Need help... will pay for small service.

[K-amps]

Guys.. I need help.

I made my DIY speakers and need help determining the frequency response. I am willing to donate $25 to you or to DIYaudio if anyone can send me a simulated frequency response (graph from 250Hz to 40kHz on db scale) for my mids and highs. Also impedence plots if possible

My speaker is a mutli-amped multi driver system. (see attached schema for mids/highs)

Low's 4x TB 740 8" woofers
Mids 2x Vifa P13's
Tweets 2x Vifa XT25's (4 ohm)
Super Tweet 1x XT25

The mids/tweets/STweet is powered by the same amp, The woofer and subwoofer, have separate power amps.

I have a have tuned the speakers purely by ear. I am well aware of the pitfalls of doing so, hence my desire to see how far off I am from a flat response. I do expect dips and peaks... some of that I am willing to live with because of my own listening biases....

I would like someone to do a simulation of these drivers with these crossover values and let me know if a response can be simulated.

I know I need to reverse the polarity of the tweeters (2nd order), but if there are other improvements/ fixes you can suggest that would be great.

Also these are installed on an open baffle, and I forgot to label the polarity of the drivers, all are drawn so the positve (hot) terminal is up.

Thank you so much in advance!

[skeptic43]

A simulation would be pure theory.
Suggest you invest in a low cost sound level meter. RS has them for about $50. Also get a test signal CD with 1/3 octave warble tones to play thru your speakers while you measure the response.

[R-Carpenter]

Better yet, buy a measurement microphone from parts express for $40 and use free software like Holmi Impuls or free version of ARTA to do a real FR measurements.

[R-Carpenter]

Parts-Express.com: Behringer ECM8000 Measurement Microphone | measurement mic measurement microphone mic microphone RTA RTA mic RTA microphone special-11-2-behr
Parts-Express.com: Dayton EMM-6 Electret Measurement Microphone | BLACK09 Dayton EMM-6 measurement mic measurement microphone mic microphone electret mic electret microphone speaker mic test microphone test mic recording mic recording microphone Audi
You'll need a cheap microphone amp as well.

[Ron E]

A RS SPL meter is not a precision instrument. You can get a FR measurement, but there is no assurance of reasonable accuracy. Taking FR measurements by writing down point using warble tones or pink noise is a royal PITA/ An extra $50 or ~$100 (~$150 calibrated) will get you a mic & preamp with which you can do actual design.

[K-amps]

Originally Posted by Ron E

A RS SPL meter is not a precision instrument. You can get a FR measurement, but there is no assurance of reasonable accuracy. Taking FR measurements by writing down point using warble tones or pink noise is a royal PITA/ An extra $50 or ~$100 (~$150 calibrated) will get you a mic & preamp with which you can do actual design.

Thank you all for your ideas.

Ron do you have any suggestions for a cheap and accurate mic + preamp. I think I already have a ECM8000.... came with my Behringer DSP-8024.

Can't anyone use the publisehd specs for the drivers and put them in some software and PRESTO!

[skeptic43]

presto-smesto it's still only theory.

DO THE MEASUREMENTS. It's real world stuff!

[K-amps]

I tried once, they were so weird that I was left scratching my head. Also tried the DSP-8024's auto EQ function to simulate an inverse FR that was weird too.. adjecent frequency bands had 24-25db differences...

[Inductor]

Originally Posted by K-amps

I tried once, they were so weird that I was left scratching my head. Also tried the DSP-8024's auto EQ function to simulate an inverse FR that was weird too.. adjecent frequency bands had 24-25db differences...

You will receive a PhD at the end of this thread...
http://sub-source.com/tribute/images/rabbit_pancake.gif

[R-Carpenter]

Originally Posted by K-amps

I tried once, they were so weird that I was left scratching my head. Also tried the DSP-8024's auto EQ function to simulate an inverse FR that was weird too.. adjecent frequency bands had 24-25db differences...

This is why I've suggested Holmi. It has automatic gating which is very useful for a beginner (in measurements)
You can't just plug manufacturer's FR and impedance in the crossover calculator and expect perfect results because the crossover will have a significant effect on the phase of each driver there for an overlap and the summed up frequency response. The baffle, it's size and the driver placement will affect FR of the loudspeaker as well. Baffle step loss comes to mind as well. Off axis response can make the loudspeaker sound great or bad in the room depending on the crossover. So, no. You can approximate the results in the crossover design software but the real world measurements and understanding is the key to a great sounding system.
If you have ECM 8000 already, all you need is a Behringer or other cheap mixer. Make sure it has phantom power supply for mic. ECM 8000 is probably the best or one of the best inexpensive measurement microphones. You can also have it calibrated for $50 if I am not mistaken.