Steinberg V-Stack Operation Manual

							V-STACKSetting up your system 4 – 41
Activating VST System Link
After setting up the inputs and outputs, you now need to define which 
input/output should carry the actual VST System Link information.
The System Link networking signal is carried on only one bit of one 
channel. This means that if you have an ADAT based system which 
normally carries eight channels of 24-bit audio, once you activate VST 
System Link you will have seven channels of 24-bit audio and one 
channel of 23-bit audio (the least significant bit of this last channel is 
what we will use for networking). In practice this makes no discernible 
difference to the audio quality, since you will still have around 138dB 
headroom on this channel.
To set things up we need to open the VST System Link panel:
1.Open the Device Setup dialog on the Devices menu.
2.Select the VST System Link device and make sure the Setup tab is 
selected to the right. 
						

							V-STACK4 – 42 Setting up your system
3.Use the ASIO Input and ASIO Output pop-up menus to define which 
channel should be the networking channel (and thus become a 23-bit 
audio channel, in our example).
Quite often you will be able to just leave these pop-ups the way they are. 
4.Click the Active checkbox at the top of the panel.
5.Repeat the steps above for every computer on the network. 
As the computers are made active, you should see the small T (Trans-
mit) and R (Receive) lights flashing on each active computer, and the 
name of each computer should appear in the list at the bottom of the 
pane. Each computer is assigned a random number – dont worry 
about this, its just so the network knows internally which one is which.
•You can double click on the name in bold (which is the name of the 
computer you’re currently working on) and set it to whatever other 
name you wish.
This name will appear in the System Link window of every computer on the network.
• If you dont see the name of each computer appearing once you have 
made it active, you may have to check your settings. 
Go through the procedure above again and make sure that all ASIO cards are listening 
to the digital clock signals correctly, and that each computer has the correct inputs 
and outputs assigned to the System Link network. 
						

							V-STACKSetting up your system 4 – 43
Setting up MIDI for VST System Link
VST System Link supplies up to 16 MIDI ports, each with 16 chan-
nels. You set this up as follows:
1.In the VST System Link Setup tab in V-STACK, use the MIDI Ins and 
Outs value boxes to specify the number of MIDI input ports you need.
For V-STACK you don’t need any MIDI output ports.
2.In the other application, specify the same number of MIDI output ports.
3.If you now check the MIDI input pop-up menu for a VST Instrument in 
V-STACK, you will find the specified System Link ports added to the 
list of MIDI inputs.
Similarly, MIDI tracks in the other application will have a number of System Link MIDI 
output ports.
To route a MIDI track from the other application to a VST Instrument in 
V-STACK, proceed as follows:
4.Select a System Link port as output for the MIDI track.
5.Select the same System Link port on the MIDI input pop-up menu for 
the VST Instrument in V-STACK.
Now, any MIDI data played back on the MIDI track is routed to the 
VST Instrument. To play the VST Instrument live, you would need to 
activate MIDI thru/monitoring for the track or record enable it (de-
pending on the application), so that incoming MIDI is routed to the 
track’s output (i.e. to the VST Instrument in V-STACK). 
						

							V-STACK4 – 44 Setting up your system
The “Active ASIO Ports for Data only” setting
If you are sending huge amounts of MIDI data at once, there is a small 
possibility that you might run out of bandwidth on your VST System 
Link network. This will manifest itself by notes “choking” or timing be-
coming erratic. 
If this happens, you can devote more bandwidth to MIDI by selecting 
Active ASIO Ports for Data only in the VST System Link Setup panel. 
When this is active, the VST System Link information will be sent on 
the entire channel instead of just one bit, more than enough for all the 
MIDI you could ever hope to use. The downside is that you can no 
longer use this ASIO channel for audio transfer (do not connect it to a 
speaker!), thus leaving you only 7 channels of audio in our ADAT ca-
ble example. Depending on how you work this might be a reasonable 
compromise. 
						

							V-STACKSetting up your system 4 – 45
Optimizing audio performance
This section of the chapter gives you some hints and tips on how to get 
the most out of your V-STACK system, performance-wise. Some of this 
text refers to hardware properties and can be used as a guide when 
upgrading your system. This text is very brief. Look for details and cur-
rent information at www.steinberg.net!
Two aspects of performance
There are two distinct aspects of performance in respect to V-STACK:
Tracks and effects
Simply put: the faster your computer, the more tracks, effects and EQ 
you will be able to play. Exactly what constitutes a “fast computer” is a 
science almost in itself, but some hints are given below.
Short response times (latency)
Another aspect of performance is response times. Latency is a phe-
nomenon based on the fact that in a computer, audio has to be “buff-
ered” (stored) in small chunks during various steps of the recording 
and playback process. The more and larger those chunks, the higher 
the latency.
High latency is most troublesome when playing VST Instruments and 
when monitoring through the computer, that is when listening to a live 
audio source via the V-STACK Mixer and effects. However, very long 
latency times (several hundred milliseconds) can hamper other pro-
cesses like mixing, since e.g. a fader movement will affect the audio 
noticeably late.
While Direct Monitoring and other techniques reduce the problems 
associated with very long latency times, a system that responds fast 
will always be more convenient to work with.
•Depending on your audio hardware, it may be possible to “trim” your 
latency times, usually by lowering the size and number of buffers.
For details, refer to the audio hardware documentation, or, if you are using a DirectX or 
MME driver under Windows, the HTML Help. 
						

							V-STACK4 – 46 Setting up your system
System factors that affect performance
CPU and processor cache
It goes without saying that the faster the computer processor, the bet-
ter. But there are a number of factors that affect the apparent speed of 
a computer: the bus speed and type (PCI is strongly recommended), 
the processor cache size and of course, the processor type and brand.
V-STACK relies heavily on floating point calculations. When shopping 
for a processor, please make sure you get one that is powerful in cal-
culating floating point arithmetics.
Audio hardware and driver
The hardware and its driver can have some effect on regular perfor-
mance. A badly written driver can reduce the performance of your com-
puter. But where the hardware driver design makes the most difference 
is with latency.
❐Again, we strongly recommend that you use audio hardware for which 
there is a specific ASIO driver, even if you don’t plan to use VST System 
Link! ASIO drivers written specifically for the hardware are more efficient 
than MME or DirectX and normally produce shorter latency times.
This is especially true when using V-STACK for Windows:
• Under Windows, ASIO drivers written specifically for the hardware are more 
efficient than MME or DirectX and normally produce shorter latency times.
• Under Mac OS X however, audio hardware with properly written Mac OS X 
(Core Audio) drivers can be very efficient and produce very low latency times. 
						

							V-STACKSetting up your system 4 – 47
Making settings that affect performance
Choosing a driver for your audio hardware
As described on page 30, it is recommended to install and use a stan-
dard ASIO driver if available for your specific hardware. Check the 
manufacturers web site for the latest drivers etc.
Making audio buffer settings
Audio buffers affect how audio is sent to and from the audio hardware. 
The size of the audio buffers affect both the latency and the audio per-
formance. Generally, the smaller the buffer size, the lower the latency. 
On the other hand, working with small buffers can be demanding for 
the computer. If the audio buffers are too small, you may get clicks, 
pops or other audio playback problems.
• Under Mac OS X, you can adjust the size of the buffers on the VST Multitrack 
page in the Device Setup dialog.
You may also find buffer settings in the control panel for the audio hardware.
• Under Windows, you adjust the buffer size settings in the control panel for the 
audio hardware (opened by clicking the Control Panel button on the VST Mul-
titrack page in the Device Setup dialog).
The Expert settings
In the VST Multitrack panel you will find a button called “Expert…”. 
Normally you will not need to touch these settings, but if you run into 
problems with audio playback you should investigate whether chang-
ing these settings will help you. Generally, they allow you to adjust 
how much processing power is used for recording and playing back 
audio. 
						

							V-STACK4 – 48 Setting up your system
Optimizing processor scheduling (Windows only)
To get the lowest possible latencies when using ASIO under Windows 
2000 or XP (on a single CPU system), the system performance has to 
be optimized for background tasks: 
Windows 2000
1.Open the Control Panel from the Start menu and select System.
2.Select the Advanced tab and click the Performance Options button.
3.In the dialog that appears, select “Optimize performance for: Back-
ground services”.
4.Click OK to close the dialogs.
Windows XP
1.Open the Control Panel from the Start menu and select System.
2.Select the Advanced tab and click the Settings button in the Perfor-
mance section.
The Performance Options dialog appears.
3.Select the Advanced tab.
4.In the Processor Scheduling section, select “Adjust for best perfor-
mance of: Background services”
5.Click OK to close the dialogs.
Related Information (Windows only)
ACPI vs. Standard PC mode
Windows 2000 users should consider the important information relat-
ing to audio performance as presented on the Steinberg Knowledge 
Base. The address is “http://service.steinberg.net/
knowledge_pro.nsf/show/acpi_and_audio_performance”. 
						

							5
Guided tour 
						

							V-STACK5 – 50 Guided tour
The main windows in V-STAC K
The Mixer
The Mixer is where you mix your VST Instrument channels, that is, ad-
just the levels (volume), stereo panning, effect sends, EQ, insert ef-
fects, etc. There are also four group channels, for submixing, etc.