Ceriatone Forum

I am putting together my first 5x3 and as I was looking over the layout I noticed two resistors on pins 4 and 5 and 6 and 7 on the gz34 tube.  I am assuming it is dropping the b+ voltage prior to the plates but it doesn't give the values of the resistors.  Any ideas? I would assume they are 10w or 5w ?  Any help is appreciated.

Also I am using a chassis and transformer from an old pa and my b+ voltage is 375vdc whereas the 5x3 layout shows 340vdc.  I guess I need to increase the resistor value even more to compensate for my higher voltage

Those aren't resistors, they are diodes.

They are they merely as an insurance policy if the tube blows.  They aren't needed, but Nik has been adding them to all of his tube rectified models for a little while now.  I'm sure he's seen something that made him start adding them.

They are polarized...so make sure the side with the line is hooked up correctly.
(http://www.gadgetjq.com/single_fire_tach_adapter_diode.jpg)
(http://www.jestineyong.com/wp-content/uploads/2009/12/diode.jpg)

Very cool Wyatt!

As for the diodes on tube recto -

The primary reason is really GZ34 with standby switches.

If you want to watch some mini fireworks, try amp that uses GZ34, and also has standby switch.

Toggle the standby switch on and off a few times and you most likely pop the GZ34. This happens to new or even NOS tubes.

The diodes prevent surges from hurting the GZ34, aided by the cap.

Actually, 5Y3, EZ81, 5U4 etc, dont have much of this issue like GZ34. But we just put it there cause, as you know, some will be itching to put GZ34s in 5E3, for example.

Thanks!

Nik

If I add those diodes to that tube rectifier, does it affect to sag?  Does that 5y3 have any affect on sound anymore  with that mod? :chairdance:

no effect on the sag, just protects in the event of a failure

Which chassis and transformer you are using?