Rectifier that drops lots of volts?

dsavitsk · 30th November 2006, 01:23 AM

I am having trouble sourceing the power transformer I want. A 250-0-250 with a gz34 gives me about the voltage I want, but the only thing I can find is 300-0-300 (I am looking for a James to match the OPTs, and euphonia is out of stock and no one else (James/THL, and a few others) will answer my emails). So, I am looking for an octal rectifier tube that does not need more than a 5V/2A winding that can drop a few more volts. Any suggestions?

Zen Mod · 30th November 2006, 01:34 AM

use LC filter

sorenj07 · 30th November 2006, 01:39 AM

Try a 5U4? This is PSUDII right? Is there no way you could sneak a little 3-amp filament transformer under the hood of the amp? I don't know any rectifiers that fit your criteria otherwise...

edit: or a LC filter. What is the desired voltage and current?

kevinkr · 30th November 2006, 02:01 AM

5R4...

Jeff Yourison · 30th November 2006, 02:07 AM

I've been working with the GZ34 (5AR4), 5R4 and 5U4GB. I can get the VDC I need from the GZ34, and the others (both directly heated) give quite a bit less, due to a voltage drop that kicks in depending on the current drawn. Try a 5R4 with a 10H choke in LC, adding an input cap well *under* 4 muF. The 5U4GB may give you a little more output (but maybe not much when under load).

As an example, in one case I got 352 VDC under load with the GZ34, and 328 VDC with the 5R4. You can source all these from Jim McShane.

Tweeker · 30th November 2006, 04:51 AM

I have 240-0-240 (read: industrial control transformers) PTs coming out of my ears. Although, they arnt purty like the James.

dsavitsk · 30th November 2006, 05:26 AM

Yeah, this is really all about purtyness. here's the "breadboard" version of the amp

and that Hammond is just ruining it. I have a fancy padauk case made and am getting the top plate machined professionally, so it just seems wrong to not have a nice looking PT. Though, if I can't get the James I may just go for a custom EP, or even a 300 series Hammond.

Thanks for all the tube suggestions too. The PS is a RCRCLC followed by a regulator. I can increase the resistors a little, too.

Jeff Yourison · 30th November 2006, 12:49 PM

Wow, that's nice looking. Your OPTs are beautiful.

The 5R4 is a bigger tube than the GZ34, but is very handsome, even inside. My version has a brown base -- would base color matter to you for a rectifier tube?

Can't wait to see the final project.

--Jeff

Sherman · 30th November 2006, 01:40 PM

A 5U4-G drops a lot of volts (forget how many) but needs a 5V, 3A secondary.

I haven't dealt with these guys but maybe they can help locate a James PTX.

http://www.tubeaudiokits.com/index.htm

30th November 2006, 01:23 AM	#1
dsavitsk diyAudio Member Join Date: Jan 2005 Location: Chicago	Rectifier that drops lots of volts? I am having trouble sourceing the power transformer I want. A 250-0-250 with a gz34 gives me about the voltage I want, but the only thing I can find is 300-0-300 (I am looking for a James to match the OPTs, and euphonia is out of stock and no one else (James/THL, and a few others) will answer my emails). So, I am looking for an octal rectifier tube that does not need more than a 5V/2A winding that can drop a few more volts. Any suggestions? __________________ http://www.ecpaudio.com

30th November 2006, 01:34 AM	#2
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	use LC filter __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; BAF Forum & Gallery;I'm dumb

30th November 2006, 02:01 AM	#4
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	5R4... __________________ www.kta-hifi.net

30th November 2006, 04:51 AM	#6
Tweeker diyAudio Member Join Date: Dec 2004 Location: Cincinnati, Ohio	I have 240-0-240 (read: industrial control transformers) PTs coming out of my ears. Although, they arnt purty like the James. __________________ Be sure your foil hat has a good low impedance ground.

30th November 2006, 05:26 AM	#7
dsavitsk diyAudio Member Join Date: Jan 2005 Location: Chicago	Yeah, this is really all about purtyness. here's the "breadboard" version of the amp and that Hammond is just ruining it. I have a fancy padauk case made and am getting the top plate machined professionally, so it just seems wrong to not have a nice looking PT. Though, if I can't get the James I may just go for a custom EP, or even a 300 series Hammond. Thanks for all the tube suggestions too. The PS is a RCRCLC followed by a regulator. I can increase the resistors a little, too. __________________ http://www.ecpaudio.com

30th November 2006, 01:39 AM	#3
sorenj07 diyAudio Member Join Date: May 2006	Try a 5U4? This is PSUDII right? Is there no way you could sneak a little 3-amp filament transformer under the hood of the amp? I don't know any rectifiers that fit your criteria otherwise... edit: or a LC filter. What is the desired voltage and current?

30th November 2006, 02:07 AM	#5
Jeff Yourison diyAudio Member Join Date: May 2004 Location: WI	I've been working with the GZ34 (5AR4), 5R4 and 5U4GB. I can get the VDC I need from the GZ34, and the others (both directly heated) give quite a bit less, due to a voltage drop that kicks in depending on the current drawn. Try a 5R4 with a 10H choke in LC, adding an input cap well under 4 muF. The 5U4GB may give you a little more output (but maybe not much when under load). As an example, in one case I got 352 VDC under load with the GZ34, and 328 VDC with the 5R4. You can source all these from Jim McShane.

30th November 2006, 12:49 PM	#8
Jeff Yourison diyAudio Member Join Date: May 2004 Location: WI	Wow, that's nice looking. Your OPTs are beautiful. The 5R4 is a bigger tube than the GZ34, but is very handsome, even inside. My version has a brown base -- would base color matter to you for a rectifier tube? Can't wait to see the final project. --Jeff

30th November 2006, 01:40 PM	#9
Sherman diyAudio Member Join Date: Feb 2004 Location: Chicago area	A 5U4-G drops a lot of volts (forget how many) but needs a 5V, 3A secondary. I haven't dealt with these guys but maybe they can help locate a James PTX. http://www.tubeaudiokits.com/index.htm __________________ --Sherman

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