PX mic and JBL EVOi 324…
BruPri
Posts: 10
Hello, two questions…I’m so new to the product that it won’t even arrive for two days.
I have a pair of EVOi 324 that came with the EVOi net processor. If you’re not familiar with these, they are a self powered 4’ tall design with dual 14� woofers and a 1.5� compression driver each, internally crossed over, balanced XLR in with no volume control.
The processor, when it was working, had a calibrated mic, auto EQ, FB, delay timing and communicated with the speakers down the signal cable, sending packets back and forth during the setup process that usually only took about 3 minutes for both speakers.
I purchased the Driverack PX to replace the JBL processor.
Mic placement question…
JBL specified for hard surfaced rooms such as gymnasiums etc…to lay the mic flat on the ground, 2/3rds of the way back in the room. For softer rooms such as theater, upholstered chairs, raked seating etc, same distance, just on a stand at ear level. Both scenarios, middle of the room, aimed straight at the front/center stage.
I’ve seen some interesting pictures and discussion here with the mic aimed directly at either the ceiling or floor, about an inch or off the surface as well as the “new auto EQ close method�
Assuming a large gymnasium with speakers firing down the long way, what technique would yield the best results.
Auto-level question…
Since I don’t run subs and basically have no control over the input volume of the speakers, do I even need to concern myself with Auto-level?
Thanks much!
Bruce
I have a pair of EVOi 324 that came with the EVOi net processor. If you’re not familiar with these, they are a self powered 4’ tall design with dual 14� woofers and a 1.5� compression driver each, internally crossed over, balanced XLR in with no volume control.
The processor, when it was working, had a calibrated mic, auto EQ, FB, delay timing and communicated with the speakers down the signal cable, sending packets back and forth during the setup process that usually only took about 3 minutes for both speakers.
I purchased the Driverack PX to replace the JBL processor.
Mic placement question…
JBL specified for hard surfaced rooms such as gymnasiums etc…to lay the mic flat on the ground, 2/3rds of the way back in the room. For softer rooms such as theater, upholstered chairs, raked seating etc, same distance, just on a stand at ear level. Both scenarios, middle of the room, aimed straight at the front/center stage.
I’ve seen some interesting pictures and discussion here with the mic aimed directly at either the ceiling or floor, about an inch or off the surface as well as the “new auto EQ close method�
Assuming a large gymnasium with speakers firing down the long way, what technique would yield the best results.
Auto-level question…
Since I don’t run subs and basically have no control over the input volume of the speakers, do I even need to concern myself with Auto-level?
Thanks much!
Bruce
0
Comments
The rest is really suspect... isn't the JBL system a stand alone room correction device? We need to know....
Did it stop working? if so what happened, and why didn't you get the JBL device fixed?
As for the mic placement it is critical for anything before he DRPA+ and has a profound effect on the product sound....
The "Lay it on the floor" method is a way of preventing reflections to the mic, and if you check you will see that the "New indoor method" described here:
viewtopic.php?f=60&t=953
describes the process and product in further detail. There is a LOT of info in the FAQ section:
viewforum.php?f=60
and here also:
viewtopic.php?f=61&t=959
We are always here for questions...
gadget
Just figured out what DRPA+ is :oops:, anyway, I have a DRPX, not PA although in either case, I have no doubts that placement is critical. Yes, there's a great deal of information, which sort of made it difficult as there's mic setup info spread across 3 or 4 different articles. I spent a good part of an hour gleaning what I could from the FAQ articles and will hopefully distill that down to something a bit more directly suited to my setup and applications. Thanks though, I do appreciate the reply...
The Driverack does basically the same thing, but has -0- delay available, for that you need the 260, the DRPA has alignment delay but thats about it...
Now, the measurement procedure specified here DOES NOT specify the mic @ 1" from a surface.. but LESS than 1/4"! This is critical and I disagree with JBL about just laying the mic on the floor, but if you don't have a mic stand that will hold it @ a very short distance and not present a huge base right next to the mic (as in a tripod able to be some distance away to not provide reflective surfaces to skew the measurement process) That distance (when the mic is laid on the floor) provides a reflection path, granted a very short wavelength, but none the less with the mic aimed AT a hard surface and a very short distance away provides the least possibility for a reflected path.
Another consideration here is the size of the surface... for instance placing the mic on a table limits the LF capability of the system. Bass waves in the 20 hz range are over 56 feet long, so a table would limit the usable frequency range in the LF domain considerably...
We know we can't equalize a room, but instead place the speakers creatively, and when all else fails equalize the speakers with respect to the room...Therefore, the best results would be realized by adopting a multiple measurement point tests and averaging the results...In professional circles the RTA based measurement system is not viewed as very useful, here what we specify is attempting to get the frequency response as flat as possible, and then using creative speaker placement to get the information on the audience and off the reflective surfaces.
Another cool feature of having and storing the Flat preset is you can then compare what the room is doing to the sound by simply taking measurements and compare those to flat preset you have stored.
What type of service do these speakers perform?
Gadget
"Is the processor doing anything?" Yes, there are two sets of LED status lights that flash error codes, the particular code indicates lack of communication with the respective speakers, I've swapped channels and the symptom does not reflect the change indicating the error is with the processor. I did notice a couple caps in the power supply had crowned so I replaced all the caps in the unit to no avail.
"Is it possible that the measurement mic went bad?" The mic is good, anyway, core system performance is not dependent on the mic being connected or not.
"how old is that system anyway?" 1997=12 years.
So if I understand what you are saying, aim the mic directly at the floor within approx. 1/4" with no obstructions around the mic. Got it.
Now the question remains, given the Gymnasium scenario with the speakers up on 4' stands putting the horns at ear level, firing down the long way. Where best to site the measurement mic? There's the 2/3 into the room method that approximates the average audience experience or the "new" method that if I understand right, is an attempt at taking the room out of the equation with an eye to just flattening out the response of the speaker alone. (I assume I would then place my cabs on the floor, tilt them down a bit, then determine the mic distance to get a reasonable blend of high/mid/lows at the calibration point. No?
"What type of service do these speakers perform?" Portable P/A work mostly, high SPL music playback.
I do studio production and live performance. Mostly I donate my services and time to school and community functions. Prior to these I had SRM 450s and there was really no comparison, the EVOi 324s are amazingly accurate, have plenty of visceral slam, and headroom like no tomorrow. Altogether not bad for a product destined for sanctuary and theater pillars.
Bruce
Yes, as I said this is a technique that has helped literally thousands of people and is one even the pro audio community agrees with...the bonus here is that along with flat response when you use this technique in lively rooms like gymnasiums you are less apt to excite the room with frequencies that are hotter than others.
I have also built an adapter for the speaker stands that tilts the speakers down a few degrees to help keep the sound off the back wall, and on the audience.
Once you have a flat preset stored to one of the PX preset locations, there is no harm in "seeing what the room is doing to your sound" and then comparing the flat preset to the ones you take in the room.
There is also no harm in trying the mic on the floor method, the mic on a stand method. trying 10 feet out on axis with one speaker...20 feet out in the center of the room, 25/30/35/ center of the room...and compare those to your flat preset.
If you have a big problem with the indoor method I have experienced success with the nearfield method, which involves simply putting the mic in the nearfield which by default places all reflected energy far enough down db wise that it has little if any affect on the auto eq. That would be about 5-8 feet out and on a stand, on axis.
No wrong way here, just options and variables...
G