22 replies to this topic

[shizzle]

Heya,

I have the following setup.
15" JBL Gti in the boot of my car, in IB, 6.5" Oz Audio Matrix Elites in kickpanels up front, in around 12L enclosures, and some USD waveguides under the dash.

My biggest problem with systems is tuning them, and just need a little guidance.
The USD waveguides can be crossed as low as 700hz (I am running them passive atm, just to get a feel for them, and this is the x-over pint I am unsing). I can increase this by running them active though.
My queston is what are some guidelines for the x-over points? Having never run horns, I am batteling a bit with getting them right.

Currently I have the USD's at 700hz (straight through on my deck), the 6.5" Oz@63Hz-1000Hz, and the 15"@63Hz. They are on a 12db slope.

Any suggestions wold be welcome, I still have some tweaks to do on the guides, but am just looking for some experienced advice.

Thanks in advance.

[~Spyne~]

every car is different, and every install is different...theres no way we can tell you what is, or is not, going to sound right/work in your situation.
just because the waveguides can play down to 700hz, doesnt mean necessarily that you should be doing that....my tweeters can play down to 1.5khz, but i have them crossed at 3.2khz because that's what sounds right to me

it's really a case of trial and error...if you cant tell the difference immediately, leave them on one setting for a couple of days, then change the crossover and listen for another couple of days...

[HEKYEH]

This is something I was thinking about posting/asking last night too...But as Adam says, every car and every install is different. There are soooooo many things to factor in, and u could have exactly the same gear but in 2 different cars, and x-over settings could be very different.

In my situation I have gear that can play the following:

Sub: 20-200Hz
Mids: 40-500Hz
Midrange: 140-10Khz
Tweeter: 1.8KHz - 20KHz

So where the heck do I set my xovers???

It's just something u have to play around with...and there is no easy answer on this one...Lots of trial and error...

[muzzy66]

As a very rough guide, i'd try something like:

Tweeter: 1.6khz @ 24dB
Midbass: 80hz @ 24dB, 1.6khz @ 24dB
Subwoofer: 80hz @ 24dB

Give that try and see how it goes. If the tweeters seem a little harsh, you may have to lift the tweeter-mid crossover to 2khz.

The mids will do 80hz - 1.6khz no problems off axis ... probably even 2.5khz on axis. It really all depends on the subs ability to play clean to 80hz. A lot of them don't like to.

[Damo95]

you do realize muzzy that he is talking about horns, not normal tweeters?

[Tiger]

USD Waveguides have been known to crossover as low as 600Hz.... They play a very broad spectrum of frequencies (I had a pair, although I never got to fitting them.) And they are extremely efficient. Anything over 50WRMS into them, you'll take your head clean off with them!

I'd cross the Horns over at about 1.2kHz, the mids down to say 40Hz (Oz Audio are an awesome midbass.. they'll handle get low enough) and let the sub handle the rest


My 2 cents

[HEKYEH]

Does anyone overlap their xover points?

i.e. Sub from 20-80Hz, then midbass from 40-280Hz, midrange from 200-3.2Khz, tweeter from 2.5KHz-20KHz...and use a 24db slope...

I've been using 24db slopes and not overlapping the xover points.

Any thoughts/ideas on this? Benefits/disadvantages? One that I can think of would be in the vocal range...having 2 different speakers playing vocals might sound strange... Or I could be totally wrong!

shizzle - Sorry if I've hijacked the thread, but hoping the answer might also be useful for u.

[Tiger]

I would think that overlapping would result in either frequency clashes or cancellation issues.
That's my opinion though

[Fury♫]

Ask yourself this:

What does a crossover do?

What information do we need to determine a cross over (ignoring our ears)?

How does a crossover effect/relate to this information?

[HEKYEH]

fury, on Jan 20 2010, 04:19 PM, said:

Ask yourself this:

What does a crossover do?

What information do we need to determine a cross over (ignoring our ears)?

How does a crossover effect/relate to this information?

My brain hurts.....

Well...a crossover splits the signal into separate frequencies so they are directed to the appropriate speaker...

Knowing the frequency response would be good....

That's where the xover points should be....


Or something like that....

But...what about when there is a midrange that will play from 140Hz to 10KHZ...and a tweeter that plays from 1.8KHz to 20KHZ...? For example

[268669♫]

Cross everything as low as possible, I'd go 600 with the horns with a steep slope, 24db or above, or if your willing to extend the mouth a bit even down to 500 with a 36db slope. The mids should play nicely down to 50hz in those sealed 12L enclosures, but i'd also give them a heavy slope above 24db, also heavy slope on the top end at same freq you cross the horns at. The sub at 50hz starting with a 12db slope and higher if it doesn't like it.

Ant

[Fury♫]

NiDeKCuS, on Jan 20 2010, 04:25 PM, said:

Knowing the frequency response would be good....

This would be INCREDIBLY useful.

How do you hope to choose xover points when you don't know the frequency response of the drivers?

And considering the OP is using horns, which very few people here would have experience with, i'd suggest grabbing some measuring tools, and measure the response.

[~Spyne~]

i use my ears...
seems to work

[muzzy66]

Even if the horns CAN go down to 600hz, there is no need. Even at 90deg off axis, a 6.5" driver should play flat to 1.2khz no problems at all. Crossing any lower will provide minimal benefit imo, and if anything will just increase distortion on the horns. If they can HANDLE 600hz, then they will LOVE 1.2khz.

Same deal with the mids - the OZ Audio do tend to play pretty low, but my modelling suggests that in 12L sealed, at 40hz, they will be at -4.5dB even after cabin gain. For best results / integration you want to keep the gap within about 1.5dB - this suggests an optimal crossover point at 90hz-100hz. You can probably get away with 80hz (-2dB) but only if the sub can play that high...if the sub is 2dB down at 80hz as well, then your going to have integration difficulties...in which case i'd suggest a different midbass or different sub.

Not only will crossing at 40hz likely give significant gap in response, it'll also likely increase distortion dramatically throughout the midrange - especially at high volumes. Keeping it at 80hz should reduce non-linear distortion dramtically, leaving you with a nice clean midrange.

I'd really suggest going with 1.2khz on the tweeters and 80hz on the mids based on the limited information available. I think one of the guys provided a response chart on the 15" JBL before, and from memory it just might handle the 80hz crossover.

[~thematt~]

First, I wouldnt cross the Oz anywhere below 100Hz. Its a 6.5" woofer, and it will struggle. Put it against some horns, and its just not going to keep up. You also have the benefit of the JBL in IB, which can be crossed over quite high (100-150Hz) quite easily without localizing (after some effort with eliminating rattles) and ridiculously low distortion.

Secondly, I'd follow Fuzz's advice and do incar measurements of the Horns. This will tell you whether you have effectively coupled the horn to the dash (and can therefore run a 600-700Hz crossover before unloading). If its not coupled, your horn will unload much high (around 1.6kHz) and any information below that will tear apart your compression driver.

Because crossing the horns is so critical on the waveguide, you'll actually find that the Compression Driver wont work 'any harder' at 800Hz (with good coupling) then it does at 1.6kHz (without coupling). You'll want the Horn crossover as low as possible, without causing increased distortion levels (which happens when the horn isnt coupled)