Author 
Modular Rack Units 
dougcl 
hi folks, can someone explain to me the way modular rack units work? I am familiar with euro only.
1) Are all (most) racks heights measured in U?
2) Euro has the width concept of HP. There are 84 per 19" rack. I think in general these can be thought of as possible module positions. Another way of looking at it is they define the minimum module width, and all module widths are a multiple of them. Is there a similar concept in noneuro formats? I probably only need a few examples.
Thanks,
Doug 

parasitk 
For rack height  1 rack unit is 1.75" high. That's the standard.
http://en.wikipedia.org/wiki/Rack_unit
Obviously Euro and Frac are 3U tall. Wiard 300 and Modcan A (in a rack frame) are 6U, MOTM/DotCom/Modcan B are 5U, Serge and Buchla are 4U...
http://synthesizers.com/formfactors.html
A "standard" Frac Rack (PAIA, Blacet) has basically 10 "spaces" for modules. Each space is 1.5" wide. Your average Blacet module is 2 spaces wide. That leaves you with "ears" which are basically useless.
Looks like some people are making new Frac Racks/cases that are 11 spaces wide (Bug Brand, Dragon's Lair). 

dougcl 
Perfect answers. Thanks for the Frac width information. Any similar info on other formats beyond Frac and euro?
Edit: and then I followed the link you posted! Yay! I think I can safely "nevermind" this question. 

parasitk 
Well...Serge are 19" wide!
(sorry, 17" according to the DotCom page + rack ears!) 
