I can confirm that they do the slew rate mod at Moog Music, because I had it done to my new Voyager as they built it. They charge $150 for the mod to be done on a Voyager Select - good advice to call for specifics. They are really great to talk to.
Hey there,
Sooooo the great people at HHB in the UK have modded my voyager. It was there for some warranty repairs, and because there was a bit of messing around, they did the mod, FOC! 
Anyhow, for anyone that’s interested, below is a link to a small wav toggling through the 4 waves A/Bing, with the slew rate mod being the second.
I don’t like to have to create an account on a web site (even if it’s free), and then log on in order to simply listen to an mp3… Why don’t you use Soundcloud that lets anyone listen for free without having to register ?
I’d love to hear this comparison, but it looks like I need to login in via facebook to do it? Sorry, but I refuse to give any more random “free” sites my facebook info - any chance you could post on soundcloud? 
Yeah sorry about that…i thought you could play it without registering. Just created a new soundcloud now.
Hey masaski - thanks for posting this. What a difference! This was fun for me to hear - I just got my Voyager a few weeks ago, with the mod as part of the build, so it’s interesting to hear the comparison since I don’t have a “before” version. I have to say, I cannot imagine being happier with the tone I am getting out of that thing. It really sings.
Now that you have a Soundcloud account you can start posting your compositions and experiments.
Thanks masaski.
BTW, for those who own a Voyager and don’t yet have had this mod done, a similar result can be obtained by offsetting the filter cutoff by setting the “amount to filter” knob to maximum in the filter envelope with sustain at max. The filter cutoff knob on Voyager doesn’t open the filter fully by default, resulting in somewhat dull sounding waveforms.