Vox AC30: swap out the GZ34 for a ???

Mik · March 25th, 2005, 10:59 PM

Requesting SAGacious advice: is it possible (safe, "not a waste of time" etc) to replace the AC30's GZ34 with a rectifier tube that delivers some sag? Which tube(s)...would a 5U4GB work?(I just want to plug in the existing socket with no modification). What are the likely results in a recent '03 or '04 AC30 "Korg era" reissue?

Thanks,
Mik

Tremo · March 26th, 2005, 12:25 AM

Go with a Weber copper cap rectifier. It's a ss rectifier with sag. Tell Ted you want a saggy one, he'll fix you right up. It plugs right into the socket.

You do realize that with the additional sag in the B+, when you are in heavy overdrive, this will increase your crossover distortion?

Wayne Alexander · March 26th, 2005, 12:59 AM

The GZ34 sags a lot in that amp. You can get the same basic amount in a copper cap, as mentioned above.

New62 · March 30th, 2005, 08:02 AM

I have found the the GZ34 sags much more than the 5U4GB. In my Matchless clone I the GZ sounds smooth and compressed and the 5U4 sounds stiffer (crisp and clean) great for country picking and that clean matchless sound.

Mik · April 1st, 2005, 12:38 PM

Thanks for the responses.

Tremo, I didn't think of the Weber copper cap option. Thanks for the warning about c/o distortion.

I don't find the GZ34 all that "saggy" in the AC30. I'll reassess. I've found the 5U4GB quite saggy in another application.

Mik

Bill Ashton · April 1st, 2005, 03:28 PM

the AC30 does not have a standby switch? I was of the impression that the GZ34 was a "slow warmup" tube that did not slam the circuit with voltage.

So ifs thats the case, perhaps you would not want to make a change. Am I off base here?

Mik · April 1st, 2005, 03:35 PM

Quote:

Originally Posted by Bill Ashton

the AC30 does not have a standby switch? I was of the impression that the GZ34 was a "slow warmup" tube that did not slam the circuit with voltage.

So ifs thats the case, perhaps you would not want to make a change. Am I off base here?

The Korg reissue has a standby switch, fwiw.

My understanding that generally any tube rectifier warms up "slow" enough not to slam and cause cathode stripping or other unwanted results.

I'm in no hurry to mess with the rectifier tube but I did want to ask about increasing sag with a swap, again thanks for the answers guys.

Do the copper caps require a standby switch? I thought copper caps behave just like tubes they replace.

Mik

March 25th, 2005, 10:59 PM	#1 (permalink)
Mik Tele-Afflicted Join Date: Mar 2003 Posts: 1,416	Vox AC30: swap out the GZ34 for a ??? Requesting SAGacious advice: is it possible (safe, "not a waste of time" etc) to replace the AC30's GZ34 with a rectifier tube that delivers some sag? Which tube(s)...would a 5U4GB work?(I just want to plug in the existing socket with no modification). What are the likely results in a recent '03 or '04 AC30 "Korg era" reissue? Thanks, Mik __________________ a "motor-bike with a touch of blood in it is better than all the riding animals on earth, because of its logical extension of our faculties, and the hint, the provocations, to excess."-T.E. Lawrence

April 1st, 2005, 12:38 PM	#5 (permalink)
Mik Tele-Afflicted Join Date: Mar 2003 Posts: 1,416	Surprised to hear about GZ34 sag Thanks for the responses. Tremo, I didn't think of the Weber copper cap option. Thanks for the warning about c/o distortion. I don't find the GZ34 all that "saggy" in the AC30. I'll reassess. I've found the 5U4GB quite saggy in another application. Mik __________________ a "motor-bike with a touch of blood in it is better than all the riding animals on earth, because of its logical extension of our faculties, and the hint, the provocations, to excess."-T.E. Lawrence

April 1st, 2005, 03:28 PM	#6 (permalink)
Bill Ashton Tele-Holic Join Date: Mar 2003 Location: Central Massachusetts Posts: 512	Am I correct that... the AC30 does not have a standby switch? I was of the impression that the GZ34 was a "slow warmup" tube that did not slam the circuit with voltage. So ifs thats the case, perhaps you would not want to make a change. Am I off base here?

March 26th, 2005, 12:25 AM	#2 (permalink)
Tremo Banned Friend of Leo's Join Date: Mar 2003 Location: Silicon Valley, CA, USA Posts: 3,803	Go with a Weber copper cap rectifier. It's a ss rectifier with sag. Tell Ted you want a saggy one, he'll fix you right up. It plugs right into the socket. You do realize that with the additional sag in the B+, when you are in heavy overdrive, this will increase your crossover distortion?

March 26th, 2005, 12:59 AM	#3 (permalink)
Wayne Alexander Tele-Afflicted Join Date: Mar 2003 Location: Los Angeles, CA, USA Posts: 1,083	The GZ34 sags a lot in that amp. You can get the same basic amount in a copper cap, as mentioned above.

March 30th, 2005, 08:02 AM	#4 (permalink)
New62 NEW MEMBER! Join Date: Apr 2003 Posts: 5	I have found the the GZ34 sags much more than the 5U4GB. In my Matchless clone I the GZ sounds smooth and compressed and the 5U4 sounds stiffer (crisp and clean) great for country picking and that clean matchless sound.