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5Y3 rect. in a 6L6 Amp???

3/2/1999 7:20 AM
5Y3 rect. in a 6L6 Amp???
I'm sure I should know this! But, will a 5Y3 rectifier hold up in a amp with 3 12AX7s and 2 6L6s?? I'm still trying to drop B+, I've got it down to 460vdc on the plates with a 5U4 I was wondering if a 5Y3 woukd drop it even more. Our damn line voltage is 125vac. Thanks RJH
3/2/1999 8:58 AM
Jim S.

Is this a tweed Bassman? If you play the amp at moderate to loud volumes regularly, a 5Y3 probably will wear out fairly quickly. It is not designed to be used in amps that put out 40 or more watts.  
As long as you're not using Chinese 6L6s, you shouldn't have any problems running at 460 plate volts or even higher. Sovtek 5881 and 6L6WXT as well as Svetlana 6L6GC should easily handle 500 volts.
3/2/1999 9:18 AM

This is a homebrew amp. I've run a 5ar4 and gotten 475 on the plates (russian 5881s) and now a 5u4 with 460 on the plates same 5881s. I played a gig (4 hours) on sunday with the 5ar4 setup no problems, however, I had a fan blowing on the tubes the whole time, they stayed nice and cool. I've got a Phillips 5y3 I was going to try, I just didn't want to blow something. I'm trying to get a pair of 6l6wxt+ any experence with this tube? If I could get the B+ low enough I'd even try 6V6s in it! RJH
3/2/1999 9:50 AM

You could try a 5V4 too.  
I'd be nervouse running that much current at those voltages through a little 5Y3 tube.  
It might go for quite a while with no damage though.  
But I didn't see where you mentioned what idle current are you running these tubes at.  
I doubt if you could blow a good 6L6GC with 500v at normal correct current levels anyhow.  
Is it the heat you are worried about or are you trying to get it tweaked so you can run a pair of 6V6GTs?  
What capacitor value are you using on the end of the rectifier tube now?  
A real small high voltage one here (.5uF to 2uF) followed by a 100-200 ohm resistor and then a larger value cap, then the lead to the rest of the amp might reduce the voltage to the OT enough to satisfy you.  
Mission Amps
3/2/1999 10:33 AM

I am somewhat worried about the heat the OT is a a hammond 1608 @ 10watts !! The damn high household voltage @ 125vac is driving me nuts! I had originally wanted to run 6v6s in the amp thus the 1608 OT. The 6l6s sound great I mainly don't want to roast something! The front end is a tweed type cathode follower, the back end is a fairly standard Fender 2Xtube design. I really don't want to go the zeiner route either, If you guys think that 6l6s will be ok, I'll letem rum. (I've got a 12vdc muffin fan on the way from Mouser, I'll hook it to the 6vdc filiments to run at 1/2 rpm, I think this will keep things cool. BTW @ 460vdc the 6l6 bias current is 26ma. Thanks guys RJH
3/2/1999 12:51 PM

I agree with Bruce's recommendation of not using a 5Y3. The 5V4 would certainly hold up in this circuit, but the voltage drop won't be much more than when using the 5AR4. The 5V4 was the low voltage drop rectifier of the day before the 5AR4 was invented.  
If your power transformer's 5volt winding has a 3amp current rating, you can try a 5U4 which will drop your B+ voltage down a bit more than the 5AR4 or 5V4.  
Early amps with either a pair of 6L6s or a quad of 6V6s, and a HV secondary of 350v rms or less (each side of center tap) used either a single 5U4 or a pair of 5Y3s in parallel to handle the current demands of the typical 30 watt amp of the day.  
A small slow speed fan is a good idea and a nice addition to any tube gear. You may not *need* it, but it will help everything last longer. It's good design if you can fit it in.
3/2/1999 3:43 PM

What about a 5R4? It only draws 2 amps and I believe it has more voltage drop than a 5u4. I'm asking as I'm curious about this tube myself and wondering why you don't hear more about it. Mark
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