EAR 825 EQ-Dont quite understand......?
« on: February 01, 2011, 12:18:01 PM »
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 ???


Re: EAR 825 EQ-Dont quite understand......?
« Reply #1 on: February 01, 2011, 09:59:43 PM »
Without a schematic no one will likely have a clue as to how to answer your questions . . .

pucho812

Re: EAR 825 EQ-Dont quite understand......?
« Reply #2 on: February 01, 2011, 11:56:41 PM »
Without a schematic no one will likely have a clue as to how to answer your questions . . .

here ya go

You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

gyraf

Re: EAR 825 EQ-Dont quite understand......?
« Reply #3 on: February 02, 2011, 05:52:39 AM »
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.



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.
« Last Edit: February 02, 2011, 06:33:20 AM by gyraf »
..note to self: don't let Harman run your company..

Re: EAR 825 EQ-Dont quite understand......?
« Reply #4 on: February 02, 2011, 05:11:52 PM »
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 :)

Re: EAR 825 EQ-Dont quite understand......?
« Reply #5 on: February 08, 2011, 07:20:44 PM »
Thansk Lassohar et al-sorted now-will go ahead and build my own version, and hopwfully post pics when done-

Re: EAR 825 EQ-Dont quite understand......?
« Reply #6 on: February 08, 2011, 07:23:15 PM »
Oh yeah-thanks to Pucho182 also!

Re: EAR 825 EQ-Dont quite understand......?
« Reply #7 on: February 08, 2011, 07:24:40 PM »
EEEEERRRRR sorry I'm p&*sed!!!Pucho812

Biasrocks

Re: EAR 825 EQ-Dont quite understand......?
« Reply #8 on: February 08, 2011, 07:33:38 PM »
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
http://SharktankPro.com

"I'd rather use an SPX90 than a UA plugin....." Joe Barresi

weiss

Re: EAR 825 EQ-Dont quite understand......?
« Reply #9 on: February 05, 2019, 05:18:25 AM »
did someone ever actually successfully clone this EQ?


gyraf

Re: EAR 825 EQ-Dont quite understand......?
« Reply #10 on: February 06, 2019, 05:34:33 AM »
I don't think so. And after all, it's still in production, I think.

Jakob E.
..note to self: don't let Harman run your company..


 

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