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DIY Pass Labs First Watt F5 amp impressions

I recently acquired a well- built DIY First Watt F5 amp for the cost of the parts, which is the understanding among those that build the designs that Nelson Pass has made available to the DIY folks.  I have been using a McCormack DNA .05 Deluxe amp and a Don Sachs 6NS7 tube amp to drive my Spatial Audio M4S Turbo S Hologram open-baffle speakers, which are ~94 db efficient.  I have raved about the McCormack amp on this forum, but swapping the F5 for the McCormack amp has been a  sheer revelation.  I have had dozens of tube and class A/B amps my system over the past 4 decades, as well as a couple of very good class D amps recently, but the tonal accuracy and 3-D representation of music with this F5 is simply stunning.  It is offers a glimpse into the inner details of the music.  I do not have the superlatives to describe the musical enjoyment of the addition  this amp provides to my system.  I am put off the heat his amp generates -- similar to that with a tube amp with a quad of KT88's, but it is a fair bargain for the most ruthlessly revealing sound reproduction I have ever heard in my system.  My regret is that I waited so long to have a Nelson Pass-designed amp in my system.  If your speakers are quite efficient, there are several variants in the First Watt line of amps that might be a great match for your system.  Mark at Reno Audio is the guy to help you sort out the best amp for your needs.
Cheers, Mark
whitestix
whitestix OP
386 posts
 
Kenny,
Did I miss your post regarding your impressions of the LTA amp you acquired?  Kosst, I am using a Don Sach's 6SN7-based preamp with my F5 and can say that it is a match made in heaven.  I have plenty of gain with my Spatial Audio OB speakers and zero noise.  Mark
kosst_amojan
2,095 posts
 
Believe it or not, the old Marantz 2252 isn’t feeding the F5 a bad sound. I totally recapped the thing about a year and a half ago with the best ELNA and Nichicon I could find. The pre-amp stage is designed to play well with a 47K ohm load which the F5 has. The soundstage is wide and enveloping as well as deep with some decent fluidity and speed. My stack sounds better than the Cambridge Audio stack I auditioned these speakers on. I’m sure it helps that the regulated supply isn’t driving an intermediate gain stage in the amp with anything more than idle current. I’ve got some stacked films for the coupling caps I bought with an order but I just haven’t opened it back up.
How are the highs with that pre-amp? I’m worried a little about that. It’s not bad with the Marantz. That old Marantz sound I guess!
skiroe's avatar
skiroe
86 posts
 
It took me since last I checked in here on this thread to fire up my XA30.5  (just now-- I was prompted by reading)   and always so refreshing to hear it sing.  Not even warmed up at this moment and can see into the music so much more viscerally than my everyday Emotiva monos.     Just off the top of my head because I just now was curious what the new xa25's looked like and noticed that the face is more in line with the no fancy business  like my XA30.5  meter front and beautifully designed sculpted aluminum.  Now Im wondering if that brings down the cost a bit on the XA25 as opposed to what the XA30.5 went for new?   I do like the face of the XA25 in its clean industrial look.   It specs at a bit less power output than the 30.5.     I will say that with my Harbeth 7ES-3 monitors  a leading bright edge is not a part of the sonic "display".   And at the moment I'm simply tuned into FM .  Important to denote though that my tuner is not run of the mill ---which is important obviously to have a be able to deliver a good signal  to begin with.  And my gone through Mitsu DA-F20 receives signal via rooftop FM only rotatable antenna from local college station in the bay area.   This quality of sound would not be possible without certain factors in place.       Will be a sad day for a big part of my listening experience when I move as then it will be via internet for any FM..    Then it will be more digital /and maybe some vinyl  can be brought more into play.  
kosst_amojan
2,095 posts
 
I'm getting some brightness especially since I played with the distortion. I need to play with that a little bit more and find the right balance of second and third. It's nice to have an amp you can do that with. 
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