Beginner question, swap .047uf for .05uf?

gilbodavid · 15th February 2010, 07:25 PM

Hello, sorry if this is a bit stupid, i've got an old trio W-46 el84 valve amp with 4 el84's in it. there are .047uf caps that are in output capacitor positions and 3 0.05uf capacitors in there as well, 2 that are near the .047uf ones and attached to valve terminals and one that is elsewhere in the circuit. I have some russian T3 .047uf capacitors that i've replaced all the .047uf ones with. i am very tempted to replace the .05uf caps with T3 .047uf caps as well, but am not sure how critical it is to use exact values.

Can you safely replace 600v .05uf caps with 630v .047uf?

thanks

HollowState · 15th February 2010, 07:33 PM

Go ahead and replace it with what you have. No problem-o. The tolerance on these things is beyond the small marked difference anyway.

aardvarkash10 · 15th February 2010, 07:59 PM

Quote:

Originally Posted by gilbodavid

Hello, sorry if this is a bit stupid...

When dealing with 300V +, the only stupid question is the unasked one!

LinuksGuru · 15th February 2010, 08:17 PM

No problem at all

gilbodavid · 15th February 2010, 10:58 PM

Thanks guys. did it, fired it up and it worked great. very sweet sounding amp, cheers

TheGimp · 16th February 2010, 12:14 AM

The caps are probably +/-20%. One rarely sees +/- 10% in older equipment and +/-5% is virtually unheard of unless it is High End Audiophile.

Using the +/- 20% value would give:

0.05*1.2 = 0.06
0.05/1.2 = 0.0416

So you have a initial value range of roughly 0.042 to 0.60.

Hence, no problem substituting a 0.05 for a 0.47

Bob, W7ETA · 16th February 2010, 07:40 AM

You might be able to use any PP EL84 schematic to better understand your unit.

The capacitor leading to the grid of each EL84 valve is called a coupling cap.
Sometimes there is a .05uF cap connected between the RCA input and the first resistor.

Best from Tucson Arizona
Bob

15th February 2010, 07:25 PM	#1
gilbodavid diyAudio Member Join Date: Oct 2005	Beginner question, swap .047uf for .05uf? Hello, sorry if this is a bit stupid, i've got an old trio W-46 el84 valve amp with 4 el84's in it. there are .047uf caps that are in output capacitor positions and 3 0.05uf capacitors in there as well, 2 that are near the .047uf ones and attached to valve terminals and one that is elsewhere in the circuit. I have some russian T3 .047uf capacitors that i've replaced all the .047uf ones with. i am very tempted to replace the .05uf caps with T3 .047uf caps as well, but am not sure how critical it is to use exact values. Can you safely replace 600v .05uf caps with 630v .047uf? thanks

15th February 2010, 07:33 PM	#2
HollowState diyAudio Member Join Date: Aug 2006 Location: Taxland, New Jersey	Go ahead and replace it with what you have. No problem-o. The tolerance on these things is beyond the small marked difference anyway. __________________ "The supercomputer is technologically impossible. It would take all of the water that flows over Niagara Falls to cool the heat generated by the number of vacuum tubes required." ~ Professor of Electrical Engineering, New York University

16th February 2010, 07:40 AM	#7
Bob, W7ETA diyAudio Member Join Date: Sep 2007	You might be able to use any PP EL84 schematic to better understand your unit. The capacitor leading to the grid of each EL84 valve is called a coupling cap. Sometimes there is a .05uF cap connected between the RCA input and the first resistor. Best from Tucson Arizona Bob __________________ Still a novice with electronics.

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15th February 2010, 08:17 PM	#4
LinuksGuru diyAudio Member Join Date: Aug 2008	No problem at all

15th February 2010, 10:58 PM	#5
gilbodavid diyAudio Member Join Date: Oct 2005	Thanks guys. did it, fired it up and it worked great. very sweet sounding amp, cheers

16th February 2010, 12:14 AM	#6
TheGimp diyAudio Member Join Date: Aug 2009 Location: Johnson City, TN	The caps are probably +/-20%. One rarely sees +/- 10% in older equipment and +/-5% is virtually unheard of unless it is High End Audiophile. Using the +/- 20% value would give: 0.05*1.2 = 0.06 0.05/1.2 = 0.0416 So you have a initial value range of roughly 0.042 to 0.60. Hence, no problem substituting a 0.05 for a 0.47

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