Guess what?

[mcblink]

Pizza pick up, the pizza is across the street.
Be right back.

But in the meantime, I would like you to set the bias to 85 ma per side.
Normally this is 90 ma, but we are setting it a bit cooler than normal.

Do you know how?

I do. I've always run it about 78mV per side... is it ma or mv??

 

[chilipeppermaniac]

Beer break very wise.
Don't let this get out of control without a cold one...

I was gonna say the opposite. Sobriety is prudent while messing with amps. But I am a fuddy duddy

 

[mcblink]

I was gonna say the opposite. Sobriety is prudent while messing with amps. But I am a fuddy duddy

No, you're not a Fudd daddy, you're experienced.
Totally different.
Guys like me could learn from guys like you

 

[Thatbastarddon]

I was gonna say the opposite. Sobriety is prudent while messing with amps. But I am a fuddy duddy

Respectfully....No sir! You are most certainly NOT a “fuddy duddy”....IMHO.

 

[mcblink]

*fuddy duddy

Jesus Christ...

 

[Thatbastarddon]

*fuddy duddy

Jesus Christ...

F-in autocorrect....

 

[Thatbastarddon]

Ok, so.....

Where are we at?...

 

[Amp Mad Scientist]

I do. I've always run it about 78mV per side... is it ma or mv??

78 is fine and mv=ma across a 1 ohm resistor.
No this is not a jack ground issue.
The cab is 16 ohm, you must use the 16 ohm amp output.
The speaker must be connected when you bias.

 

[mcblink]

@Amp Mad Scientist
Is it mA? or mV?

I know how to set the bias.

 

[Amp Mad Scientist]

*fuddy duddy

Jesus Christ...

Put the tubes in.
Plug in the speaker.
Set to 78 mv for bias.
Don't play till the bias is set first.

 

[mcblink]

Ok, gotcha
I can put the tubes in first?

 

[Amp Mad Scientist]

@Amp Mad Scientist
Is it mA? or mV?

I know how to set the bias.

If you read 78 mv on the meter that = 78 ma.

 

[mcblink]

Put the tubes in.
Plug in the speaker.
Set to 78 mv for bias.
Don't play till the bias is set first.

Ok, I posted prematurely, I will do presently and report back

 

[Amp Mad Scientist]

Ok, gotcha
I can put the tubes in first?

Yes if you say please.

 

[Thatbastarddon]

 

[Amp Mad Scientist]

Ok, I posted prematurely, I will do presently and report back

You have to say "mother, may I?"

 

[Amp Mad Scientist]

Ok, so.....
View attachment 65013
Where are we at?...

Time to bias the amp and play.

 

[chilipeppermaniac]

No, you're not a Fudd daddy, you're experienced.
Totally different.
Guys like me could learn from guys like you

Actually Blinky,, you are experienced too. I am only tip of iceberg experienced inside amps. I know enough to follow what the likes of Ampmad, Bdon, Ivan, Sysco, Sg John, 67 PLexi all tell me, as these fellas have built amps from scratch and I know how not to wind up dead or jacking up my amp.

 

[mcblink]

16 ohm speaker connections verified
Power on; standby towards "warm up"

 

[Amp Mad Scientist]

These tests will prevent the tubes from accidentally overheating.
Verify all the operation first, put the tubes in last.

These tests will work on any class AB amp such as:
Plexi 50 or 100 watt, JCM 800, JCM 900, Fender Twin or Bassman etc...
These tests will help you learn how.

The idea is to make sure everything is working without blowing the tubes up by mistake.