Rectifier Tubes

[colemaneuclid]

My friend was playing his 2ch DR the other day when he noticed the amp lost all its umph.
Upon inspection he noticed that the left rectifier tube wasn't seated in the socket, rather just sitting on top. Also the rectifier tubes in the amp had absolutely no label on them at all. He just bought it about a month ago and hadn't noticed the unlabeled tubes.

He checked out all the power tubes and they seem to be fine.

A local GC is holding a pair of 5u4gb's for him but he stopped into a local music store that also carries tubes and the guy behind the counter said he had a pair of american made rectifier tubes for $10 a piece.... I was unaware that ANY tubes were being manufactured in the states... He didn't tell me who the manufacturer was or what kind they were.

I've always used Mesa 5U4G's in my 2ch DR
Is the 5AR4 the only other type of rectifier tube usable in the DR?

 

[R_ADKINS80]

USA made tubes are vintage and if they are in good shape $10 each is a steal. You can use big bottle 5u4 and small bottle 5u4gb rectifier tubes. I don't know if he 5ar4 will work in there or not. I have heard of people using GZ34 rectifier tubes as well and some people say you would need to up the fuse rating to do so, but i say to hell with that.

 

[droptrd]

Im not sure if a 5ar4 will work either. I use GZ34's. much tighter than the 5u4's. Less sag. 5u4's would be great for blues and softer rock. Use the GZ34's if you like the tube rectifier sound but would like a faster, tighter attack.

 

[stokes]

5AR4 and GZ34 are the same tube.Never "up the fuse rating" in any amp.

 

[LerxstLee]

My friend was playing his 2ch DR the other day when he noticed the amp lost all its umph.
Upon inspection he noticed that the left rectifier tube wasn't seated in the socket, rather just sitting on top. Also the rectifier tubes in the amp had absolutely no label on them at all. He just bought it about a month ago and hadn't noticed the unlabeled tubes.

He checked out all the power tubes and they seem to be fine.

A local GC is holding a pair of 5u4gb's for him but he stopped into a local music store that also carries tubes and the guy behind the counter said he had a pair of american made rectifier tubes for $10 a piece.... I was unaware that ANY tubes were being manufactured in the states... He didn't tell me who the manufacturer was or what kind they were.

I've always used Mesa 5U4G's in my 2ch DR
Is the 5AR4 the only other type of rectifier tube usable in the DR?

Perhaps the unlabled tubes are 5u4Gs and not 5u4ga's or 5u4gb's .
5u4s sag more than 5u4gb's , the gb's should give you a tighter low end .

Rectifiers do just that , the rectify AC Current into DC current . They do this @ 60x s a second (in the U.S.)


5u4-g =s tube voltage drop per section is 44 volts @ 225mA d.c. with a max Peak inverse(p.i.v.) voltage of 1,550volts , rms per plate =s 450, and max peak current @ 800 mA per plate .

5u4-GA drops 44volts @ 225mA d.c per section max p.i.v. of 1,550 volts rms per plate =s 450 and a max peak current @ 900 mA per plate .

5u4-GB drops 50volts @ 275mA d.c. with a p.i.v of 1,550 volts rms per plate =s 450 , with a max peak current @
1000mA per plate .

Hope this helps . 5u4a-s will be slightly spongy and 5u4GB-s will be tighter with more low end .

/cheers

A 5ar4 has only 750mA,s per plate most sag BUT the plate watts are only 1.9 compared to all 5u4s that have 3 plate watts.

Thus a 5ar4 might be used to record " lower volume break up " but with the plate current I would'nt use them .
Toss in a 5u4-g they are only 50mA,s higher but the plate current is correct for the amp .
Sure there are alot of tubes you CAN use yet a 5ar4/gz34 would give the MOST sag .
It is a proven fact of the above mentioned rectifier tubes . A 5ar4 would sag giving all it lacks over the
three 5u4s it has lower current , lower piv , lower peak watts .

/cheers

 

[stokes]

Of all the rectifiers mentioned here in this post a 5AR4/GZ34 has the least sag.I really doubt you would notice the difference in the sag produced between the 5U4,5U4G, or whatever incarnation of the 5U4.The 1.9 and 3watts you are comparing are the heater current,not the plate watts.

 

[LerxstLee]

Of all the rectifiers mentioned here in this post a 5AR4/GZ34 has the least sag.I really doubt you would notice the difference in the sag produced between the 5U4,5U4G, or whatever incarnation of the 5U4.The 1.9 and 3watts you are comparing are the heater current,not the plate watts.

Filament Volts for 5ar4 =s 5.0 the same as 5u4s,
Max Plate Watts 1.9 for 5ar4 and 3.0 for 5u4gs .

I have a 63 ampeg jet 2 6v6s with a 5y3 rectifier . If I want to tighten that amp up a bit I use a gz34/5ar4 .
There is no way that transformer in the jet can handle a 5u4 even if it would fit .
A 5y3 Peak current is 375mA
A gz34/5ar4 peak current is 440mA
In the jet It is night and day . I stay with the 5y3 , and if I need a tad more I drop in the gz34s.
A 5u4 would overheat my transformer to make for a smoked rewind

 

[stokes]

You have your numbers screwed up.The 1.9a is the heater current for the 5AR4,the 3.0a is the heater current for the 5U4.The heater current for a 5Y3 is 2a's,that is why the 5U4's 3a's wont work in a 5Y3 circuit and will,as you say "over heat your transformer".As for the output curren ratings, the 5AR4 has a max 440ma's DC output current,the 5Y3 you mention is more like 175ma's DC ouptut current.It is the lowest of the 5 volt rectifiers,and has the most sag.The 5AR4 has the least sag of all the 5 volt rectifiers.The sag is also affected by the physical structure of the tubes.The 5AR4 is an indirectly heated cathode as opposed to the directly heated cathode of the 5U4.The 5AR4 is more like a solid state rectifier because it drops very little voltage in operation.

 

[LerxstLee]

You have your numbers screwed up.The 1.9a is the heater current for the 5AR4,the 3.0a is the heater current for the 5U4.The heater current for a 5Y3 is 2a's,that is why the 5U4's 3a's wont work in a 5Y3 circuit and will,as you say "over heat your transformer".As for the output curren ratings, the 5AR4 has a max 440ma's DC output current,the 5Y3 you mention is more like 175ma's DC ouptut current.It is the lowest of the 5 volt rectifiers,and has the most sag.The 5AR4 has the least sag of all the 5 volt rectifiers.The sag is also affected by the physical structure of the tubes.The 5AR4 is an indirectly heated cathode as opposed to the directly heated cathode of the 5U4.The 5AR4 is more like a solid state rectifier because it drops very little voltage in operation.

Well then there you have it . To think I wasted all that time just to be incorrect .
I put my book away , I promise not to look at it again .

 

[212Mavguy]

It's not the book's fault, rather, it is the lack of understanding it. Stokes is right. And yes, it is embarrassing to make a mistake, especially when trying to help. I know 'cause I've done it. :wink: Stokes also is an amp tech. We are lucky to have his posts here. Peace.

 

[stokes]

Once again,thanks for your kind words,Mav,you are as much an asset to this board as any of us.Lee,it is not my intention to embarass you or anyone else,in fact,there is nothing to be embarassed about.Like any topic on the 'net,there is as much misinfo as there is good info,just trying to help seperate the two as best we can.We all make mistakes and misinterpretations,no matter the level of our experience,from time to time.Dont put the books away,they are invaluable in this field.You just need to interpret a little better.Some of the values you are quoting are correct,just out of context.For instance,you are quoting plate currents as if they are the same as the output current,in a rectifier you should be more concerned with the dc output current,at least as it is related to this subject,i.e. the sag factor between the different 5 volt rctifiers.I made a misquote myself in my other response,I cited 175ma's for the 5Y3,it is actually 125ma's.The 5V4 is 175ma's and as you can see falls between the 5y3 and 5U4.

 

[LerxstLee]

Of all the rectifiers mentioned here in this post a 5AR4/GZ34 has the least sag.I really doubt you would notice the difference in the sag produced between the 5U4,5U4G, or whatever incarnation of the 5U4.The 1.9 and 3watts you are comparing are the heater current,not the plate watts.

I have tried 5u4GBs and 5u4s in a triple rectifier a few weeks ago .
There is a difference. Noticable. Maybe not using a single rectifier I would agree.
I love the sag and tubelike "compression" of the 5u4s myself. Personal preference.