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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
kdude66
1,200 posts
 
No,they would be push pull topology like my stereo version to have 40watts into 4 ohm.

The Production Sit1 mono's are single ended and only put out 10'watts.

I also own the F7 and It's still being produced as far as I know.

Kenny.
kdude66
1,200 posts
 
Whitestix,

I'm glad your are liking the F5,Maybe class d will be there someday.

All the First watt amps are very special and I really like mine also,I will be comparing them to a Linear tube audio Zotl40 paired with a MZ2s preamp,I've only had it for a few days but I like what I'm hearing so far.

Best,
Kenny.
dodgealum
1,398 posts
 
kdude66 would love to hear the details of your time with the LTA equipment in comparison with the First Watt stuff. I'm interested in the LTA stuff as well.
charles1dad's avatar
charles1dad
10,229 posts
 
Whitestix,
I’m not surprised that the Mc Carmack sounds 2 dimensional vs the First Watt amplifier in direct comparison. I just happen to believe that lower power simple circuits running exclusively in Class A offer superior sound quality. Tube or transistor, both excel with this approach.

Hi Kenny I also look forward to your listening impressions of the well regarded  LTA ZOTL amplifier compared to the  First Watt amplifier.
Charles
larryi
3,716 posts
 

I have not heard the F5, but, I have heard their J2 model in my system (a loan from a friend that I had for two weeks) and liked it very much.  It delivered the liveliness, expansive and enveloping soundstage and good low-level dynamics that is usually exclusive to tube gear, particularly, low-powered tube gear.  The only thing that was sort of "solid state" about the sound was the slightly hard edge to the initial attack of notes.  I also found the music to be engaging and held my interest in a way that I don't experience with other solid state amps (they somehow sound lifeless).  The J2's sound MUCH better, to me, than any Pass amps.

I have also heard a friend's DIY project amp that is a First Watt design.  I believe it is one of the SIT amps.  I heard it in his ultra high sensitivity system.  That amp, too, is a winner.

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