5V Preouts to amp with 2-.1V gain?

[Justintoxicated 10+ year member]

I'm already doing it but I'm not sure where to set my gain, the HU is an eclipse CD5444 with 5V pre-outs the Eclipse Amp 3321 ranges from 2V-.1V for the gain setting, it does not get that loud with it set to 2V.

Would I be better of getting an amp that has a wider range like the DLS A3 7-.2V?

Click to read more...

 

[Justintoxicated 10+ year member]

yea I'm going to follow that tutorial but I didn't know if it would work.

So it does not matter that the amp's gain only ranges from 2V and lower and the HU is sending it 5V? WOudl there be an advantage to switching to an amp that does accept more than 5V in like that A3?

 

[squeak9798 5,000+ posts]

So it does not matter that the amp's gain only ranges from 2V and lower and the HU is sending it 5V? WOudl there be an advantage to switching to an amp that does accept more than 5V in like that A3?

No and No; respectively.

 

[Justintoxicated 10+ year member]

No and No; respectively.

Well I'm still confused I guess I can use my multimeter, but the gain on the amp should be set to Maximum right? The speakers are 100w RMS and the amp is only rated for 75. I can't imagine that it will excede 20V in theory.

The A3 is a more powerful amp is this the only reason it is better or am I throwing money into the fire again? For $340 I'm tempted to get one, but I want to make sure it is a worth while investment.

 

[Justintoxicated 10+ year member]

**** now I am lost....

I don't understand how it works, everyone says that if you ahve an amp that matches the RMS of your speakers then you set the gain to the Pre-out voltage.

When I do this (as close as possible) I am turning down the gain on my amp all the way! 2V...hardly any sound comes out.

if I got an A3 I could set the Gain to 5V which is still turned down almost all the way but not quite as much hmmm..

Now using the tutorial posted in the link am I using the Speakers RMS Power or the Amps? Since my amp is less powerful than the components?

 

[Justintoxicated 10+ year member]

Whichever is the lesser of the two ... So if your speakers are rated at 100 and your amp is rated at 2x75, use the amp's rated power in the equation ...

so I should aim for about 17V output? And this will stop clipping? I don't exactly undersand how this works.....I read the article and it makes sense to me for a matched amp or amp rated higher than the speaker's power but I don't understand how it works with an underpowered amp.

 

[kuijo 10+ year member]

Theres a formula you will have to use to figure out how many volts to be used. Go check the wiring forum for the Gain setting tutorial

 

[Justintoxicated 10+ year member]

I know the rule well it's just Ohms Law V=IR But you have to ge he Value of I because we only have P=(I^2)R or P=(V^2)/R so theres a few ways to figure things out really but the easy way is to set it up to P*R=V^2 or V=sqrt(P*R)

so V=75x4 , then V=300 and the sqr of 300 is about 17V but my speakers can handle 20V.

What I'm saying is that I don't understand why this pertains to setting up an amp that has less power than the speakers can handle in the first place. Does this mean if the amp hits over 17V's that it is clipping? And if so who really cares if it clips a bit because the speakers can handle more anyways?

And why does the rule exist to never turn your HU above 2/3rd volume?

What is the point in having 5V pre-outs if they only go into an amp that is 2V sensitive? or can the amp actualy make use of the stronger signal?

Also why is it I should use 1000htz sine save? and not a lower wave that takes more power to produce, I set the crossover on the HU for 80htz why not use 80htz wave?

 

[pwnt by pat 10+ year member]

The stronger signal is only to help you get a cleaner signal to the amp. The fact that it doesn't accept over 2v is moot becuase voltage will drop through the RCAs as well as the 5v is only when the stereo is at max with all settings at max.

Also, you want to aim at 75w, not 300. It's the watts per channel, not total. Also, the fact that the speaker can handle more power than the amp can provide is moot too because, oh well. It doens't get powered to full. It can still reach full performance with less power depending on the install.

1) Set hu to max volume you usually listen to music at.

2) Sqrt(Power*Resistance) = Voltage

sqrt(75x4)=voltage

17.3205081=v

Anything higher than 17.3205081 will make the amp's signal to the speaker clip which can damage the amp.

3) http://www.teamtreo.com/view.php?showme=Free_Test_Tones

Download and burn a test tone to cd. 60hz like Jmac said is good. Play this tone in your car.

4) While the tone is playing, put a dmm on channel 1 postive and negative

5) adjust the gain until the dmm reads as close to 17.3205081 without going over.

6) adjust other channels as needed

7) hook up your speakers and you are good to go

Remember, if the amp puts out more than 75 rms then it will be a clipped signal which causes damage. Damage = b+a+d. The fact that the speakers can handle more doesn't mean anything when your amp can only put out so much power.

 

[Justintoxicated 10+ year member]

ok, well it is underrated fro wha I have been reading online, being that is is an old school model.

But now I am hearing that sending this amp a 5V signal will itself induice clipping even with the gain set all the way down, so to me this sound like I need to buy a new amp.

**** Eclipse Hu is too powerful for my amp, I am understanding the amp can be fine off 2V, but the sweet sop for the Hu seems to be around volume 45/80. Which is probably right around where it hits a 2V signal //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

This would make it extreamly hard to use with other amps that do accept a 5V Signal since I cant fade front to rear while using time alignment....

//content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

Lame...

P.S. I got the number 300 from 75x4...

Wait a second...What it really sounds like I should do is set the gain on all my amps for 2V's since that is the lowest it will go, then use the DMM to figure out what volume level I can turn the HU up to before I start clipping? Since the HU is capable of sending a Clipped Signal to the Amp at less than 1/2 volume?

(Cause the amps can't use 5V input?)

 

[pwnt by pat 10+ year member]

Voltage WILL drop from the beginning of the RCA to the end. Add in the fact that the eclipse will only put out 5v with all settings maxed and at max volume. Your amp will probably never see 5v.

Just hook everything up and adjust the gain as close to 17v as possible and you will be fine. Don't worry about it.

edit: I've run several amps that only accept upto 2v off of the 6.5v preouts MY unit uses without any problems.

 

[Justintoxicated 10+ year member]

Ok, here is the thing, I read that the pre-outs are actualy underrated on my HU and at full volume it can put out 7.9V. I also read a review that said the HU itself will not clip untill at all full volume where it will only clip at around 30htz and just slightly.

I also read that the last few clicks on the voltage knob (ranges from 0-80) dramaticaly increase the pre-out voltages.

Actualy the review I read was for the CD5443 a modle lower than my CD5444

I don' know if this is true so I assume I need to run some testing when I get some freetime.

It sounds to me as though I would benefit greatly from getting an amp that has proper gain controll? This way I can utilize the volume controll knob properly without risk of someone turning it up to high and blowing the speakers.

Anyone know offhand what a Hifonics Zeuse Z600 has for gain controll sensitivity? Can't find it online.

 

[pwnt by pat 10+ year member]

It's really not as big of an issue as you think it is.... seriously

Just hook it up, follow the gain guide, and don't worry about it. If you amp or speakers blow when everything's set up correctly then I'll buy you "proper" equipment.

 

[Justintoxicated 10+ year member]

well, if my HU deleivers a singal that the amp clips (because it only goes up to 2V), that sounds like it would create distortion to me.

 

[pwnt by pat 10+ year member]

But unless you max the eq, turn boost and digital enhancements all the way up, turn every single setting to max and then crank the volume to max, you're amp will never see 5v's. Even then, because of resistance in the RCA, it still won't see 5v's. Because of the resistance in the line, the voltaged will be dropped slightly.