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
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.
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....
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.
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.
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.
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
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.
Pardon my seemingly confusion but genuine curiosity in this thread.
I’m assuming "DIY" is "do it yourself". However, when I check the first watt FAQ page http://www.firstwatt.com/faq.html there is a question specific to Do you really build them yourself? to which the response is Yes, until this last year, when my son Colin and nephew Sean began helping with assembly. I’m assuming that means Nelson himself is building the amp.
Can the OP or someone else please clarify if the first watt amps are something Nelson Pass or the end consumer is building? Thanks.
Both,the production versions of first watts and the "Diy" versions that Nelson gives his blessings to the Diy community.Different models were available as kits on the Diy audio website store.
I own a production version of the F7,and my Sit2 is a Diy version but differs from the production version in that mine is class a push pull and uses Nos Sony Vfet's that were made available in matched pairs,The pwr supply,case and the heat sinks are the same,It just doesn't say first watt on it.
I hope this clarifies your question.
I have heard all the first watts,except the F1,and I have owned the F3,J2,and the F7.I have built the F5 and the F5 turbo version from kits and my Sit2 "Diy" I bought used from audiogon.
The F5 is a little bit aggressive from the upper midrange to the highest frequencys and does tend to have a slightly hard edge to the leading edges of notes.It's basically a very picky amp that needs the best components upstream of it.
This Offcourse is highly system and listener dependent.
Pass Labs sells factory-built First Watt amps, as well as panoply of Pass Labs amps. A great source is Mark at Reno Hifi. Mine was built by a guy who took the plans that Nelson Pass has generously made freely available for DIY folks. This fellow then sold it to me for the "price of the component parts." That is, he did not build and sell it to me as a commercial endeavor for profit, which is antithetical to the intent of Nelson Pass in making the First Watt designs available to DIY guys.
I will hasten to add that if you are DIY-inclined person, the build of the F5 can clearly be done for a fraction of the cost of a factory-built version and is consistent with the desires of Nelson Pass. The rub comes when folks use his detailed designs to build his amps for commercial profit. Reselling such a First Watt as I acquired at the "cost of the component parts" is copacetic, so far as I know. Others can clarify this understanding.
Thank you. Your response does clearly answer my inquiry. And in fact, after checking some more, I failed to take note of https://www.passdiy.com/ which further explains DIY.
I'm wondering if anyone has Tried the High Output version of the F5.... The F5 Turbo. It outputs more power, or maybe the F6, wondering how they would compare.
Mark, You've got me itching to fire up the xa30.5 here tomorrow. Maybe the cool mornings here the last 4 days or so in Oaktown will accommodate me. . Its like my Pass amp just sits there draped in the t-shirt dust cover and patiently awaits -- thinking hmm. he's got those Emotiva monos on a lot lately-- he must be just be so distracted or preoccupied with something. lol.
I agree Mark at Reno HiFi is pleasure to deal with. I have a J2 powering a pair of M3 Turbo S Spatials (just sent in for Triode upgrade). Very happy with the results and looking forward to the 16ohm version.
Update: I earlier stated that the F5 runs as hot as a tube amp with four KT88 tubes. That assertion is clearly wrong. While the F5 runs much warmer than class A/B amps I have had, it generates nowhere near the heat generated by a robust tube amp. My HK Citation II toasted the self above that in which it resided, but with the F5, the upper shelf is unaffected. In conclusion, the F5 runs much warmer than a class D or class A/B, but far cooler than a tube amp. Whitestix
I'll bet you are getting very eager to complete the project and fire it up in your system. I wish I had auditioned a First Watt amp 5 or 6 amps earlier as I would have saved a lot of dough. Let us know how your masterpiece sounds when it is up and running.
Very nice and fun to build your own amp, I built both the F5 and the turbo version from the kits from the diy store but I wasn't quick enough to buy the nos Sony Vfet's that were available as matched pairs to build the push pull version of the stereo sit.
I work at a major airline as a Avionics technician for 29 yrs now and I work on some pretty complex stuff but It's not like the satisfaction I get when I build a Amp or do mods to my gear.
My best advice is triple check every little detail of the build including every solder joint.Be sure and be careful and take your time when it comes time to set the proper bias,allow proper warm up time and stabilization periods and make small adjustments until you reach the proper bias and remeasure after a period of time.Make sure you have very minimal DC at the outputs.
If you have any issue those experienced guys on the pass labs portion on the diy site can definitely help you.
Also the amp will need about 200 hrs of breakin time,mainly for the capacitors to sound It's best.
Let me be the first to say that I am very happy to hear you are enjoying the sound of your First Watt amp build! I have had a ton of amps in the past 45 or so years and the F5, with a pair of compatible speakers, is a sheer glimpse of audio nirvana. I will say that my F5 does have a bit of a bright edge to the leading notes of music --- no amp is perfect of course, but it reveals music in my recordings with a visceral impact that I have formerly not heard. I reckon after a couple hundred hours of burn-in with your amp, you will be even happier. Cheers, Whitestix
Gents, I just returned from hearing a $6K Bryston 4B3 amp in a pal's system and got home to my system with the F5 warmed up and am hearing artifacts to the same music I was just listening to in my pal's system that were absent in his system. The Bryston sounded excellent, but it didn't provide the inner glimpse of music that the F5 does. However, I am biased so take that into account.
I kinda think I got the sweet spot of the First Watt amps with my F5, but clearly their are nuances to all of them, particularly the more robust version of the F5 that our friend has built. At retail prices, the First Watt amps are reasonably priced, but if you are a DIY sort of guy, they would be an affordable way to have some of the best amplification available, so long as they are compatible with the sensitivity of your speakers.
The F7 is slightly more forgiving and smoother sound than any of the variations of the F5 that I have heard.
The F7 has the lowest parts count of any of the first watt amps. Comparing the F7 directly to my Diy sit2,I much prefer the Sit2 for it's liquidity,texture,warmth,midrange body meat on the bones and even more overall smoothness than any of the first watts,and I've heard them all except the F1 and Sit1 Mono's. The sit2 gets the closest in overall sonics that a good tube amp brings to the sonic table.IMO.
Now comparing my Sit2 to my LTA Zotl40,both driven with the MZ2S.I'ts going to take me a couple days of proper evaluation to sort this out.
All of the first watt amps need to be paired in a quality system,the better you feed them the better they perform.
Kosst, Great information! You clearly know your way around electronics. I am going to attend Burning Amp this fall down the road in San Francisco to meet "Papa" again. It is funny that you mention the KEF LS50's. I bought them shortly after they came out and drove them with a 175 wpc Plinius 8200 MK II integrated amp and the amp rather struggled to drive them properly. There is no chance a FW amp would be compatible with them.
However, with OB speakers like my Spatial Audio Holograms, DeVores, Omegas, etc, the FW amps are a great match it seems to me. Forget about Martin Logans and the like, but a pair of Klipsch speakers would sign with these amps. You and Kenny wisely pointed out in your posts the compatibility issues one needs to be aware of to get the the best performance from the FW variants.
My very simpleminded/layman observation is some amps put out more power as the load is reduced which implies a near constant voltage delivery. Others behave the opposite which seems to imply a constant current source. The former is better for low impedance loads whereas the latter better for higher impedance speakers.This is also evident when comparing solid state and tube designs. I know I’m stating what most folks already know but a good layman view of the amplifier differences and how to find matching speakers.
Unless you are talking about the Zotl40 which has the output tubes directly coupled to the load taking transformers and capacitors completely out of the equation.
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
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