Pass Labs F4

For the three and more legged things
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pre65
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#16

Post by pre65 »

Hi-had a quick look at the web site.

Looks like 18V-if so how about these ?

http://cgi.ebay.co.uk/18-18V-400VA-Toro ... dZViewItem

He is a known supplier to some of us ! (Me,Andrew I,DTB )
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ed
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#17

Post by ed »

thanks for that Ian. For some reason I thought yours were 400va, which would have sorted me straight away.

I am in the process of moving the trannie so that its mounted vertically on the front panel. I can still measure a tiny bit of rf on the output which I can't hear at the mo, but sure as eggs is eggs if I ever connect up to Steves baffles again it will be soooo obvious. My mate Nelson :wink: said I was a fewl to mount it on the back panel anyway.....

As it seems too trixy to get a 400va clairtronic in UK I'll resolve to drop the bias a tad if the heat continues to be a problem.
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#18

Post by ed »

Hi Phil

thanks for the thought...Been watching those motor runs for a while. They were even there when I built the F4. However, my current clairtronics were £19 which fits perfectly with the under £150 amplifier. I don't want to break the philosop[hy otherwise I don't have an argument when faced by the 'must be valves' diehards :lol: .

The motor runs are $39 and when youve factored in postage then the excise brothers get interested and before you know it you've shelled out £50...
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#19 Another F4 starts

Post by IslandPink »

OK chaps , I'll barge in briefly here .
Just got a box of stuff from Rapid , with some bits for my forthcoming Pass F4 bass amp. There are two 160VA 18+18 toroids in there, I'm doing separate left & right power supplies .
Don't expect a whirlwind of activity on this .
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#20

Post by IslandPink »

Nick , did you say you had a link to 'Heatsinks R Us ' or something ?
:D
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#21 Bits

Post by IslandPink »

A couple of kind people in US and France sold me some surplus bits .
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#22 F3 and F5

Post by suds »

If any one is looking for F3 or F5 Amplifier / PSU PCB's I have few of these.
Spec : FR4, 2mm PCB, 70Microns Copper, Gold Plated, with Solder Mask and Legend.

since I am not able to attach image, or link, will mail you all details..

~suds~
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#23

Post by Dave the bass »

Slight thread detour, sorry, but at the next 'fest could some of you bring examples of these Passlab amps along? I'd like to hear a couple if poss.

Ta,

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#24

Post by Mike H »

Good idea. :D

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andrew Ivimey
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#25

Post by andrew Ivimey »

I have been impressed with the Fs we have heard. I may still want to chuck Ed in the pond but that is only a friendly gesture.

A year ago or so I bought an 'F5' kit from Analogmetric. I thought I was getting just the PCB but the mono pair arrived with all the bits and bobs, minus the heatsinks. I built it, blew a blue led,replaced it and got it up and running. It worked, it liked lots of preamp input and sounded clean and clear but it ran cool. even though I'd biased it as right as possible and really it didn't do the job... for some reason. The kit may have taken as inspiration what Nelson Pass called and F5 but it was quite a bit different even though it was push pull. Its in the shed somewhere.

My point though is that I read somewhere that the chap who owns Analogmetric (a name like David Wong but I memory is poor) had actually signed some sort of deal with the chap (see, I really can't remember names!) who invented those OTL Transcendendant amplifiers and in particular a Grounded Grid Pre-Amplifier. I've read and liked what I read this chap's book with all his circuits in and it is a jolly good read. Nelson Pass's circuits and explanations are all there on the Web and are an excellent read, too. But I haven't chased down the truth as to whether manufacturers in China really have done a proper deal on copyright of the many designs that are available, for a song, on eBay. This worries me.
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Dave the bass
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#26

Post by Dave the bass »

OTL man is Bruce Rozenblit I think.

It was the first book our Neal recommended to me on the first day we all met at Heathrow.

I think Scott had a big Pass labs amp, I can't remember it's sound though, hence 'plea' :-)

I'll bring the ducking apparatus for Ed anyway! You duck him... and I'l grab them curvy 167 horns whilst he's under....

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#27

Post by ed »

Oh waily waily......critical mass is always viewed by the evangelist as 'better late than never, I suppose'

Andrew, dear heart, are you referring to the far east Zen5 kit that you were talking about before...if so it predates the F5 by some considerable time and is a different paradigm.....

Yo the bass, full details are here, Scott now has the F2, which I think is the one you are referring to....

http://www.vitalstates.org/diy/amplifie ... ifiers.htm

I'm currently creeping up on another version of this with the new semisouth JFETs...but progress is slow

Nelson has now stated that he won't be releasing details of the J2 which is the culmination of all these endeavours....I presume he has become disillusioned by all these board copiers that have prolifierated over the last couple of years, to which our man in Bedford was referring......The change of direction with the release of the J2 info was the deciding factor for me to relook at the F2 with semisouths....
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Ali Tait
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#28

Post by Ali Tait »

So where's the best place to look for build info on the F5 then? Might give one a go...
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andrew Ivimey
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#29

Post by andrew Ivimey »

Just do a Scroogle Web search Ali, (ooo something like Nelson Pass F5 amplifier) and you will find Nelson Pass' article. It is a very easy read and he takes you through the development, then gives you his circuit. Its merely a stone's throw then from that and you will have a lovely amplifer, presumably, as I haven't built one.... (yet ;-))
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Greg
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#30

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