I recently retubed our Vox AC30 and happened to tube roll a few different preamp and power tubes.  Find our test results below:

Power Tubes Tested:

-JJ EL84

-Sovtek EL84

-Ei EL84

Preamp Tubes Tested:

-Ei ECC83

-Penta 12AX7

-Tung-Sol 12AX7

A few caveats:

Since the Vox AC30 runs power tubes extremely hot, we were only able to test EL84’s that consistently have a lower idle current draw.  Given our current inventory, your two choices would be Sovtek and JJ EL84’s, as we are not able to consistently provide Vox Amps with other brands of EL84’s.

We only tested three types of preamp tubes because tube rolling is a lengthy process in this amp.  It weighs 72 pounds and has a chassis that is time consuming to remove.

Set Up:

’06 Fender Telecaster (pickup switch all the way to the right)

Celestion Blue 12” Speakers

History & Baseline:

We’ve used this amp in our rehearsal space for about 2 years and finally it was time to change tubes.  A few issues we were having:

1)      It lacked the stereotypical bright, chimey clean that Vox’s are known for. 

2)      We also had some microphonic squealing in the Bright Channel.

3)      It took more to dial in the volume on the normal channel. 

4)      The EQ’s could be more pronounced and articulate.

Results:

Winner Combination: Ei EL84’s + Ei ECC83’s

This amp comes fully loaded with Ei EL84’s and Ei ECC83’s are a reason.  It’s simply the best combination out there and delivers full bodied, three dimensional, bright cleans.  Unfortunately, Ei EL84’s that fit the Vox specs are hard to come by and Ei ECC83’s are not in production anymore.  We’ve got some left, but ensure that we deliver you extra low noise, low microphonic tubes, as you’ll need them.

The JJ EL84’s are your next best choice for power tubes.  They might not produce such a wide wall of cleans as the Ei EL84’s, but they’ll produce the Vox chime that we’re all accustomed to.  It’s the next best thing and your best choice that’s out there.

The Sovtek EL84’s still had a great attack and nice cleans, with a little bit of grit and less chime.  They complimented the Tung-Sol’s well, but sounded too harsh with the Penta 12AX7’s.

For the preamp section, if you can’t land any Ei ECC83’s, your best bet is to run Penta 12AX7’s in the first 5 preamp spots and finish with a Sovtek 12AX7(from left to right).  The Tung-Sol 12AX7 provided some bluesy creamy breakup that the Vox AC30 doesn’t really tend to have, but the tube was still dull and provided no real bright clean tones. 

Our final recommendation:

4 x JJ EL84

4 x Penta 12AX7’s

1 x Penta 12AU7

1 x Sovtek LPS 12AX7