Try this:
http://www.generalguitargadgets.com/richardo/practiceamp/practicemaneq.gif
It Can be modified to run off of +/-15v...The 5k resistor at the bottom right is a 5k Pot with the output being the wiper of the Pot, This pot controlls Volume...You might want to put a buffer before this circuit though, You can just use a Dual Opamp with half of it used as the buffer and the other half used in the EQ circuit....You can use any number of audio opamps here...
Cheers
http://www.generalguitargadgets.com/richardo/practiceamp/practicemaneq.gif
It Can be modified to run off of +/-15v...The 5k resistor at the bottom right is a 5k Pot with the output being the wiper of the Pot, This pot controlls Volume...You might want to put a buffer before this circuit though, You can just use a Dual Opamp with half of it used as the buffer and the other half used in the EQ circuit....You can use any number of audio opamps here...
Cheers
b0nk3rs said:
That schematic does have the Volume pot...It is the 5k one at the Very bottom right...It just doesn"t say Volume in the schematic but that is what it is.....
It is basicly just a 5k Pot with the wiper of the Pot being the Output and the 3rd pin of the pot tied to ground......
I"m useing this Very circuit (with a Buffer and an extra Gain stage) for a preamp for a Guitar amp I have been working on 4 Ever.....
It is a pretty easy circuit and I was able to design the PCB with the Buffer and extra Gain stage in just a couple hours.....
Good Luck
PS: what type of Group is it that you are in that makes you Build a Preamp with Tone controlls??
Hi, yes the Input is before the 1uF cap at the top left, You could pretty much plug anything into it but Like I said before you should put a buffer before it (Just a single Opamp at unity gain)...
You can probably use this to calculate the Frequencies for the tone controlls:
http://www.duncanamps.com/tsc/
Good luck
You can probably use this to calculate the Frequencies for the tone controlls:
http://www.duncanamps.com/tsc/
Good luck
b0nk3rs said:
Well if you notice the Schematic says to use a TL082 (a Lower power version of the TL072) which is a Dual Opamp but the EQ circuit only uses half of the TL082 so you can use the other half of the TL082 as the Buffer so you don"t need any extra Parts accept for a couple resistors and maybe a couple capacitors......
So just have the main Input go into a Unity Gain Buffer (useing One Half of the TL082 or you can use any Dual audio grade Opamp like the NE5532,OPA2134,OPA2604 ect in it"s place) and use the Other half of the TL082 for the EQ circuit, so you don"t need an extra Opamp as Half of the TL082 is not being used....
Cheers
Bonkers, if you read up a bit, you will find that you could in theory have better midrange control with two controls than three...
THink outside the box, controling the midrange doesn't mean you HAVE to have a button for it...
You should be able to find some frequency plots of 3 control vs 2 controls - I know I have seen them online.
Showing an understanding for the fundementals, may earn you more credit than blindly following some schematic.
As an afterthought... imagine you would like a flat response from 20 to 20000Hz... now imagine the line on the graph was a rope.
you can only hold on to two points of the rope (the ends) (two controls).... you can more easily produce a straight line than haveing to manipulate three control points into a straight line...
say you want more emphasis on the high frequency side... its much easier to just lift or drop one end, than to have to control a third point in the middle again to get your straight line.
So ultimatley midrange can be a product of the interaction of bass and treble range...
School credit is the type that stays with you forever. Instead of going for a dual opamp, I would display more finnese and use single opamps with dc-offset control (basicaly a trimpot connected between 2 legs)
THink outside the box, controling the midrange doesn't mean you HAVE to have a button for it...
You should be able to find some frequency plots of 3 control vs 2 controls - I know I have seen them online.
Showing an understanding for the fundementals, may earn you more credit than blindly following some schematic.
As an afterthought... imagine you would like a flat response from 20 to 20000Hz... now imagine the line on the graph was a rope.
you can only hold on to two points of the rope (the ends) (two controls).... you can more easily produce a straight line than haveing to manipulate three control points into a straight line...
say you want more emphasis on the high frequency side... its much easier to just lift or drop one end, than to have to control a third point in the middle again to get your straight line.
So ultimatley midrange can be a product of the interaction of bass and treble range...
School credit is the type that stays with you forever. Instead of going for a dual opamp, I would display more finnese and use single opamps with dc-offset control (basicaly a trimpot connected between 2 legs)
this one is almost identical but easier to read:
if you look carefully you will see that the treble circuit is a variable differentiator feedback loop, the bass circuit is a variable integrator feedback loop, and the midrange is a combination of the two.
with bipolar (+/- ) supplies, the coupling caps at the outputs of both op amps aren't neccesary.
if you look carefully you will see that the treble circuit is a variable differentiator feedback loop, the bass circuit is a variable integrator feedback loop, and the midrange is a combination of the two.
with bipolar (+/- ) supplies, the coupling caps at the outputs of both op amps aren't neccesary.
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