Trying to understand what the factory speaker settings are
mathewjg
Posts: 12
I just bought the PX and trying to get a simple understanding of its working. I have been reading through FAQ's and playing with the PX in my home studio connected to a couple of JBL EON515's
Here is what I think I know/undertand
Its necessary to make sure all the levels match - mixer, PX and speakers all hit red at the same time then adjust the PX limiter to reduce the speaker level (assuming limiting is required) - But in reality my Yamaha mixer output matches the PX input and it was quite easy to turn the speaker level up to clipping and then back down a bit - much to my neighbours discomfort!
The PX has auto eq that can take account of room acoustics, but according to advice on this forum you have to be very careful in placing the microphone in the right position - and due to odd room behaviour its likely that the bass end will need to be boosted manually - definitely in my case. One other point on this - Not sure of the benefit in trying to match the acoustics of the room when its empty - many venues change drastically when the crowd arrives.
Speaker left/right balance seems a bit pointless as subtle changes are not going to make a radical difference to the overall sound but I guess when using subs this might become more critical.
Auto feedback - does what it says but in reality messes up the auto eq setting unless you go very lightly - I prefer the sound without it although I suppose the live function would help when singers hold the mic directly in front of the speaker.
Sub harmonic synth - similar to an octivider and not speaker dependant - I cant try it properly until I connect up subs
When using a sub you need to know the best crossover frequency.
So... do the factory presets just provide crossover frequency info plus suggestions for setting the speaker level?
One final point - I was hoping that the limiter feature would help protect my speakers but again after reading this forum it seems that if anything they could flatten the signal going to the speakers and cause them to fail quicker than they might have without. And.. most powered speakers have limiters built in to them so is there any point in adding another level of limiting?
Here is what I think I know/undertand
Its necessary to make sure all the levels match - mixer, PX and speakers all hit red at the same time then adjust the PX limiter to reduce the speaker level (assuming limiting is required) - But in reality my Yamaha mixer output matches the PX input and it was quite easy to turn the speaker level up to clipping and then back down a bit - much to my neighbours discomfort!
The PX has auto eq that can take account of room acoustics, but according to advice on this forum you have to be very careful in placing the microphone in the right position - and due to odd room behaviour its likely that the bass end will need to be boosted manually - definitely in my case. One other point on this - Not sure of the benefit in trying to match the acoustics of the room when its empty - many venues change drastically when the crowd arrives.
Speaker left/right balance seems a bit pointless as subtle changes are not going to make a radical difference to the overall sound but I guess when using subs this might become more critical.
Auto feedback - does what it says but in reality messes up the auto eq setting unless you go very lightly - I prefer the sound without it although I suppose the live function would help when singers hold the mic directly in front of the speaker.
Sub harmonic synth - similar to an octivider and not speaker dependant - I cant try it properly until I connect up subs
When using a sub you need to know the best crossover frequency.
So... do the factory presets just provide crossover frequency info plus suggestions for setting the speaker level?
One final point - I was hoping that the limiter feature would help protect my speakers but again after reading this forum it seems that if anything they could flatten the signal going to the speakers and cause them to fail quicker than they might have without. And.. most powered speakers have limiters built in to them so is there any point in adding another level of limiting?
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Comments
Pretty much, however we would like the driverack to NEVER CLIP... and we would like the amp/speaker to be just below clipping when the mixer clips..
Mixer= just at clipping
DRPX= below clipping ( 4-8dB of headroom)
speakers/amp= just below clipping
This way we know that when the mixer is just clipping the speakers and driverack still have some headroom...Now if you set the limiter to hit just below the clip point of the mixer it can act as a "OOPS" protection. If you try and use the limiter as system over driving protector you could very well be adding to the problem, or causing damage or long duration.
True, but I think it's a bogus pretty much useless feature unless your using it as a effect..if it gets into the vocal range at all it just ruins the sound..I don't care for it...
When using a sub you need the right "crossover point" make sure that the crossover frequency and slope (like100hz @ LR24) are the same when transitioning between subs and tops.
Factory provided setups are (especially in the PX) are predicated on a mathematical formula and should ALWAYS be looked at closely. Determine if the setup makes any sense... For instance, the DRPA called for a crossover point of 180hz between a Peavey SP118/SP218 sub and a SP2 top... now that is RIDICULOUS! Should be closer to 100hz or even loser depending on how much power you have for the tops...
With powered speakers just let the speakers do their own limiting and let the gain structure do the majority of the work.
Gadget
I am thinking that for modern powered speakers the px does not really add much specially when just using a couple of 15" units. But I always enjoy messing around with new toys so will give it a go over this weekend mainly with singers using backing tracks. It does mean extra equipment to plug in (I generally avoid anything extra in the signal path) and another possible fault point but this unit seems to get a lot of praise so I am hoping to be pleasantly suprised
I have several types of act that I work with regularly
Solo's and Duos just using backing tracks with vocal - very compressed backing tracks downloaded from the internet with vocals that are usually much louder than the track.
Suprise singing waiter act - Good quality backing tracks - Nessen Dorma, etc they are threatening to use head mics so I suspect the anti feedback will come into its own and I suspect that pinking might help.
Function/funk band - generally this is the only time I use subs. Most active subs have a built in frequency selector and output for the top speaker but I guess the PX might offer a more accurate crossover point (but to be honest I have not really had a problem doing this by ear).
Remember to get the speaker in testing into freespace (as in on a speaker stand. Get the mic out far enough for the speaker to develop, maybe take a couple measurements 8, 15, 20' out, just realize that each distance will require different volumes to get to the same point (input meter volume wise). You might also want to consider doing a couple curves as well, like "A" and "C" for comparison sake (you have a number of useless presets.. ones you'll never use anyway)
Also consider a couple different volume schemes, like for acoustic shows where the volume is not that high. We do this because the sonic characteristics of the drivers in the speaker are non linear, meaning the frequency response is different at different volumes.
Make sure to view the product EQ curves and look for any anomalies and carefully listen to these and determine if they are really a valid boost/cut, or a reflection or refraction or some other sonic anomalie, like a reflection off a mic stand for instance...
Looking forwards to following your advice tomorrow - will let you know how it turns out
I did the test using my JBL EON515's and need to play around with my 515XT's but so far so good - according to DBX support the only difference between the two speakers is that XT's are more sensitive however according to the JBL spec the 515XT's are 650watts and the 515 450watts - I smell something fishy going on with the specs because both units use the same bass driver although the XT does have a different hf unit
Was this an indoor auto eq? Did you use only one speaker? what mic position?
So many questions...
Its a small studio so the measuring microphone was about 8 maybe 10' maximum from the speakers
Its not really auto levelling - it just shows a diagram of the speaker level setting and then when the stereo balance test is done it advises you to turn one or the other up with a diagram of the recommended setting (a small diagram of a circle with the recommended position of the gain/volume control indicated)
I used the flat eq parameter and my guess is about 30 seconds to complete auto eq. Seemed to be fairly accurate (to my ears at least)
I set the anti feedback using 6 filters with high precision music setting. I had the microphone pretty high - i could flick my fingers from about 3' from the mic and it was still picked up and reasonably present in the speakers - so pretty effective.
The indoor method also has the speaker on the floor, on it's side angled down slightly towards the mic about 8-10 feet out.
Best would be outdoors away form ANY reflective surface ... similar to the setup you did.
I don't care for the auto level set anyway...