JBL PRX in full range with PA+

Mctwins

Hi
I have PRX635 and PRX618S-XLF and I would run this with a PA+ in fullrange and I only have a preamp with RCA outputs. What is best??

can I connect from pre to inputs on the PA+ and only run from Highout to PRX subs and then further to PRX635 and run it in fullrange, it has allready active crossover in the speakers and amps. I wouldn't mess with the crossover settings in the PA+. I would only use the PEQ, can I do this??

Schould I also switch the groundlift to -10dBv or leave it at +4dBu?? For me it sounds better when I have it on +4dBu on my PRX even if I have RCAout on my preamp.

I am running it like this right now without any PA+ and it sounds good but would be nice if I could mess with some PEQ.

What do you guy think??
Thanks

Gadget

You most certainly can... simply set up stereo tops no subs or use the stereo tops preset... then make usre to drag your HPF down to out or 20hz or something (unless you want the protection of the DRPA)

If you can get enough out of your preamp to drive the DRPA+ in +4 then there is no problem doing that... I would just wonder about the noise floor?

That isn't a ground lift by the way ( but there is one right next to it) it's an input attenuator...and its designed to take signals like unbalanced non pro level equipment that typically doesn't have enough output voltage to drive the input stage of the DRPA+.

McTwins, what the heck you got going now? You have without a doubt one of the most impressive stereo rooms I've ever seen and now you have some portable pa? You a Dj too?
G

Mctwins

Hi
I am not a DJ guy

I just have them for my TV setup with my computer in my livingroom and one can see it as a new computer loudspeakers, perfect when you are waching youtube and some TV programs and movies. I have a very large livingroom. I must say that it sounds great.

Don't worry, it's not gonna be a new dedicated listening room.

OK, that's good to know I can run it like you have mentioned because I was thinking of getting a dbx260 for my cinema dedicated room. Seems to have some better crossover freq setup and cinema tunings as well and have also notice the driveware feature, I like this.

I will test with and without the groundlift on PA+ and see what happens with the noisefloor. I have notice that it is more silence with +4dBu(linelevel) on PRX than with the -10dB(miclevel)

Thanks

Mctwins

Hi
I have it in dual passive mode on dbx PA+ and run from high out to jbl 618S-XLF sub and from sub to 635 main speakers. It is OK with this setup but was thinking if I could run it in stereo 2x4 mode but I would like to use the crossover settings in the speakers as it is, not via PA+. As I see it, I must high pass the PRX635 at 90Hz.

Reason for this is to use more PEQ, five instead of three.

What is the best setting??

Thanks

Gadget

I guess I've been thinking about this long enough.. kind of confusing I guess..

To my way of thinking you have much more control over the xover point (more choices and far steeper slopes plus you have variable xover points to work with... unlike the fixed slope and fixed frequency provided by the speakers. Also, you can try overlapping , and spreading the crossover points to try and minimize crossover distortion.

If you do this you will still have 3 PEQ's for the tops and 2 Peq's for the subs.... so I guess I'm still confused on what you are wanting to do?
G

Dra

Gadget,
I raised this a couple of years back.

Dual mono
Input to left channel
X-over set to full range
Out left high (3 PEQ's available)
From left hi to right input
Out right hi (3 PEQ's available) (6 total PEQ's)
to amps with DSP or powered speakers with built in x-overs.

DRA

Gadget

Ya... I remember...did you ever try it? Don't remember you ever indicating if you had?
G

Dra

No. Just a theory.
Should work though. Line in, Line out, Line in, Line out.

DRA

Gadget

Hmmm... just a theory???? :roll:

Proof rules, theory drools...
G

Mctwins

Hi
Dra....
If you have it dualmono woulden't it just be in mono not stereo. I mean the left/right speaker side would be gone. Nevertheless it sounds confusing to hook it up in this way.

Ok, let me clarify!!

I have it connected like this for the moment;
From my preamp it goes to left/right inputs to PA+ and from PA+ highout left/right to LEFT PRX618S-XLF and daisychain to PRX635 and same for the right side.
In PA+ I have it in dualpassive mode and can only use three PEQ only.
But...
If I do like this;
From my preamp it goes to left/right inputs to PA+ and from PA+ lowout left/right to PRX618S-XLF and from PA+ highout left/right to PRX635 and use 2x4
settings in PA+. Here I would be able to use more PEQ but of course use Highpass 90Hz on PRX635 with additional slope.
The quastion is?? the slope settings is higher in PRX speakers and I woulden't be able to do this in PA+.

PRX635:
Frequency Response (±3 dB):
Flat 53 Hz -18 kHz
Boost 50 Hz -18 kHz
Crossover Modes: DSP controlled. LF: 48 dB/Oct. filter slope High & Low Pass
HF: 36 dB/Oct. High Pass

PRX618S-XLF
Frequency Range (-10 dB): 30 Hz - 105 Hz
Frequency Response (±3 dB): 39 Hz - 93 Hz
Crossover Modes: DSP controlled 48 dB/Oct. filter slope

Now the ?????
What is best.
Thanks

Gadget

Dual mono can indeed be stereo but the content is key here...if the two inputs are exactly the same then it's mono but if the content is stereo it's just that the Driverack allows each speaker input (left / right )to be independently EQ'ed...

As for the question?...Hmmmm I must admit I still have questions... I guess I'll have to give it further consideration... any further clarification in the meantime would be helpful..
G

Dra

OK. I think I understand.

If this is true:

You want to run the speakers through the PA+, but allow the speakers themselves set the x-over points and slopes. YES?

You want to be able to have the 3 PEQ's for hi's and 2 PEQ'sfor lo's. YES?

---

Set up a 2x4 as you said.

In the x-over section:
Lo - run the Hi-Pass Filter (lo-cut) freq down to "Out" (I wouldn't go below 20hz)
- run the Lo-Pass Filter (Hi-cut) freq up to "Out" (or at least a couple of hundred hz higher than the freq in the speaker)

Hi -run the Hi-Pass Filter (lo-cut) freq down to "Out" ( I wouldn't go below 20hz)

In a nut shell... you are taking a smaller number set and bracketing it with a larger number set as to not interfere with the smaller set's function.

Is that what you are looking for?
Gadget already touched on this earlier.
DRA

Mctwins

Hi
Dra....
Exactly what I was after...
OK.. it is good to know, I will try this.

But, witch is better?? To use the x-over settings in the speaker or use PA+.
Thanks

Mctwins

Hi
I have connected in 2x4(stereo 2-way) and WOW, it's different.

I set the x-over settings in PA+ like this;
Low; Lowpass 90Hz BW24
High; Highpass 90Hz LR24
or any other ideas is welcome.

Some PEQ in low and high and checkt it with ARTA measurement.

Not bad at all I must say.

I discoverd when I disconnected the cables that one of the subs had out of phase and the crossover settings to out. :oops: :oops: No wonder I coulden't get the settings right.

Dual passive is OK but this sounds better.

Thanks for all help!

Dra

Generally it's best to have the same filter types at x-over points (BW24, LR18, etc) although natural cabinet response can affect it. If it sounds good, and measures good, it is good.
Don't you hate it when a brain fart....

DRA

Mctwins

You can say that again about brain fart

I will test with same filters types.

Could you explain what you mean by

"I wouldn't go below 20hz" in previuos post??

Schould I set the/or cut off 20Hz in the low pass or leave it flat out??

Thanks

Dra

20hz??

1) Won't interact with the speakers processing of the HPF.
2) if something catastrophic happened to the speakers DSP (but still pass signal), you'd still have "some" protection from sub harmonics. Might even go as high as 30hz and as steep as possible.

DRA

Mctwins

Ok, I understand.

I have set like this;

Lowout: Highpass 20Hz BW24, Lowpass 90Hz BW24

Highout: Highpass 90Hz BW24 to out...

Hope it is more understandable

Thanks

Gadget

Yup, got you loud and clear..

So even though in theory the PRX series has steeper slopes available, using the DRPA with BW24 filters in a 2x4 config has given more pleasing results. I'm not surprised...if you consider that the DRPA is a dedicated DSP and the ones in the PRX are just a small part of a small amp/dsp combo.

Have you tried seeing if there is any benefit to raising the HPF/LPF to 100 hz or slightly more? (up to say ..120hz) and leaving a slight spread in the 2 points? In theory, if the woofer in the tops isn't working so hard producing LF it can better reproduce critical midrange content, and a slight spread at the crossover point can improve the characteristics of the interaction in the crossover points.

It can also benefit overall system output. If the tops aren't producing power sapping LF information, they are freed up to get louder in the midrange frequencies, and since the subs are already reproducing the power sucking LF info, adding a little content over 100 hz will not have any real affect on the subs performance.

If you study the typical JBL crossover setups you will find that they often set these same spreads on their active setups... They do however sometimes actually overlap crossover points using high rolloff BW filters. Usually when crossing in the under 100 hz range, and perhaps to help solve some sonic inadequacy in the speaker combos.

G

Mctwins

Thanks Gadget.. It's good to know.

I will do some more testing in a couple of days and see what happens.

Mctwins

Hi
I have done some testing back and forth. I have realized that I don't need PEQ on these speakers because it sounds better without. I have to low signal from my pre out and I think this is a major problem, I don't get enough power to the speakers. I will add ARTclean box converter and see what happens. I only did auto EQ and the ARTA freq response shows pretty well. I will mix a little further after the installation with the converter.
Thanks

Gadget

Are you in -10, or +4 position on the back of the driverack?

Mctwins

Hi
I have tested both the -10 and +4 on the dbx. when I have it on -10 on the dbx and I switch to the mic button on the PRX635 it dosen't sound good, too much hiss. I then push the button back to +4 on the PRX635 and turn down the nob and have it around the mic position. The problem isin't on the PRX635 it is rather on the sub 618S-XLF, seems I don't get a strong signal when I have it on -10 on the dbx, it is very uneven when I look at the output meters on the dbx between the low and high. There is no -10 and +4 switch on the subs. But, when I have it on +4 on the dbx and +4 on the PRX635 it is more even between low and high outputs. I think it has to do with the weak signal from my pre and also the ARTcleanbox will boost up the signal to +4 allthru the dbx. We will see when I hook up the ART.
Thanks

Gadget

remember you also have crossover gain you can add or subtract as well..

Mctwins

Hi
I have tested with the ARTbox, well it is good but I dont need it. I am having it on the -10 on the dbx and it is acceptable for the moment. I have been thinking about what you have been saying, Gadget, about the x-over gain. At least it sounds better.

I am puzzled. Let me try to explain as best I can.

Seems that it is some sort of unbalanced between subs and the main if we lookt at the signal. I tested with my McIntosh MCD201 CD-player witch has a variable volume control and it sounds ok and better level between subs and main. It has XLR out from this CD-player. I did the level in the wizard setup except choosing the amps and so on only the level adjustment with everything OFF like PEQ and so on. The different was only -3dB at low and +3dB at high at the x-overgain. I had, when I did this +4dB button on the dbx. But when I do the same with the Quad pre and RCA and -10dB button on the dbx I get -8dB on low and +8db on high, don't sound good at this settings. Some thinking here has to be done. I did everything with McIntosh Cd-player again and did the auto-EQ as well. Rehooked and connected the Quad pre and lowerd the gain knobs at around 9'oclock position on my PRX subs and main and raised the low x-over gain to +10dB and the high at 0 dB and push the -10db button as well on my dbx. I can play at full volume from Quad pre and the speakers limiter is not flashing and the overall sound is better. I suspect that the signal from my pre is not strong enough for the subs, or depends how you see it(-10dBv to +4dBu). On my PRX635 I still have it on the linelevel position. And also, the outputlevel is more even now between the low and high. Strange indeed.

Hope it isin't to much info.

He He, I am still learning but it is interesting.

Thanks