Pass Labs F4

For the three and more legged things
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IslandPink
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#31

Post by IslandPink »

Info ?
http://www.diyaudio.com/forums/pass-labs/
More discussion and build info than you could shake a stick at .
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IslandPink
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#32 Nearly finished

Post by IslandPink »

As expected, there was no whirlwind of activity on this, however, see attached - one channel finished . Second one will only be a few days behind .
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pre65
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#33

Post by pre65 »

I spy star earth tags, where did you get them Mark ?
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IslandPink
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#34 Star

Post by IslandPink »

No Phil, honestly, it's just a little propeller used to move air around the inside... :)

( actually I got it from the little box upstairs in my electronics stash ... but I'm not telling anyone what my postcode is )
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#35

Post by Mike H »

lol, 'course you can make a star earth tag by putting a few "ornary" tag washers on one screw :lol:
 
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ed
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#36

Post by ed »

Hi Mark

I've just seen you're pics of the F4 progress...I might be a bit late here but one problem I had with both my first watts was the pesky rf from the toroids. There is a good chance of rf probs if you mount your transformers at the rear of the box, anywhere near the i/p circuit.

I did loads of measurements and scope pics, and after some dialogue with Nelson he said my interference problems were down to mounting the transformers at the rear, close to i/p wiring etc.

He mounts his at the front.

I had to insert steel sheets to block rf in the F2, it was easier than re-doing the whole layout.

If you do have zzz/hum probs then I found that rotating the toroids can have an effect, but it wasn't the whole answer.

just a thought, or two.
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Nick
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#37

Post by Nick »

ed wrote:Hi Mark

I've just seen you're pics of the F4 progress...I might be a bit late here but one problem I had with both my first watts was the pesky rf from the toroids. There is a good chance of rf probs if you mount your transformers at the rear of the box, anywhere near the i/p circuit.

I did loads of measurements and scope pics, and after some dialogue with Nelson he said my interference problems were down to mounting the transformers at the rear, close to i/p wiring etc.

He mounts his at the front.

I had to insert steel sheets to block rf in the F2, it was easier than re-doing the whole layout.

If you do have zzz/hum probs then I found that rotating the toroids can have an effect, but it wasn't the whole answer.

just a thought, or two.
Yep, but it has to be said Ed that your F2 board layout does cover a fair amount of space.

And remember the F4 has no gain.
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#38

Post by ed »

doesn't alter the fact that if you put the transformers at the front there is little risk of rf interference......
and..and .. and

Mark's transformers are a lot closer to the i/p circuit and wires than mine are on the F4....but I appreciate he's got less chance of nasties being dual mono.
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IslandPink
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#39

Post by IslandPink »

Mmmm..too late !
Well, I shall just have to see how it goes.
I'm using shielded input wires ( the old WAD grey stuff actually ) and will run the wires around the inside of the upper chassis lip as much as possible . As Nick says, it's coming in at a considerably higher signal level with the F4, so hopefully that will keep things acceptable . I do have some mu-metal upstairs for the LCR phono ( one day ) so should have some left over if needed for later tweeks .

Just been doing a bit more on the amp this evening . I'm about 1 or 2 hours work away from being finished now . Will try to get my friend Len over for the set-up and adjustments, with his trusty Variac .

Cheers
MJ
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Greg
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#40

Post by Greg »

IslandPink wrote:I'm using shielded input wires ( the old WAD grey stuff actually ) MJ
Surely that's not good. On just about every WAD kit the considered general opinion was replace that horrible boot lace with something better at the earliest opportunity! Most of us did. It's your turn now, Mark! :wink:
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#41

Post by Ali Tait »

Aye, I'm going to have to rewire my pre 2. What wire did you use Greg?
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Nick
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#42

Post by Nick »

Without being biased, can I put in a vote for the pink "Silver Plated Copper Screened wire" that HiFi collective sells.
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#43

Post by ed »

Nick wrote:Without being biased, can I put in a vote for the pink "Silver Plated Copper Screened wire" that HiFi collective sells.
paradox?
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#44

Post by Nick »

Bloody buddhists :-)

YNWIM :-)
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#45

Post by ed »

YKWIM?
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