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part needed for tube preamp

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thebadtall

thebadtall

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Hello, Im gathering parts for building a cathode follower tube preamp, and im stuck because Icant find a 5 μf paper capacitor @ 200v - audio grade.

Can you suggest a part shop ?

Thank you !!
 

I would recommend using a plastic film capacitor instead of a paper one. It will be easier to find, and probably better.

RS online, Digikey and Mouser are good online stores.
 
Paper capacitors are pretty rare these days, they have been superseded by plastic dielectrics which have much better performance. Is there a reason why a standard 4.7uF electrolytic can't be used?

Brian.
 

i dont want to use electrolytic / polarised capacitor.
i want to use it as c4 capacitor. wixh is 5 μf paper capacitor @ 200v.
Any suggestions ?
29kxftd.jpg
 


thebadtall said:
i dont want to use electrolytic / polarised capacitor.
Click to expand...
That's understandable. An electrolytic would be a lousy choice, but why paper? A plastic film capacitor (either polypropylene or mylar/polyester) would be better - very low loss, leakage, distortion.

It doesn't have to be as expensive as the one Brian linked to. I had a look at RS online and found suitable 4.7uF caps from about $2.50 (US dollars).

btw, 5uF seems unnecessarily high. With a load of 100K, I would consider 1uF to be more than enough. That would give a response that rolls off at 1.6Hz.
 

@thebadtall can you show the schematic please so we can see what impedance the following stage presents and what voltage is really necessary. You might be able to use a smaller value or lower voltage in your application which would make the part easier to source. If the following stage is a 'normally' biased amplifier the control grid probably has close to zero DC on it and it's rare for the cathode in a cathode follower to have 200V on it.

Brian.
 

hi thebadtall,

PIO or paper in oil are hard to find these days, i find those starting caps used in induction type electric motors are good alternative, yes they are huge & bulky but the performance is also huge:wink:
 

really? i have a sealed capacitor filter for motor of laundry... im goin to give a try !
 

thanks alexan_e for info, however I've found a really good audiophile shop in Piraeus/Greece with tons of various components
 

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