What is a Bus?

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molotov256
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Sorry to ask such a lame question, but I'm confused as to what a Bus is in Ardour and how to use it. I'm not an experienced recorder at all, and I feel like I'm lacking some basic knowledge I need in order to really use Ardour effectively.

As of now, I understand how to add effects to a track through the mixer panel, and I am under the impression a Bus can be used to do something similar to that plus a whole lot more.

So I guess my question is, after adding a Bus, what can I do with it and how do I do it?

I've tried Googling a bunch of stuff trying to find a tutorial or a walkthough or a manual. I have what I believe to be an official Ardour manual bookmarked, but in reading the section about Tracks and Buses (2.6), it only addresses tracks.

Thanks!

seablade
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There are currently two manuals, one is a good introduction for new users and strongly recommended...

http://en.flossmanuals.net/Ardour/Introduction?q=flossmanual

I don't remember if that ones covers the difference between tracks and busses or not, however the second manual that is still a WIP does...

http://ardour.org/files/reference/index.html?q=refmanual

Specifically...

http://ardour.org/files/reference/dsy24-ARDOUR.html#dsy424-ARDOUR

The second manual is intended for a technical reference manual, so it can be a bit of a dry read(Not to mention it isn't yet complete). If you are new to Ardour I strongly recommend reading through the first manual which is a quite strong introduction. The manual you likely have bookmarked if it is not one of these two, is the old reference manual and is very out of date and should be considered replaced by the second of these two manuals, which even though a WIP, is much more complete and in date with current Ardour

Seablade

mthed
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more could definitely be said in that manual. i read it and left still saying, "yeah, but how do i actually do that". here's what i've found so far. it would be better if someone more knowledgeable chimed in :-) here's one use scenario and a more detailed way of getting it done (no guarantee to be the "right way"). let's say you have three tracks and you want to be able to process them in a similar way (ex. you want to add reverb and manage their combined level in one place). well, you could create a new bus (Track->Add Track/Buss, select "Buses") and then for each track add a send (similar to adding a plugin. there is documentation for it here (http://ardour.org/files/reference/dsy365-ARDOUR.html#dsy274-ARDOUR). you could then do your processing on the bus and it would affect the tracks running through it. that's a start. i still don't understand some stuff:

1. should i then disconnect the original tracks from the master?
2. is this better to do pre or post faders?

probably lots of other questions to be asked :-)

molotov256
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Thanks seablade! Both manuals are much better than the one I'd been using. I think they pretty well cover what I needed to know. W00T!

@mthed: I'm going to try and do a little recording over the next week or so and play with buses the way you talked about. I imagine running multiple tracks to 1 bus would enable me to use one instance of a particular effect (eq's, reverb, etc) on multiple instruments, and that'd help take a load off the crummy old CPU I'm using.

seablade
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i read it and left still saying, "yeah, but how do i actually do that".

Yes but keep in mind the purpose of the manuals... The first one is a basic introduction to Ardour, the second is a technical reference so workflow aspects don't fit so well in it. There is sitll plenty of areas that could have more documentation, but by the time things get finished up on the tech ref, we will need to update it for A3, so hopefully some tutorials can step in here(And in fact IIRC the Mixbus videos that are for sale do a decent job in this area).

1. should i then disconnect the original tracks from the master?

This depends on what exactly you are doing, and you own personal needs, there is no straight yes or no answer. For instance if I am using a bus for a reverb send, I may set the reverb on the bus to 100% wet mix, and then use that to mix in reverb with the dry signal coming straight from the track to the master output. On the other hand if I am using a bus for a subgroup, where I want just one fader to control all the levels going through it, I will likely disconnect the output of the track to the master, as I want all that to go through the bus so I can easily modify all those levels.

2. is this better to do pre or post faders?

Again depends on your exact needs and setup. Often times i will do this post fader, but without thinking about it to hard, there are times I may wish to do this pre-fader as well, for some more esoteric live mix setups in particular. This is part of why the decision was made to keep that second manual as a tech ref, just covering the basic explanation of what each part of Ardour is and does is a LOT of documentation, before going into the many ways how each part can be used.

Seablade

thorgal
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Hi molotov256:

A track is a special bus connected to a "diskstream" (or audio / MIDI data sitting on your hard-disk) while a bus is simpler, it is just an audio path where you can add some processing (plugins, etc). So a track is not that different except that it reads data from your HD (or writes to it when recording). That's really the main difference, a simple bus is not connected to a diskstream.

audiodef
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"On the other hand if I am using a bus for a subgroup, where I want just one fader to control all the levels going through it, I will likely disconnect the output of the track to the master, as I want all that to go through the bus so I can easily modify all those levels."

What's the benefit of doing it this way as opposed to adding tracks to a group so that all faders in that group move in sync? One thing that comes to mind is not having to ungroup and regroup a fader every time you want to adjust an individual track, but I'm guessing there is more to it than that.

paul
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@audiodef: a single FX instance can be added to the bus, and affects all the signals fed to the bus. Ditto for panning.

seablade
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What's the benefit of doing it this way as opposed to adding tracks to a group so that all faders in that group move in sync? One thing that comes to mind is not having to ungroup and regroup a fader every time you want to adjust an individual track, but I'm guessing there is more to it than that.

Along with what Paul said, when grouping faders in A2 IIRC you are limited in the travel based off the relative levels in the group, no single fader can go above +6dB. Also when grouping faders you are also affecting all post-fader sends(Similar to a VCA), which may or may not be what you want, as some specialized mix techniques involve using post fader sends to processing or busses with processing, etc.

Seablade

audiodef
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I just knew I would go "duh!" when you guys chimed in. Thanks for reminding me of these things, though! ;-)