Ac30

[Alastair E]

Rebuilding AC30's

Around 20 years ago, I remember while working as a trainee, rebuilding many Vox AC30's. Used to really enjoy rebuilding those.
Commonly the GZ34 was a problem, even then the cost of a premium one was silly money in comparison with all the other valves in the amp.

A little dodge we used to use, was to use an old Octal Valve base, and wire BY227 diodes in series with 220ohm ( I think) resistors of 15W rating--The owners would choose this option quite often and many commented that the amp sounded just as good as with a valve rectifier--Making a pluggable rectifier like this, means that when a GZ rec was then available it could easily be changed, but few owners bothered to change it.

 

[Zen Mod]

Hi choky,
sorry but Ii think that I use better the soldering iron than english spoken.
It's my third amp realisation:
1st the octane (SE with EL34 )of AX84 site
2nd an california dream (my 1st PP of 6v6) of AX84 site
3rd THE VOX AC30 in building
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The right link of the diagram of 1960 is
http://flintholm.dk/vox/VOXAMPS/AC30/AC30NM1960.HTM
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So my question was about the value (not ol the coil, it's a wrong word) of the choke between the 2 caps of 22 microFarad.

In this diagram the filter of ht supply is given by a choke of 10 to 20 Hy (100mA) between 2 caps of 16 microFarad. Do you think that the value of the choke is the same value. For information in the last issue the fist capacity of the ht supply of the AC30-60-02-TOP BOOST is became 47 microFarad.

OK-it's just fine with me

ragrding a choke-just use whatever you have-that value isn't criticall;
in any case-most important thing is that you do not pass some voltage margins for caps and other componnents-in any moment,primary during warm up ;
one good thing is that you make some sort of delayed HT ,even in simplest way-as second switch (one main,one HT switch ).

I do that almost every time when I have AC30 in my workshop ,especially if somebody already pulled GZ34 out...........
cheers!