EF83 not equal to EF86

Tubes Asylum

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I'm always on the lookout for a good sounding EF86-type tube and I came across several well priced EF83s. 'Rumor' is that it is a variable-mu version of the EF86... I couldn't find much information on the EF83 connected as a triode, but decided to buy a pair from Ebay anyways. If I could retube with a decent NOS tube for 1/10th the price - just think! So I bought a pair of beautiful nickel plate - still sealed! - Telefunken EF83s for $9.50 for the pair.
Slapped them into my homebrew EF86 preamp and gave them a listen. Excellent sound... gain was reduced a bit - quite nicely I might add. But curiousity got the better of me and I whipped out the DMM. Hmm... bias reads double - normally around 2.25V with the EF86 - now around 4.5V. This means the current has essentially doubled. Checking the plate resistor - it is now dropping double it was before. So instead of 120V on the plate, I now had 60... simple Ohms law.
So word to the wise - the EF83 is not equivalent to the EF86. I liked what I heard, so I will play around with it some more. Again, I can't find much info o
Kevin

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Topic - EF83 not equal to EF86 - kstagger 16:23:00 09/11/06 (5)

E80F is close and has the same pinout (nt) - fatbottle 06:49:11 09/12/06 (1)

I'm using a pair of Philips SQ EF80s in my amp front-end - kstagger 07:12:36 09/12/06 (0)

Re: EF40 equal to EF86 - mwiebe 19:54:40 09/11/06 (2)

yeah! - kstagger 04:41:28 09/12/06 (1)

Re: yeah! - mwiebe 07:18:36 09/12/06 (0)

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