Suggestions for JBL Control and MRX Series

DBJunkie

Please help me with the following:

1) Crossover Settings/Sugestions including Filter Types (I'm concerned about overlap and cancelling frequencies)

2) Limiter settings

3) How should I eliminate feedback from a turntable? Use a Notch Filter or AFS and the best way to do so?

4) Any additional tips


The Equipment List:

Denon DNX 900 DJ Mixer

BBE 882 Sonic Maximizer (Used primarily to control bass heavy songs and/or mixes. It's barely activated)

DBX Driverack 260

Crown CDi 1000 (Stereo 70v Mode) Powering ( 6 ) JBL Control 29AV (100w tap activated) CH 1&2

Crown CDi 4000 (Bridged Mono Mode) Powering ( 2 ) MRX 518S and ( 1 ) JBL Control SB210 CH 3&4

AMTC Mixer Amp (130W Continuous in Mono 70v Mode) Powering ( 12 ) JBL Control 24CT Micro (8w tap activated) CH 5&6


Miscellaneous Equipment:

( 2 ) CDJ-1000MK3s

( 2 ) Technics 1210s

( 3 ) Furman Power Conditioners

Ortofon Nightclub Stylus

Alesis iMultiMix 9R 9 Mixer

SIRIUS Satellite Radio Receiver


This set up is in a restaurant/lounge with a DJ setup. It a long rectangular-shaped room with a lot of reverberations.

I'm very pleased with the sound so far but I would like to get it perfect. I can't do anything about the crappy AMTC amp powering the Control 24CTs, it was previously installed with a SIRIUS Satellite Radio Package with the Control 24s.

I set the gain structure following Gadget's tutorial and adapting as best as I can using DJ equipment. All of the amps and the DJ mixer clip at the same time and I backed the amps one click off of that point. (Thanks Gadget!!!)

I looked at all the manuals to get the speakers frequency ranges and recommended crossover points and tried to make a happy median between them.

Right now I have the subs high-passed at 45 Hz with a low-pass of 80Hz, the Control 29s highpassed at 80 Hz, and the Control 24CTs highpassed at 120 Hz. All the above using BS24 Filters all around.

I am also using 30% Sub-Harmonic Synth with default frequency boost settings (50% and 50%).

I can't remember the limiter setting off hand but it I set them using tutorial I found DBX forum.

I also used Graphic EQ for the RTA Wizard and I am not using Post EQ nor compression.

I have Driveware installed and working.


I'm confused with crossover filter types, ie BS, BS, LR. I do not know which ones to use.


If I forgot to mention any critical info, let me know. Thanks in advance

-David

Fanman20

Hi

Re your last question:-

I'm confused with crossover filter types, ie BS, BS, LR. I do not know which ones to use.

try this post by G

http://www.dbxpro.com/forum/viewtopic.php?t=1204

Third question was:-

How should I eliminate feedback from a turntable? Use a Notch Filter or AFS and the best way to do so?

What freq are feeding back??
suspect they are low freqs

Suspect most of your feed back could be \"mechanical\"
vibrations from floor - table - turntable case - turntable - stylus.

Try foam under turntable first;

Have you tried turning off the Sub-Harmonic Synth?

AFS Anti Feed back suppressor in your DR260

http://www.dbxpro.com/forum/viewtopic.php?t=1384
This pertains to Live sound mostly...

Lots of posts on AFS on how to set it up (use the search on blue bar)



Fanman 20

DBJunkie

Thanks Fanman,

Yes it is low frequencies causing the feedback. I don't have access to the place today so I couldn't tell you the exact frequency.

It only happens if the volume is at or close to max. I have tried turning sub-harmonic synthesis off but it doesn't help that much and I need to have i on or else the system sounds a little thin.

If I turn the gains on the mixer to the maximum volume without clipping (including the channel the turntable is on), you will hear a low-end rumble gradually get louder until you turn the gains back down. This is while there isn't a record playing. If you do it with a record playing, you get low-end ringing over the bassline.

I think this is caused by the close proximity to a MRX518S subwoofer. I can try playing around with foam underneath but the DJ console is still being worked on by our carpenters.

When I work on music production in Apple Logic, I can spike the EQ with a narrow Q to find ringing in the lower frequencies of my bassline, and then from there I'll cut that frequency a little to eliminate it with a very narrow Q.

Does a notch filer work the same way?

Thanks for your help Fanman.

Gadget

Ok, dude, we need a lot more info here.. I know we've touched on this before but I need more to go on here... First off a diagram... even a hand drawn one ... of where things are...ALL speakers, and your DJ booth...dimensions...H-W-L (for delay settings if NOTHING else) Some pictures here would REALLY help a lot... Now, you can send them direct to me tzone42@paulbunyan.net or you can post them @ photobucket...you'll need an account but it's free and simple I can see some changes..and you'll want to loose the BBE..

For starters I'd move the crossovers on the control 29's to 180-200 hz LR24.. they will require way less power and have a better midrange...set the xover type @ LR24, cross the 210's at 95 hz LR24 and then 180hz LR24, or just below ( a few hz spread to minimize crossover region interaction)If the 210 isn't in a corner.. it would be WAAAYYY better there.. since there is only 1.. Hopefully the MRX's aren't right next to the DJ station.. and are also together somewhere...

Has the arm on the turntable been -0- ed.. and if so what mass is the arm set to? If you were going to suspend the TT gel packs would work much better..

Get that stuff for us ok?
G
Your welcome..

DBJunkie

Gadget, your the MAN!

I'll post pictures and draw a diagram in Adobe Illustrator showing you placement of the speakers, I'm a graphic designer by day, DJ by night. Give me a day to put it together.

Unfortunately, I can't do anything about some cockamamie installation choices that were made by 2 different incompetent installers but I'm sure we can make it work. It sounds pretty good now since I added a DR 260, don't get me wrong.

Thanks a million! Stay tuned....

DBJunkie

Hey Guys,

I put together a diagram and some pre-existing photos of the place. The diagram's main room dimensions and speakers/speaker placement are pretty close to scale but not exact.

I won't be able to get more specific dimensions/pictures without going there. I wouldn't be able to get there until the weekend.

Download my PDF diagram
http://www.blueforestenergy.com/dbjunki ... layout.pdf


Link to PhotoBucket Album
http://s119.photobucket.com/albums/o151 ... X%20Forum/

Thanks!

-David

Gadget

Well... I've been puzzling over this for a bit now.. man... tough room...Your actually spinning vinyl...wow. I have a few thousand... but they have mostly been played once and recorded and placed in Mobile Fidelity Sound Labs sleeves and stored..also thousands of 45's a THorens, a couple of Dual's and a few other esoteric turntables.

Ok..some changes then due to the room...that one JBL sub is nearly useless in a stand alone frequency band...I don't think it should be depended on for much...Lets run the MRX subs up to 120 hz, run the run the control subs from 50- 150 hz and the 29's from 150 hz up these then will be primary coverage..the 24 will be fills and used at a significantly lower volume than the others...It'll kinda sux in the potties but oh well...otherwise the interaction will cause phase shifts and cancellations in certain areas...because of the uni-directional nature of lower frequencies I'd move the 24's to 200ish..hz for zone coverage only. But wait... you have the MRX and SB210's on one amp? in bridged mode...hmmmm so they have to cover the same frequency range? Need more info here...

Also what is the turntable setup info... no cover right? sitting right on those plywood boxes on that table /stand unit?
G

DBJunkie

Hey Gadget,

First, I would like to thank you for helping me.

Yeah, I still like vinyl. With the digital download era in full swing, I find that I get a lot of poorly mastered songs when I download music. So bad I have to remove ridiculous low frequencies way under 30hz before I use it. I always download a .wav file, I don't care for compressed music. The turntables will be used about 25% of the time. I back up my vinyl on an external hard drive and burn them to CD. I want the turntables working without feedback for those times that I have newly purchased music and didn't get a chance to record them into my computer and burn a CD. I also have the turntables for Serato and Traktor users but feedback isn't an issue then.

Yes, The (2) MRX subs and (1) Control SB210 are all on the CDi 4000 in Bridged Mono Mode. The original installers had 2 MRXs on the left channel and the Control SB210 on the right channel (in stereo) on the CDi 1000 so I flip flopped the amps. I felt like they were extremely underpowered the way they left them.

I have been using the Control 24s as fills to control hot spots in between the Control 29s. I also plan on pointing the
Control 29s a little bit further upward to control hot spots.

The turntables will not have the original covers on. We will have a custom cover for the whole console made when it's complete. They fit snug inside the recesses in the table top and I have rack rails for the mixer and power conditioner to be placed in between the turntables. I haven't thoroughly adjusted the turntables because the console is mid-construction.

Right now, the dead spot (for bass) is between the MRX closest to the DJ area and the Control SB210. I've been able to improve the situation my changing my RTA position and height but just an FYI. The rest of the room has fairly even bass distribution except for the obvious like in corners.

What HPF did you want to try the MRXs? I saw you put 120hz for the LPF. Are all your specs LR24 type filters?

Any suggestions for RTA mic positions?

You mentioned delay before, is it necessary?

Shoot any questions, I have answers... I hope

Gadget

Yes, all filters above the sub Hipass are LR24

What happens with the bass when you defeat the control 210?

If you aim those 29's higher you'll start having reflections off those oposite walls and facets... you'd be better off to get the sound on the people wouldn't you?


MRX hipass..45-50hz BW18

Mic position... well I'd take one of the control 29's down and do a \"new indoor method\" RTA as described in the FAQ section, or better yet outdoor.. and then get a flat preset as described using primarily the PEQ's if possible... Store that and it will probably work best in that room...Then you can put the mic in various places in the room to compare with what is being done to the sound by the room..

Unfortunately .. without individual control of each speaker, and individual DSP of each...you will not be able to apply global changes to control a specific room problem...

To bad you can't fly all the subs in the center of the room... that would be an amazing difference...

Yes,I would most likely have done things very differently...but that's a moot point now isn't it...

G

DBJunkie

Hey Gadget,

I finally got a quick chance to get in there and try your recommended crossover suggestions. The mid range frequencies sounded a little overly emphasized and unatural.

Would a new RTA setting help?

I'm going to have a full day to mess around with it on Friday, I was only there for 30 minutes.

Dra

Sounds like you \"RTA\"d the room. If you did, what changes did you make after you were through? Or did you leave everything the way that it was?

DRA

DBJunkie

Hi Dra,

I did nothing except change the crossover frequencies because I had limited time to mess around. The cross over changes were pretty drastic compared to what I had.

I did RTA the room a few weeks ago.

I will be there the whole day on Friday.

Thanks, and happy Thanksgiving.

Gadget

What part of the mids.... If were talking about the lo mids I'm not surprised since the greatest efficiency of the subs is in the 110 hz and up, a quick perusal of the RTA with the mic attached will show you visually what frequencies are hyped. There should be NO difference in the ceiling speakers or control 29's by raising the xover point.. Id put a PEQ @ 200 hz with a Q of 1.5 and slowly cut the bell till the offending frequencies are addressed. You can raise and lower the center frequency, and vary the width of the filter and zero in on the exact problem without affecting much of the other spectrum in this fashion. The same goes for enhancement.. there are also shelves for low and high tailoring...

Try aiming the mic at the floor, only a fraction of an inch above it...try the center of the room and equidistant on both sides and go for an average. this will eliminated any reflections to the measurement mic...that will skew the results.


G

DBJunkie

Hey Gadget,

Yes it's the low-mids. Everything sounds extremely punchy.

When you said PEQ did you mean post-EQ or Parametric EQ?

And when you mentioned pointing the mic at the ground were you referring for RTA wizard use or to find the offensive frequencies?

I looked at the spectrum analyzer before changing the crossover to your settings and the lows were jacked up pretty high even though it didn't sound even remotely like that. Could of been the position of the mic but it was pretty close to the original RTA location. I wasn't sure how accurate the spectrum analyzer is.

Gadget

The RTA is very accurate... BUT it only takes into consideration volume based frequency info...

This is the \"PZM\" method that eliminates reflections

This is the ceiling method, and I continually monitor my setup with this using the RTA live \"MIC\" in the RTA on the GUI...(you can select direct or mic input and compare the two also)

The 1st pic is the new indoor method and it's what I meant when I said take one down (control 29) and get a flat preset fopr them... here is the article:
http://www.dbxpro.com/forum/viewtopic.php?t=953

Here I detail the traps and problems with the auto EQ process..:
http://www.dbxpro.com/forum/viewtopic.php?t=949
and it will explain WHY you had the bass region hump you did...
http://www.dbxpro.com/forum/viewtopic.php?t=1058
This details the success I have had in my particular room with the Auto EQ.

If you incorporate all this I think you will see how to get your system singing pretty...

G

DBJunkie

Sorry for the ridiculous delay...

Gadget, thanks for your assistance and thank you to Dra as well.

I used Gadget's crossover recommendations and worked from there slightly modifying them and got excellent results.

I have the MRXs and the Control Sub at 45-120, the Control 29s at 150 and the Control 24s at 180 using the recommended filters.

I played around with different RTA methods and saved all the presets and voted on the best one playing lots of music through it, hence my delayed response.

I found moving one MRX sub firing towards the entrance from the opposite side of the room (next to the bathrooms) really enhanced the bass response. It was pretty even throughout the room. The owner wasn't thrilled on keeping it there but I'm working on it.

I got rid of the turntable rumble by putting high-density foam under the turntables. They were flush with the console surface but are half sunken now that there is foam under them.

Thanks again guys.

Gadget

Cool..
So whats your opinion of the control speakers? I have a church guy I'm working with and it seems the only \"name brand\" the committee is will to even recognize is JBL...Sad.. there's so much more out there...Why have you omitted the 120-150hz frequencies?

Anyway Let me know what you think then of the 24, and also the 29's.. and I suppose the sub as well...

Glad it all worked out for you.. though I would never have suspected that high density foam would work in that application...thanks for getting back to us..
G

DBJunkie

Gadget,

As far as omitting the 120-150hz frequencies..

I wanted to avoid any canceling of frequencies. I figured since the filter slopes still intersect each other when viewing them with Driveware software that it would prevent too much overlap.

Should they low and high pass filters be exactly on the same frequencies? I tried with a more narrow gap also. Feel free to correct me, that's why I'm here.

As far as the Control 24s go..

Although they are hooked up to a crappy 70v mixer/amp they sound pretty good. It's hard for me to tell because they are in a highly reverberant room but I've listened to them with the Control 29s and all the subs muted and they sound pretty good. The Control 24s are running on the Control 29s RTA EQ also so keep that in mind.

Do you think I should RTA with both the Control 24s and 29s on? I did with just the subs and control 29s since they are played louder.

The Control Sub is decent for a small bar setup etc. etc. It's more punchy then deep. Takes a good amount of power to get the most out of it.

The MRXs are pretty good but I would of liked to go for something else in a permanent install.

The owner originally wanted a smaller system but after hearing and feeling the difference of good and bad systems adjusted his expectations.

Let me know what you think I should do about the crossover settings, the owner keeps asking me.. \"Dave, are we done yet???\" I'm never happy and this is the hardest room I've ever had to work with.

Thanks,

David

Gadget

Well, David...
Yes, the patterns interact but I have to tell you that they most likely will be well below audibility... A slope of 24db/octave would have the signals about 4 db down at the actual xover point near as I can tell...with a 3db signal almost 50% down from the crossover point, and 9 db down over all.. the slope actually starts well above and below the point assigned as the crossover... nearly 70-400hz in scope. I'd play a sweep (as in the one available from the Binkster CD and see how the sound level falls off between those points...It may be fine.. my guess is you have a weak area there...

Gadget

Dennis

David, you said

\"I found moving one MRX sub firing towards the entrance from the opposite side of the room (next to the bathrooms) really enhanced the bass response. It was pretty even throughout the room. The owner wasn't thrilled on keeping it there but I'm working on it.\"

I don't know if any of this was covered in any of the articles that were posted (because I didn't read all of them) but it sounds like the subs,in their original positions, were not correctly time aligned to the rest of the system. Since lower frequencies are omni directional, re-aiming the speaker cabinet will have little effect. When you moved the cabinet, you accidently improved the time alignment. It is possible that you could return the sub cabinet to its original location and time align with the delay function of your DR260. The shape of the room and the layout of the sound system will make the job a little difficult and will require a program such as SMAART and someone who is familiar with more than its RTA function.

Dennis