EQ Settings for 2xDR200 + 2xT39

[thijs666]

My question still stands about freeware RTA software. If there's a decent one out there, it would be nice to know about it...

Free:
http://www.e.kth.se/~johk/jdft/

Trial:
http://www.easera.com/

Take your pick:
http://www.fileguru.com/apps/rta_spectrum_analyzer

Google is your friend .

[David Carter]

Google is your friend .

I've been trying to be friends with Google, but I've never used an RTA or done any type of audio analysis before, so I wasn't having much luck thinking of the right words to search on. "RTA" appears to be a popular acronym used for many different things.

Thanks for the links!

P.S. It may be more appropriate to start another thread for this, but given the fact that I am a complete newbie to this sort of thing, I'd really appreciate some guidance at some point regarding the best way to set everything up to do measurements. I know I've read on this site that the ideal is outdoors, and I seem to recall numbers like 2.83V, and 1m, and stuff like that, but I can't seem to find the "RTA for Dumbies" version anywhere. I have searched, but maybe using the right words...

[J_Dunavin]

not that i am the expert here, but what i do is run the jdft software here:
http://www.e.kth.se/~johk/jdft/
and measure the room as is, there might be an ac unit running or your computer might be placing some noise in there that you need to be aware of so you can ignore it when you do the measurement.
Then i run pink noise through the system and measure. ( you can generate pink noise through Audacity). and can be found here:
http://audacity.sourceforge.net/
You should see some big peaks and valleys. I try yo EQ some of it out. Keeping in mind that EQing flat just doesn't sound right to me.
NOW... i could be doing this all wrong! So hopefully others will comment on this.

[David Carter]

My second set of 200's are nearly finished, so I'll be able to run a full RTA.

Chris, did you ever RTA your DR200's running 2 per side? What driver did you use in the DR200's?

I'm still trying to find a chart that will show me 2 DR200's per side with DeltaPro drivers and melded arrays. Everything I'm reading indicates that it would not be very accurate to just add 3dB to the single DR200 chart due to the flattening response that occurs by array-ing 2 cabs per side.

[Bill Fitzmaurice]

I'm still trying to find a chart that will show me 2 DR200's per side with DeltaPro drivers and melded arrays. Everything I'm reading indicates that it would not be very accurate to just add 3dB to the single DR200 chart due to the flattening response that occurs by array-ing 2 cabs per side.

It will be close, just keep in mind that the peaks with one cab won't go as high with two, so they won't require as much cut.

[SeisTres]

A while back Tim posted that graph in his initial review of the DR200, but I don't know if it is still current. And like everyone's been saying, the curve flattens and the nearfield effect increases(however, the nearfield effect as far as mids(not highs) are concerned, doesnt really come into effect until you start flying jstacks of 8+ cabs, so dont worry about that)

And while the driver with higher impedance is harder to drive than one a lower one, they will still take the same WATTAGE, so what all it really means is that you just need more VOLTAGE to get to the same spl, but if specs are identical, they will produce the same max spl.

[David Carter]

I'm still trying to find a chart that will show me 2 DR200's per side with DeltaPro drivers and melded arrays. Everything I'm reading indicates that it would not be very accurate to just add 3dB to the single DR200 chart due to the flattening response that occurs by array-ing 2 cabs per side.

It will be close, just keep in mind that the peaks with one cab won't go as high with two, so they won't require as much cut.

Thanks, Bill. Now I need some help interpreting this chart...


Since the scale on the horizontal axis isn't linear, I need some help figuring out where the various frequencies on my 31-band EQ are located. For example, in the space between the 100Hz and the 250Hz labels, where are 125, 160, and 200? This would probably be easier if Chris had this data in his SPL Chart tool, but this data set isn't in his list.

[David Carter]

A while back Tim posted that graph in his initial review of the DR200, but I don't know if it is still current.

I asked Tim about his DR200 data, and he said that his DR200's had Beta 8's in them. I've got the DeltaPro 8B.

[Landl.livesound]

My question still stands about freeware RTA software. If there's a decent one out there, it would be nice to know about it...

Hey David,

http://campuspa.com/downloads/devil_with_rta.pdf

Some good info on how to get accurate responses of the actual cabs, as RTA's aren't able to tell you some specific details that you need to decide if your measurement is valid and if the result is coming from the actual cab being measured.

The handheld RTA's can be quite handy in finding specific bands that are feeding back when doing monitor duty.


So it might be time to buy once, cry once and invest in a nice program for doing a transfer function which would be what I would use for analyzing the response of a system.


Good Luck!

[David Carter]

Thanks for the link. Very informative article. If I were actually trying to make any money at this, I'd definitely be very interested in a something that would give me the benefit of a transfer function. As it is, this is all just a hobby for me, so I'm trying to do the best I can with what I've got. But I do try to use my ears and not rely on auto-EQ or auto-RTA no matter what gear I'm using. I just want to see the data and then decide for myself how to deal with it.

Of course, even that is a hypothetical scenario right now as I don't have any RTA capability at the moment. I'm just trying to accurately interpret the SPL charts Bill has posted in an attempt to manually EQ my system to something that remotely approximates a flat response.

[David Carter]

Since the scale on the horizontal axis isn't linear, I need some help figuring out where the various frequencies on my 31-band EQ are located. For example, in the space between the 100Hz and the 250Hz labels, where are 125, 160, and 200? This would probably be easier if Chris had this data in his SPL Chart tool, but this data set isn't in his list.

No takers? Did my question make any sense? Let me phrase it another way... If I'm seeing the chart correctly, there are two vertical lines between the 100Hz line and 250Hz line. What frequencies do those lines represent?

[DJPhatman]

150 Hz and 200 Hz

[David Carter]

150 Hz and 200 Hz

OK. I'm starting to see a pattern. If what you've said is correct, then it appears that the lines are

• 5Hz increments to 100Hz
• 50Hz increments to 1kHz
• 500Hz increments to 10KHz
• 5000Hz increments to 20kHz

Makes sense to me. If I'm way out in left field, someone please correct me.

[SeisTres]

150 Hz and 200 Hz

OK. I'm starting to see a pattern. If what you've said is correct, then it appears that the lines are

• 5Hz increments to 100Hz
• 50Hz increments to 1kHz
• 500Hz increments to 10KHz
• 5000Hz increments to 20kHz

Makes sense to me. If I'm way out in left field, someone please correct me.

That's pretty much it. But just in case you come to an sensitivity graph without that many lines, the increments will all be different. But since they are logarithmic, it just means that whatever doubling of frequency will take the same space in the graph doesn't matter where you choose to double the frequency. Or for that matter you can pick any multiple, like instead of doubling you could pick a multiple of 10 and the rule would still hold.
example, if you measure the graph, you will see that going from 25-50 will require the same difference along the x axis if you went from 100-200 or 2.5k-5.0k. Also, going from 25-250 requires the same movement along the x axis as 100-1000(1k).

If you look at the graphic equalizers (even software ones), they are arranged in this patter. look at all the frequency bars and they will follow this pattter. so the bands would be at 100,200,400,800 and so on or somewhere really close to those frequencies. However, they can pick any multiple for the increments such as factor of 3, so: 100, 300, 900 and so on. That's why the 31 eq's are named 1/3 octave becuase they have a multiple of .33. Like I said, they dont have to be exactly at those frenquencies, they are usually just close to them.

However, the 3 band eq on mixing consoles do not follow this. Most of the time they are set at 100, 2.5k, 10k. This is because they are not meant to "equalize" but to bring out certain characterics of the instrument or cut what is not needed. Like giving the voice more presence or the bass drum more of a beater sound. Or cutting the cymbals' fundamental frequencies and just leaving all the brightness.

[David Carter]

That's why the 31 eq's are named 1/3 octave becuase they have a multiple of .33. Like I said, they dont have to be exactly at those frenquencies, they are usually just close to them.

[Light bulb flickers] Aaaaahhhhh! I always wondered why the weird numbers on the sliders like 63Hz or 315Hz. Now I get it.