An illustrated guide to building an F5

Jump to Latest
W

Woody1911a1

Member
Joined 2010
no problems merlin , you can't bias it with the light bulb in series . thats just for starting up so that if you have a problem you don't let out too much smoke :)

turn off your amp , disconnect the lightbulb , RETURN !!!!your pots to ZERO !!! before connecting your amp direct to mains .

if you don't have zenmod's guide to biasing up go find it before proceeding . i believe he posted it in 6L6's original build thread .

and i repeat RETURN YOUR POTS TO ZERO !!!!

cheers Woody
 
merlin2069er

merlin2069er

Member
Joined 2008
Ok, I reviewed the first page of this thread. I'll have to print out a hard copy for reference.

Anyways, what does mosfet Iq refer to? Isn't that the voltage across R11 or R12?

DC offset it the voltage at the speaker outputs.

And max voltage is voltage between v+ & v-.

That right?
 
W

Woody1911a1

Member
Joined 2010
oh cool , just realized 6L6 saved that in diff format . was more interesting in the original zm post though :p

Iq refers to current "I" I=v/r . in this case the known is r .47 ohms so voltage is what you're monitoring over r11 &12 to arrive at that current .

and yes dc offset is the voltage at the speaker outputs .

not sure what max voltage you're reffering to .
 
6L6

6L6

Moderator
Joined 2010
Paid Member
Woody1911a1 said:
ok what happened to your original build thread 6L6 ? invalid thread ? geez
Click to expand...

According to the mod to whom I spoke with, there was a software malfunction, which (for an unknown reason) cloned the thread, and they (the mods) couldn't delete one without modifying the other... So they locked it up and reported the problem to one of the admins, who has probably forgot about it or has in buried in a to-do list.

Hopefully it will get fixed. :)
 
6L6

6L6

Moderator
Joined 2010
Paid Member
Turn the trimpots fully counter clockwise until they click. They should be at 0.

Unless you can't put a screwdriver on the pots while installed, there is no reason to dismount the board.

If you do need to take out the board to measure/verify the pot's position, take a pen or thin sharpie and mark the direction you need to turn the pot to make it go down.
 
6L6

6L6

Moderator
Joined 2010
Paid Member
Yes, the pots will click click click at the bottom or top of their range, as the adjustment doohickey clutches.

Plug in your light bulb tester in and fire it up. If the bulb glows for just a teeny bit (as the caps charge) and then get dim, you most likely have the pot adjusted down to zero.

Remove the light bulb tester and turn it on. Hook up your meters and start the bias procedure.
 
G

gsindela

Member
Joined 2011
I'm new to this forum and have to say that I am completely fascinated.

I'm seriously considering taking the plunge on building the F5 and have a couple questions:

1. I remember reading Nelson has a large stock of cases for First Watt. Is he willing to sell the cases to DIYers on a one off basis?

2. Has anyone done a F5 in a multi-channel system? I.e. 5 channels of F5 amplification in one case with one power supply? This would definitely interest me.

Thanks in advance for your help! -Gordon.
 
You must log in or register to reply here.
Top Bottom