Welcome, Guest. Please Login or Register
Decware Audio Forums
08/08/20 at 10:10:04†


       


Pages: 1
Send Topic Print
Normal to need bias adjustment after 3 months? (Read 295 times)
AlexR
Verified Member
**




Posts: 44
Normal to need bias adjustment after 3 months?
06/02/20 at 23:50:08
 
Still getting to know my new (to me) Torii Jr. Today I decided to check the bias and it was 435 millivolts. Is it normal for the Torii Jr to drift this much with 3 months of use?

Also, when I adjust bias using the multimeter, the reading doesn't stay fixed, but fluctuates rapidly by about 3 digits +/- 825 millivolts. Is this normal?

The entire tube compliment in the amp was new from Decware as of early March.

Thanks for the help!
Back to top
 
 
AlexR   IP Logged
Chester
Verified Member
**




Posts: 14
Re: Normal to need bias adjustment after 3 months?
Reply #1 - 06/03/20 at 05:22:25
 
Hi Alex,

I would say that is not normal at all. Please donít take this the wrong way, but are you sure you are using the multimeter correctly?  

The voltage will fluctuate, but in my experience not by more than one or two millivolts. So, on my meter, 826 or so.

If you are 100% on the multimeter use, then Iíd call Steve.

Good luck.
Back to top
 
 
  IP Logged
AlexR
Verified Member
**




Posts: 44
Re: Normal to need bias adjustment after 3 months?
Reply #2 - 06/03/20 at 22:34:56
 
Chester, thanks for your thoughts. I'm not the most technically minded, but I believe I'm using the multimeter correctly. That said, it's entirely possible I'm flubbing it. Here are some pics of my process, please feel free to let me know if something doesn't look correct.

Thanks again for your help.


Back to top
 
 
AlexR   IP Logged
Archie
Seasoned Member
****




Posts: 1975
Re: Normal to need bias adjustment after 3 months?
Reply #3 - 06/03/20 at 23:46:51
 
I just had a thought about the fluctuations. †First, the difference between 1 or 2 mV and 3 doesn't seem like a big difference. †Second, I wonder if the fluctuation either has to do with equipment warmup or line voltage fluctuation. †As for the former, I get a variation on my ZMA meters that can take hours to fully settle after a cold start.
Back to top
 
 

Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
ZLC
Homemade Big Betsy Speakers
Silver Cabling
DIY Isolation platforms under amps & TT.
  IP Logged
HockessinKid
Seasoned Member
****




Posts: 460
Re: Normal to need bias adjustment after 3 months?
Reply #4 - 06/04/20 at 00:40:51
 
Wow, hours for the ZMA bias meters to settle in?? Mine are usually up in no more than 10 minutes and stay rock solid. This with the TAD 7027a tubes, TungSol 7027a - 7581 - KT66 tubes, and Gold Lion KT66's. Never experienced any problems.

HK
Back to top
 
 

Nottingham Interspace TT w/ Dynavector 20x2LO cart + Modwright PH 9.0 phono pre > ZROCK2-25th OR Modwright modified Cambridge CNX V2 > CSP3-25th preamp > ZMA-25th amp > PI Audio Group UberBUSS PC > Omega SAHO XRS or Caintuck Audio Lii 15 speakers > various cables.
  IP Logged
Archie
Seasoned Member
****




Posts: 1975
Re: Normal to need bias adjustment after 3 months?
Reply #5 - 06/04/20 at 01:18:19
 
I'm talking about parts of a mA.  It does depend on the tube and the age of the tube.  If your meters are exactly the same from 10 minutes to shutdown, that's awesome.
Back to top
 
 

Technics 1200G TT w/ Ortofon Jubilee MC cart
ZMC1
ZP3 (25th A Mods)
ZR2 (25th A Mods)
CSP3 (25th A mods)
ZMA (25th A mods)
ZLC
Homemade Big Betsy Speakers
Silver Cabling
DIY Isolation platforms under amps & TT.
  IP Logged
Pages: 1
Send Topic Print