carpenter said:So what the hell, let's go for 2 amp bias.
Why not, 2A bias still leaves you with a decent safety margin.
Magura 🙂
Zen Mod said:
just imagine then what few toobz can do to ya
I'm all for tubes!!!! I just haven't built up enough confidence to build a tube amp. The class A 2A3 sounds like fun.
sounds like carpenter wants a gm100 or 212 the way he's talking about poor little f4....way to go
Ed
Ed
Zen Mod said:
Probably one used to charge the ionosphere, or obliterate the magnetosphere...😀 It's you're daddy when it comes to making the Aura-borealis Harp! 😀 😀 😀
Zen Mod said:
No, Anatech didn't get any tubes 😀
The not so greedy boyz didn't get any either
Magura 🙂
But then again, Anatech did get just about anything else besides tubes 😀
http://www.diyaudio.com/forums/attachment.php?s=&postid=1334054&stamp=1193281362
Magura 🙂
http://www.diyaudio.com/forums/attachment.php?s=&postid=1334054&stamp=1193281362
Magura 🙂
carpenter said:
carpenter said:
carpenter said:
Carpenter, P1 adjusts the TL431 (shunt regulator) voltage. It is across the gates of the upper and lower FETs. It takes about 4V (+or-) to turn one of these FETs on to a current of about an amp (+or-). So, 4V on the bottom FET gate and 4V on the top FET gate is necessary to get some current flow through a (or all the) complementary pair(s). Therfore, the TL431 is regulating at about 8V. In this circuit the current through an N Channel device also flows through it's complementary P Channel device. Measureing the voltage across the source resistor will indicate the current through it
You can set the "Bias Current" anywhere you want by monitoring the voltage at the source resistors while changing the TL431 set point with P1. When the TL431 is set a little higher, the upper gate to lower gate voltage will go up and so will the bias current (and voltage across the source Rs). Set the TL431 for a little less voltage and and the bias current will go down... I realize many responded already, and no one was wrong with there comments. I just did not see where anyone actually said the voltage across the N and P ch gates sets the output bias current 😀
vitalstates said:
I'm a bit confused - what amp have you guys been building?
When I made my F4, the service manual said 250mV which corresponds to roughly 0.5A per device - has this changed since?
Running at less than 1.5A combined will surely give you distorded music - especially into 4ohm speakers.
Anyone want to tell me more about adjusting offset?
I think: manipulate P2 and measure between output and ground. Move screwdriver until voltage = 0 volts.
Am I correct?🙂
I think: manipulate P2 and measure between output and ground. Move screwdriver until voltage = 0 volts.
Am I correct?🙂