Measuring individual drivers and EQ them

[Kermy]

I'm setting up my 2 way system with a Minidsp DDRC-24. And somethings are not clear to me.

At first you measure the individual drivers on axis and near by, how near by do you recommend me to measure them?
The former without anything set in the DDRC, so no crossovers, no EQ.

The second question is, when you know where you want to cross the drivers you have a reference how wide you want to EQ them individually. From the crossover freq, how wide in octaves do you EQ the driver?

The third has something to do with the second question, when EQ is made to the drivers, do you EQ them flat, and how wide, or do you already use the housecurve you want to use in the end? For me the Harman curve is my objective, and it sounds illogical to do flat EQ when in the end you do DIrac and use a housecurve, so opinions are welcome.

After applying the crossover, the Dirac can make the final EQ of the complete system.

Love to hear from the experts here.


With kind regards,

Kermy

 

[Sonnie Parker]

I would not measure the individual drivers of the speaker or the complete speaker near-field, unless you are in a car, then there might be some benefit. In a home in your listening room, measure each full speaker from your primary listening position. I suppose if you built the speakers and are curious what the crossover points should be, you could measure them near-field, but that is usually determined in an anechoic chamber.

Dirac will take care of the EQ without any input from you. If you have a subwoofer, you can experiment with various crossover points depending on the capability of your main speakers. 80Hz is typically a good starting point, but if your mains can handle 40-50Hz, you might try 60Hz as a crossover point too.

You can also use the parametric EQ in the DDRC to take out any large peaks in your speakers before running Dirac, but it's not really necessary... simply let Dirac take care of it all for you.

 

[Kermy]

So, what you are saying is that Dirac is my silver bullet?

With kind regards,

Kermy

 

[jtalden]

Yes, I concur.
Just create a favorable XO and apply Dirac for EQ.

Assuming a typical 1" TW and 7" MW for home:

• The XO can most easily be created using ~1 m mic measurements with mic on the listening axis.
• The XO frequency should ideally be chosen so the TW is not strained at the low end and the MW is low enough that its dispersion is still very wide and 2 kHz is most common. It varies depending on the XO filters chosen.
• An acoustical LR-24 is a good target for the XO filters. It gets very technical and unnecessary to worry too much about that however. Many acoustical XO shapes can provide favorable results given favorable delay timing.
• The REW alignment tool can be used to determine the optimal XO delay timing.

Other driver choices may require different XO setups.

 

[Kermy]

The setup is 15" bass in reflex cabinet, on top Oris 250 horn with 8" AER neodymium driver. The bass driver and horn have quit some overlap in the region 250 to 600 Hz. I would like to cross them as low as possible, so, 300 Hz comes to mind. I even could get away with 6 dB filters.

 

[jtalden]

That's fine. The same XO concepts apply to that combination as well.

Most any XO can be made to work in a favorable way with appropriate delay timing. You could; fine tune the XO filters to approach a conventional target as an acoustical LR-24, chose settings recommended of others, pick a setting of you own, or complete the XO delay setup for several of these XOs to conduct listening evaluations. It's easy to recall different XO settings in most all DSP boxes and I assume your DSP is one of them. I change my XO settings occasionally just to experiment. That is the convenience of a DSP XO.

My personal thinking is to cross a little higher (400-500 Hz) as there may be some dispersion irregularity at the bottom end of the horn response and to choose XO filters to approach an acoustical LR-24 rolloff response. If you have directivity information for the horn and woofer those can be helpful in choosing the XO frequency. With this low frequency XO however these thoughts are probably over thinking the issue. I doubt this approach would make a noticeable difference in sound quality.