Total System Tuning

Of your question, there are some CD's available with test frequencies.  Here's one I found using a Google search.  And here's a portable digital RTA.....very affordable for the average DIYer, don't ya think?     ;)

The graph chart on that webpage shows decibels on the vertical axis from +6 to -30.  Adjust that to +6 to -12 to narrow the printout as you are not interested in output softer than -12 db anyway.  The horizontal range is fine for a sub at 10 Hz to 200 Hz.

Draw an imaginary line along the 0 db line from 20 Hz all the way to 120 Hz.  Imagine that the line falls off at a steep angle below 20 Hz, and curves off at a gentle angle starting at 120 Hz.  You would have an ideal flat response if it looked like that.

Although there are times that you can create a computer-simulated workup of a response line that DOES look flat, an actual RTA reading after the installation would show you a response that looks different.  That's because of the added sound caused by the coupling with the auto environment (cabin gain) and the subtraction of sound caused by cancellation and other things.

So, DYohn's advice in his first response is true in every case -  "If nothng is clipping or distorting and you like the way it sounds, then "tuning" by ear is perfectly fine and more than sufficient."

Ha ha that's funny and so, so true!  Here's a true story with me recently:  I've been working on a crossover network for a center channel speaker system that I'm building for my HT system.  I'm using some new (to me) computer software (Speaker Workshop) that I'm becoming familiar with as I use it.  Working on the response curve, and trying to get a flat response from the woofers to the tweeter....and also trying to achieve a proper system impedance.......I ended up designing not just the crossovers but also added a Zobel network and series notch filters for both the woofer network and the tweeter.

So for this simple little two-way center channel, I had three crossovers, two series notch filters, an L-pad and a Zobel network.

In order to achieve the exact values in the components, I had to use additional components and add them together....for example I used 3 resistors in parallel to achieve a resistance value, and two capacitors in parallel to get what I needed for capacitance.  My crossover board ended up with 27 individual components!

I ordered everything from Parts Express.  Got my heavy package, looked at all those components....then went back to the drawing board and started over.  Starting as simple as possible, I found that I could remove BOTH series notch filters and the L-pad altogether and achieve the SAME response that I had with them in the mix.  I ended up taking out eight component values consisting of a total of fifteen individual components!

Just goes to show that you can work on corrections to the point of being ridiculous, as one correction sometimes necessitates a counter-correction that you're not aware is happening.  And simple is better.  Now I have a rather substantial component inventory in my workbench for future projects.....

Next time I get carried away with tweaking I'll have to think of Michael Jackson's nose....tweaked and tweaked until it fell off.

lol   ^^^^^ funny story.  Congrats on the more simple xo.  :-)

How are you liking speaker workshop?  Did you build a wallin jig, or just make some cords?

mrmsudawgs:  I use a relatively cheap RTA setup for the laptop computer.  I bought a fairly cheap Behringer 8000 Mic, the IUSB Mobile-Pre from M-Audio, and the TrueRTA software from http://www.trueaudio.com/

If you have a laptop this setup is a great value.