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

[valvusmusicus]

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 ???

 

[lassoharp]

Without a schematic no one will likely have a clue as to how to answer your questions . . .

 

[pucho812]

Without a schematic no one will likely have a clue as to how to answer your questions . . .

here ya go

 

[gyraf]

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.

 

[valvusmusicus]

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

 

[valvusmusicus]

Thansk Lassohar et al-sorted now-will go ahead and build my own version, and hopwfully post pics when done-

 

[valvusmusicus]

Oh yeah-thanks to Pucho182 also!

 

[valvusmusicus]

EEEEERRRRR sorry I'm p&*sed!!!Pucho812

 

[Biasrocks]

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

 

[weiss]

did someone ever actually successfully clone this EQ?

 

[gyraf]

I don't think so. And after all, it's still in production, I think.

Jakob E.

 

[ratrace]

i find that, maybe someone who's here ?

https://www.gb-mastering.com/equipment/ear825q

 

[gyraf]

..someone obviously made a version of this for personal use..?

/Jakob E.

 

[Ben F]

Hi All,

I'm trying to reduce the gain range on an 825Q from 12dB to +/- 6dB boost and cut. Looking at the circuit, would I just double the 620ohm summing resistors R1, R8, R5, R7, R9 in that circuit?

 

[gyraf]

.. Or just put resistors in series with each end of the pots..