RTA'd my speakers, here's what I got. What does it mean?

EQ guys are using on their cabs/systems. A good starting place if you don't have your own RTA.
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Dan56
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Joined: Tue Feb 11, 2014 10:44 pm

RTA'd my speakers, here's what I got. What does it mean?

#1 Post by Dan56 »

I set up the OT12, melded array on top of the T39 (28" wide) with the Driverack PA+. The mic was set about 18' in front about 4' off the ground. After sitting there having turned up the noise waiting for it to do it's thing and getting messages to turn up, turn down I decided to hit "next page" and bingo! It finally ran the test. Ok, got it now.

The first pass, the xover at 100/112 and zero gain, the larger variances were:
630k and 800k -6.0 db (this is consistent through out all the tests)
3.5K -3db
4.0K -5.5db (this was consistent -5.5 to -6 through out the tests)
8.0K -3.5 db
10K -3.5 dgb
Anything that was above zero was not over +3 db

So, I ended up on the final test boosting the sub+3 db and cutting the OT12 -3db and the final results that were not 2db +/- were:
50K +3 db
125 +3db
160 +3 db
250 -2.5db
315 +3 db
400 +3db
630 -6db
800 -6 db
1.6K +3 db
2K +3db
2.5K +3db
3.15K -3.5db
4K -6db
5K +5 db
8K -4 db
10K -4 db

So, not much changed with boosting or cutting the gain at the xover. The ones that got cut the most, still were cut about the same. The ones boosted were still boosted about the same (I have 2 other test and they are all boosted in the +3 range). Only the 5K band was changed in the end by boosting it 2db more (from +3 to +5).

So, is this expected? What should I make of this? Advice? Concerns?
Last edited by Dan56 on Fri Sep 05, 2014 8:32 pm, edited 1 time in total.

sine143
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Location: Raleigh NC

Re: RTA'd my speakers, here's what I got. What does it mean

#2 Post by sine143 »

dont trust the DBX mic above about... 4khz. wildly inconsistent between units imo.

Your measurment technique is not conventional, but for the sake of a "quick and dirty" test it does the job.

notes:

Dont boost 50hz (below crossover point, pointless)

heres a pic of my current eq settings for the ot i believe.
Attachments
ot12 eq setting 2512melded.jpg
Built:
2x Tuba 30s delta12lf loaded (gone)
4x Otop12 d2512 loaded
8x t48s (18, 18, 24, 24, 30, 30) 3015lf loaded
2x AT (1 mcm, 1 gto 804)
2x SLA Pro (dayton pa6, 6 goldwood piezo loaded)
1x bastard XF208

2x OT212 (delta pro 450a loaded, eminence psd)

Grant Bunter
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Re: RTA'd my speakers, here's what I got. What does it mean

#3 Post by Grant Bunter »

Dan,
Was this outdoors?
And a minimum of 50 feet of clearance all around, from the cabs, with no obstructions/fences/buildings?
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Radian
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Location: Tucson, AZ

Re: RTA'd my speakers, here's what I got. What does it mean

#4 Post by Radian »

Dan56 wrote:50K +3 db
125K +3db
160K +3 db
250K -2.5db
3.15K +3 db
4K +3db
630K -6db
800K -6 db
Calibrating the sonar? :confused:
Good food, good people, good times.

4 - AT
1 - TT
1 - THT Slim
2 - SLA Pro 4x6 Alphalite

Dan56
Posts: 164
Joined: Tue Feb 11, 2014 10:44 pm

Re: RTA'd my speakers, here's what I got. What does it mean

#5 Post by Dan56 »

sine143 wrote:dont trust the DBX mic above about... 4khz. wildly inconsistent between units imo.

Your measurement technique is not conventional, but for the sake of a "quick and dirty" test it does the job.

notes:

Dont boost 50hz (below crossover point, pointless)
Any boost or cut I posted is what the Driverack did on its own. Your eq curve kind of mimic's mine. That 4K seems to be an issue. When I had first checked the system in our practice room with my other sound meter the 4K needed to be cut 6db based on that too. So, maybe what I have is what would be expected for these speakers.

How would you have done this initial RTA? What mic?

Dan56
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Joined: Tue Feb 11, 2014 10:44 pm

Re: RTA'd my speakers, here's what I got. What does it mean

#6 Post by Dan56 »

Grant Bunter wrote:Dan,
Was this outdoors?
And a minimum of 50 feet of clearance all around, from the cabs, with no obstructions/fences/buildings?
Yes it was. Had at least 100' in front of the speakers and 50' on the sides.

Dan56
Posts: 164
Joined: Tue Feb 11, 2014 10:44 pm

Re: RTA'd my speakers, here's what I got. What does it mean

#7 Post by Dan56 »

Radian wrote:
Dan56 wrote:50K +3 db
125K +3db
160K +3 db
250K -2.5db
3.15K +3 db
4K +3db
630K -6db
800K -6 db
Calibrating the sonar? :confused:
Thank you Radian for pointing out my posting error. This is what I get for being in a hurry while helping my brother inlaw do his front brakes. I just corrected the numbers.
But, here they are again.
50K +3 db
125 +3db
160 +3 db
250 -2.5db
315 +3 db
400 +3db
630 -6db
800 -6 db
1.6K +3 db
2K +3db
2.5K +3db
3.15K -3.5db
4K -6db
5K +5 db
8K -4 db
10K -4 db

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Radian
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Location: Tucson, AZ

Re: RTA'd my speakers, here's what I got. What does it mean

#8 Post by Radian »

Just a little sound guy ribbing. :lol:

Knew what you meant to type. 8)
Good food, good people, good times.

4 - AT
1 - TT
1 - THT Slim
2 - SLA Pro 4x6 Alphalite

Dan56
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Re: RTA'd my speakers, here's what I got. What does it mean

#9 Post by Dan56 »

Radian wrote:Just a little sound guy ribbing. :lol:

Knew what you meant to type. 8)
I got a laugh out of it. But, I had not noticed until you posted.

Dan56
Posts: 164
Joined: Tue Feb 11, 2014 10:44 pm

Re: RTA'd my speakers, here's what I got. What does it mean

#10 Post by Dan56 »

Sine's response got me thinking so I went looking for more info on reference mics and came up with this article by Real Traps.
http://realtraps.com/art_microphones.htm

This was a comparison of 11 mics ranging from $40 to a Josephson with a Microtech Gefell capsul. The boundaries of the test are:
Note that this test did not attempt to evaluate anything other than raw frequency response. We didn't measure distortion, off-axis response, maximum SPL capability, build quality, or residual noise. Nor did we record any musical instruments. Our only goal was to determine the suitability of these microphones for measuring in-room loudspeaker response.

And: Since this is not a true anechoic chamber you will see some influence from the room, especially at low frequencies. So even if a particular microphone is perfectly flat, its response will not appear flat in the graphs due to the room. However, the relative responses are valid, letting you compare how closely the inexpensive microphones match the expensive calibrated models that are known to be highly accurate.

It is interesting that they all start to dip a bit after 3k and more so after 7K. But they are all within a few db. Only the Radio Shack meters get stupid after about 1.5K.

So, for our purposes the DBX and such are adequate.

The other thing Sine noted was that my setup was not conventional. So what do others do for setting up their initial sound test? I'm thinking I'm going to retest leaving the xover gain at zero and leave that as the base setting. Should it matter where the xovers are set as to the system being flat?

Dan56
Posts: 164
Joined: Tue Feb 11, 2014 10:44 pm

Re: RTA'd my speakers, here's what I got. What does it mean

#11 Post by Dan56 »

I got to redo my tuning today. I used the same setup (x overs at zero gain) and then ran it for Flat, Band and Speech. I recorded the db changes for each frequency and then charted them in a spreadsheet and graphed. Here is what I got.
BFS Tuning chart 1.jpg
Interesting where the changes are with each tuning type vs how similar.

Also, a bit off topic, but I just picked up an Allen & Heath GL2400 24 channel board. So system is getting more pro a little at a time.

byacey
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Location: Edmonton, Alberta, Canada

Re: RTA'd my speakers, here's what I got. What does it mean

#12 Post by byacey »

I think you'll really like the GL2400. I got a GL2400/32, it's a nice compact, well built board. It sure beats the Yamaha PM3000 32 in the convenience and weight department.
Built
T48s
WH8s
SX212

leamy_f
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Location: Ireland

Re: RTA'd my speakers, here's what I got. What does it mean

#13 Post by leamy_f »

Dan56 wrote:I got to redo my tuning today. I used the same setup (x overs at zero gain) and then ran it for Flat, Band and Speech. I recorded the db changes for each frequency and then charted them in a spreadsheet and graphed. Here is what I got.
BFS Tuning chart 1.jpg
Interesting where the changes are with each tuning type vs how similar.

Also, a bit off topic, but I just picked up an Allen & Heath GL2400 24 channel board. So system is getting more pro a little at a time.
I use the same mixer from time to time and imho this board has one of the best sounding eq sections bar none, you won't be disappointed...regards

byacey
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Location: Edmonton, Alberta, Canada

Re: RTA'd my speakers, here's what I got. What does it mean

#14 Post by byacey »

I think I would forget about the various "tunings" and just set it flat as possible and then adjust it to taste from there. Full response more or less flat will sound good for music and speech.
Built
T48s
WH8s
SX212

Dan56
Posts: 164
Joined: Tue Feb 11, 2014 10:44 pm

Re: RTA'd my speakers, here's what I got. What does it mean

#15 Post by Dan56 »

byacey wrote:I think I would forget about the various "tunings" and just set it flat as possible and then adjust it to taste from there. Full response more or less flat will sound good for music and speech.

Yes, that is what I was thinking. But, I just wanted to see what it did and how it sounded. Running a song via the computer, flat actually sounds best. I'll hear the band tonight with it.

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