Help with 6x9's and amp

[leighk18]

hey i just got some new vibe 6x9s and have wired them all up to the amp today and when you trun it up they just fart and i no it is no the 6x9s as they are 475 watt and its only 300 watt amp any body no what the problem mite be? amp mayb? cheers guys

 

[Dink]

have you got a lpf enabled on the amp?

also have you got the gain set right?

also those figures you quoted mean nothing as they are not rms

 

[leighk18]

yes the amp has got a gain but that is turned right down

the 6x9's are 160 rms

the amp give 75 per channle as it 4 channle and the 6x9s says min 75 rms

and no it jsut has a gain on it

 

[clioruss]

did you buy the 6x9 at a dodgy car boot???????

 

[jjoe90]

if the amp is a max 75rms and the speakers ar min75 thres ya problem there getting jak poo power, turn he gin up even bette buy the vibe amp designed to power thm

 

[leighk18]

if i turn the gain up they just fart more

 

[jjoe90]

try it yu got the reciept thts wot i do turn it to try if theyblow take um bak

 

[Dink]

what have you got the hu on?

have you connected it to the sub pre out?

 

[sambonebs]

Right, you need to have an amp that's rated higher (RMS Wattage) than the speakers. In your situation, you're pushing the amp which is causing it to clip, so that the AC Signal going to your 6x9s is becoming DC.

Using an underpowered amp is the main cause of dead speakers, it'll f**k them much, much quicker than using an amp that's too powerful.

Sorry to say, but you've probably blown your speakers...

 

[Dink]

the amp will never go to dc. it will send out a square wave that is still ac but will contain more power as the tansistors will be in a full on state for longer.

as for having an amp with a higher output than the speaker input.

yes it is ideal but your not going to blow a speaker by only gving it 1/2 it's rated input. the main cause of speaker failure is people turning the gain up too high trying to get more out of an amp than it is able to give.

so the fault lies with the user and not the amp

 

[sambonebs]

Fair play, but that's how it's always been in my experience. I've worked with live sound for 10 years and never seen speakers blow with an amp rated higher than the speakers.

And as for the AC/DC thing, I'll take what you say as correct as I've not got a detailed understanding of Electronics. I'm just going of what I'd had explained to me by an Audio/Electrical Engineer.

 

[leighk18]

ok thanks or help if i just join the speackers to the back speackers as this is were i had my old 6x9s they work fine just not very loud as head unit only 50 watts so do ya think the amp is knackerd as mate who got it off had probs with with his sub using this amp but thort was the sub that had gone not the amp

 

[leighk18]

oops double post

 

[BrianR]

ok thanks or help if i just join the speackers to the back speackers as this is were i had my old 6x9s they work fine just not very loud as head unit only 50 watts so do ya think the amp is knackerd as mate who got it off had probs with with his sub using this amp but thort was the sub that had gone not the amp

Probably nothing wrong with the amp, you may have a power supply problem or a mis-match on the input side.

If you check the voltage at the feed point on the amp when it’s on but not playing it should be no less than 13volts.

Switch it on and play it at low volume and check the voltage again, if it drops more than a couple of volts, chances are the cables and connections are inadequate or the cars battery is knackered.

The more you turn it up, the worse the situation becomes. What you are hearing is distortion caused by an amp running under voltage, not overpowering the speakers.
Forget square waves and the like, you wouldn’t have the equipment to measure them anyway.

You have proved the speakers work, now check the amp supply.

Check the input requirement for the amp and the output from the H/U against the makers spec. (I am not talking about speaker levels, but the line levels, should be something less than 3volts output from the set.) a big difference will cause the problem.

 

[leighk18]

have not got round to checking amp voltage yet but i checked and my mate who i got it off never added the fuse to the power cable could this be casuing the probelm as the fuse help resistace the voltage?