What do the EQ switches on the back of a VRX932 really do?

I am guilty of spreading rumors about the dangers of using these filters. I used to tell people not to use them because of the phase shift they would case the resulting summation problems at the acoustics crossover.
I was wrong. I've been wrong many times before, but this was a great opportunity to document it and explain my confusion. Hope it helps!
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I love to geek out about the physics of sound. This channel focuses on the growing opportunity for live sound engineers to improve their confidence and consistency through the understanding of the principles of sound system design and optimization. My goal is to make this channel upfront and honest about my success and failure, so you can learn from both.
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[@Soundaudio1]

Hey Nathan, great info. And thanks to you (and Bob McCarthy) for the bonus of clarifying the relationship between summation/cancelation, and phase shift.

[@nathanlively]

Hi Andy! Glad it was helpful!

[@vivekpatel264]

Then i guess the idea behind putting that switch and achieving that freq response is brilliant

[@nathanlively]

Yeah, I definitely have more respect for it now that I understand it a bit better.

[@tomshannon213]

Thanks for the great info, Nathan. I have an off-topic question regarding the VRX932 - I have/had/may still consider purchasing them. I have only heard the boxes used once and was quite impressed with the output. As far as vocal reproduction, they seemed to be missing something in the midrange. It certainly could have been operator error - what has been your experience, and do you do anything to sweeten the vocals?

[@nathanlively]

Hey Tom, I've used them a bunch. They're fine. I don't remember hearing anything special or irregular in the vocal region.

[@tomshannon213]

@@nathanlively Thanks for the reply, Nathan - maybe I owe them a closer look.

[@Whathandle-e2g]

hey, Nathan Lively! I'm getting a lot of help from your video and I'm learning. I am not a system engineer but a mixing engineer. I think the switch on the back of VRX is a high-pitched switch for sound that occurs when positive combinations are made from low to high when elements that make up the array are added. What do you think of this opinion? Oh! And another question is, how do you tune in a straight array and tune in a curve in a system of line arrays that can freely specify actual curvature? And when the curvature is widened as much as possible, the high-pitched coverage between the speaker and the speaker becomes empty, so does this actually have the effect of a line array? Will it be a system that meets coverage and sound?

[@nathanlively]

Hey -, good to hear from you. I think the switch just engages an HF filter. > how do you tune in a straight array and tune in a curve in a system of line arrays that can freely specify actual curvature? Are you asking about combining a constant curvature array with a variable line array? hmmmm, I'm never run into that. Interesting! > so does this actually have the effect of a line array? Huh, yes, I suppose you could think of a constant curvature array as a variable line array stuck in a single position.

[@haroldchristian5212]

I recently had these speakers on a Dura Truss crank stand about 9 ft. up outside 2 per side with the settings at +3 along with 2JBL SRX 828sp and 2JBL SRX 818sp with SRX 835P. I normally just leave the VRX's at 0. What do you recommend?

[@nathanlively]

Hey Harold, I had to use some of these recently as well. At short distances I’ll use 0dB or -3dB and longer +3dB to overcome air losses. I guess I’m not doing anything special.

[@haroldchristian5212]

Thanks Nathan!! I really like this SoundcraftUI24R Group because I learn something from many people.

[@Basha-Bhai]

Great information sir

[@nathanlively]

Thanks and welcome

[@pauljohnson4590]

I must admit I'd never noticed a problem - I have to say that I assumed the difference in level was simply the extra resistance switched in to the HF driver - so the switch really acts as a volume pad. I'm now confused as where the phase shift comes from you are describing. We have HF from two sources at the overlap zone, but surely they are still phase aligned, apart from the tiny extra distance from the other driver? If they were bi-amped and individually connected to different amps (which mine occasionally are) then I have always left them set to the far +3dB position and adjusted the output via the amp controls. Sonically, I have not noticed any difference, but of course wasn't even expecting there to be one. Are we sure that these differences are not just plain old ordinary comb filtering? I'm thinking that perhaps we are just seeing multiple arrivals from slightly different lengths, not any changes due to the actual level adjustment?

[@nathanlively]

Hey Paul, thanks for checking out the video. > I'm now confused as where the phase shift comes from you are describing. It comes from the EQ filter. Any time you insert a filter, there is phase shift, except for some special ones like APF. > We have HF from two sources at the overlap zone, but surely they are still phase aligned This is the point I was trying to make in the video that I must not have communicated very well. At the acoustic crossover they are not phase aligned in the HF, but the phase difference is small enough not to create a significant problem. I used to worry about it. Now I don't and neither should you. :)

[@pauljohnson4590]

@@nathanlively It's fine, I was just pleased somebody took the trouble to consider the science then the practical results. I've not actually looked at the circuit of the crossoverin my passive units, but I wonder if (keeping in mind the similarities in the EQ curve when you overlaid them, if the big ceramic simply change the level. The three HF units are also distributed evenly, so one box actually has three overlapping beams, so with another cabinet on top, the first horn couples the same way, but with the rear switches set, the next box up is just a bit louder? How does this impact on the phase cancellation. I bought my system when our band went abroad and we were supplied with a VRX - I really liked it, and was very confused by the real slagging off they got, when I really found them useful. I have a repeat job with them in a 1400 seater theatre which is very wide, very deep but quite restricted in height. The VRX manages to really get the levels as you go back sorted. Far better than many other systems that come through! Thanks again.

[@llanero1005]

In your opinion, what is the best setting? -3, 0 or 3 db?

[@justahobby4]

For one box it depends on your ears For more boxes ,,it should be set according to coverage ,,like upper +3,then middle 0, -3last

[@llanero1005]

@@justahobby4 and if u put 4 boxes in each side?

[@justahobby4]

@@llanero1005 create three zones Ex-2,1,1 ,,since far audience needs more box While three presets have some limitations

[@vadimmartynyuk]

those switches are not eq switches, they are attenuators for tweeters. that's why there's is almost no phase shift

[@martingajta]

Hey Nathan, I measured VRX months ago, and I realized that -3 settings has different delay comparing to other two, that's maybe what your friend heard. Here is the link to my fb album so you can see result. facebook.com/photo/?fbid=2064354267038280&set=a.504167079723681