SlimRisk

Okay so I have a Sony CD FX7500 head unit. The specs say its 52 watts x 4 channels. My front door speakers were 100 watt max and those blew. So I upgraded to Pioneer 250 watt, 4 ohm. I turned it up and I noticed that it started clipping about 85%-90% volume up. Is that normal? I kept my eq at normal, and the other speakers disconnected.

gearbox

iTrader: (95)

youre blowing speakers by underpowering them, which causes distortion. you should be supplying at least 1/2-3/4 of the rms wattage the speaker can handle. no deck will be able to do this without an external amp. most aftermarket radios are 15-22w rms per channel at best. most lower end speakers are around 60w rms power handling, so they would need at least 30w rms power which pretty much the only standalone deck capable of doing that is an old alpine unit with a built in power amp. better speakers need even more power, well over 100w rms. peak wattage is completely meaningless, so dont even bother with those numbers.

SlimRisk

So I'm blowing them because I'm under powering them? Does that mean I underpower my speakers everytime I turn down the volume, or does my deck produce a consistant amount of voltage and amperage? That can't be!

Here's what, take a 9 volt battery, and plug the positive wire on the speaker to the positive side of the battery, and the negative to the negative. The speaker then activates, and stays in one postion. Thus we conclude that we need a range of voltages to make a speaker work. Under powering a speaker is a common misconception in the audio world, as far as I know.

scooty

I have the same issue. I think it has something to do with listening to mp3s encoded at excessively high bass levels, so even though your EQ is flat the audio file isn't

gearbox

iTrader: (95)

good point, i forgot that many people also listen to low quality audio, like fm and xm and even some lower encoded mp3. i can easily tell the quality difference, but not everyone can. i think the op might have a combination of all these issues. ive had base model infinity speakers for 10 yrs with an alpine amp and they were still functioning like new with daily use, sometimes at very loud volume levels and a good amount of bass dialed in (at least enough to shake the mirrors). always listened to hq mp3 192kbps and above. if you havent heard an amped system before, you will never know what youre missing.

pjb3

Most people are more likely to blow speakers with a lower power amp than a higher powered one. I'm not sure I can explain this well but I'll try.

First, music has dynamic range. I'll use classical music as an example because it is common for passages to be very soft and others very loud. Lets say that the volume you like to listen to is 80db and for your speakers to produce this they need 10 watts. If you change to 74db which will seem like half the volume you will use 2.5 watts (every 3db requires twice the power). if you were to increase the volume to 86db you would use 40 watts.

If I'm listening to the 1812 Overture at an average of 80db there will be passages at 65 or 70db and others at 100db. When the cannons go off it might be 110db. The power to go from 80db to 110db would be 10 watts to 5120 watts while 100db would only need about 640 watts. (at 68db it would be 0.625 watts) It's fine for the system to clip and distort at 110db because it is for a short burst, the problem comes when you have a sytem that is clipping and distorting most of the time. If you have a low power or a high power amp you will probably listen to your music at about the same volume because that's the level you like. The difference is the high power amp can supply a clean signal which is easier on the speakers than a distorted one. Speakers also use the time between notes to allow the voice coil to dissipate heat. If the music is distorted and the notes aren't clean the voice coil may never have the time to get rid of the heat.

It is possible to blow speakers with too much power. As you mentioned above, the greater the voltage the more the voice coil moves. If you were to apply too much power (voltage) to a low quality speaker you can overdrive the voice coil and damage it. With good speakers they are usually so loud you would not listen at that volume.

There are many other factors that come into play, the efficiency of the speakers, type of music as well as the quality of the amp (distortion). You are not underpowering the speakers when you turn the volume down, you are just sending less power which leaves the amp with more power in reserve for parts of the music that need it.

pjb3

Looking at your first post again I would say you may be aggravating the problem. My guess is the Sony is probably putting out about 15 to 18 watts RMS. There is only so much air a 6 1/2 inch speaker can move and if the other speakers are disconnected you probably are trying to get more sound out of the speakers than they can produce. Try using the rears as well and you may find you are setting the volume lower on the head unit.

SlimRisk

@gearbox - ill make sure to get a few HQ mp3s and tell you what my findings are

SlimRisk

Dang, so I tried exactly what gearbox said. I am a small time electronic producer (www.soundcloud.com/djaxle) and I had some hq mp3s on my phone and tested it out. Cranked it all they way up and the synths were still crisp and clear along with nice deep bass. Thanks again everyone, I'll make sure to keep an eye on the quality of my mp3s

gearbox

iTrader: (95)

yeah quality is a big part of it and becomes even more of an issue when amped (whether thru the deck or external amp). i still havent thrown away my cds because they sound better than any mp3 could ever hope for. nice website

ThatDude

No doubt man. I was downloading & burning cdsfor a few months before i realized that the quality sucks & i researched it. i just gave them away and started from scratch. most people have no idea about the quality of mp3s but i believe at least 192 kbps is very close to cd quality. i know vbr is good to (i think thats what its called??)

pjb3

I'm curious whaht bit rate you were using on the original mp3s that caused problems.