I just spent several days trying to get reaper to connect to mixbus via Jack. I almost gave up several times and I read every forum I could find on the subject from top to bottom several times. Most responses have been something like "start jack and choose jack router as your ASIO soundcard" but they don't offer any assistance for people who can't get Jackrouter to connect to Reaper. Here are detailed instructions on what I did to make it work with 64-bit apps. I'm using my setup as I think most people want to, recording and editing in reaper and simply sending channels out to mixbus upon mix to use like a console.
First off, I'm running 64-bit Windows 8.1 with 64-bit Reaper 5, 32/64-bit Jack and I beleive I'm running 64-bit mixbus3
I'm going to assume you have Reaper and Mixbus3 already, but not Jack.
Also just a tip make sure you open jack control before opening reaper and mixbus
1: Download Jack2 "Installer for windows 64-bit" and install it normally.
http://www.jackaudio.org/downloads/
2: Open Jack audioport and it will show a command prompt, now Open Jack Control and Audioport can be closed.
In Jack Control go to settings and under paramataters
-Set Server Prefix to "Jackd -S"
-Set Driver to "portaudio"
-Set Interface to your interface, in my case "ASIO::US-2000"
-Set Frames/Period to "32"
-Choose your Sample Rate, I used "96000"
-Set timeout to its max "10000"
-Set input device to your interface again in my case "ASIO::US-2000"
-Set output device to your interface again in my case "ASIO::US-2000"
-Choose how many channels I/O. I chose "64" for both
Save and close
I messed with these settings for hours and had no problem seeing mixbus, but Reaper would not show Jack Router no matter what settings I chose. Most forum posts said that it Jack would not work with Reaper 64 bit, but there is a work around.
3: While in Windows Explorer navigate to C:\windows\system32, and right click on "cmd.exe" and right click to choose "Run As Administrator" from the context menu. In the command prompt, type: cd\Program Files (x86)\Jack\64bits and hit enter. now that you have "navigated" to the proper folder, type: regsvr32 JackRouter.dll and hit enter again.
once I did this, Reaper was able to see Jackrouter and I could connect.
4: If you want more than 4 channels to send and receive, got to C:\Program Files (x86)\Jack\64bits and right click on JackRouter and go to properties. under the security tab edit permissions and give full control to your USER. hit ok and open Jack router and where it says "4" type how many in and outs you want. Again in my case, I chose 64 for both.
Save and close and you should be set to use as many channels as you need.
Thats all you need to do to get started but there are some other things to setup within reaper and mixbus.
5: within Reaper preferences>device, Set Inputs: first to "1: IN1" and last to "64: IN64" and set Output Range: first to "1: OUT1" and last to "64: OUT64" the last channel will be whatever number of channels you chose earlier in the setup.
6: Now within reaper go to preferences>audio and uncheck the first box: "close audio device when stopped and application is inactive" if you don't do this than any time you minimize reaper or stop playback, it will disconnect jack and you will lose part of your setup.
7: Simply open mixbus and create as many audio tracks as you need. with my 64 channel setup i can send 32 stereo tracks or 64 mono tracks to mixbus from reaper. I'm also able to send anything i need back to reaper, for instance sending my master out from mixbus back to reaper.
8: Now that you created your mixbus tracks go to jack control and click "Connect" which will open up your routing between reaper and mixbus. you can simply choose reaper for outputs and choose mixbus for inputs. You'll also have to send your Master outputs 1 and to from mixbus to system outputs 1 and 2 or setup routing back to reaper and from reaper out to system.
At this point routing is really up to you and there is a lot of creative possibilities once you have an understanding of the inputs and outputs and routing grids of both programs.
9: You still have to send your reaper tracks to hardware outputs now and you have to simply select "IN" at the top of each mixbus channelstrip otherwise you will not hear or see anything.
Sorry if I explained anything that was unnecessary for a lot of users, but I wanted to make a resource that explained a lot so people don't have to go on a 3 day forum hunt to find resources to make this thing work. If I was unclear about anything I'd be glad to elaborate.
Some of the resources that helped me a lot were:
* READ ME file include with jack located in \program files (x86)\Jack
*
http://music.tutsplus.com/articles/w...o--audio-20601
*
http://jackaudio.org/faq/jack_on_windows.html
*
http://www.computerhope.com/issues/chusedos.htm