EL33 I’ll sell this pair on eBay

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Paul Barker
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#1 EL33 I’ll sell this pair on eBay

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Because they are no use to me with only 6.5 mA/V Triode connected transconductance against 11 for the el84.

I checked price on ebay and did’t have to think about it. List on eBay.

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Paul Barker
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#2 Re: EL33 I’ll sell this pair on eBay

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OTOH I’m liking that its octal due to my left hand motor control improving but not mended.

So as an input valve, the only capacitance data is a,g1 which is stated as :

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But what is that, is it 1 pf? If so it compares close enough to el84 which is 0.7pf. Hence acceptable and as its easier for me to work with and looks cooler. I’d like to use it.

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Firstly is my conversion correct, secondly is the input capacitance low enough for an input valve?

Did you know some of these Mullard EL33’s were mesh plate ? But they want £60 plus postage . Shucks!

Anyway I have two that are grey plate for nothing, those will have to do.

Or, shall I connect the EL33 in pentode for input valve duty?
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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Paul Barker
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#3 Re: EL33 I’ll sell this pair on eBay

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OK so if I use it pentode mode :

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Roughly speaking 1.5v peak input gives gain of 66 into 13kohm 180v anode bias 20mA -8v 400ohm auto bias.

That would give all the voltage gain to drive a 300b through a cf, and a dc cf would make a good high impedance load for the pentode.

What do you think?
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Nick
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#4 Re: EL33 I’ll sell this pair on eBay

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Yes, uuF is pF. And that input capacitance is more than low enough for audio use. Though I guess the quoted figure is for pentode operation. I would expect it to be higher as a triode.
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Paul Barker
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#5 Re: EL33 I’ll sell this pair on eBay

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How about this then, and thanks.

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I know the thd means way beyond anything you build these days, But it will drive my Celestians and my Quad 57’s .

On say my 8 ohm Kef Correli 7.3 watts 1.42 thd.

It will then fit the smaller chassis.


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Paul Barker
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#6 Re: EL33 I’ll sell this pair on eBay

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With two spare chassis punch, maybe the two screen supplies share raise the current and one vr in each hole rather than punch another two.

Or two more holes could fit into the diagonal space between each 300b and each EL33.

Although not really necesary because a smoothed dc supply isn’t going to affect anything at the two screens. Or is it?

By the way g3 internally tied to kathode.
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Nick
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#7 Re: EL33 I’ll sell this pair on eBay

Unread post by Nick »

Yep, the gm is probably a bit low to drive the 300b directly. so should work, cant see why not.
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#8 Re: EL33 I’ll sell this pair on eBay

Unread post by Paul Barker »

Thank you?
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