Mark D Mark H and others,tube question

Post by **Plexi** » Mon 03/14/05 11:52 pm

I have a little story first how this came about. I was at a friends house,and he's been collecting tube gear. And was showing me a little bogen challenger. Had a 6L6, and 6av6 6au6..and for the recto it had labeled on it 6BW4/EZ81 So i started looking for data,and its all confusing. Both EZ81 and 6BW4 say their are no subs for either.
But i did find this.

http://www.4tubes.com/All-Files/datashe ... /6BW4.html

Which has the same thing listed. The 6BW4 looks more like a EZ80 in size. But anyway,it still might be a great tube to try. If it can run the bogen with the 6L6 etc..it should run an 18 watter. The thing is,the data has different pin outs for these.. I should have looked at the amp he had,but it was late,maybe some way to wire the socket to use either tube.
The 6BW4,you can buy 5 of these for the cost of 1 6CA4/EZ81.

So any thoughts?

Richie

JonFrum · Post by **JonFrum** » Tue 03/15/05 12:54 am

Duncan's TDSL gives EZ81 as a substitute.

RMSin: 350-0-350

IRect: 150

Cout: 50

RSer: 230

for both.

Groundpath · Post by **Groundpath** » Tue 03/15/05 1:04 am

It does? Where? Pin 3 of the EZ81 would have to be moved to pin 9 of the 6BW4. You can not just put a jumper from 3 to 9 as pin 9 of the EZ81 is an "Internal connection". Would be easy to put in a switch to run both.

Groundpath · Post by **Groundpath** » Tue 03/15/05 1:09 am

I just saw your friends amp runs both. Maybe the internal connection is nothing on the EZ81. If so you could jumper pins 3 and 9 and run both types.

Post by **Plexi** » Tue 03/15/05 1:20 am

""""I just saw your friends amp runs both""""
yeah thats what was weird,but labeled right on the chassis.. It does look like the only way would be to just use a jumper on the socket. I 'll have to call him tomorrow,and ask him to look for sure. But i thought it was interesting. Another thing is,alot of the tube data sites,conflict with the rating of the 6BW4. I did find a link that someone built an amp,and the voltages were about what the 18 is running.

Richie

markd · Post by **markd** » Tue 03/15/05 8:56 am

Plexi wrote: Another thing is, a lot of the tube data sites conflict with the rating of the 6BW4.
Richie

The RCA tube manual (RC-30) on page 543 list the max. DC output of a 6BW4 as 62Â·5 mA. Most tube manuals(Sylvania, Tung-Sol, etc.) list it at 100 mA. RCA didn't make a 6BW4, so perhaps that's just misinformation.

Even at 100mA, it's marginal. It's on the euro tube sites where the 6BW4 is listed at 150mA max DC output. Perhaps there was a euro tube that was an equivalent to the 6BW4, that was capable of 150mA output? The 6BW4 is only $3.80 even at Antique, so it would be great if it would give similar voltages to an EZ81, and stand up to the current draw of an 18watt. Thanks Richie.
markd

markd · Post by **markd** » Tue 03/15/05 9:05 am

Groundpath wrote:Pin 3 of the EZ81 would have to be moved to pin 9 of the 6BW4. You can not just put a jumper from 3 to 9 as pin 9 of the EZ81 is an "Internal connection". Would be easy to put in a switch to run both.

All my euro tube manuals and the euro tube sites do show the EZ81 as having pin 9 internally connected. But all my american tube manuals show the 6CA4(US equivalent to the EZ81) doesn't have pin 9 internally connected. Perhaps they are using a 6CA4 that has been rebranded as an EZ81? Just a thought, markd

s2 · Post by s2 » Tue 03/15/05 10:52 am

Hey, Mark! While we are on the subject of rectifier substitutes, you once mentioned a 5V equivalent (or rough equivalent) to the EZ81. Can you jog my memory as to what that tube was? I would like to try it out and see how it goes.

Thanks!

Post by **Plexi** » Tue 03/15/05 11:43 am

Mark: """Perhaps they are using a 6CA4 that has been rebranded as an EZ81? Just a thought, markd""""

I've also seen some 6CA4 that were small or labeled 6CA4/EZ81.. which could also be just EZ80's rebranded.
But you see when looking at the tube data for the 6BW4,it has alot of differences between manuals. And they all say 9M and 9DJ for the socket.
So the only way to use either would have to be a jumper wire on the socket. If you look here..

http://www.enjoythemusic.com/magazine/e ... vinson.htm

About halfway down the page,is a schematic posted of the power supply of an amp. It was useing a Hammond transformer. But it does look like a good tube that would work for different builds,or one to keep in mind since it doesn't cost much at all. But it sure made me think, when i seen the chassis label for the recto tube. Alot of Bogens used rebranded mullards and other similar tubes. I looked for that model challenger but couldn't find any.

Richie

koa-dogg · Post by **koa-dogg** » Tue 03/15/05 11:50 am

Has anyone tried the Weber Copper Cap replacement for the EZ81?

JonFrum · Post by **JonFrum** » Tue 03/15/05 12:32 pm

koa-dogg wrote:Has anyone tried the Weber Copper Cap replacement for the EZ81?

Not much to say - it works. I liked the idea that they don't draw heater current.

markd · Post by **markd** » Tue 03/15/05 12:57 pm

s2 wrote:
Hey, Mark! While we are on the subject of rectifier substitutes, you once mentioned a 5V equivalent (or rough equivalent) to the EZ81. Can you jog my memory as to what that tube was? I would like to try it out and see how it goes.
Thanks!

The one I mentioned was the 5V4(max DC output 175mA). It will have less sag than the EZ81(max DC output 150mA) at a given current draw, so the 5V4 would be good for a PT with lower secondary voltages and a 5V filament winding(some Hammonds). Or if you liked the tone of a higher plate voltage with an 18watt PT.

Several people on the board have reported using the 5Y3(max DC output 125mA) with good results. Their experience leads me to believe the 5Y3 also works well. The lower DC output of the 5Y3 isn't a concern because that is the maximum full time operating limit, not the extreme maximum current the tube can handle. The 5Y4 is also an equivalent to a 5Y3.
I have been wary of using a 5Y3 because of the greater voltage sag. But there are several situations where that might be a plus. The Lite series tends to run the voltages a bit high. Using a 5Y3 in a Lite(with an 18watt PT) should get the voltages down.
The effect of plate voltage on tone is easy to hear. Getting guitarist to agree on what voltage gives the "best" tone is something else entirely( I like 330v across an EL84). It might be interesting to have an octal rectifier tube socket in an 18watt, as well as the 9pin for the EZ81, to swap between the 5Y3, EZ81, and 5V4 to hear the change in tone between the different voltages. Why don't you hop right on that. You could call it the dual rectifier. Maybe not. ha!
If anyone has experience with 5v rectifiers in an 18watt maybe you could hop in here. What is your plate voltage?

The 5Y3,5Y4, and 5V4 are all available for around $11.00, or even less. They are cheaper than a EZ81 and may be more available for some people. markd

s2 · Post by s2 » Tue 03/15/05 1:29 pm

LMAO!!!

I think I'll throw in a SS and call it a triple rectifier. Maybe I'll patent the idea! Heck, why not?! I did just secure a patent on the noval tube socket afterall :)

Thanks Mark! I put a 5V rectifier tap on my new PT to allow folks to use a 5V tube with the 5Y3 in mind for the Lite applications. I remembered you mentioning the 5V4, but I must have lost the scrap of paper I wrote it on. So much for my filing system!

Newt · Post by **Newt** » Tue 03/15/05 2:30 pm

The Knight kit amp I used for a donor for a Lite II had an EZ80/6V4 rectifier. With the same pinout as an EZ81/6CA4, it only draws 600ma of heater current and puts out a max of 90ma. DC I was prepared to switch to a 6CA4, but it worked fine. AES has those for $8.30 now.

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Mark D Mark H and others,tube question

Mark D Mark H and others,tube question