programs will be found in the Help file for the program. Each program has it’s own procedure and it’s beyond the scope of this document to list the specific steps for each program. There are many programs available for "recording" such as Roxio Easy CD Creator Platinum versions (Versions 5 and 6) however the procedure differs in each version. Music Match Jukebox has an analog recording function. The Creative (SoundBlaster) Play Center provides this capability (may or may not be included with OEM SoundBlaster application software). There are many other programs that will provide recording capability such as the GoldWave (shareware) audio editor program (one that I recommend having if you do much audio recording or editing).

 

Special note on recording with a microphone. The computer microphone input is designed for special "computer microphones’ which are a condenser type, that requires a DC voltage to power them and have a relatively high signal level. This voltage is not the same DC voltage that is used in commercial condenser microphones that require the 48VDC Phantom Power. Computer microphones are designed for voice frequencies and generally do not work well for recording music. Also, because of the configuration of the microphone port (input) on computers a standard Hi-Fi or PA system microphone will not work properly (PA microphones have a low signal level output and are a different impedence than the computer mics). If you want to use a better quality mic, use an external mixer (designed for mics) that will amplify the microphone signal to line level (generally 0 DB or 1 V) and then connect the mixer output to the Line In.

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7-9-2: Ripping Vinyl to CD (Care of ~ Nick)

Ripping Vinyl to CD

By Nick44 (call me Nick)

OK, if you have read the previous article, you should have everything connected up and you should be familiar with the Line In source on your recording panel. Now you should be ready to rip some tunes from your vinyl, and make a CD.

The general sequence is going to be as follows. First, you have to get that music or whatever to your hard drive (we’ll call that recording). Second, you have to process it to get an acceptable audio quality and get the tracks ready for the CD (we’ll call that processing). Third, you have to actually make the CD (we’ll call that burning).

There are a number of programs that claim to do this all with "one touch". For example, Roxio Easy CD has an application called Audio Central. I’m not going to discuss these "one touch" applications because (a) if you have them, you can read the manual, and (b) I don’t think they work very well.

I’m going to cover processing at a very basic level. Audio restoration is really an "art" rather than a computer technology, and it is dependent on the application you use, the significance of your source, and how much time you want to spend learning to do it. If this arouses your interest, the links and discussions at the end of the article will give you plenty of food for thought.

As a general observation, if the vinyl was in reasonably good shape to begin with, you can get some pretty good sounds with only minimal processing.

Also, you’ll notice I keep emphasizing recording from "vinyl". This is shorthand for LPs and 45s made from about 1950 on. Earlier recordings, especially old 78rpm records, are a whole topic unto themselves.

Recording

There are three steps involved here: connecting the source, setting a level, transferring to disk.

Connecting the source

The general principles of connecting an audio source to a PC were covered in the previous article. Just a few specifics that pertain to vinyl, and we are on our way.

Obviously, to record from vinyl, you are going to need a turntable. A turntable basically consists of a platter that rotates, an arm, and a cartridge at the business end of the arm. The cartridge holds the stylus, a needle-like device that is the actual contact with the record on the platter. The stylus is moved by the grooves in the record, and the cartridge converts that movement to electrical signals.

A typical turntable will look something like the one in Figure 1.

turntable.jpg (8267 bytes) Figurre 1. Typical Turntable

 

Turntables like this one will run at 33 RPM or 45 RPM (RPM is shorthand for "revolutions per minute".) Those are the only speeds we are going to need for our purposes. This turntable model comes with a cartridge and stylus. Others do not come with cartridge and you have to purchase one separately. Just make sure you have all the pieces in place before you start. For LPs and 45s, you will use a microgroove stylus and a magnetic cartridge.

Older turntables often had more speeds (like 78 RPM and 16 RPM) and even came with multiple cartridges or styluses. If you have or can get one of these, you can certainly use it.

The other required equipment is a phonograph preamplifier, usually just called a preamp. Why? Two reasons. First, the signals from the cartridge are very weak, not enough to drive a Line In device. They need to be boosted before they can be used. Second, all the records that we are referring to here used a frequency compensation, called the RIAA equalization. That equalization must be removed or the audio will be severely distorted. Both these jobs are the functions of a preamp. Good quality stereos or A/V receivers that have a Phono input already include a preamp. If you don’t have a receiver available, though, you’ll have to use a stand-alone preamp (Figure 2). Note that some turntables come with built in preamps. If you have this type of turntable, you won’t need a receiver or a stand-alone preamp.

preamp.jpg (3195 bytes) Figure 2. Typical Stand-alone Phono Preamp

 

If you are using a receiver, follow the previous article for the connections to your PC. If you are using a stand-alone preamp or a turntable with a built-in preamp, you may connect the outputs directly to your PC - you don’t need to go thorough a receiver if you don’t want to. However, many people prefer to use a receiver as a handy control panel even when it isn’t strictly required.

Everything connected OK?

Now you are ready to set your recording level.

Setting a level

Launch your favorite recording application on your PC. There are so many of these it will be impossible to give the specifics, but typically you will have a window similar to one of those shown. Most recording programs allow for various audio quality settings and some even allow you to specify the file type. Don’t worry about all the options. Just be sure that you are set up to record to a stereo WAV file at a 44.1 KHz sampling rate with 16 bit resolution. This will produce a file that corresponds exactly to the CD audio specification, known as the "Red Book".

For advanced readers: the first window is the recording pop-up from an audio editor. The second window is a Test Level menu item from a straight recorder/ripping program. Most applications allow for other quality levels of recording and other formats, but we are not going to cover this here.

meterrec.jpg (22918 bytes) Figure 3. Typical Dual Meter Recorder

The dual meter window in Figure 3 looks complicated. All we want to point out with this type of recording application is the Pause button on the right, and the level indicator bars on the far left. The sample size (16 bits) and the rate (44.1 KHz) are also shown on this application, and we’ve already covered that. Don’t fret about all the other stuff because your particular application may look different.

singlemrec.jpg (5621 bytes) Figure 4. Typical Single Meter Recorder

The single meter window in Figure 4 is very simple because there is only one thing to look at. All we need to pay attention to is the level itself, which in this particular application is labeled "VU meter". Again, don’t fret about what that means here because your application may use completely different labels.

Set the actual LP or 45 that you want to record from on the turntable and start it spinning. Find what you think will be the loudest passage and drop the arm there. Watch the part of the window labeled Rec Level or VU Meter (or whatever label your application uses). Notice the level readings bouncing up and down. Adjust the level to slightly below full scale (for application windows similar to Figure 1, that would be between –2 dB and –3 dB; for application windows similar to Figure 2, that would be the line labeled ‘Optimal’)

You say you don’t how to adjust the level? Please see the previous article.

Once you have the level set, replace the turntable tone arm at the beginning of the record.

Transferring to the Hard Drive

This is the easiest step, because you’ve already launched your recorder application and set the level.

Start the actual recorder (you usually have a very visible button in your application which is labeled Record – that’s the one to click). Now lower the arm to the record. Notice that we start the recording program before we start the source. This is very important. Some recording programs have a threshold setting so you don’t get a lot of silent time at the beginning. Or we can remove the unnecessary silence later.

That’s about it. But don’t go off and walk the dog at this point. You should monitor what is going on. You want to monitor both the sound and the level. You monitor the sound for particularly noisy spots or bad audio that you may want to look at later during processing. You monitor the level to make sure you don’t exceed the 0 dB (or red) level. One or two very short exceeds is not a problem, but anything significant means you will have noticeable clipping in the recording. This makes for really bad audio on the CD. The only solution is to stop the recording, reset the level, and restart the recording.

When the side is finished, turn off the recorder. Most applications store the recorded result in a temporary location and you have to permanently save it at the end. So when the recording is done, save it to a file with a descriptive name.

If everything went well, you should now have a WAV file of one side of the LP, approximately 300 MB in size. Do the same thing with the other side of the LP (or with each 45)

Notice that I haven’t mentioned anything about tracks yet. That’s because the preferred method is to record one entire side of an LP, and then insert the track markers and/or track splits during processing. Most 45s consist of one track, so the issue doesn’t come up.

Notice also that I haven’t said anything about compressing, or any kind of recording except making a WAV file. There are programs that will record and compress at the same time, but that is a whole other topic.

Processing

As I mentioned, I’m not going into any great detail about this. In fact, you may not want to clean up the sound at all. You may be perfectly satisfied with the recording as it comes off the vinyl. In that case, simply skip the first part of this step and go directly to Splitting into tracks.

Cleaning up the sound

There are quite a few applications that will do the job, and you can find out what they are in the references. Whichever application (or applications) that you use, make sure you have an impulse noise filter (sometimes called a declicker) to remove clicks and pops, a high pass filter to remove rumble, and finally a low pass filter or equivalent to remove any light surface noise. Also, make sure you can normalize a WAV file.

First, though, save the original WAV files before you do any processing on them. Best would be to make a data CD containing whatever makes up the total project, such as the two original WAV files that represent both sides of an LP. Put that data CD away in a safe place. If you really mess up for any reason, you can simply restart without going through the whole recording routine again.

Now let’s begin to process the audio. A typical application will look something like Figure 5.

 audioeditor.jpg (20563 bytes) Figure 5. Typical Audio Editor

Notice the two windows in the editor. The top window is the source, and the bottom is the destination (blank in this view). The general approach is to listen to the source and apply a particular filter to it, which then fills the destination window with the result. Then listen to the destination to decide if the sound is clean and has not lost any significant audio. With LPs and 45s that are in reasonably good shape and are being played back on good equipment, you can often get a pretty decent result using only the three simple filters mentioned above. There are a lot of other filters that may be used to do a premium job, but these three will often be sufficient.

After cleaning up the audio, the sound will sometimes be a bit dull. This could be due to the filtering, or to a deficiency in the original record. To do a premium job, restorers often apply some special "sweetening" effects at this point to improve the sound; the better audio editors include quite a few of them to choose from. But you can get by without it.

A final consideration - which may or may not apply - is to convert a one-channel ("mono") file into a two-channel ("stereo") file. You would do this if your original source was in mono format and you recorded it as a single channel. Conversion is then necessary because an audio CD must have two channels. Many CD burning programs, and even some recording programs, can do this conversion automatically. So it’s not strictly necessary in many cases. But you may want to control how it is done, so this is the place to do it.

After cleaning up the sound, it’s often necessary to normalize the file. This is something that you really can’t get around. Normalization will adjust the volume level of the file so that it is maximized for CD audio. Otherwise, you may find the resulting CD plays at too low a volume. As with the one-channel to two-channel conversion, some CD burning programs will do this for you automatically. Just as before, it’s a question of how much control you want to keep on the finished product.

The final thing I want to mention is marking the file into tracks and getting the tracks ready for a CD.

Splitting the file into tracks and other finishing touches

There are a number of applications that will automatically "split" a WAV file into tracks. Some CD burning programs include a splitting function. Most general-purpose editors come with some sort of splitter as well. There are standalone programs, too. I’m not going to tell you which one to use. But I want to note some important considerations for any application that you may look at.

  1. Even if your application inserts the splits ‘automatically’, it should allow you to manually insert a track marker in the file. Sometimes, you want to have a track marker on a non-silent part of the file.
  2. It should allow you to undo a track marker if it was inserted incorrectly.
  3. It should adjust or ‘quantize’ the track markers for CD audio – complicated to explain, but necessary.

A typical stand-alone splitter is shown in Figure 6.

filesplitter.jpg (32521 bytes) Figure 6. Typical File Splitter

Run your splitting application and make whatever adjustments are required (adding or removing markers). If your application ‘quantizes’ as a separate step, don’t forget to do it!

You should now have individual WAV files for each track. Most applications give helpful names to the files like Track_1, Track_2, etc. But you can change the names if you want to.

Burning the CD

This is the fun part, but it can also cause problems. You can use any application that will make an audio CD. But whichever one you use, be sure that you are actually making an audio CD. Different programs use different terminology. For example, Roxio Easy CD calls this a "Music Project".

Set up your program to record Disk at Once (DAO). Set the burning speed to whatever is optimal for your particular system. Now select the tracks in the order that they appear on the LP (or change the order if you want).

Remember to convert to stereo and check off the normalize function if you are doing those in the burner application.

Start the burn and you’re done!

If you did things correctly, you will not get any gaps between the CD tracks or any extraneous noise at the beginning of your tracks. If you do get them, make sure that you are in DAO mode, and that you quantized the tracks.

And have fun!

Extra added feature – Burning from cassettes

Ripping and burning from a cassette is essentially the same as from vinyl. Obviously, you will need a cassette deck (see figure 7). The main differences are (1) a cassette deck is a high level device and doesn’t need a preamp, and (2) most cassettes use some form of proprietary noise reduction such as Dolby that has to be applied within the deck.

Otherwise, everything else is pretty much the same.

casdeck.jpg (5282 bytes) Figure 7. Typical cassette deck

For Further Information, see the following sources.

Forum threads:

http://forums.us.dell.com/supportforums/board/message?board.id=dim_audio&message.id=31845

http://forums.us.dell.com/supportforums/board/message?board.id=dim_audio&message.id=32251

http://forums.us.dell.com/supportforums/board/message?board.id=dim_audio&message.id=32775

http://forums.us.dell.com/supportforums/board/message?board.id=dim_audio&message.id=30971

http://forums.us.dell.com/supportforums/board/message?board.id=dim_audio&message.id=30818

 

Other useful links (I don't necessarily agree with everything on these sites):

http://www.pcabusers.net/vinyllp/vinyllp.htm

http://www.delback.co.uk/lp-cdr.htm

http://www.br0wn.co.uk/vinyltocd.htm

http://www.techtv.com/callforhelp/howto/story/0,24330,3333231,00.html

http://www.sospubs.co.uk/sos/aug02/articles/pcmusician0802.asp

Here is a portal to mostly technical sites:

http://www.lib.washington.edu/Music/preservation.html

 

Nick

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