5u4g rectifier OK in simple SE?

bwp · 9th November 2010, 07:05 PM

I am piecing together the parts for a simple SE build. I have some 5u4g rectifiers around from another amp and am wondering if they can be used as a direct replacement for the 5ar4? Do any other parts needs to be changed to accomodate it?

I have swapped it into another amp that speced the 5ar4 and it was fine, the 5u4 does not have the slow start feature of the 5ar4 so it is a bit tougher on the tubes.

Ty_Bower · 9th November 2010, 08:45 PM

I've used the 5U4 in my Simple SE. As you point out, it is a directly heated tube and does not provide the slow start of a 5AR4. It will be harder on the tubes, and especially the power supply capacitors at each startup.

If my power transformer were rated 750VCT or less, and my power supply caps were rated 500WVDC or higher (with at least 550V surge) I'd probably use the 5U4 and not worry to much. Overall, however, I think the 5AR4 is a better choice.

If you plan to use the 5U4 on a regular basis, I might recommend substituting a smaller capacitor for C1. I think the standard parts list calls for a 47uF cap at this location. I'd probably try a 22uF instead.

w5jag · 10:31 PM

Maybe - it's not a direct replacement for a 5AR4.

5U4 will drop about 25 more volts than 5AR4. It also takes an extra amp of filament current. I don't think your tubes will care whether or not it has a separate cathode, I wouldn't worry about that.

In theory, C1 can be larger for a 5AR4 than a 5U4; in practice, old U.S. made 5U4's are pretty tough beasts so I wouldn't worry much about the C values. I've never killed a 5U4, and it hasn't been from lack of effort.

Win W5JAG

edit: the only rectifier tubes I've ever killed were 5AR4's and that Sovtek "5Y3", and I wasn't even trying to kill those ....

bwp · 10th November 2010, 12:56 PM

Thanks for the replies, I will likely give both a try and see how it goes. I do like the large coke bottle shape of the 5u4, it definitely fills out the chassis nicely.

chrisb · 22nd November 2010, 07:21 PM

Quote:

Originally Posted by bwp

Thanks for the replies, I will likely give both a try and see how it goes. I do like the large coke bottle shape of the 5u4, it definitely fills out the chassis nicely.

get serious dude, and try one of these:

274A Data sheet. Emission Labs.

bwp · 24th November 2010, 10:14 PM

I would love to..... for $20. They do make great tubes but man o man are they spendy. On a side note, anyone know where I can find a 22uf 550v or 47uf 550v caps? I am having a heck of a time finding radial caps in those ratings.

nic6paul · 24th November 2010, 10:35 PM

Could use a 440vac motor run capacitor. Something like this one would work LINK

shortwave · 25th November 2010, 05:36 AM

Quote:

Originally Posted by bwp

I would love to..... for $20. They do make great tubes but man o man are they spendy. On a side note, anyone know where I can find a 22uf 550v or 47uf 550v caps? I am having a heck of a time finding radial caps in those ratings.

You might try MCM electronics on the web

9th November 2010, 07:05 PM	#1
bwp diyAudio Member Join Date: Oct 2010	5u4g rectifier OK in simple SE? I am piecing together the parts for a simple SE build. I have some 5u4g rectifiers around from another amp and am wondering if they can be used as a direct replacement for the 5ar4? Do any other parts needs to be changed to accomodate it? I have swapped it into another amp that speced the 5ar4 and it was fine, the 5u4 does not have the slow start feature of the 5ar4 so it is a bit tougher on the tubes.

9th November 2010, 10:27 PM	#3
w5jag diyAudio Member Join Date: Feb 2007 Location: Arkansas	Maybe - it's not a direct replacement for a 5AR4. 5U4 will drop about 25 more volts than 5AR4. It also takes an extra amp of filament current. I don't think your tubes will care whether or not it has a separate cathode, I wouldn't worry about that. In theory, C1 can be larger for a 5AR4 than a 5U4; in practice, old U.S. made 5U4's are pretty tough beasts so I wouldn't worry much about the C values. I've never killed a 5U4, and it hasn't been from lack of effort. Win W5JAG edit: the only rectifier tubes I've ever killed were 5AR4's and that Sovtek "5Y3", and I wasn't even trying to kill those .... Last edited by w5jag; 9th November 2010 at 10:31 PM.

24th November 2010, 10:35 PM	#7
nic6paul diyAudio Member Join Date: Jan 2007 Location: Minnesota	Could use a 440vac motor run capacitor. Something like this one would work LINK __________________ - Nic

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Simple SE and Rectifier Manipulation	bigjppop	Tubelab	1	16th January 2010 11:11 AM
simple se blowing rectifier and fuse	newtube	Tubes / Valves	15	16th May 2009 10:54 PM
Tubelab Simple SE Rectifier Problem?	eddiemeddiem	Tubes / Valves	45	21st June 2008 03:27 AM
rectifier tube 5u4g	karma	Tubes / Valves	10	1st April 2004 04:45 AM
5AR4 & 5U4G Rectifier Questions...	Guiness	Tubes / Valves	6	29th April 2003 10:37 PM

9th November 2010, 08:45 PM	#2
Ty_Bower diyAudio Member Join Date: Mar 2007 Location: Newark, DE	I've used the 5U4 in my Simple SE. As you point out, it is a directly heated tube and does not provide the slow start of a 5AR4. It will be harder on the tubes, and especially the power supply capacitors at each startup. If my power transformer were rated 750VCT or less, and my power supply caps were rated 500WVDC or higher (with at least 550V surge) I'd probably use the 5U4 and not worry to much. Overall, however, I think the 5AR4 is a better choice. If you plan to use the 5U4 on a regular basis, I might recommend substituting a smaller capacitor for C1. I think the standard parts list calls for a 47uF cap at this location. I'd probably try a 22uF instead.

10th November 2010, 12:56 PM	#4
bwp diyAudio Member Join Date: Oct 2010	Thanks for the replies, I will likely give both a try and see how it goes. I do like the large coke bottle shape of the 5u4, it definitely fills out the chassis nicely.

24th November 2010, 10:14 PM	#6
bwp diyAudio Member Join Date: Oct 2010	I would love to..... for $20. They do make great tubes but man o man are they spendy. On a side note, anyone know where I can find a 22uf 550v or 47uf 550v caps? I am having a heck of a time finding radial caps in those ratings.

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read