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In Reply to: RE: PLLXO files posted by savvito on March 27, 2014 at 15:50:13
I did not use a spreadsheet to come up with my recommendations for you. I used LT Spice. Here are the instructions on how to run it yourself as well as a Spice file I created for your Zpre and Zamp values.Here is how to use the spice file:
1. download LT Spice free here:
http://www.linear.com/designtools/software/2. download the asc file link with this post.
3. Run LT Spice and "file" menu "open" the asc file.
4. From the menu, select "simulate" and then "run" (the running man)
5. Hoover the mouse over the left Y axis and right click. Select "visible traces" and make sure the V_oem V_neo traces are selected.
6. For best viewing, hoover the mouse over the left Y axis again and right click. Select "manual limits" and then set the Y axis as follows: 0db, 3db, -42db (left side) and 120, 30, -120 (right side).
7. Note that R13 and R15 are the Z input of the power amps. R14 is the Z output of the preamp. These values have been set to 137 ohm and 19,500 ohm for your setup.
8. You can change the values of the C and R components by hoovering the mouse over the components and then right clicking. After each component change you have to go back and select the "running man" again to see the changes.
9. The circuit on the top is the "OEM" speaker level crossover that you can use for comparison as you tweak the PLLXO values for the circuit on the bottom.
Also note that this circuit does not have a trim adjustment in it. I have found that when I used this circuit I did need to adjust the volume level of the bass vs tweeter panels of my Magnepan 1.6. So at least for me, there was some sort of behavior that was not being modeled correctly. However, this circuit should get you close. I recommend you prototype the board as I did before committing to a soldered PCB.
Edits: 03/28/14Follow Ups:
Very good.
Minor notes:
R14 should be wired in series with the signal source (V2) vice shunting it.
Also, you could include a resistor in series with L1 to simulate DCR.
Dave.
note updated LT Spice file with davey recommended fixes.
again,
thanks guys, you are most helpfull
best regards to everyone
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