understanding components

[lithium 358]

I was thinking about doing 2 of these in each door http://www.parts-express.com/pe/showdetl.cfm?partnumber=297-122 then putting 1 of these in each A-pillar since I already have holes up there for them. http://www.parts-express.com/pe/showdetl.cfm?partnumber=277-084 I would be using a Pioneer 880prs and more than likely an rf 360.3 everything will be off-axis

 

start with establishing your goals. blindly picking random speakers is pointless. 

[OuTLaWeD 110]

I was thinking about doing 2 of these in each door http://www.parts-express.com/pe/showdetl.cfm?partnumber=297-122 then putting 1 of these in each A-pillar since I already have holes up there for them. http://www.parts-express.com/pe/showdetl.cfm?partnumber=277-084 I would be using a Pioneer 880prs and more than likely an rf 360.3 everything will be off-axis

 

start with establishing your goals. blindly picking random speakers is pointless. 

I want something that will play smooth and have smooth transition from the mid to tweet. I also need something that will keep up with my pair of 18's full tilt on roughly 5k or so. what I'm now planning is getting the 2 pairs of the mids and putting those in the doors (2 in each door) then putting the tweets in the A-pillars facing across the windshield. I'll probably cross the mids over at 80hz@12db to start and the tweets at around 2khz@18db. I think that should get me going anyways

[Impious 1,476]

What's the purpose behind the dual mids? 

 

You are still limited on how high you can run the mids based on the center-to-center distances between the two speakers.  So running multiple smaller speakers isn't necessarily going to be better (as far as LPF crossover point) than a single larger speakers, depending on the circumstances.

[OuTLaWeD 110]

What's the purpose behind the dual mids? 

 

You are still limited on how high you can run the mids based on the center-to-center distances between the two speakers.  So running multiple smaller speakers isn't necessarily going to be better (as far as LPF crossover point) than a single larger speakers, depending on the circumstances.

my thought with the 2 mids were to keep beaming to a minimum and get me the volume I'll need to keep up with the sub stage. like I said before, I have never put much thought into my front stage. I have always just thrown something in there, tuned it the best I could and let it go. I want something this time that I actually put a good bit of thought into

[Impious 1,476]

Beaming is only an issue if you need to mate with a high playing tweeter....which goes back to my prior point of finding a mid first then selecting a tweeter that can low enough to mate with the mid.  And again, center-to-center distance plays a role when using multiple speakers in the same range (also ideally between two speakers at the crossover point, but another story for another day), so it's not only about diameter.

 

Really two 5.25's aren't going to have significantly more area than a 7", and the 7" is probably going to have parameters that lend itself more towards better midbass performance without a ported enclosure.

[OuTLaWeD 110]

alright I think I'm starting to understand this a little better.  also, if I use an 8in mid where roughly would it start to beam since it will be lower than a 6.5in? how do you do the math behind that also?

[ssh 924]

Beaming will occur when the frequency wavelength is less than or equal to the diameter of the cone.

 

Make sure your units are the same:

 

wavelength(cm) = 34029 (cm) / frequency (hz), so:

Beaming Frequency (hz) = 34029 (cm) / diameter from Sd in cm

Sd being T/S value for surface area of cone.

 

IE:

Exodus ex-anarchy driver: Sd: 131cm^2, area circle = pi*radius^2, so squareroot(131/pi)=radius=6.457, radius*2=diameter, 6.457*2=12.9cm

34029 / 12.9 = 2638hz

So this driver, or any other driver with the Sd in the same realm would start to beam around 2638hz.

 

If you know the cone diameter in inches then you could also do 13397 / diameter(in).

 

Ultimately you'd want to be using measurements for the cone, and not the overall diameter of the driver.

IE: 

Exodus ex-anarchy driver cone diameter = ~5", and OD is ~7" 13397/5=2679hz, 13397/7=1913hz That's a significant difference.

 

-------------------------------------------------------------------

 

So a rudimentary answer to 8" mid and 6.5" mid would be:

8" OD, so let's say the cone diameter is 7", 13397/7 = 1913hz

6.5" OD, ~5.5", 13397/5.5 = 2435hz

Edited February 20, 2013 by stefanhinote

[ricksi30 923]

Nice explanation! Thanks for posting Stefan.

[OuTLaWeD 110]

so using the example above where the 8in starts to beam at 1.9k and the 6.5's at 2.4k would those numbers stay the same using multiple drivers of the same size? ie: using two 6.5in drivers in each door will still start to beam at 2.4k. thanks for the help guys

[ssh 924]

so using the example above where the 8in starts to beam at 1.9k and the 6.5's at 2.4k would those numbers stay the same using multiple drivers of the same size? ie: using two 6.5in drivers in each door will still start to beam at 2.4k. thanks for the help guys

Well those numbers are going to vary a bit because the cone size on one 6.5 driver is likely different than another 6.5 driver (ie: different brands, models, etc), but whatever point one beams at, the other will too.

 

Honestly it doesn't make ANY sense to use multiple drivers to avoid beaming issues, and then turn around, and create more issues from the use of multiple drivers. Reread Impious' posts.

 

I think you would be surprised how much midbass output one can get out of 7-8" OD driver in a proper install. The only issue is expecting it to keep up with your subs at full tilt. In that case you need to prioritize what exactly you want, and what exactly your willing to compromise for it.

[Notorious97200 339]

tuned in. I like that.

[///M5 2,833]

Before even starting with a mid you need to determine potential mounting locations.  EVERYTHING is a compromise, no need to add more by deciding things without the background.

 

Oh, and give up on keeping up with an 18".  No way, no how that is going to happen in the midbass realm.  Going to have a gap, no way around that if you are comparing to full tilt levels.  Of course if you are like most other bassheads "keeping up" means hearing the words.  In that case, it's easy.

[Impious 1,476]

so using the example above where the 8in starts to beam at 1.9k and the 6.5's at 2.4k would those numbers stay the same using multiple drivers of the same size? ie: using two 6.5in drivers in each door will still start to beam at 2.4k. thanks for the help guys

It's like you didn't even read my posts

 

When using multiple drivers the center-to-center distance should ideally be no more than one wavelength of the highest frequency played by the drivers.  Or, to put it another way, the drivers should ideally be crossed at a frequency with a wavelength no more than their center-to-center distance of the drivers.  Since the center-to-center distance is going to include the diameter of the basket but the beaming frequency does not, then two drivers will actually require a lower crossover frequency than a single driver of the same "stated" diameter.  I.E. a 7" driver might only have a ~6" cone, but the center-to-center distance between two 7" drivers would be ~7" assuming they were placed directly next to each other with baskets touching.  If they were spaced 1" apart then the center-to-center distance increases to 8" and they would require an even lower crossover point (ideally).

 

These rules aren't hard-n-fast and there is some leeway, but they are good starting points to figure out approximately where things might start to go haywire.

[OuTLaWeD 110]

so using the example above where the 8in starts to beam at 1.9k and the 6.5's at 2.4k would those numbers stay the same using multiple drivers of the same size? ie: using two 6.5in drivers in each door will still start to beam at 2.4k. thanks for the help guys

It's like you didn't even read my posts

 

When using multiple drivers the center-to-center distance should ideally be no more than one wavelength of the highest frequency played by the drivers.  Or, to put it another way, the drivers should ideally be crossed at a frequency with a wavelength no more than their center-to-center distance of the drivers.  Since the center-to-center distance is going to include the diameter of the basket but the beaming frequency does not, then two drivers will actually require a lower crossover frequency than a single driver of the same "stated" diameter.  I.E. a 7" driver might only have a ~6" cone, but the center-to-center distance between two 7" drivers would be ~7" assuming they were placed directly next to each other with baskets touching.  If they were spaced 1" apart then the center-to-center distance increases to 8" and they would require an even lower crossover point (ideally).

 

These rules aren't hard-n-fast and there is some leeway, but they are good starting points to figure out approximately where things might start to go haywire.

thank you for clarifying that impious. I really am dumb whenit comes to almost anything front stage.

[OuTLaWeD 110]

another question......why would a guy want to use PA mids in place of regular mid bass/mid range drivers?

[Impious 1,476]

Some gross generalizations here but IMO there isn't a use for a 6.5" pro audio driver in car audio except, for example, as a midrange in a high efficiency 3-way such as with horns.

 

For 8" they generally have a little more snap to them in the upper midbass with the trade-off being significantly reduced low frequency extension/output.  They also generally play a little higher than a normal home/car audio 8" driver since in pro audio an 8" is really more of a midrange...so the additional high frequency extension may be needed/desired.  Well designed PA drivers still offer low distortion performance, so that could be a consideration. 

 

If you are talking about the guys who run a shit ton of PA speakers with bullet tweeters, then it's simply because they are 'tards. 

[handman84 60]

Lol, none of these threads are giving me confidence in creating a decent 2 way active front stage...what a learning curve!

[///M5 2,833]

This isn't one in particular you should read for your goals...

[OuTLaWeD 110]

Some gross generalizations here but IMO there isn't a use for a 6.5" pro audio driver in car audio except, for example, as a midrange in a high efficiency 3-way such as with horns.

 

For 8" they generally have a little more snap to them in the upper midbass with the trade-off being significantly reduced low frequency extension/output.  They also generally play a little higher than a normal home/car audio 8" driver since in pro audio an 8" is really more of a midrange...so the additional high frequency extension may be needed/desired.  Well designed PA drivers still offer low distortion performance, so that could be a consideration. 

 

If you are talking about the guys who run a shit ton of PA speakers with bullet tweeters, then it's simply because they are 'tards. 

thinking about my application i thin an 8in. PA  would probably better suit my needs. having a louder system i wont be able to hear the lower extension of the mid bass anyway.having a more efficient driver that can usually handle more power and play a little higher in the spectrum more efficient as well sounds just right.

[KyleBrown 121]

Good thread here. Passive isn't always so bad. My three way comps did decent. I should have gone higher with my mids to imagine better. 

 

 

Lots of good info in here though. 

[eggyhustles 33]

Lots of good info in here

 

I will say this..tuning a 3 way was more difficult than 4 years of college, lol. 

 

I had the midranges in the kicks off for almost 2 months since it was hair pulling getting them to mate with the horns and midbass. Sounds good now..well to my ears. 

[lithium 358]

Lots of good info in here

 

I will say this..tuning a 3 way was more difficult than 4 years of college, lol. 

 

I had the midranges in the kicks off for almost 2 months since it was hair pulling getting them to mate with the horns and midbass. Sounds good now..well to my ears. 

4 years of physics helped in my case haha

[ramteid 17]

So, what does beaming sound like?

[Impious 1,476]

I don't think it's possible to describe beaming in subjective "sounds like" terms.  It's also going to "sound" different depending on the severity of the beaming (i.e. how far off-axis you are from the speaker) and the frequency range over which it's occurring (midrange, treble, etc).  Every speaker will begin beaming at some point, from subwoofers to tweeters. 

 

Beaming is basically a reduction in the amplitude of high frequency off-axis response of the speaker compared to the on-axis frequency response.  If you were walking around a single speaker playing full range you would notice the high frequencies start to taper off as you walked from on-axis to off-axis.  The higher frequencies wouldn't be as loud off-axis compared to on-axis.  Where the driver begins to beam depends on the diameter of the speaker.  A larger speaker will begin to beam lower in frequency than a smaller speaker.

 

Beaming can create several potential problems....undesirable frequency response at the listening position from the direct sound from the speaker due to the "dip" or "hole" created by the beaming, uneven frequency response between the left-side and right-side speakers since you generally don't sit at the same degrees off-axis from both speakers, and larger deviations in direct vs reflected sound at the listening position.  All of this cause issues with frequency response and imaging causing things to simply sound wrong.  You might not be able to point a finger at it and say "Ah ha, that sounds like beaming!".  But if the problem is in the midrange (for example) then the midrange frequencies might sound wrong or off compared to the rest of the bandwidth and the imaging will be skewed or scattered, for example.

 

FWIW, I really like Andy Wehmeyer's philosophy behind designing a car audio system.  He didn't invent the idea, but he's one of the bigger proponents and has spent a significant amount of time explaining it from an acoustics stand point.  Pretty simple really.  Cross all of the drivers within their piston range to avoid beaming, wave guide the tweeter (since you can't avoid beaming) to create a smooth on- to off-axis transistion, and don't mount the driver's right next to reflective surfaces (i.e. avoid A-pillar or top of the dash installations).  Certainly it's possible to break the rules and create a system that sounds subjectively good without taking all of this advice....but it provides a good foundation to start from if you keep these things in mind.

[ramteid 17]

Oh, alright i understand it a little better now. My speakers, on certain songs when the volume is up, tend to be fine to a point and then part of the frequency range just drops off significantly, although, at much lower volumes it does not seem to happen. Not sure what would cause that? im also not using compnents.