Threshold 400A how to set bias?

[Raccoon1400]

I've just rebuilt a threshold 400A that was blown in both channels. I used onsemi MJ121195/96.
All seems to have been successful (full power test pending) but I don't have a bias adjustment procedure for this one.


All emitter resistors were changed, as well as all electrolytics except the mains.

 

[Indigent Audio]

Should be in the Pass Labs forum, bet you’ll get an answer right away

 

[Raccoon1400]

Oops, I'll see if I can find a mod to move it for me.

 

[Mooly]

thread moved.

 

[Zen Mod]

.

 

[coolnose]

7 min ZM, that's too slow.... keep the standard up

 

[Zen Mod]

sorry, I was flying

I mean , dealing with Eagle


I'll try better, next time

 

[Raccoon1400]

thanks! I figured it wouldnt be too hard to get an answer here partly since Nelson Pass himself is a member!


This amp is for a client but I'm looking foward to giving it a good listen. It will be up against my kenwood 700m on a pair of Radford S90 transmission line speakers

 

[Indigent Audio]

7 minutes is pretty good for a Sunday

 

[Nelson Pass]

thanks! I figured it wouldnt be too hard to get an answer here partly since Nelson Pass himself is a member!

Pass always defers to the expertise of ZM.

 

[Raccoon1400]

I'm pretty sure I got the bias set pretty close. It passed the full power test. 10kHz squarewave looks decent.


Tomorrow I'll do some listening tests. I'm curious about this one. Lots of amps come through here but only a select few get plugged into my main system.

 

[Nelson Pass]

Rule of thumb, after an hour tops of sinks at temp where you can put your hand on them for only about 10 seconds.

 

[Raccoon1400]

I didnt get it quite that hot, adjusting it more now.

 

[Mooly]

Well let's see if your temperature calibration nomenclature
matches mine:

Blimey hot is 10 seconds hands on = 45 deg C.
Crikey hot is 5 seconds = 50 deg C.
Bloody hot is 2 seconds = 55 deg C.
X*?@! is 60 deg C.

All of these are within an acceptable range, although
X*?@! is resrved for the more mature constructor.

 

[Raccoon1400]

Sounds more like a rule of hand as opposed to a rule of thumb though...

 

[Zen Mod]

this one is more thumb of rule

 

[peppennino]

7 minutes is pretty good for a Sunday

...also considering the strike of Eagles 😀

@ZM: Seen now this thread. Thanks for answers

 

[Zen Mod]

...also considering the strike of Eagles 😀

@ZM: Seen now this thread. Thanks for answers

that would be EAGLE 6.3.0

🙂

 

[peppennino]

Yes, even with my pooooor English I understood
With 7.0 you'll be here in 3 minutes...

Fly with your favourite EDA 😀