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Old 12th May 2004, 07:04 PM   #1
niacin is offline niacin  United States
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Question Car speakers for PA?

So, I want to make a small PA system, maybe 200 watts/side, for coffeehouse use, or small outdoor parties. I want to use a four-element line array of maybe 6.5 inch speakers, so I can cross over to the tweeter higher up, and carry mostly the whole voice band in the mids.

A friend suggested that I use car speakers, first because they are rugged for the outdoor use, also because they seem to have BOTH higher efficiency and power handling, compared to your typical hi-fi speakers-- for example the Dayton 6.5 inch paper cone types you see in Parts Express.

I was looking at the 6.5 inch clear poly cone "Pyramid" brand car speaker, advertised in PE, which claim to be "classic quality". Does that really mean "S**t quality? I cant find frequency curves for these speakers anywhere.

When you find two speakers that more or less tune into the same size box, but one claims to have much higher power handling AND higher efficiency, well, something must suffer, right? Does that mean they used a super light cone, and the frequency response will be all over the place?

What gives???

please enlighten me
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Old 12th May 2004, 10:12 PM   #2
Andy G is offline Andy G  Australia
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Default its hard not to be rude....

... about power ratings on most car speakers.... HiFi speakers are usually rated at rms level (root mean square), where as car speakers often seem to be rated at destruction level... ie. you can't compare them !!!

secondly.. what sort of things are going to be going through these speakers...if it is live music it is much wiser to stick to speakers designed for that task !!! ie PA drivers !!

if its just for music from a cd player etc.. then you can probably use some quality HiFi speakers..... but steer clear of the car stuff !!!!!
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Old 13th May 2004, 02:24 AM   #3
Ap is offline Ap
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Default Re: Car speakers for PA?

Quote:
Originally posted by niacin
A friend suggested that I use car speakers, first because they are rugged for the outdoor use, also because they seem to have BOTH higher efficiency and power handling, compared to your typical hi-fi speakers-- for example the Dayton 6.5 inch paper cone types you see in Parts Express.
please enlighten me
(Hard not to sound rude, but I will be blunt.)
No way - dont do it.
Car speakers are not rugged & designed for outdoor use, they are desgined to go inside a car.
Most car sepakers are completely over-rated, as for efficiency they maybe higher due to being 4ohm.


Quote:
Originally posted by niacin
When you find two speakers that more or less tune into the same size box, but one claims to have much higher power handling AND higher efficiency, well, something must suffer, right? Does that mean they used a super light cone, and the frequency response will be all over the place?

Not necesarily, Efficiency is magnet/motor size & strength (Bl)
power handling is excursion (xmax) & thermal rating.
There are many factors which effect freq. response.

I would advise using PA drivers in part due to higher efficiency & power handling. Check out the Eminence line array series.

Alternatively mutiple drivers, like the Dayton 6.5", will give you an increase, if you wire series/parallel you will gain 6db & maintain 8ohm load. Judging by its' graph will bring this up to about 90db.

So for 4 x Daytons at $17 - you will have 200w power handling, & 90db.

1 x Eminence at $60 you will have 92db & 150w power handling.

If you can afford it 2 of the Eminence per box would be rockin!
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Old 13th May 2004, 03:04 AM   #4
Andy G is offline Andy G  Australia
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Default yep.. I like the Eminence idea

... but just be very careful that your amp can cope with low impedances...

I haven't check those particular drivers, but I used a pair of Kappa 12's in parallel, with a zobel on each......not a good idea as it turned out... was having problems with an amp cutting out.... and when I actually checked the impedance, it turned out to be running at something like 1.9ohms !!!!!

just be a bit wary of low impedances... another reason to avaoid car speakers !!!
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Old 13th May 2004, 04:06 AM   #5
imix500 is offline imix500  United States
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All good points here. Also keep in mind that you can't just use any HF driver in line arrays. They must be high quality drivers with purpose built horns. I've actually seen such horn on ebay for less than $100. You will also need a decent amount of processing to align the drivers in the box or you will just end up with a center channel home theater speaker. The line array effects are dependant on closely aligned components. And most certainly check the ratings of your amps. Bi-amping is always better, but if you must use one amp channel you will be dealing with some pretty low impedances.
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Old 13th May 2004, 06:15 AM   #6
niacin is offline niacin  United States
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Default Re: Re: Car speakers for PA?

Quote:
Originally posted by Ap


Car speakers are not rugged & designed for outdoor use, they are desgined to go inside a car.....

Alternatively mutiple drivers, like the Dayton 6.5", will give you an increase, if you wire series/parallel you will gain 6db & maintain 8ohm load. Judging by its' graph will bring this up to about 90db.

First, a speaker in a car door has to be designed to take multiple cycles of damn hot, then cold, high humidity, then bone dry, etc. Not to mention the constant banging and jolting of the road. And it has to do this for years. Does not that mean it must be far more rugged than your typical paper-cone indoor hifi speaker?

Second, I thought you got 6dB electrically due to the series/parallel connection, then another 4-6 dB acoustically due to "mutual coupling". Or am I misreading Vance Dickason's book?

Guess I was really wondering whether poly cone car speakers like the Pyramid 6.5 inch were really that crappy. If so it would be funny, because when I ride in people's cars typically the speakers sound pretty good, not like there is a huge hole or peak, and I can listen for hours. Wheras when I listen to many club PA's with your typical 15' woofer and a horn, they sound beamy, peaky, harsh, and they quickly fatigue my ears. I don't even understand how they work. Last I saw the laws of physics say a 15 inch woofer gets very beamy above about 600 Hz or so. And I know the horn doesn't go that low--its only a foot wide. So something is wrong there.

Emionances would be great, but the "pro" drivers are so expensive, so I thought about car drivers...
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Old 13th May 2004, 06:51 AM   #7
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Cars tend to sound pretty good because of their extremely small airspace which requires considerably less energy to compress/rarify. Also cars have mostly soft furnishings : seats, people and acoustic damping on all the panels (or else you would hear a pretty loud sound driving around). If you lock yourself in an airtight cupboard with a pair of 100W hifi speakers on full blast you will go deaf very fast. Also the example of the club with horns and a 15" sub is a classic example of what I call sonic pinball. In the absence of soft furnishings ie: your average club, you get multiple multiple reflections bouncing around creating all kinds of interferences, usually in the high frequencies. Also most cheap PAs contain either Piezo or Compression high frequency drivers, which sound pretty harsh in most cases. Unless the club owners are mad the sub will be running on a crossover which will filter out everything above about 120Hz at the most. Your intention is to make a small PA for outdoor use, where you get what is called the infinite baffle effect. Sound leaves the speaker, goes past the listener and keeps on going. No echo and no walls to increase pressure. This means you need much more power outdoors than you do either in a club or in a car. If the music does not contain much bass I would recommend using 3 or 4 5" polypropylene hifi drivers in either a triangle or square configuration. If you want plenty of bass go for single 10" or 12" paper cones with soft dome tweeters. It might cost slightly more than your initial budget, but it would be worth listening to.

Also, car speakers are not designed to fit into enclosures and therefore tend to have a higher sensitivity than hifi speakers. If you put them in boxes then they will have no bass at all. If you don't put them in boxes then the opposite phase signal generated by the back of the driver will just leak round the edge of the speaker and cause it to sound absolutely foul. You would need to install a car speaker in a circular board about 2" across to get decent performance out of it and it would probably blow over in the wind if you put that lollipop on a stand.

Another tack would just be to buy some passive Bose cubes. They are not the highest of hifi but they are tiny and push a surprising quantity of air.
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Old 13th May 2004, 02:49 PM   #8
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Default Re: Re: Re: Car speakers for PA?

Quote:
Originally posted by niacin


Wheras when I listen to many club PA's with your typical 15' woofer and a horn, they sound beamy, peaky, harsh, and they quickly fatigue my ears.

Dont blame the equpment for that.
It is almost always the people that runs it (Clubowners, DJs, etc) who has done a bad job.
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Old 13th May 2004, 05:37 PM   #9
imix500 is offline imix500  United States
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Indeed. Some of the most respected and best sounding cabinets out there are basically a 15" and a horn. It's all about design and the competency of the person running it.
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Old 14th May 2004, 12:31 AM   #10
Ap is offline Ap
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Quote:
Originally posted by bishopdante

"car speakers are not designed to fit into enclosures and therefore tend to have a higher sensitivity than hifi speakers. If you put them in boxes then they will have no bass at all. If you don't put them in boxes then the opposite phase signal generated by the back of the driver will just leak round the edge of the speaker and cause it to sound absolutely foul. You would need to install a car speaker in a circular board about 2" across to get decent performance out of it"
Huh?
Sorry but car speakers do go into enclosures they are the doors & the boot (trunk).
They generally have high Qts which means they have limited low bass & need a large enclosure to work in.
They are more efficient because they are 4ohm & have a higher resonance - thats it!

No speaker will have decent performance on a 2" wide baffle, car PA, hi-fi whatever.

As for car speakers being rugged - they may use poly cones & rubber surrounds but thats about it they are no more rugged than home hi-fi drivers.
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