More Tube Questions

[viewaskew2k5]

OK!!
So i have been racking my brain....
So you have a 30W Tube Amp.

4xEL 84's and 4x ECC 8(0)3's. So!! Where do the 30 whats come from? And the 12AX7 Variant? ? Is there a lower power/same socket tube, to lower the amp from 30 to 25? 20?? Just curious

 

[jeremy]

Re: More Tube Questions

the power comes from the four el84's, two will give you 15-18w, four will give you 30-36w. any more than that are you may be pushing the tubes too hard. all but one of the 12ax7 vairants are for the preamp stages. the other is the phase inverter which feeds the signal to the power tubes

the difference between the overall volume of 30w and 20w isnt all that much at all, a little more clean headroom on the 30w but thats about it.

 

[viewaskew2k5]

Re: More Tube Questions

Thanks jeremy, thats what i needed to hear

 

[viewaskew2k5]

Re: More Tube Questions

So just to double check, say if i have a 30/20 w head, and its just..a bit to loud, or i want to fiddle with it, i take out 2 el 84's as they work in Push/pull?

 

[missionamps]

Re: More Tube Questions

Yes it will work, if you pull two tubes from the amp but you must pull two tubes who are at opposite sides of the relative center tap in the output tranny.
The down side is that the power supply will be under loaded and the B+ voltage will rise, causing the remaining two power tubes to be underbiased and running very hot, and, you will now need to double the speaker ohms to get the correct power tube impedance ratio back.
That means something like this...
running a 16 ohm load on the 8 ohm output jack/tap or an 8 ohm load on the 4 ohm output jack/tap. etc.

 

[viewaskew2k5]

Re: More Tube Questions

Hmmm interesting!!! Sorry guys i'm still learning the full in's and outs of amps!