Speakers/power

Hi

I'd like to know what your opinion is about the right speakers to choose (in terms of power-watts) when you have only the radio amp that is 4x 45 watts.

I'm asking this because i believe that choosing speakers prepared for too much watts will keep the radio from exciting them, therefore producing less sound specially at low volume.

What would be the maximum value of peak power that you would choose with such a radio output?

Thank you.

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Nuno Gomes

well your best guess is a speaker that does 22.5 WRMS and 45 WPEAK ... Unless you want to get a separate amp, which is what i recommend.

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"I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.

I don't mean to be rude, after all, i was the one who asked for info, but i find it hard to believe that with an Alpine 7860R with 4x 45 watts i will get the most of it with 45 watt speakers.

Please don't be offended, it's just a persistent doubt.

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Nuno Gomes

A speaker will only put out what it is given. Speakers produce sound in decibels, not watts. Throw the wattage rating out the window for now. Your deck will struggle to produce a real honest to god 18 watts in most cases. Your speakers can be rated as high as you like in the terms of watts, they will only produce what you send into them. Thus the speaker can be as high as you want as far as a wattage rating goes. If speaker A has a db rating of 93 db 1w/1m and speaker B has a rating of 90db 1w/1m, speaker A will play noticeably louder. What should be more important for you is how the speaker sounds, not the wattage rating.

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Top Secret, I can tell you but then my wife will kill me.

I don't know if  you directed your post to me, but to my understanding you were running these speakers off of your head unit, and not a separate amp. Forbidden makes a valuable point though. It will struggle to put out that kind of power.

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"I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.

I have 4 JBL 180 watt peak, 60 watt rms and 90db sensitivity. At low levels you can´t hear them very well

So, getting speakers with lower power in watts and lower sensitivity would help keeping sound at low volume better and not so good at higher volume?

If you could choose from all the values in watts and sensitivity for this situation (4x 45 watts from radio), can you please tell me what your choice would be? So that i can understand exactly.

Thanks.

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Nuno Gomes

90 db is a good starting point, like I said, forget all about the watts. At lower volume levels there is just not alot of power being produced by the tiny little amplifier in the cd player. If you want the speaker to be louder at lower volume, then you would need a speaker with a higher sensitivity rating. Unfortunately they may sound like bat barf though. I would choose my speakers knowing this.

(1) no speakers sound alike, buy the ones that your ears like.

(2) your tiny little amp will always be a tiny little amp no matter what speakers are used.

Based on this, if you want better sound at a lower volume level, you need an amplifier to drive those speakers much better. Power from an amp will clean up your sound, give more definition at lower volume levels and of course will play much louder if you want it to.

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Top Secret, I can tell you but then my wife will kill me.

I have an old Sony XM-2020 amp 20watt x2. Do you think it would help if connected to my rear speakers?

If not i can´t think of buying a good amp right now.

Thanks.

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Nuno Gomes

It would give you a marginal increase in output levels. If you have it, try it. You might learn a little about how power affects speakers at the same time.

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Top Secret, I can tell you but then my wife will kill me.

Thank you. I´ll try it and let you know.

I´ll wait for the rain to stop. :)

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Nuno Gomes

It's been raining here all day as well, the snow is coming guys......

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Top Secret, I can tell you but then my wife will kill me.

Here in Portugal the rain will go away soon as always and a glorious sun will allow me to install my old amp. :)

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Nuno Gomes

Now that the rain has stopped, here's what i'm thinking of doing:

-connecting the amp to the rca output on the head unit that can be controlled separately. The radio instructions say that when that connection (display indicates "subwoofer on or off") is on, amp will be used, when it´s off, speakers will be used without the amp.

My doubt is:

1-What would happen if i connected the amp not to rca's on the HU, but where my rear speakers are, replacing the speaker with the amp and then connecting the speaker to the amp. The signal that used to go to the speakers from the HU would go to the amp and then to the speakers. Would that be different from connecting it to rca's?

2-Since the HU is 4x 45 watts, by replacing the power that feeds my rear speakers (because it's a 2 channel amp) with the power from the amp that is 2x 20 watts, isn't it correct to think that the speakers are going to have less power to them?

Thank you

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Nuno Gomes

nunog] wrote:

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-Since the HU is 4x 45 watts, by replacing the power that feeds my rear speakers (because it's a 2 channel amp) with the power from the amp that is 2x 20 watts, isn't it correct to think that the speakers are going to have less power to them?

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Actually, that is incorrect.  You keep quoting 4x45.  That is MAX power, not RMS.  Speak in terms of RMS.  MAX power means nothing, it is simply a marketing tool.  Your HU probably does 20x4 RMS AT MOST.  Most HU manufacturers totally overrate their power specs.  (i.e. they cheat by only taking the power rating with one speaker being driven and pushing some specific frequency for a very short period of time)  In other words your REAL RMS power from a head unit across the entire frequency range with all channels being driven for a long period of time may be much less than the head unit's stated rating.  Most standalone amplifiers, even if rated similarly to a head unit, will totally blow head unit power away.  They can usually use much higher quality parts, will run cooler, have more available headroom, have much lower distortion, much higher signal to noise ratio, and the list goes on and on.  Unless your other amp is total crap it will almost always be better and more powerful than head unit power.  There simply isn't space in head units for quality amps. 

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New Project: 2003 Pathfinder

Thank you kfr01. That makes sense. My doubt number 2 is no longer a doubt.

I´d still like to know the answer to doubt number 1 if it's not too much to ask you guys.

Thank you.

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Nuno Gomes

I´m thinking that my rear speakers will get two sources getting to them, the mini amp from the HU and the amp (rca's).

Even knowing that when rca's are activated, the mini amp from HU will be deactivated (as i read in the service manual), isn't it odd that the rear speakers will have 4 wires in common and the signal from the amp will also enter the HU because the wires touch?

I'd like to keep the wires from the HU to the speakers directly AND the rca's so that i could choose on the HU at any time if i wanted amplified signal or direct signal to rear speakers.

It doesn't feel right. What do you think?

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Nuno Gomes

Ok, now I have an idea of what you are trying to do.  Don't do it!  You'll harm the head unit if you do.  Only have one amplifier hooked up to each speaker.  If you really want to switch back and forth I'm sure you can pick up a home audio speaker selector and try it that way.  I don't see any reason to leave the head unit speaker level output hooked up if you have rca's to the amp. 

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New Project: 2003 Pathfinder

Now THAT was USEFUL. I was about to make the connection my way.

Thank you kfr01.

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Nuno Gomes

My amp, even as simple as it it, has a yellow wire and a blue/white wire. I assume that the blue/white one is the remote turn on, but about the yellow wire, if i connect it to the yellow one on the HU, isn't it correct that there will always be power heading for the amp? even with the ignition off?

This my last doubt before connecting the amp. I´ve got a lot of wires hanging in my car. :)

Thank you.

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Nuno Gomes

I couldn't tell you what the yellow wire is coming out of the amplifier.  Anyone else?

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New Project: 2003 Pathfinder

Hi guys.

It's done. Uff!

I ended up connecting the yellow wire (the amp wouldn't work without it) to the red wire on the HU.

I figured that if the amp required a (+) wire (yellow), then i should connect it to a (+) wire that turns off when i turn off the ignition so that my battery can live long and prosper. :)

The front speakers are still my car's weakness, but the sound is clearer now.

Thank you for your help.

Portugal congratulates you guys for your knowledge.

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Nuno Gomes