How to choose crossover settings for your specific system

Dr. J

To Gadget and Dra -- I totally love what you guys have done here with the forum and I am floored at the expertise you guys have as well. After reading through the posts for a total of some 15-20 hours, I have noticed you guys answer a lot of questions regarding crossover settings. I am assuming these settings are always based on what an individual's setup is. Ie. Speakers, poweramps, stereo, mono....etc. I have tried to figure out exactly what you look for when the specs are provided to you. Could you tell us what to look for when analyzing the specs of a system? I will provide all of my system specs and maybe you could help me to understand what is best for this particular system. I run a three-way stereo setup. All speakers are 8 ohms and moving in the same direction. My subs get an EP 2500 (one 18 each side - I will have another set soon), my mids get an EP 2500 (one 15 each side) & my horns get a Carver PM-175. The only thing between my board and amps is of course \"The DriveRack PA\". Here is the exact link for my subs: http://www.harbingerproaudio.com/produc ... hx118s.cfm
My mid cabinet is a hybrid JBL setup. The cabinets are JBL TR 126's BUT ALL components have been taken out and replaced with the 15 inch woofer from the MR series JBL 835. My horn drivers are \"Eminence PSD2002\". The crossovers in the top cabinets have been yanked out of there and now bi-amped. Don't laugh -- this Mutt of a system isn't bad! Here are the other links to my system: EP2500 - http://www.behringerdownload.de/EP1500_ ... _Rev.6.pdf
Carver PM-175: http://www.tom-scholz.com/Manuals/PA500.pdf pg.6
JBL tops TR 126: http://www.jblpro.com/pub/mi/tr_broch.pdf
JBL MR 835: http://www.jblproservice.com/pdf/MR800% ... /MR835.pdf
Eminence PSD 2002: http://www.eminence.com/pdf/psd2002.pdf

Any insight into all of this will hopefully make others and myself be able to make decent decisions on our own setups therefore reducing the endless questions regarding \"Crossover Settings\".
I will go with the BW18, then the LR 24 & LR 24. Right?
Thank you for your time and expertise!

Gadget

Funny

Suck up to the big wigs... sorry...I digress

You know with all the reading you did.. did you NOT see our proclivity to send everyone to the READ ME FIRST BEFORE POSTING section? In that did you not find the FAQ section mentioned a lot also? Because if you had read the FAQ section you would have seen...
http://www.dbxpro.com/forum/viewtopic.php?t=1204
Where we discuss what xover/filter type and why...
Or this ..
http://www.dbxpro.com/forum/viewtopic.php?t=1081
http://www.dbxpro.com/forum/viewtopic.php?t=1080
Where we discuss biamping a two way with a 15 and a horn... with and without bi-amp setup

You are correct .. we usually spec the BW for the sub hipass, and we usually spec LR24 filters for most things above that... but read the material so I don't have to regurgitate it again...please.

Glad you figured out the TR series were TRASH... made about a year in the JBL inventory and were discontinued...go figure... You using the same horn? Don't know that woofer and don't have time to look it up right now.. but I need the specs for it...
Gotta run
G

Dr. J

Thanks for the reply. I am using the factory horn on the TR 126 just like the picture shows but the driver I screwed on it is the eminence psd2002. It is a 8 ohm with a 1 inch throat on it. As far as the actual 15 inch woofer that JBL put in their MR series 835 -- i'm not sure. If the above links don't provide the details you need from JBL then I will look inside the cabinet and see if I can find anything helpful.

hemihem

1 x JBL 265H 380 mm (15 in) Differential Drive® woofer
Low Frequency Driver : 1 x JBL 2044G 457 mm
this is what is in the MR series

Gadget

So then it's a quasi three way design where they hipass the 265 H to limit interference in the lf extension...Thanks Hemingway..

You better have a look see J and make sure that's true.. if it is, this could pose a problem...

G

Dr. J

Gadget --- I opened the thing up and stamped right on the speaker is \"2032H\". That is it. I did a search on JBL's site that basically showed that it is a 15 inch diameter woofer, 8 ohm, 380mm. I couldn't find any other specs. As far a quasi three way ... not sure what you mean by that but the top cabinet houses the 15 along with the horn driver. There is no separate enclosure for the 15 or the horn BUT they are in fact separately wired to their own jack -- \"HI's\" & \"Mids\" which of course --each get their own poweramp.

Gadget

Ok so it's a SINGLE 15\" 500 watt woofer...hemihem was indicating that the the speaker had 2 different woofers...as in a dual 15\" with horn...and the horn has a PSD 2002...unfortunately the cabinet design is flawed as well..

As you have no doubt noticed we try and determine what the 3db down point for the woofer on the tops is, and it's size and try to find a happy medium. With your setup I think I'd start @ Part of the problem is.. as a speaker builder myself I see a lot of speakers and so I know what they will and won't do... and those subs WON\"T do 32 hz...no way! first off they'd fly apart, and second with 3\" voice coil likely stamped frame woofers they are probably 10 db down @ 40 hz IF you hipass those too low they will get HURT.. If you apply too much power you will burn the voice coils...That said,

1. Hipass the subs @ 45- 50 hz BW18 (I'd lean towards 50)The BW filter falls off rapidly and will protect the driver from overexcrusion if implemented properly.

2. Lopass the subs @ 100-120hz LR 24. We choose LR filters for a number of reasons, not the least of which is that the majority of the manufacturers use them as well. We also use similar filters when they are on the same crossover point.

3. That said, use an LR24 for the hipass to the TR NOT 125's... we also like to see a few hz spread here to limit interaction in the crossover region (the area where both drivers are producing the same frequencies...even though they are falling off rapidly at the crossover region, there is still some of the same frequencies on both sides, and when they are 1/2 wavelength apart, and out of phase they can cancel completely, or somewhat. There are other interactions that can happen also but lets just say their generally BAD.

4. Now The PSD is a 1 \" exit 1.75\" diaphragm horn driver made by P audio for Eminence (P audio is the largest speaker MFGR in the world and a side by side of the drivers there is too many similarities.). anyway, this could be crossed as low as 1700 hz, but that horn likely has a cutoff somewhere near there so I'd recommend 200 hz, for that reason, and the longevity of the diaphragm... So LR 24 @ 2000 hz

For delay and other fun stuff read the FAQ section, and Welcome.. start here..

gadget

Dr. J

G -- thanks for the info! I am glad you checked that for me because I just looked at my current crossover settings and it looks like this (BTW a buddy of mine who is into sound did this - not me):

Low 26.5 Hz - 80Hz LR 24 12.0 db
Mid 80.0 Hz- 3.15 Khz LR24 0.0db
Highs 3.00Khz LR24 0.5 db

It doesn't sound bad at all but I don't want to trash anything. I will make the changes, redo the gain structure and RTA it outside.
Do amateur sound guys always try to cross too low thinking that it will give them that extra low end? I have seen too many bands in this area where the low end is \"farting out\" & the guitar is in the horn piercing your ear half to death. Last time I checked -- my 4x12 cab didn't have a horn in it.
Thanks again G have a great weekend!

Gadget

Good grief...that's ridiculous! There is NO WAY those subs will go that low and yes... they would fart and clack and the speakers would be damaged quickly...if over driven..

The problem as I see it is most don't realize that the xtra low extension on the tops woofer affects it's ability to be a good midrange.. the more excrusion the more distortion and the poorer the midrange performance.. make sense? Let the subs do what they do best, just stay out of the region where the subs start to sound honky.. usually 100-150 hz depending on the sub.. and some.. where the tops are capable of only 200-250 hz.. like with 10\" drivers.. crossing higher and working with the PEQs to smooth the upper low end can work well. I have helped several people here that have had phenomenal success with this. I don't think in all the years I've been recommending these setups using these settings, I never had anyone that didn't feel their system sounded FAR SUPERIOR when these edicts were followed...These are not just ramblings, but time tested and proven techniques that I personally have come up with, and implemented on systems from small disco and Karaoke systems to churches and portable PA's to big concert systems and everything in between...I build and recone speakers, and instruments as well. so I know what I'm talking about...I live and breath this stuff..

What the heck was that overlap on the horn all about.. I would think that would set up all sorts of clarity killing (critical) upper midrange frequency interactions in the crossover overlap... not good!

Let me know what you think...
G

Dr. J

Thanks for the info Gadget. I will let you know when I get those changes completed. While I am on my quest in making my cheap rig sound better than anyones elses in town with a fraction of the money (thanks to you) I am going to align the delay times on my cabs. When aligning the delay times for the subs to the tops can you switch the polarity of one or the other and play some tones through it just like you suggested for the mids and the horns in article: http://www.dbxpro.com/forum/viewtopic.php?t=1080 If so -- what frequency would you use to line up the subs to the mids?
Or is it just as well to sweep through the delay until it sounds tighter? I think it would be easier to do the horns to the mids first using the inverted polarity method till cancellation occurs or diminishes (to ensure that it is dead on) then do the subs to the mids/horns.
As Always Thanks Gadget.

Gadget

At least pink noise.. but if you want better results use a tone that falls in the crossover region... 2000hz...and 120 hz or whatever frequency you landed on. this will give the greatest dip in response but it still isn't going to bowl you over. It will be a subtle difference at best.

If you switch the polarity you will be too far out...It's important to have all the cones going out with a positive pulse, and inward when hit with a negative pulse...this can be checked with a 9 volt battery.. except for the the horn driver.. make sure your paying attention to the polarity of the horn driver. The idea is to delay the DISTANCE the sound travels... therefore if the horn is deep in the speaker, you would delay the sound whatever distance it would be from the bottom of the diaphragm of the horn to the bottom of the cone on the midrange, and so on.

g

Dr. J

Hey Gadget -- I was checking polarity in my monitors (they are going the right way -- out) and I noticed the dust covers were coming loose. What is best to re-glue the covers back down before the drivers quit working?

Gadget

If you are speaking of the dome (and if so you are using the correct term) in the center of the speaker, I'd suggest any good carpenter glue, even silicone in small amounts would work. I use a special glue since I'm a speaker re-coner. use a pencil, or marker and hold the cap down and trace around it...then either remove the cap completely if it comes off easy and apply a thin layer of glue and replace it within the marks, or if the rest won't come off, us a toothpick and work the glue under as you raise the cap a little to do so.
Gagdet

Dra

A re-coner told me that \"Permatex\" (car engine gasket stuff) works pretty good. The \"black\" is what he recommended. I believe that the \"real stuff\" can be got from Parts Express or similar. Rubber cement works pretty good in a pinch.

DRA