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Old 7th June 2012, 10:37 AM   #41
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Quote:
Originally Posted by ElectricMan View Post
Hi

While all you are saying is basic and true, you do not know enough about tube amps to really write a tech article
....
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Old 24th June 2012, 05:21 PM   #42
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Quote:
Originally Posted by nazaroo View Post
Lets look again:


Click to Enlarge:

Click the image to open in full size.

While a center-tap connection is not beneficial,
it indeed DOES make a difference which end of the D.C. supply is grounded!

If one grounds the +ve side, one can force the current
to flow all the way along the cathode. This will equalize both current loads and temperature across the cathode.
Hi,

until a long time ago I also believed in this.

But, initiated by a discussion with a friend, I hooked up an old directly heated rectifier diode (RGN 354) with two resistors of identical values in both heater leads for measuring reasons. And, to my surprise, the current flowing into the negative heater terminal always is, by the amount of plate current, higher than the positive one - regardless where grounding is connected!

This means: If the positive terminal is grounded, plate current is completely flowing through the heater supply! You've described the disadvantage of this issue in an earlier posting very well.

Best regards!
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Old 1st July 2012, 09:04 AM   #43
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Default In japan , Shishido amp exists.

Dear Guys, My name is jun.
In japan , Shishido amp exixts, it has + grid single amp,and DC heater power supply.and low bias.

But , in japan , these amps are working very well for these past dozens of years. In Japan, is anything different?
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Old 15th July 2012, 04:13 AM   #44
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Quote:
Originally Posted by Kay Pirinha View Post
Hi,

until a long time ago I also believed in this.

But, initiated by a discussion with a friend, I hooked up an old directly heated rectifier diode (RGN 354) with two resistors of identical values in both heater leads for measuring reasons. And, to my surprise, the current flowing into the negative heater terminal always is, by the amount of plate current, higher than the positive one - regardless where grounding is connected!

This means: If the positive terminal is grounded, plate current is completely flowing through the heater supply! You've described the disadvantage of this issue in an earlier posting very well.

Best regards!
Thank You!

For providing real empirical data.

And for understanding what to optimize.

Rare things indeed these days.
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Old 16th July 2012, 02:10 PM   #45
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Thanks, very enlightening. Could we shield the twisted wires as well. Like input leads in old tube components. Fisher, for example used chassis grounded small flex metal "conduit" over the input wires from the RCA's to the circuit.
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Old 16th July 2012, 03:38 PM   #46
disco is offline disco  Netherlands
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The Fisher used a metal shield to keep unwanted pulses from signal carrying wires. If you would want to shield the 60Hz electro magnetical field itself it takes brute force with metal sheets of several millimeters thickness, depending on current. It's much easier to shield for RF
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Old 17th July 2012, 05:56 PM   #47
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Quote:
Originally Posted by Michael Koster View Post
Thank You!

For providing real empirical data.

And for understanding what to optimize.

Rare things indeed these days.
Meanwhile I've found my measurements from 2004. But, sadly, I don't manage showing a table here. Could someone please help me?

Best regards!
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Old 24th July 2012, 03:47 AM   #48
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Dear Kay Prinha san
I found below doc.

http://www.tentlabs.com/Products/Tub...e_V01_AN02.pdf

They(tentlabs) said that "The + side of the filament goes to groud".
It is opposite of your figure. European people have different thinking.
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Old 8th September 2012, 12:40 PM   #49
gabdx is online now gabdx  Canada
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This is my ugly examples of perfect AC heaters for DAC buffers of digital source and headphones.

http://gabdx.webs.com/DACG/DSCN2184.jpg

http://gabdx.webs.com/DACG/dac1.jpg
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Old 8th September 2012, 01:12 PM   #50
jam is offline jam  United States
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nazaroo,

An excellent thread, thank you for the time and effort. It was an eye opener for me.............so how about a thread about the high voltage side of things and maybe one on preffered grounding techniques.
Thanks again.

Jam
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