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Auto Leveling on a PA+

smoralmsmoralm Posts: 14
edited July 2009 in PA General Discussion
I got my PA+ a couple days ago. I have been playing with the front panel but i have not hooked it up and done any wizards. my question is about Auto Leveling the Amp. when you go through the Wizard I select my power amp (a XLS202D, yes I know it is small (200W@8) but we are a small Acoustic Bluegrass band) it then shows a simulated knob position in the LCD and i think it says to set the gain knobs on the front of the XLS202 to match the position that it shows on the PA+. Is this correct ? Also you can turn the data wheel and change the postion. So my other question is \"Won't this setting be different depending on how loud you want the PA to be ? I usually try to keep all my mixer settings at the Unity Position and adjust the gain on the XLS for how loud I want it to be. then do fine adjustments on the mixer.

Comments

  • DraDra Posts: 3,777
    The Auto leveling feature is for systems that are bi-amped, tri-amped, etc where different components have different amps powering them. So your set-up does not have a need for it.
    It is best to do a manual gain structure as details in the READ ME FIRST SECTION / Start Here. Lots of other good info in the RMF section, also. After doing that, set the individual channels to unity and use the master faders to control the volume (leave the amp where you determine by the gain set-up).

    DRA
  • smoralmsmoralm Posts: 14
    Thanks for the quick reply...
    I am wanting to use the PA+ in a Stereo config (2 Full Range SP5 speakers) with NO Sub. So on the intial system setup wizard I used user #25 Dual Passive, Then i selected
    1) Stereo
    2) Stereo Linked (changed from Dual Mono)
    3) Custom Passive
    4) None
    5) XLS202
    6) then the display says \"High Amp Level\" and defaults to \"72% level\" with the pic of the knob and says \"Adjust knob same as on your amp\"
    So I guess i set the gain knob on the amp where i normally put it for a certain show/venue and then i set the PA+ to match it.

    So if the PA knows i am using Custom Passive (meaning 1 pair of Full Range Speakers) and NO Sub then why is it asking me to do this this ?
    Or is their another default config i should be using to get where i want to be.
    thanks
  • DraDra Posts: 3,777
    The wizard is telling you that someone tested that amp and they found the amp to provide it's full output without clipping when set to 72% and the x-over gain at what it is set to (I assume) -0- gain. It has a lot to do with system noise also. You can trust an apprentice at DBX if you wish, but we advise here to \"see for yourself\" where the amp should be. As I point to earlier.... from the start here post.



    The single MOST IMPORTANT thing you can do is set up your GAIN STRUCTURE so we will deal with that as one of our first orders of business. The Gain Structure gets all the equipment \"talking the same language\" and in the process offers the benefit of giving you a visual picture of where the system is at with regard to headroom. If you are running your system in the red all the time you are heading for disaster! Below is a general gain structure setup to give you an idea where to begin...there is MUCH more on this subject in the study hall @ the PSW (the third link provided) and the below example is a starting point for those that have never done a Gain Structure before..
    Gain Structure...

    1. Turn amplifier(s) attenuators all of the way down to zero (fully counter clockwise), disable amplifier(s) clip limiters (if used), and disconnect the speaker cables.

    2. Make sure all DriveRack dynamic processors like GEQ, Compressor, limiters, PEQ, AFS, SubSynth, etc., are disabled. We will set those things after we are roughed in...

    3. Play pink noise through one of input channels of the mixer because it's consistent dynamically...(equal energy to all frequencies with a crest factor that is consistent across the full spectrum)

    Note: Please click here to download a 20 minute pink noise track (track58.zip) by courtesy of Michael \"Bink\" Knowles... His entire test CD can be found here...
    http://binkster.net/extras.shtml#cd

    4. Set the mixer input channel fader (with pink noise) at \"unity\" (0dB). Also zero the EQ.

    5. Disable the AFL(s) (after fader listen) on the mixers master output channel(s) and enable the PFL (pre fader listen) on the mixer input channel (with pink noise). If your mixer does not have these features just make sure you have no clipping and sufficient signal to not run into signal to noise problems.

    6. Turn up the mixer input channel gain trim pot (with pink noise) until the meter bounces in the yellow at least 6dB below clipping. MAKE SURE THERE IS NO CLIPPING! (actually anything over 0 VU will be fine)

    Note: If your mixer doesn't have PFL simply set the input gain just below the point where the channel \"clip light\" barely (occasionally) bounces on.

    7. Disable the PFL on the mixer input channel and enable the AFL(s) on the mixer master output channel(s). Again if you don't have these features just make sure that your output meters are just at the clip point.

    8. Slide your mixer's master fader(s) up until meter is just barely (occasionally) bounces in the red at clipping.

    9. With the DriveWare GUI open the DriveRack panel meter and then one of the mixer input dialogs (click on the \"M\"). Put the master fader at “unity� (0dB). Watch the DriveRack’s panel meter and pull the input fader up or down until the output meters are bouncing in the yellow about 3dB just below clipping. Absolutely no clipping (red) on the DriveRack’s input or output panel meters!
    If you are using a DRPA you have a button on the back that sets the input sensitivity to +4db (pro level) or -10 (consumer level) if the meters on the mixer are at just clipping and your using +4 and the meters on the Driverack are anywhere above the 0vu but below the clip light your fine... there is no input mixer to adjust... If the signal is low try the -10 setting and see if that gets you to a more appropriate setting.

    10. Click on the other channel’s mixer input dialog (click on the “M�), set the master fader at “unity� and put the input fader at the very same location as the previous channel.

    In the DRPA, output levels are controlled by the crossover gain... this means that if your at 0db as we discussed earlier the output meters will be showing the output gain... as long as they show a decent signal this is fine... remember this is all in the digital domain so signal to noise is not as big a problem as in analog circuits... try adjusting the amps before you change the gain of the crossovers, if you cannot get the amps to clip, or your amp sensitivity is perceived to be too high... then adjust the crossover gains...

    11. Make sure all speakers are DISCONNECTED FROM THE AMPS..(unplug speakers as proscribed in step #1).. modern amps have open circuit protection) Turn up the amplifier gain trim pot (clockwise) until the amplifiers red clip light barely bounces on.

    12. Turn back the amplifier gain trim pot (counter clockwise) about 3dB to 4dB from the clip position. Mark this position. This position provides approximately 3 to 4dB of headroom before clipping. This is the highest the pots should ever be turned...More headroom can be achieved here by turning DOWN the control but it is NEVER to be turned up past this point!

    13. Repeat steps 11 and 12 for all amplifier(s) channels driven by the DriveRack. Return the master faders on the mixer to -0- . Plug the speakers back in.

    Now we have all the equipment talking the same language.. but we haven't balanced the system yet... it's most likely that one set of speakers will be louder than the other so we need to balance them before we move on... it's a good bet that the subs will be the quietest since they require the most power... put some good full range music on your system.. I like Steely Dan, Toto, Dread Zeppelin, ETC and set the input fader on the input channel on the design center( unity gain point) (this gives the best signal to noise in the analog domain) again press the PFL button and view the output meters and verify that the signal is well below clipping but above or about 0vu.. those lucky enough to have channel meters on each strip a yellow indication is acceptable..if only a two light LED is available turn up till red then turn down below clip point.. disable PFL. Turn master fader up till the system comes to life and if the tops are much louder than the subs... turn the tops amp down... get a good balance and turn the system up till near performance volume and assure it still sounds balanced...

    If you intend to Do an Auto EQ please follow the \"Former forum\" link above and read the \"Tutorials\" section, and Mikey Kovachs user submitted white paper. Maje sure you have a dead flat omni directional mic for the job, like the RTA \"M\" available from DBX or better yet the TR40 by Audix...

    Note: If you're planning on setting-up your DriveRack output limiters follow Mr. Dra's \"Super Duper Limiter Procedure\" (below) before going to step 14.

    A. Determine the clip point of all amps by setting the gain structure.
    B. After turning down the amp and marking the point where the amp stops clipping, turn the amp up to where it clips again.
    C. Press the \"Comp / Limiter\" button 2 times to get to the Limiter section.
    D. There is a limiter for each x-over section that it set up. For example: 2-way (Hi and lo) has 2 limiters, 3-way (hi, mid, & lo) has 3 limiters. Select the section that needs to be limited (all need to be limited).
    E. For the selected output, select Over Easy as on. This gives a softer, less noticeable limiting effect. Select setting 4 as a starting point.
    F. Lower the threshold until the amp stops clipping.
    G. Return the amp to the previously marked spot.
    H. Repeat steps E - G for all output bands.

    Note: It is highly recommended to re-check the DriveRacks output limiters if the X-over gains have been changed, or if any \"enhancements\" have beem made using GEQ, PEQ, or Sub-Synth afterwards

    Note: The DRPA, unlike the 260, DOES NOT have a brick wall limiter. For example: With a clip point for the amp at +20db and a limiter threshold at +17db and the limiter, depending on the use and setting of the Over Easy, may successfully reduce an output at the limiter section of a +19db input. But, if the signal spikes to +24 db. The limiter may reduce the output by 2 or 3db, but it WILL let pass the remaining peak output, which is well into, and beyond, the clip point of the amp.

    Note: The DR260 can be set with a maximum \"Overshoot\". Regardless of the Over Easy setting, if the Limiter threshold is set to +17 db and the amp will clip at +20, the 260 can have an \"Overshoot\" set as 2db (or more). This feature (along with Attack and Hold time settings) will take a +24db signal that will be limited, starting at +17db, then at +19db the 260 slams the door and lets nothing more pass. The amp will never clip, if proper gain structure and limiter setting techniques are observed.


    14. Bring mixer's master fader(s) all the way back down to off, re-enable your DriveRack’s dynamic processors, re-enable amplifier(s) clip limiters (if used), and reconnect the speakers.

    Note: It is highly recommended to re-check the gain structure and output limiters if the X-over gains have been changed, or if any \"enhancements\" have been made using GEQ, PEQ, or Sub Synth afterwards. It is also recommended to keep the amplifier's clip limiters disabled If using the DriveRack's output limiters.


    More to come folks, thanks to Kevin and Dra for their efforts on this work. If you have any corrections, concerns, additions, or comments please feel free to PM me

    Now, go to the FAQ section right below this and find out why all this works the way it does...

    Be well, and good luck!


    Gadget
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