Squires Natural Reference 1 - Compression and Distortion

Comparing the 95 db and 70 db signals.  What errors you can see are probably due to me being lazy and using the Logitech Squeezebox volume control.

Distortion elements

Please note that while the shape of the distortion in these charts is accurate the scale is NOT!   You cannot read the actual distortion values off these charts due to a limitation (or feature) in OmniMic.  The distortion figures on on a scale not shown.  What I will say here is that the actual distortion figures are ridiculously low all the way to 100 db. :)

Distortion at 70 db

Distortion at 80 db

Distortion at 85 db

Distortion at 90 db

Distortion at 95 db

Energy Storage, flat EQ

Noes - XSin vs. Actual

A big thanks go out to Bill Waslow for his excellent and free XSim.  Together with OminMic and DATS I did in weeks what it would have taken me years if ever.

To make the long story short, here is a comparison between the simulated crossover, and XSim's expectation.  Blue is simulated.  Differences in phase are probably due to inexact placement of the microphone between early measurements and now. 

If we take that data, and overlay it on the simulation from LEAP

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I love XSim! 

Here is the test schematic

Sorry about the part numbers.  I can't reorder them.  On top is the 2nd order design, on the bottom is the first order. 

Here we have the impedance of each, seen from the amplifier's point of view:

The top, yellow curve is the 2nd order filter, the bottom green line is the first order. 

Next, let's take a look at the power dissipation in the series resistors in each. 

R1 and R6 are part of the first order , R3 and R5 part of the second order filter.  You can see in each case the power of the 2nd order filter lags (is lower) than the first order filter, except at the very end for the first resistors in the circuits.  

Here are the simulated frequency responses, but please bear in mind having a good response was not part of the experiment.   Tweaking the crossover becomes very arbitrary.  The goal of this experiment was just to examine how power and impedances changed based on 1st vs. 2nd order.  Also, the first resistor is not really needed, it's again there for the investigation.

 

XSim - Simulated Noes Xrossover

A quick posting for the currently simulated crossover.  As soon as the real one is built we'll compare!  

And here is a weird pre-ringing issue with the tweeter.  minor, but weird.