Wayne's BA 2018 linestage

[Russellc]

I will give it the 92% isopropanol and toothbrush treatment. I will be firing up via variac. What should I monitor voltage wise as I power up?

Russellc

 

[Zen Mod]

if you did everything well , just bang it

then set offset and that's it

 

[6L6]

You’ve tested the PSU by itself, yes? If that’s good attach the Burning OpAmp boards and adjust offset as mighty ZM says.

 

[Russellc]

I will fire them up not hooked to any thing, RCA or volume pot, should I short inputs, or just fire up and set offset? I guess if LEDs light and offset can be set to zero it is good to go.

Russellc

 

[6L6]

Yup. Apply power and see if smoke remains properly contained.

 

[Russellc]

Okay doky...

Russellc

 

[Zen Mod]

Boom
BigBadaBoom!

 

[Dennis Hui]

Multipass?

 

[Russellc]

Boom
BigBadaBoom!

You Joking or am I doing something way stupid for 18 millionth time causing big Badda Bang?

Russellc

 

[Dennis Hui]

Nah....The Notorious MZM is only joking (and quoting The Fifth Element)

 

[Russellc]

Nah....The Notorious MZM is only joking (and quoting The Fifth Element)

Always must check....with my "experience" or lack there of, many big picture items are often missed.

Russellc

 

[Russellc]

How should off set be. Just brought up and only cooked 20 minutes or so. Either channel seems to get down to .4 mv or so, then up to 4-8 mv, drifting around.

What should I check? Little nervous with that much on preamp output.... input not shorted, does it need to be shorted to prevent off set swings?

Russellc

 

[6L6]

0.4mV ? That is to say, 0.0004 of one V?

I wouldn’t be overly concerned...

That said, look at your offset and blow on the boards, if it moves much it’s going to be much more stable when it’s in a box.

 

[Dennis Hui]

I usually do my offset adjustment with inputs shorted.

 

[Zen Mod]

oh no........

just send it to OPLDF , from recent we are accepting uncased projects , too

 

[Dennis Hui]

Proper disposal is important. Thank you, Mighty Zen Mod.

 

[Russellc]

well, .4 isn't much, but it will go up to 10 mv, then drift down to .4, lower, lower then start climbing negative numbers, then back down, and back up the positive numbers.

I will try it with shorted inputs, then try with boards in a box of some sort. Failing that, off to ZM's OPLDF. I will take the board off for lower shipping costs.

Russellc

 

[6L6]

That much drift is inconsequential, and did you blow on it? If it’s temp related it will get much more stable once it’s in a box and can stay temp stable.

If it really bugs you, put a cap on the output.

 

[Russellc]

Most of my amps have some sort of cap on the input somewhere........ I don't think F5 does.

Russellc

 

[Russellc]

Out of curiosity, how is the off set on those who have built this? One channel is a few mv, the other I cant help but think could be lower. It floats from acceptable under 1 mv, to 11 or 12 mv. I know I could put a cap on the output, but seems like it should be lower.

I guess this is an acceptable level, but I would feel better if it were lower. Maybe I just need a comfort level adjustment! Nightmares of speaker frying.

Russellc