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CMoy buffered outputs ==Need Help==.

post #1 of 6
Thread Starter 

The CMoy that I've been bugging everyone here about is undergoing another mod at the present moment. I /believe/ I understand buffers (I dont have a buffer but have 2 high current opamps that I'm using) and so I'm going to go ahead and add them on....I have one question though. Since I have a bass boost circuit in here I get a boosted DC offset (will disappear with new opamp but need to fix in the meantime) so the new opamp (in buffer configuration) will make this problem even worse wont it? If this is the case, is there a way to add the bass boost after the buffer like in the PIMETA v2? I believe this is called a jung multiloop but I'm not certain if it will work with my current configuration....

 

any help greatly appreciated.

 

EDIT: here is a diagram of what I /think/ the buffer should look like:

 

 

 

sorry about the fingers....held this up to a webcam ;) 

 

also my opamps have some pins I'm not sure of...it has the + - and vss but it has a gnd pin instead of a v- pin and it has a "bypass" and two "gain" pins.....any help with meanings?


Edited by backspace119 - 2/6/14 at 12:26pm
post #2 of 6

 

Study this...it's pretty much what you are trying to build.

post #3 of 6

Download Eagle, DesignSpark or at very least LTSpice to draw your schematics, then you can post a screenshot. If you learn to use LTSpice then you can simulate your designs and you won't need to ask if you've got it right. All you have to do is copy the spice commands from one of the sims posted here into your design, tell it to run, and it'll automatically compute frequency response, transient response including THD and a load of other things. Most manufacturers provide spice models for their components that will either work direct in LTSpice, or only require minor editing.

 

w

post #4 of 6
Thread Starter 
Quote:
Originally Posted by wakibaki View Post
 

Download Eagle, DesignSpark or at very least LTSpice to draw your schematics, then you can post a screenshot. If you learn to use LTSpice then you can simulate your designs and you won't need to ask if you've got it right. All you have to do is copy the spice commands from one of the sims posted here into your design, tell it to run, and it'll automatically compute frequency response, transient response including THD and a load of other things. Most manufacturers provide spice models for their components that will either work direct in LTSpice, or only require minor editing.

 

w

Ok. I have LTSpice but i'm not entirely sure how to use it yet. Ill google some tutorials and start using it. As for copy pasted commands what do you mean?

post #5 of 6

OK, look here:- http://www.head-fi.org/t/702166/tube-and-dmosfet-electrostatic-headphone-amplifiers you will see some sims. If you click on them to see the detail you will see a chunk of text and an AC source. The text and source are in example.asc zipped into this file:-

 

http://wakibaki.com/example.zip

 

Open the file example.asc and save it under a new name. Draw your circuit using the AC source as the input. Use the simulations you can see as a general guide. You may have to find models for e.g. NE5532 and put them in the right LTSpice directory so that the program can find them. (.lib NE5532.sub). Sometimes the models are in \lib, sometimes they are .inc.

 

Right click on the schematic and choose 'Edit Simulation Cmd.'

 

Select the type of simulation, Transient, AC, DC op. point etc... close the dialog box.

 

Right click on the schematic again, select Run.

 

The simulation will run. DC operating point will throw up a box showing voltages and currents. Otherwise when the simulation is complete click on the output (or any other point in the circuit) with the probe cursor to see the results. THD can be seen by selecting 'View' >> 'Spice Error Log'

 

w

post #6 of 6
Thread Starter 
Quote:
Originally Posted by wakibaki View Post
 

OK, look here:- http://www.head-fi.org/t/702166/tube-and-dmosfet-electrostatic-headphone-amplifiers you will see some sims. If you click on them to see the detail you will see a chunk of text and an AC source. The text and source are in example.asc zipped into this file:-

 

http://wakibaki.com/example.zip

 

Open the file example.asc and save it under a new name. Draw your circuit using the AC source as the input. Use the simulations you can see as a general guide. You may have to find models for e.g. NE5532 and put them in the right LTSpice directory so that the program can find them. (.lib NE5532.sub). Sometimes the models are in \lib, sometimes they are .inc.

 

Right click on the schematic and choose 'Edit Simulation Cmd.'

 

Select the type of simulation, Transient, AC, DC op. point etc... close the dialog box.

 

Right click on the schematic again, select Run.

 

The simulation will run. DC operating point will throw up a box showing voltages and currents. Otherwise when the simulation is complete click on the output (or any other point in the circuit) with the probe cursor to see the results. THD can be seen by selecting 'View' >> 'Spice Error Log'

 

w

Thank you for the info. I'm beginning to learn the software and it really helps being able to simulate things before you build. I was asked to move this discussion to here though by nikongod so if you or anyone else has any ideas they would be greatly appreciated. I am in the middle of resoldering everything and I will let you guys know how it goes.

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