amek m2500 eq schematics...

[electrichild]

Hi,
I'm planning to make an EQ based on the amek m2500 eq section. On the schematics I find on the forum there aren't the original bell/shelf switches I would implement...Adding resistors and switches in the HF and LF path between R6/C5 and R45/C20 will affect the curve of Q pots?
Which values are right?
Respect
Electrichild

http://www.gyraf.dk/schematics/amek_m2500_eq.gif

 

[jdbakker]

Have you read this thread, and the older threads that its first post links to?

JDB.

 

[electrichild]

[quote author="jdbakker"]Have you read this thread, and the older threads that its first post links to?

JDB.[/quote]

Thanks for reply.
Yes I read all posts inherent but it's not clear which are the values of the resistors. I imagine 220k would be ok for HF and greater for LF.
Have anybody really realized a good working eq based on that schematic?

 

[12afael]

the schematic from jakob site have the mods for the shef/bell sw.
http://www.gyraf.dk/schematics/amek_m2500_eq.gif

IIRC you must make a shortcircuit in R137 (one half of the 50 rev log) and add a 1M resistor between r144(pot) and R50.

I have some schematics for LTspice if you want to play :razz:

cheers
Rafael

 

[electrichild]

[quote author="12afael"]

I have some schematics for LTspice if you want to play :razz:

[/quote]

LTspice? What's?

 

[jdbakker]

[quote author="12afael"]I have some schematics for LTspice if you want to play :razz: [/quote]
I'd be interested!

[quote author="electrichild"]LTspice? What's?[/quote]
Linear Technology's free SPICE-based circuit simulator. you can download it from their site.

JDB.

 

[electrichild]

Very cool!

 

[12afael]

here are the simulation files and some models needed for the simulation. the models IIRC were from the yahoo ltspice group.

http://www.twin-x.com/groupdiy/albums/userpics/amek2500_nemek_Harrisonfilter.zip

Enjoy :razz:

Rafael

 

[electrichild]

About decoupling caps for the amek m2500 circuit of this topic
http://www.gyraf.dk/schematics/amek_m2500_eq.gif
are C22-23 on schems 1uF 35V tantalum right?
Can I change the C4 39NF cap (hard to find) with 4 X 10NF in parallel?
Any suggestions?
Thankz again

 

[12afael]

tantalium or a small esr cap should do the work, 1uF film should work too.
I also put a small film cap in the power pins of each tl074.

39nF shouldn´t be so hard to find, but yes, you can use four 10nF in parallel.