Specifications

ABOUT AUDIO ON COMPUTERS
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Reason’s built in sequencer is not affected by latency!
When Reason’s sequencer is playing back a song, the timing between notes is
perfect! Once playback of a Reason pattern or song is up and running, latency
isn’t a consideration at all. The computer clocks the audio between the steps
and does this with perfect quartz accuracy! The timing is immaculate!
ReWire and Latency
When you run Reason as a ReWire slave, it is the other program, the Rewire
master that is responsible for actually creating the audio and playing it back via
the audio card. This means that it is the master program’s latency you will get as
a final result.
! When Reason runs as a ReWire slave, what audio card you have,
what driver you use, and settings you have made in the Preferences
dialog are of no importance at all! All audio card settings are then
instead done in the ReWire master application!
For information on ReWire, see “Using Reason as a ReWire Slave”.
Reducing latency
✪ Please note that internal audio under Mac OS 9 has a fixed latency
of 11ms which is very stable under all normal circumstances. The
tips below are for Windows users and for Mac OS 9 users with addi-
tional audio cards.
There are a few general methods for making sure latency is as low as possible:
D Use a card with an ASIO driver.
While this in itself is no guarantee for low latency, ASIO drivers generally
perform better than MME or DirectX.
D Select an audio card that supports low latency (small buffers) and
which is known for well written ASIO drivers.
D Remove background tasks on your computer.
This might be any background utility you have installed as well as network-
ing, background internet activities etc.
D Optimize your songs.
You might run into situations where you have to raise the Output Latency
setting to be able to play back a very demanding song on your computer.
Another option would be to actually optimize the song. See “Optimizing Per-
formance” for details.
D Get a faster computer.
This is related to the point above and only required if you find that you need
to increase Output Latency because your computer can’t really cope with
the songs you try to play.
PC Specific Information
About ASIO DirectX, MME and the Sound Buffer
setting
There are three ways for Windows to access an audio card:
Via an MME (MultiMedia Extensions) driver
This system has been around since Windows 3.0, and it is this type of driver that
is normally installed in the Control Panel and via Plug’n’Play. Most regular sound
playback (like when Windows goes “bing” on startup) happens via MME.
• Practically all cards come with an MME driver. If your card appears in the
System part of the Control Panel, you have an MME driver installed.
• Using a card via an MME driver gives you the worst latency figures, espe-
cially under Windows 98.
• Only one program at a time can use a card accessed via MME.
Via a DirectX driver
DirectX is a later system developed by Microsoft to provide developers with
more efficient routines to access audio.
• Not all cards come with DirectX drivers. However, drivers for some cards are
included with DirectX itself.
• Using a card via a DirectX driver gives you a shorter latency, between 40
and 90 milliseconds.
• If you use DirectX 3 or later, all programs that access the card via DirectX
and make use of the DirectX “secondary buffer” feature can use it at the
same time, and Reason can play in the background.
! Only use DirectX if you are sure that there is a “certified” DirectX
driver installed for your sound card.
• If in doubt, contact your audio card vendor to check whether there’s a Di-
rectX driver for your card or not.
✪ More information about DirectX can be found on Microsoft’s Di-
rectX web pages, at www.microsoft.com/directx.
Via an ASIO Driver
This is your best option if it is available. More and more audio cards designed for
serious music and audio use come with ASIO drivers.
As stated above, ASIO does not guarantee low latency, but it allows for it if the
audio card designers take advantage of its possibilities.