ProSoundWeb Community

Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Eddie Ybarra on June 21, 2019, 08:36:35 pm

Title: More VRX help needed
Post by: Eddie Ybarra on June 21, 2019, 08:36:35 pm
Hi guys so Iím back with more questions about the dreaded VRX hf. So I took a look at the house eq on the DriveRack 260 and there are cuts around 2k and 5k seems logical right. Then I took look at the graphic eq on the m32 and things got interesting, everything from 600 and up was cut by 5 or 6 dB. Also 400 and 200 were pretty much taken out as well. So would that explain the ďhollowĒ sound Iím getting from the rig? Itís a 3 aside rig btw powered with xti6002 one box per channel. My question is what would be some ideal frequencies to cut cause cutting all of them doesnít seem cut it haha
Title: Re: More VRX help needed
Post by: Chris Hindle on June 21, 2019, 09:21:05 pm
Hi guys so Iím back with more questions about the dreaded VRX hf. So I took a look at the house eq on the DriveRack 260 and there are cuts around 2k and 5k seems logical right. Then I took look at the graphic eq on the m32 and things got interesting, everything from 600 and up was cut by 5 or 6 dB. Also 400 and 200 were pretty much taken out as well. So would that explain the ďhollowĒ sound Iím getting from the rig? Itís a 3 aside rig btw powered with xti6002 one box per channel. My question is what would be some ideal frequencies to cut cause cutting all of them doesnít seem cut it haha

I'd start with everything flat, then EQ from the DriveRack or M32. Not both.
If you see other boards being used, EQ from the DriveRack. Period.
That 5 or 6db cut across the range is loosing a shitload of gain, never mind the added distortion. Was there a specific reason for this?
Better check the XTi's too. Is any processing being done there too?
Chris.
Title: Re: More VRX help needed
Post by: Eddie Ybarra on June 22, 2019, 01:01:47 am
Im not sure about the whole graphic eq thing, nothing is being done in the XTI's, all processing is being done in the dr260 which is just high pass for tops and low pass for subs and time alignment. Has anyone used the tunings for the VRX in the XTI 2 amps, would gain anything for them?
Title: Re: More VRX help needed
Post by: Tim McCulloch on June 22, 2019, 03:02:28 am
Im not sure about the whole graphic eq thing, nothing is being done in the XTI's, all processing is being done in the dr260 which is just high pass for tops and low pass for subs and time alignment. Has anyone used the tunings for the VRX in the XTI 2 amps, would gain anything for them?

Presumably there is some form of protective limiting but I haven't looked to confirm.  IIRC the rest is the basic crossover functions.
Title: Re: More VRX help needed
Post by: Chris Grimshaw on June 22, 2019, 04:09:36 am

That 5 or 6db cut across the range is loosing a shitload of gain, never mind the added distortion. Was there a specific reason for this?
Better check the XTi's too. Is any processing being done there too?
Chris.

5-6dB of gain isn't a big deal unless you're having to redline the mixer. Where is the extra distortion coming from?

Chris
Title: Re: More VRX help needed
Post by: Riley Casey on June 22, 2019, 01:29:05 pm
FWIW this is a screen cap of the EQ required in the DSP of a Lab Gruppen 2400 to flatten a pair of VRX on a sub pole when measured with Smaart at ten feet on axis with the lower box. The high end roll off was a low pass of 16K in the crossover to flatten the excessive 16k peak in the drivers.
Title: Re: More VRX help needed
Post by: Jamin Lynch on June 22, 2019, 01:39:55 pm
How are the switches on the back of the speakers set?

I've found the +3 "long throw" setting is like sticking an ice pick in your ears.
Title: Re: More VRX help needed
Post by: Eddie Ybarra on June 22, 2019, 04:35:00 pm
I have seen the M32 redline on bass drum hits and also trying to get the vocals sit in the mix. The switches on the back iirc are top is +3 middle flat bottom -3. When I flattened out the graphic eq on the board a little I definitely got back a fair amount of clarity of the overall mix. The next thing I wanna take a swing at is the amps, so on paper the xti6002 pretty much aperfect match for the VRX. So the knobs are pulled back a bit at the same time I feel Iím running the board a little hot and clipping it maybe half show. So obviously just run the amps wide open right but with out the VRX tuning loaded in the amp and I havenít seen how the dr260 limiter is set up, Iím still scared Iím gonna blow something up. Has anyone used VRXs with out any Dsp?
Title: Re: More VRX help needed
Post by: Chris Grimshaw on June 23, 2019, 10:56:47 am
Generally, boxes will tell you they're in pain before they stop working. Seems to me like your gain structure needs looking at - clipping the desk because the amps are attenuated isn't the way to do it.

Chris
Title: Re: More VRX help needed
Post by: Tim McCulloch on June 23, 2019, 12:21:40 pm
Generally, boxes will tell you they're in pain before they stop working. Seems to me like your gain structure needs looking at - clipping the desk because the amps are attenuated isn't the way to do it.

Chris

It sounds to me l like there isn't Enough Rig for the Gigģ.  I suspect if the console is being driven that hard it's likely the amp inputs are being clipped even if the amp outputs are not clipping.  I'd guess the console outputs are within 3dB of clip, too.

Title: Re: More VRX help needed
Post by: Luke Geis on June 23, 2019, 11:42:18 pm
I concur with Chris; the speakers will give you evident signs that they are in distress before they let out the magic smoke. There are things that can happen that can take out speakers immediately, but you have to mess up pretty bad. If it sounds like it is hurting, it probably is.

The amp attenuator knobs are decidedly useless unless you have a need to reduce the noise floor ( which isn't needed; as systems are getting ever quieter and cleaner in sound ) due to the self-noise of the amplifier circuit. The standard practice these days is to simply turn the input attenuator knob all the way up. The amps input will clip at the same relative input voltage regardless, so turning it down just means you're adding noise from an upstream device as you turn it up to get the desired volume.

With modern digital amps, you can generally set the output volume and limiter values to suit most basic needs. The XTI series I believe allows for a -12db limiter setting threshold, which should start protecting the speakers rather early. Even a -6db setting will give modest protection for an occasional oopsie.
Title: Re: More VRX help needed
Post by: Eddie Ybarra on June 24, 2019, 12:09:44 am
Inputs aren't clipping except maybe a snare drum hit after a drum fill little things like that. So check this out, before flattening out the eq on the board and drive rack the board was clipping a lot more, after i gained headroom and a better overall mix. During the show the board hovers around -6 with peaks at -3.

Title: Re: More VRX help needed
Post by: Paul G. OBrien on June 24, 2019, 12:30:33 am
During the show the board hovers around -6 with peaks at -3.
OK but.. would you push an analog board to +16 to +19 dB on the mains and consider that good? That is the equivalent signal level and it suggests either your gain stages are still way off or you are pushing the system really hard.
Title: Re: More VRX help needed
Post by: Eddie Ybarra on June 24, 2019, 01:23:15 am
I see your point I'm still working on getting the gain staging right, then again not having enough rig doesn't help either.
Title: Re: More VRX help needed
Post by: Caleb Dueck on June 24, 2019, 01:32:37 am
OK but.. would you push an analog board to +16 to +19 dB on the mains and consider that good? That is the equivalent signal level and it suggests either your gain stages are still way off or you are pushing the system really hard.

Sounds like you've outgrown the "dash array" format and need to look at buying or renting something else.
Title: Re: More VRX help needed
Post by: Tim McCulloch on June 24, 2019, 04:10:20 am
Inputs aren't clipping except maybe a snare drum hit after a drum fill little things like that. So check this out, before flattening out the eq on the board and drive rack the board was clipping a lot more, after i gained headroom and a better overall mix. During the show the board hovers around -6 with peaks at -3.

That's way, way too hot.  Is there another device in the signal chain?  Perhaps hidden somewhere?
Title: Re: More VRX help needed
Post by: Chris Grimshaw on June 24, 2019, 11:36:17 am
I see your point I'm still working on getting the gain staging right, then again not having enough rig doesn't help either.

I'm not certain you know for sure whether you have enough rig for the gig. If the amp attenuators were one click up from -infinity, then putting +22dBU in there still won't get them to reach full output.

Pull the desk master down, turn the amp gains up, and then you'll be able to find the limits of the amps/speakers, instead of a line-level device that shouldn't be clipping.

Chris
Title: Re: More VRX help needed
Post by: Tim McCulloch on June 24, 2019, 03:38:22 pm
I'm not certain you know for sure whether you have enough rig for the gig. If the amp attenuators were one click up from -infinity, then putting +22dBU in there still won't get them to reach full output.

Pull the desk master down, turn the amp gains up, and then you'll be able to find the limits of the amps/speakers, instead of a line-level device that shouldn't be clipping.

Chris

Chris, I think Eddie is kind of stuck.  If I'm correctly understanding all of this he's a tech at a venue with an A1 or tech director above him on the organizational chart.  He's previously expressed some skepticism with regard to the deployment and processing of the house system.  Eddie is trying to make the best use of the tools available to him.

After reading about console output levels, the mid-band -6dB carve-out (which may or may not be similar to the traces Riley posted, and the possible rolled back XTi input levels... I can't decide if these are the product of tech-creep (the eventual modification of settings, routing, etc that happens in club installs), or was purposely instituted to voice the rig AND gain stage the system for simultaneous clipping, i.e. red lights on the console mean red lights on the amplifiers.

What we don't know is Eddie's expectation of his mixes; we don't know how he voices individual inputs or what his idea of musical balance is.  Those are important and as a system engineer I observe that those things can illustrate how much more rig some mixerpersons need in order to achieve a certain density of mix.  When "typical" operation of the system requires Full Tilt Boogie levels from the desk and the power amps are into occasional clip, there isn't much left.  This is also the point where power compression becomes a factor.

So while I'm making guesses my next one is that this venue's VRX rig was not intended to be pushed as hard as it is (or whoever specified it had no real world experience with it).  I think they need loudspeakers that better cover the room and that deliver more SPL for voltage in.

I wish Eddie the best with this.  It's frustrating to mix on a rig that responds (or doesn't) like this.
Title: Re: More VRX help needed
Post by: Eddie Ybarra on June 24, 2019, 06:09:53 pm
Tim you're correct I am a tech at a theme/amusement park with three venues two of which have VRX rigs and the other a Meyer UPA-2B rig. The only thing between the mixer and amps is the driverack260. When the audio supervisor was mixing the show during rehearsals the board was clipping regularly so i went to check out the amps and drive rack and what i saw had me scratching my head a little bit. Inputs on the DR were in the green and every so often with a bass drum hit, outputs were at 0 and +5. The meters on the amps were at -10 and -20 so nothing too out of the ordinary in my opinion but what I'm hearing and what I'm seeing doesn't make sense, to me anyways. Regarding my mix vocals are on top and up front as much as possible and that's coming from the big boss no biggie right but when the rest of the band needs to be at the same volume then we have a problem then the big boss say he wants it louder than that then we have a real big problem. Good thing is after some explaining and some reasoning we're able to talk him down to something that works but still at the end of the day this VRX rig is just a struggle to mix on.
Title: Re: More VRX help needed
Post by: Paul G. OBrien on June 24, 2019, 07:29:59 pm
Inputs on the DR were in the green and every so often with a bass drum hit, outputs were at 0 and +5. The meters on the amps were at -10 and -20
That isn't right, the amps should be right at clipping with that input signal.
Title: Re: More VRX help needed
Post by: Luke Geis on June 26, 2019, 06:06:48 pm
I am not 100% familiar with the DR260, but if you are pushing near clip on the mixer which should be right close to +20dbu give or take a few dbu, the input of the DR 260 is capable of accepting a +30dbu signal before clipping, so it should have nearly 10db of headroom with the M32. The outputs of the DR260 have a max level of +22dbu, so they have a lot of spank to pass on to the next device, but with a 0 to +5 metered output, you should expect the output level to be right around +4dbu to +9dbu if it is metered as such. All this means is that after the signal has gone through the X-overs and gain staging, the output is set to set right around a unity level ( which again I assume to be +4dbu in this case ).

So, you have TONS of headroom left in the DR260 and subsequently, the amplifier as well since the metering of the amp is showing that you have at least 20sb - 10db of headroom. Not knowing exactly where the amplifiers input attenuators knobs are set, my guess would be that if the DR260 clips the inputs, the amplifiers will be as well. You have about the same amount of available headroom in those two parts. What I can say is that you should have about double the SPL available from out of the VRX's if you open the amps up all the way, or turn up a setting within the DR260 to drive the amps harder. Although I would say that if the signal is setting around -10db on the amplifier during normal use, this is a good target range to live in. If you are happy with the volume you have, I would simply adjust the gain staging so that the mixer is doing less work and the relative output remains the same. This will make it so that you are not cooking the HA's of the mixer and subsequently the mix busses and thus dropping the output level closer to a unity operating point of around -18dbfs ( or +4dbu ). This will allow gobs of headroom at the DR260 which does have a staged input attenuator that can be switched between +30dbu and +22dbu. Based on the info, it seems to be in the +30dbu setting. If it were set for +22dbu as it comes from the factory, the input would be clipping the same time as the M32's output does. There is an input volume setting on the DR260 that goes from off to +20db. You could adjust that as well I guess?

From what it sounds like to me, the system gets loud enough, it just has the mixer working very hard, or at least beyond best operational standards, and a slight shift in gain staging from one devise to the next can allow you to achieve a balance that doesn't change the sound of the mixes so much as it shifts the level of responsibility. If you change the gain structure to allow you the ability to clip the amplifiers, you and you alone are responsible for not abusing that ability. I would imagine that a +10 to potentially +20db increase in SPL would be MORE than evident and easy to monitor, but that alone doesn't preclude safety or responsibility which is perhaps why it was set up the way it was?

Knowing what the end goal is, helps the most I think. If you know what you want and need, then getting it is easy. If you are not 100% sure, then you are guessing and taking crap shots in the dark to achieve an unknown result. Do an easy assessment to see what you want. I do it like this.

1. Listen first. What is the quantifiable problem that you can actually fix that physics won't disallow?

2. Look at what is going on and how does it contrast to best operational standards. The mixer is clipping, but nothing else is, this needs to be changed so that things are in a better operational standard. That sort of stuff. If the amps are clipping and you don't have enough volume, what is causing that? Observe what the problems are and how they can be addressed.

3. Know what is achievable. What is each piece of gear capable of and how will it all work together? What are the limitations? What are the reasonable expectations of everything? If you want a speaker that is only capable of 120db to produce 130db, obviously that is an unreasonable expectation. If you need 270* of coverage but only have 90* speakers, that is a limitation. What do you have, what is it capable of and what can YOU get from it.

4. Having a goal in mind. I like to think of it more as the very basic minimum standards of operation. I need 100db at 50' away with 180* of coverage from the front to the back with a system capable of 32 inputs and 10 outputs for monitors, front fill's, subs, and mains that will allow linear sound reproduction and have 10db of available headroom in any part of the system. Pretty basic and easy. Does what you have allow that basic goal? Does what you want allow that basic goal? If you don't know what the goal is, you can't quantify if the gear you have will meet your demands. This is where product knowledge and understanding plays in. Knowing your tools.

Our job, in essence, is to design, implement and optimize PA systems. If you can design a system to meet a goal, then you also need to be able to put that system together and implement that design, then finally the part that ties it all together is the optimization. Optimization is the part you are currently wrapping your head around. You have this system that was already designed and implemented, you are trying to optimize it. Optimization is the hard part. Mostly because of opinion, subjective impressions and individuality. What you like another may not and vice-versa. I say that a good engineer is one who can achieve a sound that 7 out of 10 people can agree with or enjoy. It may not be great ( by some unknown standard ), but no one is really complaining either. Optimization includes things like settings crossover points, EQ, time alignment and limiting or system protections. This is where all the math, product knowledge, and skill really lies. This is the part most struggle with and or fall short of grace with. It requires the largest amount of knowledge and the highest level of objective skill to do. Having the end goal all ties into this part of the process. Start by trying to build the system you currently have ( virtually ) from beginning to end and see what your objective goal is and then go back and see what your outcome actually is ( what it's doing right now ). And then tell us what the deficiencies are and what you feel is the best possible fix to those issues after going through the whole process.
Title: Re: More VRX help needed
Post by: jon.duffin on June 26, 2019, 06:22:10 pm
Just a quick note on the gain structure of the dbx 260.  There are jumpers internal to the unit that will allow the 260 to clip at +30dBu, +22dBu, or +14dBu.  There are separate jumpers for each input channel and each output channel.  The 260 ships with the jumpers in the +22dBu position.  This is explained in the user manual on page 66.  The manual can be downloaded from the dbx website. 
Title: Re: More VRX help needed
Post by: Jordan Wolf on June 27, 2019, 04:17:08 pm
Just a quick note on the gain structure of the dbx 260.  There are jumpers internal to the unit that will allow the 260 to clip at +30dBu, +22dBu, or +14dBu.  There are separate jumpers for each input channel and each output channel.  The 260 ships with the jumpers in the +22dBu position.  This is explained in the user manual on page 66.  The manual can be downloaded from the dbx website.
Nifty! Thanks for the heads-up!
Title: Re: More VRX help needed
Post by: Eddie Ybarra on June 29, 2019, 05:50:44 pm
Luke thanks for the insight, after a couple of more days the mix has gotten better and itís a little easier on the ears. Bypassing the DR260 house eq along with the m32 graphic eq on mains really opened up the rig. Now on too the eq for the monitors check this out, the eq sliders are down in some way or another from 80 all the way to 16k any logical reason behind this?
Title: Re: More VRX help needed
Post by: Russell Ault on June 29, 2019, 06:35:53 pm
Now on too the eq for the monitors check this out, the eq sliders are down in some way or another from 80 all the way to 16k any logical reason behind this?

Operator inexperience?

-Russ
Title: Re: More VRX help needed
Post by: Eddie Ybarra on June 30, 2019, 02:32:16 pm
Word haha
So I got the call from the guy above my pay grade to put all the house eq back cause it didnít sound right I guess we canít win them all lol
Title: Re: More VRX help needed
Post by: Tim McCulloch on June 30, 2019, 04:14:03 pm
Word haha
So I got the call from the guy above my pay grade to put all the house eq back cause it didnít sound right I guess we canít win them all lol

One of the long time participants here is a BE whose approach, when he sees "house EQ" as you describe, is to hit "bypass".

Always restore whatever you change.  Other users may be depending on the existing system voicing.  Especially when the other users include your boss...
Title: Re: More VRX help needed
Post by: Luke Geis on June 30, 2019, 06:49:22 pm
My rule with monitors is that the less you touch it, the better. I will typically roll off ( using a Hi-Pass filter ) all the low end up to as high as 200hz. This is dependent upon the monitor and the application though. Monitors that are for vocalists only will get this treatment. Monitors that go to keyboardists and non-singing musicians only get the lows rolled off up to around 80hz. The idea is to get as much boom and muck out of the monitors as possible freeing up headroom and allowing the ability to cut through the stage wash easier. I roll off the lows just to the point where it begins to sound thin and unnatural and then back down just a tad so it still sounds full and balanced, but not boomy and heavy. Err to the thin side if you really need it to cut like a razor.

If you cut anything more than 6 frequencies, STOP, you are no longer doing anything productive. If you are cutting much more than 6db, again, STOP, you are no longer doing anything productive. I do it like this:

1. With all EQ OFF, listen to the monitors with the mic on your voice. The monitors should sound pretty natural and a bit boomy ( proximity effect and floor coupling at work here ).

2. Using a Hi-Pass filter roll off the lows until the vocals sound natural and not boomy or too full. This is typically somewhere between 140hz -200hz.

3. Next is to turn things up. If it is obviously loud and clear your work should be easy. Keep going until it starts to squeal when you are in front of the mic. Probably around 1.2khz - 2.6khz is likely. In any case, wherever the mic with you utilizing and handling it seems to be sensitive, reduce only the frequency that is affected. If it sets between two frequencies, go ahead and drop the two around it. Only drop as much as is needed to become stable.

4. As few frequencies as possible and as little of them as possible too. As long as you keep turning the mic up in the mix, you will continue to acquire feedback. So then that leaves you with how much to cut? I try and not cut much more than 6db. Beyond that, you are taking a lot of other information with it and if the mic and the speaker are that sensitive at that frequency, you may need to find another approach. Either a different mic or a different EQ type ( like parametric ). With 1/3rd-octave Graphic EQ's, you really have to know what type you are working with before you go crazy with it. Some are more suited for monitors and others, FOH. Constant Q is the most common these days and by the time you cut 10db you are taking out most all of that 1/3rd octave with it! Much more than is needed for the task. Get the mic stable with as little work as can be done to do so. Once you are loud clear and stable, there is not much more to extract.

I prefer to NOT use Graphic EQ's. I find I can get all of the work I need to do with just the Parametric. Most mixers have a 6 band or at least a 4 band available and an insert that has another couple in it. I find that I can get 95% of the work done with 4 bands of EQ alone and if I need all 6 ( which is pretty rare ) I have a couple left. The next thing I do is copy my vocal channels to a second layer or channel group and use those for monitors only, set up as post EQ sends to the mix. This allows me to tailor the mic a little more for sonic quality and or another frequency or two of feedback. Since a parametric is more fine-tunable, you can generally notch out the feedback problems easier and with less effect on the surrounding frequencies.

My Mantra is this: Monitors are meant to be heard, not sound good, once loud enough with full stability, then you can make them sound pretty.

As for your current situation with the boss man...... No, you cannot win them all. Be sure the original preset is saved before messing with it and do what you think is best and then return it to normal. The hard pill to swallow is that it is NOT YOURS to play with. Whether they trust you or not really isn't the debate, it's not yours and the powers that be said NO. Now if it were my venue, I would let the talent do as they do and I would only hire those I trust to not be destructive. Too me, the art of the job is allowing the individuality of it to shine. The cream rises to the top. If what you did got more positive reviews, the other operators there should probably take note. I don't like the idea of saying this is what it is and don't you dare touch it unless there is a reason to instruct as such. In your case, you may just have to wait until it is your time to shine.   
Title: Re: More VRX help needed
Post by: Eddie Ybarra on June 30, 2019, 08:43:11 pm
Everything is put back the way it was and damn, parametric and graphic EQs can be your best friend or your worst enemy guess which one I got lol 
Title: Re: More VRX help needed
Post by: Eric Snodgrass on June 30, 2019, 10:34:30 pm
Everything is put back the way it was and damn, parametric and graphic EQs can be your best friend or your worst enemy guess which one I got lol
As was said in a previous post, the BYPASS button is your friend.  When you mix just hit the bypass buttons on those EQs and then, if needed, create your own EQs on the console and save them in the EQ Library.  When you're done mixing you can just restore the EQ curve on the console and disengage the bypass on the external EQs.  You could even create and save your own Scene for when you mix that will bring up any and all of your preferences.  Hopefully the house has its own default scene that restores the console to your boss's preferred settings. 
I do this at a venue where I am brought in occasionally to mix.  I have my own EQ curves for the house P.A. and monitor wedges saved in the console.  The venue doesn't mind at all as long as I restore the EQ curves in the console. 
Title: Re: More VRX help needed
Post by: Eddie Ybarra on July 01, 2019, 12:28:51 am
Luke always good to hear your input simple and strait to the point. I'm defiantly gonna make my own eq presets and with a month to go for this run of the show it shouldn't be too bad.