Tube amp Theater 5u4 vrs 5AR4 GZ34 Tube Guitar amplifier by D-lab

An often asked question. Can I swap my 5U4 with a 5AR4? The answer is Yes and NO. It all depends on your application. Hopefully the highly technical production here makes it all as clear as mud.

[@Rodedog55]

Thanks man! Great knowledge ! See you soon in another installment.

[@johnpick8336]

Thank you for this info that has been plauging me for over 40 years !

[@bryanfreisinger2304]

Thank you!!!! I am planning a 1690t Supro build project, and you totally answered my question. 5u4 it is!

[@barrychristiansen4579]

beautiful striaght shooting info. Terry! thx!

[@pleximanic]

Great info HUGE thanks !

[@judges69]

Great info, thanks

[@lousekoya1803]

GREAT TUTORIAL !

[@larsschulting7014]

wow thnx men.. your great

[@vikingmike8139]

Very helpful. Cheers!

[@whatsstefon]

I was going to do a similar video. I don't have to now. Found this one. I might do one anyway and link to this video. The 5y3 is okay for amps designed to use them. ie: Champ, Tweed Deluxe. But so is the rest of the circuit, like Terry says. The caps are rated for the lower B+ DC voltage. I've repaired many Tweed Deluxe clones by discovering the solid state thing in the rectifier socket. Followed by blown or severely fatigued caps. Then seeing this dropping resistors looking like they're on their way too because they've used under rated ones for the task. I usually replace the caps with 500v ones, and drop in 3W or 5W resistors. Throw a new old stock 5y3 in there. And the customers call me back to say how good the amp sounds. Would you throw in a 5AR4? No. Well, yes. With the higher rated caps, no problemo. But then bias needs adjusting. And those amps are cathode biased. So it's a matter of then either experimenting with different value cathode resistors or doing the math and estimating what you need and getting close enough to that value. As Terry says, it's all possible. But you have to think before you do any of these changes. Don't just throw in a different rectifier tube because some guy on a forum did he did.

[@theguitaramptech]

Too many years in the entertainment industry, means I just love corny videos. This was fun Terry.

[@artofnoly9754]

Here... Teddy! Great info, Lad. I have just tested all 8 of my JJ set of boobs (toobs, sorry) for my AC30-CC1 and all is well, but it previously blew a 2A main fuse, so I'm still a bit worried. Perhaps it was just a glitch in the local power supply... fingers crossed. I'm going in from the shallow end, cost wise... a new fuse is .39 cents... as opposed to big bux for new toobs. Here's hoping!

[@johnsimms3957]

My favorite amp design is an all tube signal path with a solid state rectifier. I don't like sag.

[@cliftonwright7081]

This guy yelling over that roaring organ music is hilarious. Great video.

[@gabrieln3613]

Yes, I had to hit pause, with A/C on I knew I was hearing something (irritating!) but, could not tell if it was in the video or music down the street or a man coming up the road with an organ grinder selling hot dogs or something. Geez

[@AndyWragg]

Hi Terry great video once again. One thing that I've come across between different brands of 5AR4/GZ34 rectifiers is the forward voltage drop differs a lot from brand to brand. My JTM45 clone initially used a JJ Electronic GZ34 but was unusable because the tube was arcing on power up of the HT circuit (closing the standby switch) and kept blowing the mains fuse. I've replaced this with a TAD (which from what I've read is a premium selected Shuguang, but this was on the internet forums so does need verification) and the measured HT voltage is at least 15v lower than the JJ. Maybe this was due to the JJ being bad from the start. My research also concluded that the old Mullard GZ34 which is highly sought after in cork sniffing circles, had very little forward drop, whereas the modern alternatives were much greater at dropping the volts. My amp has been rebiased since the rectifier tube swap and now seems to be behaving itself. Take care and keep up the excellent work!!

[@d-labelectronics]

+Andy Wragg Thanks for the info Andy. A comparison between brands would be a good video. I found that the electro-Harmonix 6V6 tubes do the same thing. Arc at the top. Had quite a few bad builds due to them. I stick with Tung-Sols.

[@ThuyTran-di1ij]

Hi , Terry I want to build the rca jack dummy for 4,8 ohm can you give me the instructions of how to do it and the parts I need. Thank you

[@Newwaver2007]

Cool to see this one. Tho I have a question, I am checking my tube tester I got from a friend, and I see there's no 5u4gb in the list, but there is 5u4. I want to know, should i check the 5u4gb tube with the 5u4 setting? Have happy Yule or Christmas for now :)

[@michel333100]

Hi Terry, just wanted to ask you a question. can you use a 5V4G rectifier RCA in a JTM 45 Marshall amp?

[@jimioconnor8039]

What would i have to do to change a 59' supro Coronado with the baffle swap from 2 10" speakers to a single 12"...which im told is a 2ohm transformer into an 8ohm speaker to make a 5u4 into a gz34 rectifier tube work any help would be so greatly appreciated....i like the vids keep em coming

[@ali2ndmail]

Great info Terry. By the way, I like Clarke’s trumpet voluntary., though maybe it is a bit loud and distracting to be used as background music.

[@RicCortezMusic]

Mr. D Lab, what if I'm designing a tube amp with a pair of 6L6s? Which tube rectifier would you recommend?

[@patthegunsmith]

Very well done! '73 de Pat KC2EEB

[@michel333100]

Hi Terry, one last question, can you use a GZ32 or a 5V4G in Vox AC30 ?

[@kbkman7742]

I had a quad el84 30 watt amp. I bought it second hand, it requires a 5ar4 but the previous owner stuck a 5y3 in it. No pops, no noises, no smoke or fire, and the tube didn't blow surprisingly. Would this have harmed the amp though? or in the 5y3s case is it just a matter of the tube being under all the stress? I have a 5ar4 back in it now, running no issue. With the 5y3 the amp had no balls at all

[@AliKiani7887]

Thank you for your nice videos... I have one fender super reveb silverface ab763 1969 model...i only use vibrato channel , the clean sound of it is nice and awesome but when i use big muff or fuzz pedals the sound is not good and its harsh...what kind of power and pre amp tubes do you suggest for getting smooth sound when i use big muff snd fuzz ? Consider that My amp is totally restored and i change all the caps with new one but the tubes are old and russian and i didnt change them...rectifier is 5u4 sylvania and power tube are russian Do you thing any modification in the amp circuit will help or not? Actually I want the dave gilmour tones I will apprecite you if you help me ...

[@125southernnh2]

How about substituting a GZ33 for a 5U4?

[@rustycalvera977]

if the 5ar4 has less voltage drop than the 5u4...you'd think the output current with the 5ar4 would be less vs an output tube using a 5u4......what am I missing?

[@Alvolta25]

Someone know about these modern russian made Sovtek 5Y3-GT? We read here and there they operate more like smalls 5AR4/GZ34. It sounds very good in my ''Epiphone Blues Custom 30'', but i'm running the amp at the lower 15 watts setting instead of 30 watts, with smalls Tung Sol 5881. The sound is just perfect to me. It's a lot quieter than with the stock 5AR4. Will it damage this amp? THANKS A LOT!

[@fakundofrontera]

i have the same readings when i turn on the amp, and my filter caps are for 450v, but in the initial peaks go to 480v...Is that an issue to resolve or the caps can deale with that voltajes for this five seconds every time i turn on the amp?

[@profile_01]

what about swapping a stock 5AR4 rectifier tube to a 5Y3 ? Is there any danger of damaging components. power tubes?

[@TheBrownfish420]

What can i use to replace a 5z4p rectifier ?

[@michel333100]

Hi Terry, my problem is this. I have a 100 watt mesa Boogie Tremoverb amp from 1995. The amp has been modded with two bias pots for either 6l6's or el34's. Can this amp be used with 2 GZ34 rectifier valves in place of the 2 stock 5U4GB rectifier valves? I read on the net that people were putting these GZ34 RECTIFIER valves in mesa dual rectifier amps. Even Eurotubes in Oregon suggests using them in place of the stock 5U4GB rectifier valves. My problem is that when I shut my amp off with only the power switch, my amp blows the fuse. If I turn the amp off with using the standby switch first then there's no problem. Any advice on what could be wrong and if in fact you can safely use the GZ34 rectifier valves in this amp. Thanks from Michael Newell from Niagara Falls, Ontario, Canada foot note here, the 2 GZ34 rectifier valves are the JJ'S brand. Seems like this other guy on this forum commented on these JJ'S blowing the mains fuse the same as mine.

[@fugamante]

How about 5R4?

[@smokinblue151]

What about using a 5r4 tube ?

[@DeadKoby]

Do you have any thoughts on Weber "Copper Cap" rectifiers? they are solid state alternatives that are supposed to replicate the sag. (even though I still use tubes anyway)

[@d-labelectronics]

Hello, sorry, never tried them

[@DeadKoby]

Simply put, they are diodes, and resistors networked together in a tube base... considered an alternative to a tube rectifier. It's their standard practice to stick those in the kits, rather than a rectifier tube. They have different versions to simulate popular rectifiers.

[@bernhardnizynski4403]

Give me a 5AR4 any time! Do they both have an indirectly heated cathode?

[@jasonkirkham550]

I have an Hammond Ao35 reverb amp. converted to a guitar amp. It uses a 5y3 and 2x el84. I would like to use 5AR4. can I ?

[@d-labelectronics]

Yes, that should not be an issue. You will gain a little more HV and punch to playing. Keep an eye on your output tubes to ensure they dont run to hot. May need bias adjusted.

[@jasonkirkham550]

D-lab Electronics Thank you.

[@BrokebackBob]

Why not just use the rectifier that the designers and manufacturers recommend?

[@jackcraven4591]

Tube Amp Theetahhh is always crucial

[@d-labelectronics]

+Jack Craven Someday there may be a series on PBS!

[@dinosworkshop6870]

Now i am confused!

[@FluxCondenser]

I’ve had good luck with Weber copper cap solid state rectifiers. Plug right into the tube socket. Works great as you can see in this video: kzbin.info/www/bejne/mX2sgIpobberjtE

[@allanjohnston8049]

You gotta kill thst darn music stuff