Hi Everyone! A question.
How to set up the bias on the UL?
Best wishes
Bob
Hi Bob,
Welcome to the forum!
We’ll get you all taken care of.
Thank You,
Terry
Hi, hopping in this thread to see if @Terry can share whatever info was shared with BobSIGX regarding Pittbull UL bias? Finally had a power tube go in mine after ten years of heavy usage, will need to crack this open when I retube it but there is no paperwork regarding UltraLead bias available. Thank you!
Hi, Alden!
Several months ago I biased my SIGx and the UL. Everything works great. So I’ll give all the info I have
Attached the manual, that Terry gave me. On the picture I signed the check point for red probe of the multimeter, I used. Connect the red probe to this point and the black probe to the ground point. Multimeter should be set to scale the VDC, as it looks 9n the picture 3. Hope it’ll help.
With Best Regards,
Bob
понедельник, 08 декабря 2025г., 03:48 +07:00 от alden via Fryette Forum noreply@forum.fryette.com:
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Hi Bob,
Great - thanks for sharing!
Thanks for posting the Sig:X photos and UL bias procedure.
Just a quick clarification, the photo showing the white arrow is not the correct test point.
You should use the “BIAS TEST POINTS” printed on the board in that photo.
The black probe lead would be TP2, which is the back lead of the 1 ohm resistor in the middle, and the red probe lead on TP1 on the front pin of the same resistor.
To set low power bias set any channel to Low Power mode. To set high power bias, set any channel to High Power mode.
Now, set your meter to the DC Volt setting that will give you good resolution in the milivolt range.
Use the BIAS LP trimpot for setting Low Power bias to .140V or 140mV as printed on the board.
Use the BIAS HP trimpot for setting High Power bias to .110V or 110mV. This is different than the .135V value printed on the board. The .135V spec is a typo.
Cheers,
Dave
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Hi, Dave!
Thank you for the info, because actually I did not understand all tips from the manual and set the bias by using 6550’s datasheet and by ears.
Now I’ll try to do it properly, thanx a lot.
Best Regards
Bob
четверг, 11 декабря 2025г., 06:12 +07:00 от David Phelge via Fryette Forum noreply@forum.fryette.com:
