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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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PostPosted: 05 Jan 2011, 20:51 
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This is all great information.

How about SE vs. PP? PP amps have a fairly significant peak to quiescent PS current ratio (PQCR) whereas in SE amps this ratio is usually fairly small (usually pretty close to 1). So, if as Rock4016 says...
Quote:
... the reason SS diodes have a reputation for great bass is due to their low impedance.
then in amps where PQCR is highest (i.e. where PS impedance is going to have the most pronounced effect) shouldn't we look for the lowest loss rectifiers?

Here is a plot of rectifier plate characteristics (albeit a fairly old one) showing plate current vs voltage for various tubes.
Attachment:
Rectifier PLate Curves.jpg
The tubes corresponding to lines on the left have lower losses then those to the right. Should we endeavor to use these tubes when the PQCR is higher?

What do people think?


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PostPosted: 09 Jan 2011, 16:07 
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Well, obviously not a lot of interest here. But before I drop it, I decided to generate a more up-to-date version of the plot above. So, using GE data sheets for consistency, I generated the following plot.
Attachment:
Plate Voltage Curves.png

The thing that really surprised me is the behavior of the 5AR4/GZ34. I had always considered the 6CA4 a low loss regulator but the 5AR4 really blows it away. In cases where I can't stand the voltage drop of the 5U4 I'll definitely be looking at the 5AR4.


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PostPosted: 09 Jan 2011, 21:51 
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Thank you for the plot! :thumbsup:

Cheers!

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PostPosted: 11 Jan 2011, 13:15 
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Thanks for sharing this great info. I've book marked the thread and will definitely refer back to it in the future.
Cheers

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PostPosted: 11 Jan 2011, 14:16 
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Wow, Matt. That 5U4 is a saggy tube. I hadn't ever looked at the 5U4. I've looked at the 6CA4 and the 5AR4. I've a build on the back burner that will be using the 6CA4. I looked at the 5AR4 for that build, but I like the small size of the 6CA4 and its current handling is sufficient for my build. If I were needing something with a little more umph, I would consider the 5AR4. But after looking at the 5U4, I can't under stand any use for that one unless you just needed some real current hog of an amplifier. To over come that sag, you would need a pretty high voltage PT supplying it.

Good thread Matt. Definitely gets the brain juices flowing. :thumbsup:

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PostPosted: 17 Jan 2011, 08:30 
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Location: Denmark
Hi
Dos anyone know the the Shuguang 274B rectifier tube,and are thy enny good,planning to use them in a single ended, b+ voltage abut 450-500 volts

nkdk


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PostPosted: 18 Jan 2011, 11:06 
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Here's a data sheet I found.
http://www.westernelectric.com/products/274b.html

Should be similar to the Shuguang.


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PostPosted: 24 Feb 2011, 13:01 
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It's been a while but I was looking over a power supply design and I began to think about the rectifier voltage drop plot out of Herbert Reich's 1944 book "Theory and Applications of Electron Tubes", 2nd ed. shown here in this thread. I had originally thought that the straight lines were just approximations but then I wasn't so sure. So I went back to my plot of voltage drops vs peak plate current and changed the axes types from linear to log. These two plots show the result.
Attachment:
lin-lin Plot.png
Attachment:
log-log Plot.png

The first is just the plot of numbers taken directly off curves in the data sheets. The second is the same plot with the axes changed.

Now I am wondering if there is anything to be learned about how these tubes operate from these relationships. And why are the slopes of all the lines on the log-log plot nearly identical. This must correspond to some fundamental characteristic of the tubes but I'm not sure what. Is this behavior a consequence of Child's Law? Do the tubes lower on the plot represent those with cathode materials having lower electron affinity? Does anyone have any ideas here. I'm curious.


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PostPosted: 24 Feb 2011, 14:08 
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With mention of Chinese 274 rectifiers : don't bother ! You'll get better sonics from a USA 5Z3 which is a 5U4G on a UX4 base . Cheaper and no doubt more reliable too . Try a paralleled pair of 5Z3 and you may thank me later...

I'm a big fan of DH rectifiers such as 5Z3 CV31 U19 and type 83 :)

BDA


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PostPosted: 24 Feb 2011, 20:08 
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Probably not a good idea to use the 83 since It's a MV type and has the usual hazards associated with those type of tubes. Also I've heard Chinese 274B that did sound good, but NOS 5U4GB did sound better in the mono-blocks I heard them in.


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