Re: Replacement tubes for a Sonny Jr

[Howard Young <blues_harp68@xxxxxxxxx>]

First, Robert, welcome to the world of the Sonny Jr.  A great amp. 
Mine is #152.  I played it about 25 to 35 hours per month for the past
three years and love it.

If you get too many conflicting opinions on this issue, I suggest you
give Gary Onofrio (the amp's daddy) a call and let him be the final
authority.

Bias refers to an adjustment to the current fed to the tubes in an
amplifier.  Too great or too little bias can cause problems.  Some amps
have bias adjustments and require rebiasing any time you change the
final power tubes to be sure the tubes operate within spec.  However,
the Sonny Jr has a self adjusting bias, called cathode bias, in the
final amp stage.  So, within reason, you do not adjust the bias in this
amp when putting in new final amp tubes (5881's or 6L6's).  This
assumes the tubes are good quality and reasonably matched.  Slight
miss-match isn't too big a deal.  Two tubes way out of match would not
be a good thing even if bias were adjusted.  I've swapped out finals in
my Sonny Jr. several times over the past three years without rebias and
without any problems in over 1,000 hours of play time.

The Sovtek 5881WXT's should work OK.  They are not the quality of and
most likely do not have the durability and tone of the Jan Phillips.  I
have heard/read mixed reviews on them but do not have any personal
experience with them.  However, I know you can slap them into the Sonny
Jr and start playing while you look for better tubes.

I've heard/read good reviews on the Electro Harmonix tubes.  Again, no
personal experience.  Shortly after I got my Sonny Jr. I was lucky
enough to be able to stock up on NOS Jan Phillips and Tung Sol 5881's. 
If you can find any of those, grab 'em.

Enjoy the amp.

Howard


- --- Robert Koch <rok68@xxxxxx> wrote:
>  
>    Dear list,
>  
>    I am the proud owner of a Sonny Jr amplifier (serial # 51) that I
> got
> this morning. Unfortunately, a tube broke during the transport. It is
> a
> Philips ECG JAN 6L6 WGB made in the US. A have a pair of matched
> Sovteks
> 5881 WXT. Can I use those for replacement? Was the 6L6 biased and do
> I
> need biased tubes to get my amp working? I don't know if the Sovteks
> are
> biased... And, BTW,  what does "biased" mean? I don't want to ruin
> this
> beautiful amp and all help/advice is welcome. Thanks
> Robert aka Sunnyside Bob.
>  
> 
> 


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