2 Tube questions,

Trout · 14th April 2006, 01:08 PM

#1,

I had ordered some Rectifier tubes a while back, I was looking for garden variety 5U4's for some guitar amps. They sent me J&J GZ34's instead.

I amp not sure if they can be swapped? This is for some older fender designs using PP 6L6's.

#2,

Rumaging around and organizing the hoard of tubes I have.
I came across some 6DT5's. Power Amplifier Pentodes.

Looked up the specs and wondered if these might make a couple nice SE amps. Say using those 5K Edcor transformers.
I searched the forum here and found nothing on this particular tube.

Trout

Nigel Goodwin · 14th April 2006, 01:31 PM

Quote:

Originally posted by Trout
[B]#1,

I had ordered some Rectifier tubes a while back, I was looking for garden variety 5U4's for some guitar amps. They sent me J&J GZ34's instead.

No idea on a 5U4, but a GZ34 is the standard European valve rectifier used in PA and HiFi valve amps it's rated at:

Vin 2x450V
Iout 250mA
C max 60uF
Vh 5V
Ih 1.9A

Pin connections:

1. IC
2. h
3. NP
4. a'
5. NP
6. a''
7. NP
8. h, k

SY · 14th April 2006, 02:09 PM

5U4 vs 5AR4/GZ34: 5U4 is filamentary, 5AR4 is unipotential (indirectly heated) cathode. Different heater/filament currents. Different pinout. Different forward drop.

Other than that, they're the same.

tubelab.com · 14th April 2006, 02:14 PM

The 5AR4 draws less filament current than the 5U4 and has a longer warm up time than the 5U4. Both of these things are generally good for your amp.

On the other hand you will get a few more volts by using a 5AR4. If you are already on the edge of melting output tubes, or blowing filter caps, as many older guitar amps are, these may not be so good.

The two tubes will give a slightly different sound in a guitar amp. The 5U4 has a higher internal resistance. This adds to the "B+ sag" effect that gives an amp good sustain when it is cranked up. The 5AR4 will give slightly more power with slightly less sustain than a 5U4.

Trout · 14th April 2006, 09:05 PM

Quote:

Originally posted by SY
5U4 vs 5AR4/GZ34: 5U4 is filamentary, 5AR4 is unipotential (indirectly heated) cathode. Different heater/filament currents. Different pinout. Different forward drop.

Other than that, they're the same.

So, In essence it should drop in ok because my B+ comes off the 5U4 Pin 8 All the other pins match, 2+8 Filaments, 4 & 6 Plates.

Extra voltage shouldnt be a problem. I have these set less than the normal self destruct critical zone.

How about those 6DT5's?

Think those could pump out a few watts in an SE amp?
Gene

SY · 14th April 2006, 09:57 PM

I'd think you could get two or three watts out of them.

14th April 2006, 02:09 PM	#3
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	5U4 vs 5AR4/GZ34: 5U4 is filamentary, 5AR4 is unipotential (indirectly heated) cathode. Different heater/filament currents. Different pinout. Different forward drop. Other than that, they're the same. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

14th April 2006, 02:14 PM	#4
tubelab.com diyAudio Member Join Date: Jul 2005 Location: South Florida	The 5AR4 draws less filament current than the 5U4 and has a longer warm up time than the 5U4. Both of these things are generally good for your amp. On the other hand you will get a few more volts by using a 5AR4. If you are already on the edge of melting output tubes, or blowing filter caps, as many older guitar amps are, these may not be so good. The two tubes will give a slightly different sound in a guitar amp. The 5U4 has a higher internal resistance. This adds to the "B+ sag" effect that gives an amp good sustain when it is cranked up. The 5AR4 will give slightly more power with slightly less sustain than a 5U4. __________________ Too much power is almost enough! Turn it up till it explodes - then back up just a little.

14th April 2006, 09:57 PM	#6
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	I'd think you could get two or three watts out of them. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

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14th April 2006, 01:08 PM	#1
Trout diyAudio Member Join Date: Nov 2004 Location: Midwest Madman	2 Tube questions, #1, I had ordered some Rectifier tubes a while back, I was looking for garden variety 5U4's for some guitar amps. They sent me J&J GZ34's instead. I amp not sure if they can be swapped? This is for some older fender designs using PP 6L6's. #2, Rumaging around and organizing the hoard of tubes I have. I came across some 6DT5's. Power Amplifier Pentodes. Looked up the specs and wondered if these might make a couple nice SE amps. Say using those 5K Edcor transformers. I searched the forum here and found nothing on this particular tube. Trout

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