Hissing coming through Mackie 1530z from DRPX

MDRussell

I recently bought a DRPX. I used it with seemingly no problem through EON G2's. I am now in the process of doing a concert series where I will be using 8 Mackie SRM 1530z stacks on top of 8 Mackie SWA1801 subwoofers. I used this setup once before and was baffled with some serious hiss coming from the speakers. As soon as I removed the DRPX from the chain and ran straight out of the board, the hiss disappeared. I have tried the same setup again in our warehouse with the same effect. I have tried loading all different presets with all different gain structures but to no avail. Its doubly frustrating because the 1530's have no gain control. ALL cables are balanced I am 100% positive, soldered em myself Smile

Anyway, I am wondering if there is something dumb I may be overlooking or whether I need to try to send it in to DBX....problem is I want to use it in less than a week so I dont really have the time for servicing.

Gadget

Are you daisy chaining the speakers off the outputs?
Are you using all 4 outputs?
Do you get the same hiss with 1 speaker hooked up?
What mixer are you usiing?
Have you done a gain structure through the mixer and DRPX
So many possibilities...
Gadget

MDRussell

Thanks for the reply.

I am using all 4 outputs. I'm running into one of the 1530's on each side then daisy chaining to the others. Same thing with the subs. I don't believe I have used it with only one speaker, I'll give that a try today.

As far as the console is concerned, I have had the problem with both a Mackie 32x8 and a Mackie CFX20.

Yes I've structured the gain optimally between the mixer and DRPX and fiddled around from there with different gain settings with no change.

So I suppose in the mean time I can test it with just one speaker and with the A&H board I just got back from service and see if that has any noticeable effect.

BruPri

Just reading this post and I am experiencing the same issue with hiss/noise from my speakers...

Soundcraft Spirit Live and Allen Heath ZED 14, DRPX, JBL EVOi 324 (x2)

The gain switch is set to +4 dBu, and the Gain Setup Wizard not used. Sending pink noise through the board, the gain structure was set and the console L & R output at 0dB corresponds identically with the DRPX input ladders, both climbing in unison as the master fader of the console was brought up, until the red indicators on both components peaked simultaneously. Since I have no volume control on the speakers and there's no clip indicators, I've no way of knowing, short of researching the input specs on the EVOi s to tell exactly where the noise is coming from, it is not present when the speakers are connected directly to the console outputs....

Gadget

Try raising the gain of the xover and lowering the mixer output...Also conversely, lowering the gain of the xover and raising the gain of the mixer to see if either works...I find that with my cheapie Behringer DJ mixers that the more gain on the master faders the more noise @ the speakers...

Try and make sure that you set the channel faders @ unity and use the input gain controls to set the channel levels using the PFL on the meters to get a good strong signal on each channel... that is the largest noise generator in the system...

Gadget

BruPri

Gadget, is your recommendation for the Mackies or also applicable to the EVOi?
From what I got from the info I've read, is that on the PX, the only place to change gain is the switch on the back.
Since I don't use the Setup Wizard as my speakers have no volume adj. or clip lights, nor do I use AFS.
The only function I use is is the Auto EQ which I access directly.

Two questions, what should the correlation be between the Input and Output meters on the PX, and is that adjustable?
Right now my gain structure is aligned between my board output and the Input meters, the Output meters however are a bit lower. i.e., if I'm averaging around -0dB on the input, the Output indicates -12dB

Even though my system is full range, is there direct access to the x-over level main out internally to play with the gain?

Thanks much!
Bruce

Gadget

rom what I got from the info I've read, is that on the PX, the only place to change gain is the switch on the back.

Nope, just went through that with my Karaoke rig and needed to raise the gains in the xover. Press the xover button repeatedly to access the different xover functions...one screen HPF >slope> and gain one LPf >slope etc for lows and highs have HPF> slope> and gain NO LPF use the xover button to select the xover point to then next> <prev to move to the parameter you want to affect, and I believe encoder toggles values.

what should the correlation be between the Input and Output meters on the PX, and is that adjustable?
Right now my gain structure is aligned between my board output and the Input meters, the Output meters however are a bit lower. i.e., if I'm averaging around -0dB on the input, the Output indicates -12dB

You have only got the ability to choose +4 or -10 and the xover gain setting and slope type If you want to run a fullrange top run them out of the hi outs and you'll get 3 PEq's but no LPF but thats no biggie, let the natural limit of the speakers rule the LPF limit...

Even though my system is full range, is there direct access to the x-over level main out internally to play with the gain?

Yes... as above, as I recall the screen is like...

HPF(hz) LR24 gain( db)

That's from memory and the PX isn't here right now but it's something like that...

As I said it works not only with the SRM's but any speaker, powered /un-powered/ with gain control or without...

G

BruPri

"Press the xover button repeatedly to access the different xover functions."
I don't seem to have a x-over button...

Gadget

Sorry.. I do so many DRPA, PA+ and 260 tunings it's difficult top remember the scheme of the PX...which is very different...and doing duty in a club I visit only once a week...It's the [setup] button on the PX. That will get you into the "filter editor" as they call it in the PX...same principle though find the filter section, it will have a "gain" setting in the lower right corner of the display...

Keep us informed on youe progress...

G

BruPri

Great, found that and I was able to then adjust each preset to match the output with input.

The one thing that is puzzling me is the way my now defunct JBL EVOiNET controller worked compared to the DRPX.
With the JBL, I just set the mic up 2/3 way into the listening area and pressed one button. With the mic on the stand, in the middle of the room and aimed between the speakers, I got consistently good results right off the bat. With the DRPX, the whole bit about the mic 1/8th" from the floor, not in the center of the room etc...and wildly unpredictable results to boot is making be rethink how to really best set up my system quickly using the DRPX, without alot of mucking around. I did create and store some Flat and C-curves in a controlled environment using the new indoor method for a starting point with good results.

Gadget

And that is the best thing to do in my opinion unless you want to start taking room measurements at various locations and averaging them, and comparing them to the flat preset ... the New algorithm in the PA+ is much better at room mode and cancellation rejection but the PA and PX still are plagued by those things. There is very little useful in RTA based room measurement anyway...
G

Dra

MD , Bru

Hiss problem gone?

DRA

BruPri

Hmmm, not gone completely, but after following the tip about the crossover output adjustment, the DRPX is at least not adding unnecessary gain and the residual noise is kept to a minimum.
I wish I knew what role as far as gain, the EVOiNet controller did to the signal, when in use between the mixer and speakers....dead quiet, perhaps some kind of internal noise gate threshold or simply it attenuated and matched the signal some how. When the speakers come straight off the mixer, at a distance of 1 meter, you can hear that distant hiss. Before the gain adjustment to the DRPX, it was really noticeable, now it's on par with direct speaker connection.

Thanks for checking!

Bruce

Dra

Do a comparative volume check between the different hook ups with the mixer and speaker and the same settings. Do you have a db meter? I bet that the extra hiss is a symptom of extra volume (speaker knob at the same position). Have you tried turning down the speaker until the hiss goes away?

DRA

Gadget

No controls of any kind on the speaker...

I'm betting it's in the pre-emphasis circuit..

Dra

Rub it in, why don't ya.

BruPri

Dra wrote:

Rub it in, why don't ya.

Ouch! Don't feel too bad...I own the speakers and they haven't mentioned anything to me about their having a "Pre-emphasis circuit"