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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
 
Whitestix,

I can relate to the F5, I built the F5 and the F5 turbo version from the kits that were sold on Diy Audio.But know I have a Diy version of the Sit 2 but mine is class a push pull using Nos Sony Vjeft's and produces 40 watts into 4ohm.I also own the production version of the F7 and It's very nice as well.They all run hot and that is just the nature of the beast,but the sound qualities make up for that as you are finding out.

I'm like you I was kinda enamored with the latest Class d amps but after trying several of the latest they don't have all the sonic qualities I desire.

Best,
Kenny.
dodgealum
1,398 posts
 
Anyone know if there is a version of the SIT-1 monoblocks available that will put out more watts than the production version? I'd be interested in these if there were a pair that put out 40 wpc or thereabouts....
whitestix OP
684 posts
 
Kenny,
We evidently traveled the same path with the Class D amps. I do think they have a lot to commend themselves, but after listening to them for a few weeks, something was missing.  The lacuna of sound is only apparent by comparing it to other amps. Interesting other SS amps you have.  As I mentioned, I have admired Pass gear just like I do fancy car that drive by, but this oppty to get a well-constructed F5 ranks as the all time audio score of my life.  

I swapped my McCormack amp back in place of the F5 after the post above and immediately had a frown on my brow!  It is just two-dimensional compared to the 3-D presentation of the F5.  Folks on this forum might note that I have never had a piece of gear that I did have something good to say about -- very little gear now days sounds bad, I am literally awestruck with the sound of my speakers with the F5.  

In terms of the heat generated by the amp, it is rather like having big tube amp... but never having to bias it or replace pricey tubes.   Cheers. 
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.
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