GroupDIY
General Discussions => The Lab => Topic started by: electrichild on August 19, 2008, 11:34:32 AM
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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
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Have you read this thread (http://www.groupdiy.com/index.php?topic=23120), and the older threads that its first post links to?
JDB.
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Have you read this thread (http://www.groupdiy.com/index.php?topic=23120), and the older threads that its first post links to?
JDB.
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?
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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
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I have some schematics for LTspice if you want to play :razz:
LTspice? What's?
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I have some schematics for LTspice if you want to play :razz:
I'd be interested!
LTspice? What's?
Linear Technology's free SPICE-based circuit simulator. you can download it from their site.
JDB.
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Very cool!
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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
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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
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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.