GZ34S (5AR4)

The JJ GZ34S is a modern production replacement for all classic GZ34/5AR4 rectifier applications. The JJ is a proper indirectly heated recreation that has the correct voltage output and feel. If you’re used to using the Sovtek and Chinese variants you’ll be pleasantly surprised.

This tube is as close as it gets the old Mullard GZ34 that we all know and love. In fact the plate construction looks to be almost identical to our large base Mullards with the straight edge plates.

For the guitar players: We’ve been using these in Bob’s old SUNN amps now for years with great results. They seem to know just when to give-in to get that wonderful rectifier sag. We also use these in Mesa Dual and Triple Rectifier amps in place of the stock 5U4’s to get a little less sag but to maintain that rectifier sound. A perfect tube to replace the chinese or sovtek 5AR4’s that we have all grown to dislike so much… The JJ GZ34 will get your Deluxe sounding like a vintage amp.

These tubes are rated for a maximum reservoir capacitance of 60uF. This can be exceeded under the correct conditions. However if great care is not taken, exceeding this rating will greatly shorten the tubes life. If you’re experiencing short rectifier tube life it’s a good indication your amp either needs to be serviced, or the peak currents need to be verified and handled accordingly.

If you’re swapping rectifier tubes of like types the bias will not need be adjusted. If you’re substituting dissimilar rectifier tubes the bias should be checked and adjusted as necessary (excepted as noted in our Retube kits).

All our rectifier tubes are tested for forward and reverse voltages, along with a peak current test to check for arcing.