To date, no one in the Vixen forum has responded with a solution. I think that if the plugin developer has to re-compiled the code to allow it to run under 64bit. This lack of support causes me concern about using Vixen. I do not like using unsupported software.
I don't know who wrote the analog frequency spectrum add-in, but I can give you some insight on Vixen support:
Vixen itself is very well supported, but this is not the official support forum. That is at You are not allowed to view links.
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Login ... as far as I can tell, you didn't post over there.
The Vixen author, KC, distributes the software for free. Writing it and supporting it is his hobby. In the summer of 2009, he released an upgrade to Vixen, the 2.5.x series, that didn't meet his personal expectations for robustness and quality. He provided a converter to take users' sequences back to the 2.1 series format, called 2.5 a failure and said he would regroup with a new version of the software, completely rewritten from the ground up.
The vast majority of DIY Christmas light shows (probably 10s of thousands) were sequenced and run on Vixen 2.1 or 2.5 during the 2009 and 2010 seasons with only a few glitches.
About three months ago, on the official forum, KC posted a note saying that 3.0 wouldn't be available for the 2010 season and asked what features people were anxious to see implemented.
Whoever wrote the analog frequency spectrum add-in -- undoubtedly another volunteer who does this as a hobby, not a career -- knows all this. I assume they are reluctant to put any more time into working with that add-in until KC releases a spec for the 3.0 add-ins. While probably not the entire universe of disgruntled potential Windows 7, 64-bit users, only two have shown up here, so that person may not even realize that there is a problem.
You are welcome to use any software you want to sequence your show; I, in fact, may not use Vixen in 2011, but I didn't want to let your comment about lack-of-support slide, because I know that KC prides himself on providing quality, professional-level support. For free. It just isn't here.
HTH.
\dmc