5r4-gy and 5u4g rectifiers - differences?

Jcricket

Jcricket

not someday, but today
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ANyone know the differences between the 5u4g series and the 5r4-gy rectifier tubes? They use the same settings for testing on my mighty might tube tester. There is clearly an additional part in the 5r4-gy tube though. See the pics the 5r4 is on the left.

Notice the difference in the shape of the plates and the two additional wires in the 5r4
 

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But what about the "sound" guys?:scratch2: For me, the R4 is better in SET apps. while the U4 is killer for higher powered PP designs. (Usual disclaimer); it could be all in my head, but hey, that's where my ears is.:yes:
 
I wouldn't have an idea bout the sound differences. I only use 5r4 myself, and even then, have only listened to them for about 45 minutes...

Another question though, I heard that you can't hear a difference if you try rolling rectifier tubes?

WHich also gets me to wondering.. I wonder what configuration my Bogen amps are.. :headscrat
 
OH.. and BTW Allan... Those tubes you had given me and said they were EL34 tubes? Turns out the were actually 6V6 tubes.. no ownder I redplated one.. DOH!! Shocked my amps ran on them though..
 
If your amplifier calls for a 5R4-GY I'd make sure your power transformer can handle the additional current draw of the 5U4.
I'm sure many PT's were ruined by that swap.

I have tried both in the same amplifier and did notice a slight sound difference. I have read where people say that there can be no difference in sound by swapping rectifiers, and I didn't really expect anything ....but I heard it!
 
vendo81 said:
If your amplifier calls for a 5R4-GY I'd make sure your power transformer can handle the additional current draw of the 5U4.
I'm sure many PT's were ruined by that swap.

I have tried both in the same amplifier and did notice a slight sound difference. I have read where people say that there can be no difference in sound by swapping rectifiers, and I didn't really expect anything ....but I heard it!
Click to expand...

Good point about the filament current.:yes: I can hear a slight difference too, it's just one of those things you don't talk about at parties.:D
 
It's easy to understand why changing rectifiers may make your gear sound different. By changing the rectifier you can end up changing the operating points of the rest of the tubes, since the rectifier supplies the voltages. So you are really moving the tube operating points up and down, not directly affecting the signal. I can hear differences between rectifiers and especially regulators pretty easily in my Supratek preamp.
 
Maxamillion said:
It's easy to understand why changing rectifiers may make your gear sound different. By changing the rectifier you can end up changing the operating points of the rest of the tubes, since the rectifier supplies the voltages. So you are really moving the tube operating points up and down, not directly affecting the signal. I can hear differences between rectifiers and especially regulators pretty easily in my Supratek preamp.
Click to expand...

I woulda thought the same thing. If the B+ is a little different, or the amount of current the rectifier consumes and/or can supply is different, it's going to affect the other tubes. Whether that's audible may vary, but there is a potential cause there.
 
I was speaking more "generally" about the sonic differences of the two tubes, not switching tubes in the same circuit.:no: That would indeed get you some differences I bet. :yes:
 
Heh...

similost said:
OH.. and BTW Allan... Those tubes you had given me and said they were EL34 tubes? Turns out the were actually 6V6 tubes.. no ownder I redplated one.. DOH!! Shocked my amps ran on them though..
Click to expand...

That's interesting. they came as a package deal on the "Green Monster" amp I got from Cableguy. Far as I knew, they came billed as EL34's. To tell you the truth, I never even tried them on that amp. Thye were sitting around, and I wasn't going to use them, so off they went.

We gotta find you a tester. Those 12AU7's weren't the picture of health either...:D

PS Sorry for the hijack....
 
I like the astegma behind my tester. It was calibrated, but it only test go/nogo.. which for me is good enough I guess..

What got me to realize they weren't EL34's was when I pulled a tube a few weeks ago, I noticed it looked completely different than the EL34 I was holding, so I looked up the strange numbers on them, and found they were a 6V6 replacement..

No worries though... I got uses.. :thmbsp:
 
Maxamillion said:
It's easy to understand why changing rectifiers may make your gear sound different. By changing the rectifier you can end up changing the operating points of the rest of the tubes, since the rectifier supplies the voltages. So you are really moving the tube operating points up and down, not directly affecting the signal. I can hear differences between rectifiers and especially regulators pretty easily in my Supratek preamp.
Click to expand...

I should have been more clear on my message. The 5U4 and 5R4 do have different voltage drops. That would change the B+ and possibly the sound of an amplifier.
Jaymanaa mentioned that he liked the sound of the 5R4 in Set amplifiers and the 5U4 in higher powered PP designs. I took that as a overall sonic liking for a perticular type of amplifier design.

Before I knew the possible danger of trying a 5U4 in my w5M amplifiers (because of the filament current draw possibly damaging the PT) I gave one a try using a 10W dropping resistor of aprox. 10 volts to keep the B+ the same as my reading using the 5R4-GY. This was because a person I met at a Ham Radio swapmeet told me that he liked the sound of his DIY 6L6GC powered amplifier using a 5U4 instead of a 5R4-GY and suggested I swap them out. He said the B+ would change and a dropping resistor would possibly be needed. I didn't really think it would make a difference but I had the time and lots of 5U4's.
After changing them out and keeping the B+ the same I found I prefered the 5U4 better. A month or so later I ended up swapping them back when I found out that my fragile PT could fry! Thats possibly why many W5M's are found with blown PT's and 5U4's in them.
I'm sure there may be other changes that occur with this setup that I'm not aware of but there is a definate slight change of sound "while keeping the B+ the same". I'm sure there was something else going on that I just wasn't aware of but could possibly be explained by the experts here. I did do quite a few other mods but left the 5R4-GY's in them.

I've tried rolling every tube I could find as I figured I was going to listen to these for quite awhile. I ended up with the RCA 5R4-GY rectifier, swapping the 12AU7's to RCA cleartop 6CG7's and keeping the original vintage GEC KT66's for output.
 
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