EAR 825 EQ-Dont quite understand......?

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valvusmusicus

Active member
Joined
Jan 24, 2011
Messages
41
Hi all
I understand the EQ part of the circuit-but not sure how it is implemented into the circuit-this is basically a pultec network is it not? Why are the transformers neccessary? are the middle 3 triodes and associated components a discrete op-amp? Ive been trying to work out how it works (with my limited knowledgfe) but....alas!!

anyone help-I would love to build this-as from reading posts, it seems to be very different to other topolies about ???
 
Without a schematic no one will likely have a clue as to how to answer your questions . . .
 
lassoharp said:
Without a schematic no one will likely have a clue as to how to answer your questions . . .

here ya go

Ear_825_EQ.GIF
 
Not at all pultec-like or passive - it's a simple boost/cut L/C gyrator circuit halfway inside the feedback loop of an amplifier.

More or less like a standard 1980's car-radio graphic eq, but with a tube amplifier.

parmet1.gif


http://4.bp.blogspot.com/_FdGFE8NBDgc/TCb9RaaqLRI/AAAAAAAADm8/Z8fWHTxw6gA/s1600/Ten-Band_Equalizer_Circuit_Diagram.GIF
http://farm6.static.flickr.com/5206/5278034584_9a51733691_b.jpg

Jakob E.
 
Aaaah!!.the mists are clearing!! I see now what you mean-just confused by the complexity of the EAR schematic.
hanks to all who replied :)
 
Thansk Lassohar et al-sorted now-will go ahead and build my own version, and hopwfully post pics when done-
 
Any ideas on suitable iron for this?

I'm guessing step down on the input and a similar step up on the output.

Looks like there's feedback taps on the interstage and output transformers.

Mark
 
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