rca 829b bias ? Audioromy 828

oleslot · 7th April 2009, 02:04 PM

Please help me.
I have a Adioromy 828 from China and I am very fond of it. I will lchance tubes fu29 to rca 829b, but I don know the right bias. Please help me
yours Ole

nhuwar · 8th April 2009, 01:42 AM

The graph on the spec sheet should get you started.

Here's the link for the spec sheet.

http://www.mif.pg.gda.pl/homepages/f...049/8/829B.pdf

Hope this helps,

Nick

oleslot · 14th April 2009, 01:01 PM

Thank you for your respons Nick but I need a little more information.
Can I simply put another fu 29 / GU 29 / 829b tube in
the amplifier without imposing Bais on the amplifier?
Are there any who have a picture (diagram) of the amplifier?
to better see what is what?
The 4 potmeter at the bottom of the amplifier is to
making Bais, or what?
Are there any others who have modified this amp?
Or can come up with some tips
thanks in advance.

Yours Ole Slot

azazello · 14th April 2009, 02:13 PM

You must know how many is current plate of every old tube.
If You have some knowledge to measure I, U, R, You can
try to measure Ia /current plate/ and them adjust the same current of new tube. First, if there is cathode resistor You can measure its U.
Then put new tube, and adjust the same U with bias pot.
Or disconnect every anode and connect serial ampermetre to measure Ia. And them put new tube and adjust the same Ia with bias pot.
If there isn't bias pot. You must put new cathode resistor that
Ia=Ucathode/Rcathods. Ia old and new tube must be the sames.
Ucath resistor old and new tube must be also the sames.

7th April 2009, 02:04 PM	#1
oleslot diyAudio Member Join Date: Mar 2006 Location: denmark	rca 829b bias ? Audioromy 828 Please help me. I have a Adioromy 828 from China and I am very fond of it. I will lchance tubes fu29 to rca 829b, but I don know the right bias. Please help me yours Ole

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8th April 2009, 01:42 AM	#2
nhuwar diyAudio Member Join Date: Jan 2007 Location: Tomball Texas	The graph on the spec sheet should get you started. Here's the link for the spec sheet. http://www.mif.pg.gda.pl/homepages/f...049/8/829B.pdf Hope this helps, Nick

14th April 2009, 01:01 PM	#3
oleslot diyAudio Member Join Date: Mar 2006 Location: denmark	Thank you for your respons Nick but I need a little more information. Can I simply put another fu 29 / GU 29 / 829b tube in the amplifier without imposing Bais on the amplifier? Are there any who have a picture (diagram) of the amplifier? to better see what is what? The 4 potmeter at the bottom of the amplifier is to making Bais, or what? Are there any others who have modified this amp? Or can come up with some tips thanks in advance. Yours Ole Slot

14th April 2009, 02:13 PM	#4
azazello diyAudio Member Join Date: Aug 2008 Location: Bulgaria	You must know how many is current plate of every old tube. If You have some knowledge to measure I, U, R, You can try to measure Ia /current plate/ and them adjust the same current of new tube. First, if there is cathode resistor You can measure its U. Then put new tube, and adjust the same U with bias pot. Or disconnect every anode and connect serial ampermetre to measure Ia. And them put new tube and adjust the same Ia with bias pot. If there isn't bias pot. You must put new cathode resistor that Ia=Ucathode/Rcathods. Ia old and new tube must be the sames. Ucath resistor old and new tube must be also the sames.

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