Here are a few things to help you reliably get glitchless audio and no-coaster CD burning.
Most of these were learned the hard way.
These tips are geared towards recording and playback of 48KHz/16bit stereo audio
for hours at a time, such as digitally transferring 2-3 hour DAT tapes, or for recording
CDs at 2x or 4x.

Please look over all the categories, as a tip in the general section may fix a problem in
Windows95, etc.

This text is copyright 1998 Celestial Audio, and may not be reproduced in any
manner without permission.  Please do not email any part of this - instead, email the
homepage URL: http://www.celestialaudio.com.  Thank you.
 

First:    DOS

Don't use Smartdrive.  (that's smartdrv.exe)

Smartdrive does a great job for "typical" PC use, back in the day (like running Windows 3.1).
However, when streaming data it simply gets in the way.  The disk caching it does is useless
when data moves to/from the harddisk just once, and there is CPU overhead maintaining
the cache.  Also, when the cache fills and is emptied, there is a sudden need for significant disk
and CPU use.  This can cause dropouts.  Just don't use it.

Make sure you have the BUFFERS= setting in config.sys set properly.

While there is little information as to exactly what the BUFFERS=x,y line in config.sys does,
it was the culprit for a 1/4sec dropout every 30-50minutes on one PC used for audio editing.
This PC had in the config.sys file:
BUFFERS=10,0
changing this to the maximum,
BUFFERS=99,8
solved the problem.  Since there was no need to conserve memory in DOS, other, smaller
settings like BUFFERS=40,0 were not tried.  This fix took two days to find.

Don't use a compression manager (like Stacker and DiskSpace/DriveSpace).

Audio does not compress well using LZW-type algorithms (also used in .zip archives) and
compression consumes significant CPU resources.  Don't use them.  You will only get
10-15% compression anyway; just buy a bigger harddrive.
 

Second:    Windows95

Windows95 can be a challenge to get audio running smoothly.  Windows (all versions) was
never designed to be a real-time OS, with guaranteed latencies and throughput.  Thus,
the only way to get the performance you want from it is to ensure nothing but the task at
hand gets CPU and disk resources, and making sure the hardware is up to the task.
(see the General section below for more on this.)

The strategy here is to do everything possible to minimize overhead and avoid potential
pitfalls.  Once a system is deemed to be reliable, you can try re-enabling features and
see if it is still o.k. for your audio work.

Set [vcache] in system.ini.

The importance of doing this cannot be overstated.  This is the #1 tip in this whole
document.
First: locate system.ini.  It is probably in C:\windows.  Use the find utility in Explorer
to find it (Tools menu, Find, Files or folders).
Run notepad, open the file.
Add to the bottom of the file:

[vcache]
minfilecache=X
maxfilecache=X

where X is a minimum of 4096 and a maximum of 16384.  The general rule is:
take the amount of physical, real RAM in your PC, in kilobytes, and divide by 4.
This number is the min and max amount of memory in kilobytes that Windows
will use for the vcache.  Sticking with nice round (in binary) numbers is safest.
Use the table below.

RAM                       X
<16Mb                 buy more memory.  Or try 2048.
16 - 24Mb            4096
>24 - 48Mb          8192
>48Mb                 16384

A word of caution.  Don't change anything else in system.ini, and if there is any
possibility you may have changed something else while adding this [vcache] stuff,
close notepad w/o saving and start over.  You should probably make a backup
copy of system.ini before editing.  Also, in notepad search system.ini for any other
[vcache] setting an audio application may have already made when it was installed.
If there already is a setting, make sure the number they use is reasonably close to
what is in the table above.  Don't add another [vcache] section!  After you have
made the change and saved the file, reboot.

So what is this [vcache] stuff anyway?  It is the Windows95 version of SmartDrive,
described in the DOS tips section.  It does file caching.  The problem is that it
dynamically grows and shrinks as running applications use more or less memory,
new applications are started or exited, as the cache fills and must be flushed, etc.
When that happens, the vcache may decide to spend significant CPU and disk
resources to read or write a lot of cached data.  This WILL cause dropouts,
usually 3 to 15 minutes into a recording or playback.  This was also the culprit
behind a high coaster rate on a CD-R on a "fresh" (i.e. untweaked with this tip)
Windows 95 installation.

The side effect of setting [vcache] is if you are running one app that does a lot of
file i/o, but is not time-critical (searching a database, or processing/creating a lot
of files, say) there will be free memory that Windows could have used to try to
optimize the file i/o.  Additionally, since minfilecache is set to the same number
as maxfilecache, Windows will not shrink the cache to make room for more
application memory (and instead will use virtual memory).  We have not found
the impact to be noticeable.

For (a little) more information:  Microsoft vcache information

Disable the screen saver.

Unless you are sure the screen saver won't come on while recording or playing back
a long file, turn it off.  To do this: right-click on the desktop, choose Screen Saver
tab, choose None from dropdown list.  When transferring a long recording, just
turn off the monitor.  It won't hurt it.  Really.

Disable power-saving modes.

This should be done both in the BIOS and in Windows.  When the computer boots up,
there is a special key that enters BIOS configuration mode.  Each BIOS uses a different
key (DEL, ctrl-DEL and ESC are common) so you will have to find out what it is for
your PC yourself.  Also, be careful when changing settings in the BIOS.  It is quite
possible to make the PC unreliable or unbootable.  Consult the manual for your PC
on how to set the power-saving modes, and turn them all off.  Since you turn off your
PC and monitor when not using it, there is no need to for automatic powerdown, right?
If the power-saving system is smart enough to not shut anything off when there are no
mouse motion or keystrokes but the harddisk is running then this isn't necessary.

How to disable power-saving in Windows95: power management is a control panel
applet.

Disable Microsoft Office Fast Find / Indexer.

By default, Microsoft Office includes a utility to build a mini-database of all the Word
and Excel documents on your harddisks.  This is kicked off automatically.  Not a
good idea to have it start running while you are recording, eh?  Look in the StartUp
section off the Start menu.  Disable it.

Disable ALL "background" utilities.

This includes: anti-virus software that periodically scans harddisks for viruses,
programs to defragment harddisks, software that checks a website for updated
versions of itself, etc.  Make sure everything in the StartUp section is set to NOT
periodically run something "in the background" "when the PC is idle".  While
these programs may be smart enough to not run when recording w/o a mouse
move or keystroke for an hour, don't trust them.  Problems caused by programs
like these can be very hard to track down.

Set a fixed virtual memory size.

Right-mouseclick on the "My Computer" icon in the upper-left corner of the desktop.
Choose Properties, then Performance tab, then Virtual Memory... button.  Choose
the "Let me specify my own virtual memory settings" radiobutton.  Choose a
harddisk with some space on it (preferably C: but that's not essential) and choose
a good-sized amount of memory... like 64 or 96 megabytes.  Be sure to set the
SAME amount as the minimum and maximum!  This will prevent Windows from
expanding or shrinking a special file used to provide "virtual" memory to applications.
The expanding and shrinking take significant disk resources... not what you want to
have happening while doing recording or playback.  Note: if you tend to run many
applications simultaneously you may run out of memory with a setting of 64 megabytes.
Just bump the number to 96, or 128, or 196, or whatever you need (and have disk
space for).  But be sure you set the minimum and the maximum to the same number.

Turn off auto insert notify for CD-ROM drives.

This applies to all CD-ROM drives, including recorders and rewriters.
Right-mouseclick on the "My Computer" icon in the upper-left corner of the desktop.
Choose Properties, then Device Manager tab.  You will see a list of all the different
types of hardware in your PC.  Click on the + next to CD-ROM.  For each drive
listed, choose it and click the Properties button.  Choose the Settings tab.  Now
uncheck the Auto Insert Notification checkbox.  What the auto-insert does is
instruct Windows to scan the CD-ROM drive every so often to see if there has been
a new disc placed in it.  This check can interfere with CD-R recording.  It may also
instruct the CD-ROM drive to tell Windows when a new disc has been inserted.
Either way, it uses CPU and disk resources that should not be used when recording
CDs.  Two different CD-R recording programs used here both claim turning this off is
a must-do.  The side effects of turning this off: "Autoplay", whereby a program will
automatically be run when a CD-ROM is inserted (like an install program) won't
happen, and if a CD-ROM is being viewed in Explorer, and a new disc is inserted,
the Explorer view won't automatically update (press F5 to force the view to update).

Don't use a compressed drive.

Compressed drives require significant CPU resources for the compress & decompress,
and digital audio doesn't compress very well anyway (around 10-15%).  Buy a bigger
harddisk.
 

Third:    General PC/Windows tips

General stuff.  Applies mainly to Windows 95.

Defragment your harddrive.

While it isn't generally necessary to do this, if you are having problems try it.  If your
audio work involves seamless playback of many audio files, this is important to do.
If you never have run the defragmenter do it now!  Double-click with the left mousebutton
on the My Computer icon in the upper-left corner of the desktop.  For each
harddisk in turn, right-mouseclick on it, choose Properties, then choose Defragment
Now.  If you haven't checked the drive for errors recently, do it now!

Use a different harddisk for audio and Windows.

When streaming audio, the harddrive is continuously running.  If Windows needs to
access system files during this time, the audio and Windows competes for the drive.
This can cause dropouts.  Keep the audio and Windows on separate physical drives.
Separate partitions on the same physical harddisk does NOT help in this situation.
It DOES help keep the fragmentation of audio files down; see the tip above.

Use a different harddisk for audio than for everything else.

This is the best case, and is what we do.  This helps with both the competing for
the drive and fragmentation problems.  This makes working in other apps while audio
is streaming or CDs are being burned much safer.

Install IDE harddisks and IDE CD-R / CD-RW on different chains.

This tip comes from Chad Klausing, chadk@hal.com.  Thanks Chad for spending
the time to write this up!

       In regards to your Win95 and PC hardware tips and tricks,
here is another issue which some users will find is VERY
important, especially in the case where you are dumping an audio
file to disk or doing disk->disk:

        For those users that can't afford SCSI drives (such
as myself) and are therefore limited to transfer over IDE
drives, it is very important to make sure your source device
and your destination device are physically installed on different
IDE chains.  Most PCs using IDE controllers offer the following:

IDE Primary Master
IDE Primary Slave
IDE Secondary Master
IDE Secondary Slave

You basically want to have one device on primary and one
on secondary.  The reason behind this is that IDE does not
allow simultaneous transfer between multiple devices on
the same chain (as is allowed with SCSI).  Therefore, if
both devices are on the same chain, they well be competing
for time, making buffer underwrite and overwrite highly
possible, which will result in data loss (ie coasters).

I suggest the following arrangement:

IDE Primary Master : Hard drive
IDE Primary Slave  : CD-ROM
IDE Secondary Master : CD-RW
IDE Secondary Slave  : whatever

This arrangement has a small drawback in that if you use
your regular old CD-ROM to run most things, it will be
fighting with the hard drive for transfer time, slowing
performance down a bit.  However, the cases we are interested
in here involve transfer from CD->CD or HD->CD.   In both of
these cases, the two devices involved are on separate chains
and will operate much more reliably.

Get enough memory to avoid swapping (virtual memory use).

How much you need depends on how many apps are running at once, and how
much memory they need.  In this day and age 32Mb should be the minimum;
24Mb is o.k. if you run one application at a time.  64Mb is good, and 128Mb
is excellent (this is what we use).  When you run out of physical memory, Windows
"fakes" memory for the blissfully-unaware apps running by using the harddisk set
for virtual memory (see Set a fixed virtual memory size above).  This causes
the harddisk to be accessed.  This is bad to do while audio is streaming or CDs
are being recorded.  Windows all by itself sometimes decides it needs more
memory, so even if you aren't using any apps swapping can happen.

Have a reasonably fast processor.

Anything Pentium class will be fine, i.e. anything sold since January 1997.  We
have done audio work and CD recording on Windows 95 with a 486-100.
Having enough memory to avoid swapping (see tip above) is far more important.

Don't run other apps while streaming audio or recording CDs.

Depending on the computer, and the application, this can be no problem to do or
it can cause problems every time.  The beefier the computer, the less likely you are
to have problems.  Start out by doing NOTHING with the PC while streaming
audio or recording CDs.  Once that is working well, try doing "light" things like
email or websurfing (watch out for Java!) or word processing.  Try to NOT launch
new applications!  This uses much CPU and disk resources, usually more so than
anytime when the app is running, so it is likely to cause problems.  Have the apps
you want to use running before starting the audio or CD burn.

Keep the computer cool.

Try this if there are intermittent lockups/bluescreens/reboots.  Take the computer
case off, and put an ordinary household fan near it.  This is particularly important
if you have several harddrives and no air conditioning.  Harddrives can get
surprisingly hot, and will heat up circuitry near them (that may not be designed to
take this additional heat).  This goes for CD-R drives too: if they are next to a hot
harddrive, they may fail.  In our experience, temperature problems are significantly
more prevalent in low-end computers/peripherals than pricier "good brand name"
equipment.  Make sure you have a mini fan on the CPU!  If the power is poor
in your area or building (do the lights dim when the fridge or elevator or AC
starts?) a UPS may help.

Know the settings in the audio / CD-R app you use.

What buffering does it do?  Where does it keep its temporary files?  Does it have
options to limit how much "extra stuff" it does while streaming audio or recording
a CD  (like fancy progress indicators or scrolling views)?  Have you read the
troubleshooting section in the Help system?  Application-specific tips are
important to know.
 

That's all the tips for now.  Feel free to email other tips, corrections, questions, etc.

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