THE amp for low-power tube aficionados

[djk]

(Who don't want tubes)

Available factory assembled, or as a DIY effort using less than $10 worth of transistors.

(the reviewer) "approached this assignment unapologetically from the 'tube guy criticizes transistors' angle".

A transistor amp that should appeal to all lovers of glowing glass and allow those who can't go there (because of heat, kids, pets, expense, impedance issues, reliability issues) to enjoy its sound without the liabilities. A price that's lower than any similarly powered tube SET and eliminates tube aging, bias drift and tube rush/noise.

"There's nothing now, in the wake of the review, that compels me to reinsert the 2-watt Yamamoto Soundcraft A-08S single-ended 45 amp."

http://6moons.com/audioreviews/firstwatt4/f3_3.html

Has Nelson Pass finally fashioned the transistor amp to make the thermionic crowd cry uncle?

[tigerwoodKhorns]

This sounds great from the review and I'm all for a test drive. But these things are not $10 worth of transistors:

http://www.marksammut.com/List.html

From the article, it appears that the F3 is the only one to have if you are after SET-like sound. Try $2400 for the F3's. I would need 4 of these. At $4800 it is not worth the risk. When the schematics for the F3's become available, I'm all for a weekend project building a quad of them if the parts are cheap. I love the ides of SET like sound without the heat (I live in the desert) and I love DIY projects but I'll stick with my class t amps untilo the F3 becomes a DIY.

When will the schematics be available and where do you obtain the JFET transistors?

Chris

[Daddy Dee]

djk,

I hope you take on the DIY project. 6moons thinks these things are the cats pajamas. I'd love to hear some. The turn key amps aren't cheap for sure.

[leok]

Very interesting. I wonder if it was the pwm scare that put a little

low power religion into the ss analog camp. It's good to see (and hear)

them finally clean up the mess they've been delivering for 40 years. I

know, there were a few good ones all along, but I never found them. now

there's the Crown D-45, several Gain Card/Clones, and for those with a

few $, the F3. Real choices for good ss.

Leo

[kev313]

This has been an interesting line from Pass with the F1 and 2 getting similar reviews. Very strong words from Srjaen tho about giving up the Yamamoto since RAVING (over the top even by reviewer standards) about it 3 mos. ago and putting it on his best of 2005 list. That element is actually one of the things that turns me off to 6moons. Some of their better writers (Coleman, J. Day and Srjaen) seem to find a new absolute best with each and every review and either buy it for their own system or indicate that they would if funds were available. Maybe reviewing gear that they have an interest in is a review criteria, but the end result is that it turns the site - which is quite enjoyable as it offers reviews of some unusual gear and is really well written and photographed - into a flavor of the month club.

[tigerwoodKhorns]

I'd be very interested in a DIY F2 project if it performs as stated. Now my questions is does this guy just recommend everything he hears? This reminds me of reading Stereo Review in teh 80's and they never had a bad thing to say about anything. Kind of useless.

Anyone here interetsed in building these? I'd like to share some notes.

Chris

[mike stehr]

First watt is about all this thing can muster.

Suprising boogie factor for what it is, it actually has a little bass.

[djk]

This is the F3 we're talking about. Not too many out there. Untill last week the Lovoltec J-FET was almost impossible to get, no distribution exists in the US. I have samples I received from Lovoltec back in September, and I know Nelson Pass does, but they are quite scarce.

The basic design is at the Nelson Pass site, along with the write-up from AudioXpress magazine. The actual F3 schematic will be released after the first 100 hand-made units are sold. Audio Video Logic in Des Moines IA is one of only two dealers for them.

The J-FET costs less than $1, and the IRF part that cascodes it is also less than $1, so my estimate of $10 for a stereo amp complement of transistors is actually high. The production F3 has an active current source(probably the Aleph type), so that is another $1. Still under $10 of transistors for stereo.

New designs are coming, my guess would be a bridge design with the X feedback scheme (SuperSymetry). That should really give the power a boost.

[djk]

Best guess as to what is in an F3

http://www.diyaudio.com/forums/attachment.php?s=1f030f0867f3af794499fe38485de15a&postid=818391&stamp=1137460798http://www.p-audio.co.uk/products/db_product_2_5_pa-d38.htm'>

[sunnysal]

This looks like it is going to be a great amp. I am anxious to see the full Schematic after he sells the first 100, pass is a great guy to support the DIY community! I am sure he will come up with a bunch of evolutionary tweaks to this circuit (supersymmetry is one I expect we will see as dennis mentioned) a la zen...what a wonderful world we live in.

When the time comes I just need to find someone who wants to make me one, LOL! regards, tony

[tigerwoodKhorns]

djk wrote the following post at 01-17-2006 11:54 AM:

Best guess as to what is in an F3

http://www.diyaudio.com/forums/attachment.php?s=1f030f0867f3af794499fe38485de15a&postid=818391&stamp=1137460798

DJ,

The link syas that you need a password. Can you post more info (a schematic and any text available) or a link that can be accessed.

Thanks,

Chris

[djk]

You need to register and get a password to view images.

The AudioXpress article is in the Pass Labs discussion, the actual F3 is not yet published.

The link to my best guess will click through when you get registered(takes about 2 minutes).

http://www.passlabs.com/np/ZV8_POWER_JFET.pdf

[tigerwoodKhorns]

Thanks for posting. I was able to get to this article from homw without a password but cannot find the link.

I'm a little afraid of getting a set (uh pair) of SET amps because of the heat that they throw off. Not a good idea where I live. But if I can build a set (uh pair) of these for a few bucks in parts, I'll give it a roll. Why not? The manual says that they use 200 watts so I figure it is like having a 200 watt heater in the room.

Where do I get the parts from, Digitkey? (sp??)

Chris

[djk]

Right now the only USA source for the Lovoltec J-FET is Grey Rollins. See thread here:

http://www.diyaudio.com/forums/showthread.php?s=f890748857e7df387d9c81f1f6a67a35&threadid=68401&perpage=10&pagenumber=37

Most of the other parts may be had from Digi-Key. You might try Parts Express for a transformer, or Mouser.

[tigerwoodKhorns]

I found it. When the F3 schematic is released I will build one. I just can't resist. I'll just have to limit to winter use.

Chris

[Chris A]

Has Nelson Pass finally fashioned the transistor amp to make the thermionic crowd cry uncle?

I don't know about that question, but I can say that this amp sounds very good on K-402s with TAD TD-4002s - amazingly good, in fact. Other than list price (...and I got mine second-hand for a lot less than list...), I'm wondering why it is that others on the forum haven't also tried them out.

These First Watt FET amps appear have all the advantages of tube class "A" single-ended designs, and almost none of the disadvantages of tube including very high THD, output-transformer coupling, and very low overall gain of their tube counterparts. In addition, they appear to have no maintenance required, and a very long MTBF.

My $0.02.

(BTW: sorry for resurrecting an old thread, but there doesn't seem to be other discussion on Nelson Pass's JFET and MOSFET amps on this forum. This is interesting in view of Klipsch's market share of consumer horn-loaded speakers. [*-)])

Chris

[djk]

The Lovoltech part is now unobtainable,

BUT,

IXYS now has some depletion mode parts that are similar, and will handle a lot more power as well.

See some of the discussion for the 'Burning Amp' at DIYaudio.

[T.H.E. Droid]

gosh, and only the price of a used car. unfortunately, I'm never surprised at the gullability of audiophiles and their willingness to to pump huge piles of cash to dubious characters like Mr. Pass and his dealer cohort. One should be clued in by the reviewer's disturbing monstrosity of a system which I can be sure costs far more than it can possibly deliver.

[Chris A]

gosh, and only the price of a used car.

I didn't know that you could buy a used car for that little...[]? 1980 mint Yugo?

I'm never surprised at the gullibility of audiophiles and their willingness to to pump huge piles of cash to dubious characters like Mr. Pass and his dealer cohort.

Dennis (djk) is pointing out the DIY version, whose parts are a few $s, and that is something that Nelson Pass clearly supports and encourages - he actually wants innovative and knowledgeable competitors (not that many have taken him up on the offer...).

Nelson Pass sold 100 units--which apparently went fast--then released the schematics--a policy that he never fails to follow for his "First Watt" company (this is NOT "Pass Labs") that he runs on the side with his son and a son's friend. Pretty cool, I'd say. I wish that I could do that for my son and friends--as well as he has done.

I don't begrudge paying someone for innovation, quality and outstanding performance not available elsewhere (...sounds like PWK's M.O. ...), because this amplifier exhibits all three characteristics. I'm delighted with paying him for that. If I want to make clones for myself, that is apparently okay with Nelson Pass.

It seems to me that the really big electronics giants like Sony, Yamaha, HK, Philips, GE, etc., don't do that--at least in my experience...

Chris [8-)]

[djk]

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