Pass Labs Xyyy.? , checking/adjusting offsets ,Iq and gain

[Zen Mod]

Already made some attempts in explaining procedure , for instance HERE

Lately being approached few times for same issues , so I decided to make it properly , in my bloggie ;

Pass Labs X150.5 , checking/adjusting offsets ,Iq and gain | Zen Mod Blog

If I made some mistake(s) , feel free to correct me .

Amp (and pictures) - Old'n'Cranky

 

[dady]

Finally you got one !!

 

[Zen Mod]

Que?

 

[dady]

Conseguiste un X150.5!!!!
Congratulations dude

 

[Nelson Pass]

You are always a big help ZM, thanks.

😎

 

[dady]

I getting the mine Mr Pass.
Thanks for share your knowledge....

 

[Zen Mod]

Pa , ZM is here to serve and protect ..... (when possible , mostly from own stupidity )

Dady - amp is Old'n'Cranky's , not mine .

so , congrats to him

😉

 

[dady]

Now you are seeing a XA amp, could you tell me if is a good thing?

 

[Zen Mod]

Now you are seeing a XA amp.....

clarify .

again - amp pictured in my blog isn't mine , what I had is only pictures from Old'n'Cranky

however , if you take a look at this :
Some shameful FW and PL clonning – First Watt M2 and Pass Labs XA60.5 …….. by Mighty Zen Mod | Zen Mod Blog

yes , I can tell few things about XA amps ........

 

[dady]

Thank you dear friend.

 

[dady]

clarify .

again - amp pictured in my blog isn't mine , what I had is only pictures from Old'n'Cranky

however , if you take a look at this :
Some shameful FW and PL clonning – First Watt M2 and Pass Labs XA60.5 …….. by Mighty Zen Mod | Zen Mod Blog

yes , I can tell few things about XA amps ........

Beautiful construction but can't leave my comment inside cause I am not registered in your blog.
Anyway your construction babies are fantastic

 

[Old'n'Cranky]

Whoopee ! I'm infamous again 😀

Yes the 'featured' x150.5 above is mine.
It came up for sale at a price I didn't argue with.

I now have an x150 and an x150.5

To Nelson and Sascia, I bow with gratitude and admiration.

 

[Old'n'Cranky]

I hate to do this, but, what is P100, and the two 'Bypass' jumpers in the 'Switch circuit' ??
Would I be correct in thinking its to do with the standby power level ?

 

[wayne]

The bypass jumpers are for first power up and then not used again. It allows circuit to power up using a variac.

 

[Old'n'Cranky]

Ah ok.
I understand.
Thank you Wayne 🙂

 

[Zen Mod]

Whoopee ! I'm infamous again 😀.......:

Old'n'Cranky ..... did you checked your Precious one ?

 

[Old'n'Cranky]

Old'n'Cranky ..... did you checked your Precious one ?

Baby is only 4 years old.
I doubt it needs even a thought.

Besides, I've been flat out with business etc.
I might have a chance in a week or three.
I'll report back once I have 🙂

 

[Zen Mod]

........ week or three.
......

 

[Old'n'Cranky]

So while I wait for parts for other jobs...........
Got into the .5 check up.

Bias (both sides) was low.
Was 87ma ish, now sitting at 100ma all four.
The heatsinks now run 25 degrees Celsius above ambient.
Yes, I know it should be higher, but in Papa terms, 'I can't touch it any longer' is around 4-5 seconds.
Even the front panel (obviously) gets HOT.

I'm gunna love this amp in winter 😀
In summer, I'm going to have build a 'baby sitter'.

Slowly oh so slowly adjusting offsets now.
It takes time for it to stabilise after lifting the lid that few seconds for tweaking.
Yeah I know. I could make a cardboard lid with holes.
But I'm lazy. Um. Yeah. making the cardboard lid would make it faster and easier.....

Product improvement suggestion.
Maybe swap out the single turn pots for multi turn. Even 5 turn would be an improvement.
The single turns are just to sensitive. Foward a touch, back a touch, foward a touch. . . . . .
Like a game of cat and mouse. 🙂

 

[Zen Mod]

...... swap out the single turn pots for multi turn.....

that's your problem ...... and mine and any other Greedy Boy's problem

Pap is turning da pots with mind power