2. amps-preamps
  3. 1313116554

XA 30.5 or mod S/500?

I've been watching the 'Gon fruitlessly for some time to get a Threshold S/500, "late Series II w/Optical Bias" (per Jon Soderberg, this is what he needs in order to do his modification to produce a Class A one-chassis SA/1 "clone" [my word, not his]). I'm beginning to wonder if a Pass XA 30.5 might not be equivalent or better sounding; I know they're easier to find. Unless I get lucky and find an already-Soderberg-ed S/500, the cost of amp and mod might even be approaching the price of a used XA 30.5(?). Either amp will be used with a FET 9 preamp. Speakers are currently Vandersteen 2CEs, but contemplating future purchase of 3A Sigs, or Maggie 3.6s, and a REL sub. Anyone heard SA/1s AND heard XA 30.5? Thanks.
Ag insider logo xs@2xcippoliner
danielk141
489 posts
 
Cippoliner,

I believe your Threshold preamp is not balanced.
As long as your using this preamp, you will not be using any truly balanced amp to it's full potential.
An Adcom GFP 750 would be an instant upgrade, cheap.
unsound
7,329 posts
 
Like your Threshold fet 9, the Threshold S/500 Series II amplifiers are single ended. The Pass XA 30.5 is balanced, and would benefit from a true differential balanced pre.
Ag insider logo xs@2x
cippoliner OP
4 posts
 
Thanks to all for relating your experiences and advice. I'll have to digest it all in light of potential costs - the cheapest Passes I've seen on the 'Gon were already more than I HAD been thinking of spending (you can see from my system that I've not got a high-zoot kinda rig). However, I've heard so many accolades about the Pass XA.5 series that if I don't find a good price on a Threshold to send to Jon soon, I may have to bite the Eichmann and go upmarket (won't be any unit beyond the 30.5, though, due to my budget). Thanks again to all.
danielk141
489 posts
 
Cippoliner,

If you live somewhere where you can use true Class A amps,
you should try a pair of Pass Aleph 2s. These are not balanced (even though they have balanced & single ended inputs). I believe they will mate well with your current preamp.
These list used between $2500.00 & $3K. They sell when the price is close to $2500.00.
These sound very good, to me. I've had mine for 9 years.
liguy
228 posts
 
The big advantage of the XA30.5 is the SuSy [super-symetry]circuitry that Nelson patented. Here is the url:

http://www.passlabs.com/pdfs/articles/susy.pdf

I don't know if the XA30.5 will drive all the speakers to volume levels acceptable to you.
More to discover