how do i wire up and what amp do i use?

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Gibby86

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Joined 2013
hello im a novice to sound systems and I am building my first. ive got a lot of it sorted but stuck with some speakers im building.

im going to be using four 8ohms drivers that run at 50watt rms each. with each driver will be a "Piezo Horn Tweeter" 60 to 80 ohms 150watt max.

now I don't no how to wire these up or what size amp to use, I was thinking of using a 500watt 4ohm 2 channel amp will wireing all these speakers up to 2 channels cause the ohms to get to high for the amp? do I need to use a passive crossover with each speaker? I will be using a active crossover anyway but like I said im a novice.

any help would be great :)

Thanks

Gibby
 
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Gibby86

Member
Joined 2013
So the total max power of the tweeters is 600watts dose this mean The rms is 300watts? The rms of all the drivers is 200watts so if I have a 500watt 2 channel amp would i Run two drivers and two tweeters in pararell to each channel? Do the tweeter need a passive crossover before they go to the amp? How will the ohms be affected by all this? And can someone please make me a sandwich?

Please explain every detail because I'm new to all this and it can easily go over my head.

Thanks

Gibby
 
KatieandDad

KatieandDad

Member
Joined 2011
You need to specify what power is being fed to which channel.

An amplifier is "usually" specified with Watts/Channel. However, car audio manufacturers often bend the rules to make their equipment look more powerful than it actually is.

You cannot just add the power of all the speakers together and feed them with that amount of power.

Although not strictly true (because different drivers have different sensitivities), each driver (ie bass and tweeter) will be fed with the same power, just at different frequencies.

So if you have 50W Bass drivers, two in series or parallel will be able to take 100W MAX.

So the Tweeter will also be fed with the same 100W.

Often the Tweeter is more sensitive than the Bass driver (often about 3dB more sensitive). In this case the Bass would be fed with 100W and the Tweeter attenuated to 10W in order to maintain linearity throughout the audio band.
 
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KatieandDad

KatieandDad

Member
Joined 2011
It is, however, common for the tweeter to be of a lower power than the bass driver because of the relative sensitivity of the two units. This has to be catered for in the crossover.

Let us consider this very simple crossover.

At very low frequencies the reactance of the capacitor is very high and that of the inductor is very low. Therefore low frequencies will pass through the two bass drivers. As they are in parallel each can dissipate 50W so the maximum amplifier power is 100W.

At high (for audio) frequencies the reactance of the capacitor is low and that of the inductor is high. Therefore high frequencies will pass through the tweeter.

If the sensitivity of the tweeter is higher than that of the bass drivers (which is common), if R wasn't included the speaker would sound VERY bright and would be horrible to listen to. R is included to attenuate the high frequency signals to the tweeter to dull it down a bit.

You can see that it makes no difference if the tweeter is 150W, the bass drivers still have to cope with the full amplifier power.

This is a simplistic crossover, there is a bit more to them that I have detailed above, but my explanation holds true.
 

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FoMoCo

Member
Joined 2012
KatieandDad said:
So you are telling the newbies to buy a 1000W amplifier and feed their 50W speakers with it, just fit a few fuses.
Click to expand...
Don't exaggerate things. I did not recommend a 20 fold power increase.

I'm not going to trash this thread by arguing with you. So... Don't go putting words in my mouth. Remember how lost you were on the series relay thread? The same one where you got rude and then were proven to be utterly wrong.

I stand by my statement that he can use his existing amp if he's careful or let's a fuse be careful for him. This is a true statement regardless of whether either of you understand the concept.

The OP would do very well to head over to Rod Elliot's website for some great tutorials that will explain why he can use his amp (and why a small amp isn't a problem either), and why he can't simply add the tweeter to the woofer when calculating power.
 
KatieandDad

KatieandDad

Member
Joined 2011
FoMoCo said:
Don't exaggerate things. I did not recommend a 20 fold power increase.

I'm not going to trash this thread by arguing with you. So... Don't go putting words in my mouth. Remember how lost you were on the series relay thread? The same one where you got rude and then were proven to be utterly wrong.

I stand by my statement that he can use his existing amp if he's careful or let's a fuse be careful for him. This is a true statement regardless of whether either of you understand the concept.

The OP would do very well to head over to Rod Elliot's website for some great tutorials that will explain why he can use his amp (and why a small amp isn't a problem either), and why he can't simply add the tweeter to the woofer when calculating power.
Click to expand...

How banal.

If you re-read the thread that you are talking about, we were just discussing possible ways of switch HV.
 
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FoMoCo

Member
Joined 2012
Gibby86 said:
if im using a active crossover is the passive crossover still needed? if it is can u point me the right direction to buy one?

thanks for the help by the way its much appreciated
Click to expand...
Not if you're using the active crossover properly. But, you may wish to keep a capacitor in series with your tweeter to protect it from DC. Others here may argue yay or nay for that, for what it's worth.
 
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