Go Back   Home > Forums > > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubelab Discussion and support of Tubelab products, prototypes and experiments

Thread Tools Search this Thread
Old 8th September 2008, 04:04 PM   #11
Zap is offline Zap  United States
diyAudio Member
Join Date: Jan 2006
Location: Milwaukee, WI
A while back I thought I remember reading that the CL80 was recommended... which I believe is the part installed in my Simple SE. How does that compare to the others recommended here? I have one in the B+ CT and one in the primary of the power transformer.
  Reply With Quote
Old 8th September 2008, 10:13 PM   #12
whitelabrat is offline whitelabrat  United States
diyAudio Member
whitelabrat's Avatar
Join Date: Dec 2006
Location: Maryland
Tried an RCA 5U4GB out and had no problems. I just assume stay with the 5AR4 which puts the voltage a wee bit over 450v with a 274BX power transformer.
  Reply With Quote
Old 8th September 2008, 10:43 PM   #13
Tom Bavis is offline Tom Bavis
diyAudio Member
Tom Bavis's Avatar
Join Date: Jun 2002
Location: Macedon NY
Regarding the inrush limiters, here's the GE data sheet: http://www.gesensing.com/products/re...asheets/cl.pdf

I use the CL-80 and CL-70 mostly, with 3A and 4A ratings. The CL-90 is good for 2A, enough for smaller amps and secondary side use.
  Reply With Quote
Old 9th September 2008, 01:07 AM   #14
Tubelab_com is offline Tubelab_com  United States
diyAudio Member
Tubelab_com's Avatar
Join Date: Jul 2005
Location: West Virginia panhandle
I use the CL-80 and CL-70 mostly
So do I. I have the CL-80 in one of my Simple SE's on the primary of the transformer. The 90 gets pretty hot in a Simple SE with fat tubes (EH KT88's) when biased hot (near 100 mA).

I think that these things work best when the average current through them is about half their rating. If operated too cold (not enough current compared to their rating) they never "warm up". Their resistance may remain too high leading to poor power supply regulation. If operated too hot, they may fail. The failure is often ugly involving smoke. It usually takes a lot to blow one, but I did have one explode. The exploding CL80 involved a shorted filter cap and a 20 amp fuse, don't do that!
Tubelab, it's 5 year mission. To explore strange new tubes, to seek out new circuits and topologies, to boldly go where no tube has gone before......
  Reply With Quote
Old 9th September 2008, 10:53 AM   #15
ray_moth is offline ray_moth  Indonesia
diyAudio Moderator Emeritus
ray_moth's Avatar
Join Date: Jan 2004
Location: Jakarta

Thanks for the GE data sheet! Very much appreciated.
  Reply With Quote
Old 27th September 2008, 03:19 AM   #16
Ty_Bower is offline Ty_Bower  United States
diyAudio Member
Ty_Bower's Avatar
Join Date: Mar 2007
Location: Newark, DE
I stuck in an old GE 5U4GA. In another thread I've been noting some of the other tubes I've been playing in my Simple SE. Some of them seem to be on the edge of their dissipation limit, notably the Reflektor 6p3s-e and some brown base Shuguang 6L6GC.

I put in the 5U4 to try to drop the voltage a little, and hopefully ease the burden on the output tubes. I think I succeeded here. Measured supply voltage just upstream of the PSU choke is just under 420 volts DC.

I had the voltmeter attached while I powered it up. As expected, the voltage comes up within seconds of hitting the power switch. I wish I had paid closer attention to the peak voltage, but it definitely went way past 420 and came back down again after the output tubes heated up. (edit: saw a peak of 532 volts on the digital meter)

I suppose the initial surge voltage puts a little more abuse on the power supply caps, but overall it reduces the punishment on the output tubes. I'll probably experiment a bit more and see if I feel it affects the sound.
  Reply With Quote
Old 27th September 2008, 04:09 AM   #17
Ty_Bower is offline Ty_Bower  United States
diyAudio Member
Ty_Bower's Avatar
Join Date: Mar 2007
Location: Newark, DE
It seems that GE 5U4 was weak on one section. I tossed it in favor of an unused Sylvania. Now I see 450 volts just before the choke. I guess I ought to test my tubes before I stick them in...
  Reply With Quote
Old 28th September 2008, 04:56 AM   #18
Ty_Bower is offline Ty_Bower  United States
diyAudio Member
Ty_Bower's Avatar
Join Date: Mar 2007
Location: Newark, DE
Stupid question... I can add a switch on the 5v filament winding going to the rectifier? Leave it open when I first power up the amp. Give the output tubes twenty seconds or so to warm up, then close the switch. Then the rectifier warms up quickly and starts to conduct.

Or another idea would be to add an IRCL in series with the 5v winding. Might be problematic, since the IRCL should be sized according to the current draw, and that varies from one type of rectifier tube to another...
  Reply With Quote
Old 28th September 2008, 01:28 PM   #19
Rod Coleman is offline Rod Coleman  United Kingdom
diyAudio Member
Rod Coleman's Avatar
Join Date: Jul 2004
Location: Warwickshire UK
Rectifier tube 5AR4 vs. 5U4GB?
Heating the Outputs before the rectifier filament may make things worse for a directly heated rectifier, since it will face a big current demand during its warmup. 5R4GYs will arc-over very easily in that case.

Check out the RCA 5R4GY data sheet - it suggests warming the rectifier filament for 10 seconds before applying the HT, when higher loads are to be served.

How about a Standby switch in the HT trafo secondary's centre-tap? Power-ON, warm up the filaments & heaters in all the valves, then switch in the HT. If you also use the CL-80, that will be the kindest arrangement for all the components.
  Reply With Quote
Old 28th September 2008, 10:11 PM   #20
ChrisMmm is offline ChrisMmm  New Zealand
diyAudio Member
ChrisMmm's Avatar
Join Date: Jul 2005
Location: Aotearoa
I am interested in Jeff's observations on the sonic effect of different rectifier tubes. Can anybody enlighten me as to what is causing sonic differenceces? All I can think is the degree of voltage "sag" that each tube has - or have I missed something?

And I also wonder where SS diodes (e.g. the FREDs as optionaly used in the SimpleSE) fit in terms of sonics.

This is of pactical interest to be as I embark on a SimpleSE build.

  Reply With Quote


Rectifier tube 5AR4 vs. 5U4GB?Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
5AR4 Tube trade IFixAudio Swap Meet 0 28th January 2007 09:41 AM
Perplexed by 5AR4 Tube Socket? Picture Included ted777ted Tubes / Valves 4 26th September 2005 11:04 PM
Anybody heard about Tarzian Silicon Rectifier for Tube Rectifier Replacement? zxx123 Tubes / Valves 4 21st February 2005 05:02 AM
Tube rectifier for VDIGC tube psu ebijma Chip Amps 2 11th March 2004 05:02 PM
5AR4 & 5U4G Rectifier Questions... Guiness Tubes / Valves 6 29th April 2003 11:37 PM

New To Site? Need Help?

All times are GMT. The time now is 08:16 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio