Northwind's 400 to WOPL 500

[Northwinds]

Sometimes stuff happens like that Jer, so you could hear the cap sizzling? WOW blue hot dogs!

 

[laatsch55]

No Jer, Nav has some new, silver ,twisted, shielded black/white pair.

 

[jbeckva]

Gotcha

Ok.. big sigh of relief... offsets around -13mV and match L to R. Bias dialed in to 380 for both sides, but hmm.. it did start around 120mV at dead center on the pots. Worry or no?

Anywhoo.. going to quit not while I'm ahead... time to eat.

 

[laatsch55]

What's your low and high / min/max movement readings?

 

[Northwinds]

Bias dialed in to 380 for both sides, but hmm.. it did start around 120mV at dead center on the pots. Worry or no?

When you get done eating and have a chance later, could you explain in layman's terms what you mean above? Is that with the old silver caps installed or the big ones?

 

[laatsch55]

Joe's boards are so precise the recommended bias is usually right in the middle of the pot adjustment using the 2N5088's for the bias trannie. Variations on component tolerences can throw that off, but if the bias can be adjusted to .380 that's what counts.

 

[Northwinds]

So it should have read 380mV in the center position but actually read 120mV. Ok, I get it. Are these pots turned with a screwhead adjuster?

 

[laatsch55]

Yeah, I believe that's what he was refering to. They're supposed to be adjustable to 380, that's what matters.

 

[Gepetto]

Yep nice and "stiffy" heheh.. Tried to keep all the AC lines crossin over to their own bundle, and keeping any of the bundles away from the top center screw hole (did I tell ya about the time when I didn't pay close attention to that? It was on a 700 and I had the 4 "black" fuses to show for it.. hehe)

That is what that short screw in the kit is for Jer. To protect from things like that happening

 

[Gepetto]

Gotcha

Ok.. big sigh of relief... offsets around -13mV and match L to R. Bias dialed in to 380 for both sides, but hmm.. it did start around 120mV at dead center on the pots. Worry or no?

Anywhoo.. going to quit not while I'm ahead... time to eat.

No worry, bias transistor and Q7/10 and predriver variation will put you all over the map which is why such a large range of adjustment is provided.

 

[Gepetto]

Gotcha

Ok.. big sigh of relief... offsets around -13mV and match L to R. Bias dialed in to 380 for both sides, but hmm.. it did start around 120mV at dead center on the pots. Worry or no?

Anywhoo.. going to quit not while I'm ahead... time to eat.

Hi Jer
Please make sure you have replacement Pico fuses coming too. They are there for a reason...

 

[jbeckva]

Well I don't know about the above but....

I'm listening to it now.. heheh... couldn't resist. It sounds pretty dern good for the old caps!!

Anyway.. so yeah, for now the old caps are "in". Had to get to this point. Courtesy of Mr. Lee (owe ya man), we have another pair of the biggins coming. That and I believe the LED board for the meters. Once that stuff is in, the construction should be completed pretty quick - switch the caps back out and replace the blown fuses... punch the hole for the switch.. and put the LED board in. Until then, time for a rest (if'n I be not paying attention where "red dots go".. probably a good idea).

Yeah man.. it sounds good... not really going to push it until it's all together... Here it is, popping a wheelie but I'm listening right now and it sounds great.

 

[jbeckva]

Hi Jer
Please make sure you have replacement Pico fuses coming too. They are there for a reason...

Been seeing my emails, Joe?

Yes, those I will now stock up on and got 'em coming with the caps.. Not going to push it with lil cat whiskers for temp fuses put in, for obvious reasons

 

[jbeckva]

Jamming on some Queens Of The Stone Age...

Ey Ron... how 'bout you get my old tried and true 8 finner, already tested... works good lasts long time.. can probably handle the "Ron Test" pretty dern good, 400 FC?

heheheh just messin... We got a delay on this one, but it's going to be pretty sitting on your rack.

 

[jbeckva]

That is what that short screw in the kit is for Jer. To protect from things like that happening

Yessir realized that, but wow was that zapping ... invigorating. Looked and sounded like an old Dio concert.

 

[laatsch55]

If I lose the Joe screw, I grind the point off the old one...

 

[jbeckva]

Yessir realized that, but wow was that zapping ... invigorating. Looked and sounded like an old Dio concert.

And the last time I ever just threw caution to the wind and powered up FULL after working on one, however small the amount of work done to it. That point forward, variac... every time.

 

[Northwinds]

I'm stoked! Glad to hear it's running!!!! I was catnapping and just got up to take a peek

 

[jbeckva]

I'm stoked! Glad to hear it's running!!!! I was catnapping and just got up to take a peek

It's doing more than just runnin.. it's singing clear and proud! I'm probably going to end up doing my 400 FC up the same way. Every optimization so far has made a serious impact in final sound quality.

 

[laatsch55]

Plus 1 on that...