Pass Labs F4

Greg · Post by **Greg** » Fri Jul 08, 2011 10:54 pm

Paul Barker wrote:If you find any odd ones without toe nail holes I might have some matches for them.

That's cool. Can we have a sock sharing/matching table at the next fest please

Dave the bass · Post by **Dave the bass** » Fri Jul 08, 2011 11:18 pm

Greg wrote:
Paul Barker wrote:If you find any odd ones without toe nail holes I might have some matches for them.
That's cool. Can we have a sock sharing/matching table at the next fest please

Aaah!

You'll both be wanting 'Sock-Talk.co.uk'

Thats the forum next door along on the internet, glad to be of service.

*doffs cap*

DTB

Post by **Nick** » Sat Jul 09, 2011 1:47 am

Forget Facebook, this could be big, We set up a site where people can post pictures of their single socks, and people with matches can either buy the other one, or offer it for sale.

al newall · Post by **al newall** » Sat Jul 09, 2011 7:06 am

Funnily enough.
We were considering some sort of odd sock auction at our Youth Club fun day.
But weren't sure if people would be bothered to bring their odd socks along.
Chester parents have an issue with supporting the fun day at all.
It means they have to put themselves out, and break their normal routine for an hour or two. That's a big ask around these parts.
Apathy abounds.

Doing it online would give the lazy beggars chance to swap socks from the comfort of their armchairs.
Go for it.

ed · Post by ed » Sat Jul 09, 2011 8:29 am

don't mess with the sock monkey guys, it's like playing with voodoo

Paul Barker · Post by **Paul Barker** » Sat Jul 09, 2011 9:17 am

Nick wrote:Forget Facebook, this could be big, We set up a site where people can post pictures of their single socks, and people with matches can either buy the other one, or offer it for sale.

is that Bonzo Dog Doo Daa Band?

Post by **Nick** » Sat Jul 09, 2011 10:34 am

Its Viv Stanshall, after he left of the Bonzos.

IslandPink · Post by **IslandPink** » Sat Jul 09, 2011 11:47 am

"Sir Henry at Rawlinson End"
Thanks Nick, just reminded me what a great guy he was , superb !

Latest news : Len 'Variac' Edwards is coming round in about 2 hours to see if we can set-up the F4 .

Mike H · Post by **Mike H** » Sat Jul 09, 2011 12:25 pm

LOL ..

IslandPink wrote:I can see a 'date modified - 16th Feb 2004 ' if I right-click > 'properties' on the image file when it's in my directory here, but I don't see any such info when I access the picture from the forum .

I had to save it first

IslandPink · Post by **IslandPink** » Sat Jul 09, 2011 7:01 pm

Well, it's been a very fine afternoon . My consultant Leonard arrived about half past one, with another voltmeter, a Variac and some odds & sods of test leads, load resistors and clipleads.
We had an anxious half hour where nothing seemed to be working out , but then we got it going, and all seems to be well .
In the process we learnt that :
(i) you cannot assume that starting off feeding-in 100 volts or 120 volts you will get anything meaningful in terms of test voltages. Because of the zeners and voltage reference in the signal circuit, nothing much happens till about 180V
(ii) Don't assume that Nelson Pass's simple notes on how to adjust the amp are right ! In real life, both pot P1 and P2 both affect DC offset and Mosfet bias value . It's a case of fiddling around with both - as Nick later said - like adjusting both ends of a see-saw .

So, we had it going about 2 hours all told, played music for about an hour on various speakers . Sounding 'pretty good' so far . Good overall tonality , good edge ( detail ) definition, solid in the bass and a good sound overall . Gain is enough to play into the Ariels ( 92dB/w) at good-ish volume, not enough to rock out, but fine 'evening listening' level. It's TOO LOUD through the compression drivers - had me backing up to the far wall in fright ! We're probably only getting about 0.1 to 0.2W per channel when fed direct by the phono .
I have some hum ( i think ) and some noise. Need to quanitfy this better , so will post more later . Maybe some wire-routing improvements once i get a handle on what's there.
Heatsink temp in the centre was around 52degC as best I could measure . Might try to borrow a pyrometer from work

Hoorah !
MJ ( photo of speaker madness in front room this afternoon - F4 on floor )

IslandPink · Post by **IslandPink** » Sun Jul 10, 2011 9:44 pm

Picture of amp complete with lid - for Ed

Working nicely .
This morning I had an hour & half or so listening to a few things. Stevie Wonder 'Innervisions' and 'Fullfillingness first finale' , Yes 'Time and a Word' and a bit of 'Time Further Out' (Brubeck) . All very listenable.
It's obvious how the amp improves significantly as it goes from 20degC up to the design temp of 50deg C .
At the proper temperature, it has lots of tone, space and reverb decay . Very SE-like . Bass on the other hand is nicely quick and a bit better than my 300B SE at the lowest frequencies - very easy to follow bass lines. Bass tone is excellent . Top end at the moment still has a little of that SS 'artificial' sound , but not much . We'll see how it goes with more running-in .
Hum is there and seems to be due to that old chestnut, signal earths 'fighting' , as it comes on just by connecting the input interconnects with the phono switched off. Might have to disconnect the signal earths at input .
Sounds great feeding the Onken bass speaker on one channel - loads of 'Oomph' !

ILPS

ed · Post by ed » Mon Jul 11, 2011 7:58 am

brill, looks fantastic. I asked about the lid because mine still doesn't have one, and I'm looking for ideas, thanks.

It sounds like you like it already, only right and proper.

IslandPink · Post by **IslandPink** » Mon Jul 11, 2011 5:55 pm

Thanks Ed
I paid a lot for the box , but at least it's rigid and has a proper lid . All I want to do now is get a front panel made with a bit of script on the front and two holes to allow the little green LED's to shine through . They were a faff to wire-up, but proved very useful in the set-up when it told us there was power reaching both signal boards . They are also quite old ones which are not too bright , unlike most of the modern superbright ones.

I might play some Beefheart tonight .

ed · Post by ed » Mon Jul 11, 2011 8:12 pm

way to go...

the moon was a drip on a dark hood

I've been looking at the perforated aluminium on ebay...I have two pieces of 10mm ali for the front panels(F2 is not finished either) and have been meaning to take them to the engravers for more than a few years now.......I had the idea of deep engraving the front then drilling through to the engraving. Fill the engraving with epoxy and mount the led behind.....I have no idea if it will work.....

My biggest problem is letting the heat out so it has to be fairly open perforations...at this time of the year, with my bias setting, I can only just hold my hand on the heatsinks for the prescribed 5 seconds...

one day......

IslandPink · Post by **IslandPink** » Mon Jul 11, 2011 9:35 pm

Oh my god Ed, "The moon was a drip on a dark hood" -
I go weak at the knees with some of those lyrics.
Takes me back to my time in Leeds mid-80's when I got into Beefheart and borrowed a copy of 'The Spotlight Kid' from someone . What did Peel say ? " He's never been equalled , really" . What a singular talent .

Keep me posted on the front panel . I might try that front panel website thing or something . This could end up being my most fully-realised amp-build ever . It's actually got a box !!!

MJ

audio-talk

Pass Labs F4

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#70 Back of the Net !

#71 Grooving to the SS sounds

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