Introduced in June but, as far as I know, there has been a delay in actual shipping, the newest FIRST WATT F8 amplifier...

As you can appreciate I think from the schematic below, this is another exceptionally small parts-count power amp by Nelson Pass, with just 3 active devices (2 x JFETs + 1 x MOSFET) per channel, for 25 Watts into 8 ohms (15W into 4 ohms).

It is a design variation (current feedback vs voltage feedback) & a "modest improvement" (Nelson Pass) on the best-selling FIRST WATT J2 amp (~2016) - fewer transistors, higher Damping Factor, better HF response, lower distortion.

But better sound?...

" You will have noticed, I enjoy amplifiers with a little personality. They don't have to measure perfectly, they just have to sound good. This is a simple little Class A amplifier with a very nice personality, and I hope you like it. " (Nelson Pass , 10 Jun '20)



(Simplified schematic.)





See - - Nelson Pass - FIRST WATT F8 Power Amplifier description.

MSRP - US$4000

DarkLantern blog - darklanternforowen.wordpress.com

mmm cant fault the designer credibility or anything but this doesnt make sense to me. A low parts count, low power amplifier for $4k USD ?

You pay for the sound and the hand of the master, not the parts count. For many of his amps the low parts count is only possible by careful matching and I imagine the rejected parts count is considerable. An anecdote from Saint Nelson might help. Whilst many designers opt for heroic power supplies, vanishing distortion and a dampening factor that would silence a fish wife, Nelson designs for sound. He notes that when we go to a restaurant we are likely to ask for Perrier, Wairewa or tap water - and wine. No one asks for distilled water and so it is with amplifiers. SET amps are a good example.

Reminds me of this old wives tale about an engineer who fixed something by hitting it with a hammer and sent a bill for $1000.

Hi-fi products (& most commercially sold products) aren't priced based on materials (+ a mark up). Or even materials + manufacturing cost/labour.
There's many other costs invested into bringing a product to market - see Steve Guttenberg AUDIOPHILIAC discussion on this thread.

In the case of the FIRST WATT F8, aside from R&D / intellectual value, there's also factors such as limited production qtys & the unobtainium value of the long OOP transistors.

I have a hi-fi pal who says he's always suspicious of hi-fi manufacturers who put an inordinate amount of work/cost into the product's cosmetics

DarkLantern blog - darklanternforowen.wordpress.com

looks sell

Let’s remember that he publishes and releases for free a lot of his designs for the DIY community as well. Some of the same skepticism was heard when Junji Kimura released the gaincard due to the limited number of parts as wel but how do you account for the long development costs? Nelson Pass is really a legend and I love his philosophy: “Simplicity is a common element of the best and most subtle designs. It is preferred for purely aesthetic reasons, but also because fewer elements color the sound less, and lose less information. Many audiophiles, including myself, are willing to sacrifice other areas of performance to achieve the intimacy with the sound available through a simple circuit.”

What’s going on, you are all making sense!

AMR-iFi R&D

Thanks for the (re) introduction to Nelson Pass, First Watt, the DIY aspects & etc.
I'd been aware of the name for years (decades?) but hadn't really looked into him or his work.
www.firstwatt.com/index.html

So nice then to read some articles.
Well written reminder tutorials like

www.firstwatt.com/pdf/art_leaving_class_a_2019_redux.pdf
www.firstwatt.com/pdf/art_the_square_law.pdf

So nicely and clearly written.

Perhaps I shouldn't yet cut my hair so fast, post CoVid lock-downs, as I was thinking to.

I almost did!

;=})

www.youtube.com/results?search_query=almost+cut+my+hair+crosby+stills+nash+young

But you know all this, and that.  Never mind

I have in my stash here a few of the early topology capacitor output transistor amp types, so it's interesting.

I'll study further.

Why not ?

Thanks again!

Gosh! ;=})

Herb Reichert (STEREOPHILE 3 Dec '20) reviews the FIRST WATT F8, comparing it with:

- FIRST WATT J2
- PASS LABS XA25
- Line Magnetic LM-518 IA

All 22-25Wpc amplifiers.

DarkLantern blog - darklanternforowen.wordpress.com

Strangely enough I have been thinking of this to use as a solid state amplifier, to compliment my SET tube one. Got to save up for it though

Vice deputy sub assistant at Turned On Audio

audiosatori.wordpress.com

Here are some of Nelson Pass's responses to a question about his favourite First Watt amp. They don't include the F7, SIT-3 and now the F8. This link (http://www.firstwatt.com/prod.html) gives a summary of his earlier amps (e.g. F1 / F1J and F2/F2J) and F4. Of interest he offered to update original purchasers for the F1 and F2 (both are current amps and the F1 has an output impedance of ohms 80 BUT prodigious bass and can only be used on wide-banders or speakers with series crossover) and replace the output MOSFETs with JFets. For free! (More information on current source amplifiers can be found on the First Watt website - search products). The only FW amp that I didn't like much is the M2 which sound like a typical p-p valve amp without the lushness. The SIT-3 in my opinion is the pick of the bunch but of course I have not tried the new F8.

You may not be able to name a favorite child, but a parent always has an
opinion about the characteristics.

"I always keep in mind that someone else's experience will not duplicate mine.

Speaking strictly of the FW amplifiers, my listening is generally restricted
to 90+ dB sensitivity and no tough loads, as the amps are low power and
typically low damping factor.

F5: Dynamic, accurate, a little unforgiving. On speakers with peaks in the
top end, it will reveal as too bright and annoying. On speakers with a slightly
diminished top end, it adds a little sparkle, this in spite of being flat out at
high as 500 KHz. Good control - if your speaker is a little boomy, it will tend
to tighten it up. Overall, probably the most neutral of the FW amps. It will
drive 4 ohm loads without particular issues. Oh, and it does sound very good.

J2: A more relaxed version of the F5. Decent bottom end control, a warm
midrange, excellent depth. Overall, one of the most popular pieces. Still
in production, it best hits the mainstream taste of the FW audience, probably
because it delivers a consistently pleasant sound. Not intended for 4 ohms
unless the speaker is particularly efficient, which is rare.

F3: An even more relaxed version of the J2. Not much power or control. Popular
with Avant Gardes and other horn drivers, and does smooth out the peaks in
the tops of a lot of full range drivers. Used to be my favorite for the
Feastrex and Lowthers over the F5, now has to compete with SIT-1 and
SIT-2 for that spot.

M2: Some people just like the sound of push-pull output stages, transformers
and no feedback, and this is what the M2 delivers. Limited bandwidth and
control, but a pleasant sound, and it will drive 4 ohms. Has a bit more noise
than the other amps due to hum pickup on the input transformers, although
nobody seems to mind very much.

SIT-1: Broke the mold in the ability to play with the load line of a no-feedback
Common Source amplifier that still has any damping factor. A very unique
harmonic signature that can be dialed in to taste - Lots or little of 2nd
harmonic of either phase. Literally the sound of one transistor clapping -
without the input buffer (which no one seems to use) there is only 1
transistor in the amp. Has tremendous clarity and depth, depending on
setting, spectral consistency with warmth and detail. It allows you to focus
on a single instrument in an ensemble, almost to the exclusion of all else if
you want. This is the amp that convinced me that absolute phase is not
such a subtle factor.

SIT-2: A SIT-1 with a constant current source load instead of a stack of
power resistors. More efficient but similar to the SIT-1, it is set at a single
load line setting, so is not quite as flexible or fun.

Sony SIT amp (the big one shown at CES): This is a push pull VFET follower
output stage. Dynamic, high power, good control, drives the crap out of 4
ohms. It was voiced around AR-1's, and shows them to good advantage. It
is primarily 3rd harmonic in character, so the aspect is a little different than
the single ended SIT designs, but it is very impressive, detailed and easy to
listen to.

You realize that the original VFET (SIT) designs from the 70's were not
Class A and had more complex gain paths. I speculate that things might have
turned out a little different if they had gone for simple Class A designs that
play more to the strength of these parts.

Of course tastes have changed over time."

That was really interesting, thanks peter0c.

A couple of recent interviews with Nelson Pass (Steve Guttenberg) focusing on the First Watt F7, F8 and SIT 3.


In the second video Nelson divulges that the F8 has current feedback and describes the evolution of his amps, all of which apart from the F7 have second order harmonic characteristics.
I think Steve's interview with him on the distortion characteristics may have been posted before.
Here it is again.
He is very approving of the Magneplanar LRS speaker, apart from with the F7. The F7 is his preferred amplifier with multi-driver speakers.

Indeed all the low-power (25Wpc or less) FIRST WATT amplifiers from Nelson Pass offer different personalities, eg....

Steve Guttenberg AUDIOPHILIAC has assembled all the currently still-in-production FIRST WATT amplifiers & compares the new 25Wpc F8 with the other (3) FIRST WATT designs.


Compared to the FIRST WATT SIT-3 (18Wpc, driving Klipsch Cornwall IVs):

"the bottom end...is deep, powerful...bigger & ballsier than the F8 "

" darker, richer, fuller bodied but a less transparent, agile sounding amp. "

The F8 - " more 'accurate'...communicated rhythms better. "


Compared to the FIRST WATT J2 (25Wpc):

" (similar but) the F8 is considerably more transparent than the J2. "


Compared to the FIRST WATT F7 (20Wpc):

" The F7 is...very relaxed, open...3D imaging is really incredible, better than the F8. "

(The J2 is also significantly less costly at US$3000)


Additionally, Steve has the lowest powered PASS LABS XA-25 (25Wpc Class-A P-P, US$4900) amplifier in-house:

" It just feels considerably more powerful than any of the FIRST WATTS. "

DarkLantern blog - darklanternforowen.wordpress.com

Three extremely interesting interviews with Nelson Pass. His design philosophy for First Watt amps starts with the selection of output devices based on their electrical characteristics (e.g. transfer curves) and subjective sound characteristics, and the seemingly automatic selection of a J-FET input device. Some FW amps have readily obtainable output devices but Nelson has a mortgage on SITs and power Toshiba J-FETs, unsurprisngly used in his best amps. Since FW amps have a low parts count Nelson doesn't emphasise the quality of the components used, rather ensures very tight tolerances and compatibility. Other decidedly not mainstream high-end designers (mostly valve) e.g. Audio Note empahsise parts quality (Black Gate capacitors, silver wire in the signal path, Craddock resistors) but seem to put little effort into circuit designs apart from triple C-cored output transformers, all of which are elderly and readily available. In contrast Shindo circuits are unavailable and presumably a trade secret. Shindo also uses exotic parts as above (including unobtainium F2a valves) and avoids plastic and some other materials. Berning amps use readily available parts but have a very exotic circuit, the gain coming from radio frequency amplification. Lamm amps have an exotic circuit, use expensive parts and Russian output tubes. So is Nelson the only ss designer to go out on a limb, at least in his FW amps if not the mainstream Pass Labs amps? Interesting factoid. Nelson has sold about 2k FW amps over 20 years but sells 4 to 5k Pass Labs amps every year.

Sept 4, 2020 22:26:42 GMT 12 cartridgeguyonline said:

mmm cant fault the designer credibility or anything but this doesn't make sense to me. A low parts count, low power amplifier for $4k USD ?

A bit like the MONA LISA.  "All this money for a bit of paint and canvas..."  

I think $4K for (potentially) a worlds best 25W amp - brand new with warranty - is reasonable, as far as hi-fi exotica goes.

We owned the FIRST WATT J2 for many years and it was a sublime amp that - to our ears and in our system - was only bettered by the very best of tube amps.

I'd love to hear the F8!




(Sorry I couldn't get this photo to align.  I really tried... but it wasn't having any of it!) Edit -fixed.

Here is the link to Dick Olsher's (The Absolute Sound, 15 6 21) review of the F8 and a handy comparison to the SIT-3. www.theabsolutesound.com/articles/first-watt-f8-stereo-power-amplifier/2
There is little else to be said about this little gem except that it would be at least NZ$6.5k landed. In my experience most First Watt amps benefit from having a valve preamp. Then there is no going back.

Jul 19, 2021 11:56:53 GMT 12 peter0c said:

Here is the link to Dick Olsher's (The Absolute Sound, 15 6 21) review of the F8 and a handy comparison to the SIT-3. www.theabsolutesound.com/articles/first-watt-f8-stereo-power-amplifier/2
There is little else to be said about this little gem except that it would be at least NZ$6.5k landed. In my experience most First Watt amps benefit from having a valve preamp. Then there is no going back.

I agree re a valve preamp, however a valve preamp with a low output impedance, sounds better with FW amps. This was suggested to me and I tested it out with 2 different FW amps and found the same.

I agree with that also. I use either a Transcendent grounded grid or an Ecofan 12 tube with 600 ohm output.

Jul 19, 2021 22:49:56 GMT 12 peter0c said:

I agree with that also. I use either a Transcendent grounded grid or an Ecofan 12 tube with 600 ohm output.

If you can try a pre with 100ohm output imp. I had an AM RT-2 pre (600ohm) and a Herron VTSP-3 (100ohm) and with my Yamamoto amp (100k input) the RT-2 was superb and so was the Herron. Different flavours only. The RT-2 with my F6 was disappointing where the Herron was excellent. 
Hence I kept the Herron and sold the RT-2 for that reason.

I found the same with my previous F5 where the DAC feeding directly into the F5 was superior to the preamp I had at the time (600ohm).

I could lower the output impedance of my preamp but that would also lower the output voltage. The SIT-3 has only 11.5dB of gain so needs a little help - i.e. about 3.2 volts to reach full output - but unlike the SIT 1 and 2 has a commendably high input impedance.

The attached video is a teaser for the new First Watt SIT-4 which has no release date. www.theabsolutesound.com/articles/introducing-the-first-watt-sit-4-power-amplifier-2/ There is no information on it's circuit other than the use of currently available V-FETs (aka SITs) and the likelihood that it will come out in monoblock form. Nelson bought one thousand silicon carbide SIT's (as used in the SIT 1, 2 and 3) from SemiSouth which is now defunct whilst the SIT-4 uses Tokin V-FETs.

There is a V-FET amp on Trade Me (Listing #4229837443) using the original Sony V-FETs (2SK82 and 2SJ28) which are now also unobtainium and NOS Toshiba input J-FETs. The origins of this amp is not obvious but I note that it has a similar casing to all of the First Watt amplifiers but the circuit board has a few more components than any of the FW SITs. It could be an Absolute Audio SIT A-15 which has a Tokin - V-FET / SIT, and like the one in Nelson's amps was probably intended for switching functions in hybrid cars. Here is a link: www.stereonet.com/forums/topic/538434-absolute-audio-labs-sit-a15-power-amp/ The TM link is www.trademe.co.nz/a/marketplace/electronics-photography/home-audio/amplifiers-tuners/listing/4229837443?bof=LHXSQ1XE. There is a 'buy now' of $1750 which I think this is a fair price. If I didn't have a SIT-3 I would buy it! The overheating issue is an easy fix. I use two 12 volt computer fans in series and powered by a 6 volt wall-wart to blow air over the cooling fins. The reduced voltage means no noise and you only need to maintain an airflow rather than a hurricane to cool the amplifier fins.

There was also a Pass Labs XA25 amplifier recently on TM

www.trademe.co.nz/a/marketplace/electronics-photography/home-audio/amplifiers-tuners/listing/4214931286?archive=1&bof=dRdxt5cc

I think I'd prefer to do a PP version myself, and I have a chassis that looks close to that in appearance.