Distortion Question

[DOOM_NX 10+ year member]

2 x 95W RMS 4Ohm speakers

1 x 60W RMS per channel 4Ohm amplifier (total 4 channels)

To set gains with a DMM, I used the following formula: sqrt(60W * 4Ohm)= 15.49V

So amplifier is giving 60W, speaker can take up to 95W. Yet when playing 1kHz sine wave at 0dB it sounds distorted. What's wrong? //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

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[mokedaddy 5,000+ posts]

Crappy speaker, amp or install would be my guess.

 

[DOOM_NX 10+ year member]

could be all 3...

Speaker: Hertz DCX690

Amp: Hertz EP4

now, cables are Audison Connection, but I don't know exact specs... should be the right though...

 

[mokedaddy 5,000+ posts]

Do you have any sort of high pass filter on the speakers?

 

[DOOM_NX 10+ year member]

Hmmm yes, at around 150Hz... Set by the amplifier Xover...

 

[mokedaddy 5,000+ posts]

How are the speakers mounted and what are they mounted to?

 

[Immacomputer 10+ year member]

You shouldn't be setting your gains with a DMM for speakers. Set them by ear with music playing.

 

[DOOM_NX 10+ year member]

Those speakers are mounted to the rear deck... like the pic below:

So, Immacomputer, you suggest I set speakers by ear, no DMM, no tones? I'm afraid I don't think I have a trained ear to do that and they might clip as hell... But for subwoofer, you do suggest a DMM, right? Cause there is no way I can hear distortion...

To make matters worse, I think the right speaker is distorting and the left isn't... help?

 

[Haunz 10+ year member]

It could be the HU sending out a distorted signal, it could be that the gains on the amp are too high, or the speakers may not be able to handle that much power without distorting..

either way you need to turn something down..

 

[Rashaddd 5,000+ posts]

You shouldn't be setting your gains with a DMM for speakers. Set them by ear with music playing.

^^unless of course you need to limit the amount of power and not give them everything your amp can

mids/highs distortion/clipping is VERY audible, it'll sound like a stock system when you just crank the volume all the way up

 

[DOOM_NX 10+ year member]

So we got a pair of speakers rated 95W, but not even being able to manage 60W... great...

HU volume is at 46/62 and gains set with DMM as I said...

EDIT: I'd like to emphasize that I don't hear any distortion when playing music, just the 1kHz sine wave at 0dB...

 

[groundpound4200 5,000+ posts]

yeah... you'll notice if you're clipping the hell out of your mids and highs. Do it by ear and double check the mounting baffle. It should be as solid as possible.

 

[DOOM_NX 10+ year member]

The mounting baffle... I don't know if it's considered solid... It's just the original baffle, just cut out to mount the speakers...

Car is a Nissan Micra K11, '98 model by the way...

 

[Immacomputer 10+ year member]

^^unless of course you need to limit the amount of power and not give them everything your amp can

Your eyes and ears will keep you from reaching that point safer than a DMM will. Setting gains with a DMM for mids/highs will almost always limit your max potential clean output while listening to music.

Even when it comes to subs, I use my eyes ears and nose to set gains as I don't trust DMMs nor will the load be as simple as the nominal resistance and it won't be purely resistive either. It's a good way to be safe for subs if your judgment is bad.

 

[DOOM_NX 10+ year member]

So nobody uses the 1kHz sine wave at 0dB some people are talking about? It's easy to tell when speakers start to distort that way... I'm almost sure I won't understand when MUSIC starts clipping.