5003 eq building and help.

[jensenmann]

Here´s the result of a slightly modified version of this EQ. I´ve changed the switches to on-off-on types which makes it possible to chose between three frequencies. Inductors are different because I´ve lowered the LF-band frequencies. Output trannies are Edcor XS1100. Due to the different winding arrangement the gain of the amplifier needed to be modified.

 

[jensenmann]

And the guts:

 

[3nity]

Looks really good.
Can you tell me if you used the Edcor backwards?
normally is 2:1 but backwards it is 1:2?

Thanks.

 

[jensenmann]

Yes, it´s wired backwards, of course.

 

[3nity]

So how do you like it in that app?

 

[jensenmann]

No realworld expierience upto now. I´ve tested it with a few soundfiles at the workbench and it´s doing what it´s supposed to. I´ll need to take it to the studio when I´m back to work next week to compare it with my other 5003s in a mix.
I´ve used XS1100 trannies in other applications before and always liked the lowend distortion it adds. So I´m pretty confident that my plan for a lowend colourbox will work out.

 

[AudioCommand]

hey ... have a problem...

I finishd my pair 5003 eq's and make the first test's ... now I have a crazy noise only on the Hi band ... if I turn the pot in position 0db it's all right
I turn the pot in +db position I get a oscillating noise ... any ideas...???

Thank's Dom

 

[Indecline]

hey ... have a problem...

I finishd my pair 5003 eq's and make the first test's ... now I have a crazy noise only on the Hi band ... if I turn the pot in position 0db it's all right
I turn the pot in +db position I get a oscillating noise ... any ideas...???

Thank's Dom

What opamp are you using? Could be in the opamp or a bad solder joint somewhere.

Does it only happen when you're boosting the eq? (Zero posistion being mid-way) or is it present all the time?

 

[AudioCommand]

I use a melcor 1731 clone for opamp ... and I have the noise onley when I boosting...!

 

[Indecline]

I use a melcor 1731 clone for opamp ... and I have the noise onley when I boosting...!

Check the value of feedback cap C3, it should be 180pf.

It could also be noise getting into the inductors. Try moving it away from any power supplies and see if that helps.

You can also run it into your DAW with an analyzer and see how much and what noise you're picking up. We have a pair of 1081s that had to be moved a few times to find lowest noise spot in our rack.

 

[desol]

I still have 6 of these EQ's not built, but I still want to build them at some point. Schematic is missing now, but I still have a copy here. I have the original pots and I think switches too.

 

[fallout]

Nice, I still have a pair of these that I use. Cool EQ's that I find myself using on electric guitars often.

 

[jensenmann]

Same here, el. Guitars and Drums are my main use for these.