Dear Group,
I recently replaced the rear speakers of my car with 4 ohm speakers. The old speakers were 8 ohms, and though older, sounded clearer than the new ones. Am I trying to pump too much power to these new rear
6.5" speakers? The RMS rating of the speakers is only 30 w, and I know that my lexus Es 250 has an amp, so maybe the speakers just don't have a high enough RMS for my car. They sound crappy and are new so PLEASE HELP!
WHAT possessed you to do that?
Go back to 8 ohms and PRAY you didn't ruin your amplifiers.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
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Easy, put the old ones back in. BTW, all 6.5" speakers sound like crap.
With 4 ohms speakers, theoretically you are able to put more power into your speakers. At the same postition of your volume control, you get more power now. This may cause that the loudness control is much more active at normal soundlevels, giving your more bass than desireable. There's also an increased risk that you damage your radio, when played (very) loud.
-- Thanks, Frank. (remove \'q\' and \'.invalid\' when replying by email)
Maybe your new speakers *are* crappy and the impedance mis-match is a red herring..
-- "What is now proved was once only imagin\'d" - William Blake
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Yes, it's a red herring. There's an impedance mismatch whatever the speaker impedance.
Oh, Good Lord. More assinine waffle.
Graham
The speaker impedance is relatively unlikely to be an issue. If it was you'd likely have found the amplifier had fried by now.
Most car audio uses 4 ohm speakers IME. If the speakers' rms rating wasn't enough, they would have fried too.
It's obvious you're tinkering with stuff you don't understand so......take some good advice from a car audio specialist and don't replace stuff willy-nilly.
Graham
The most likely problem is that you bought cheap crappy speakers. Or you are overloading them. Try turning down the volume a bit. If things don't improve ask for your money back and buy 8-ohm speakers.
Anyway, 2 by 30 watts in a car can cause a gradual loss of hearing to both you and the passengers.
What are you talking about? You aren't suggesting that the source impedance of the stereo system is 4 or 8 Ohms, are you? Most likely it is nowhere near that high, so it would seem Reg is totally correct. In fact, I have rarely seen him be anything but correct on issues such as impedance mismatches and transmission lines and so-on.
--Mac
Respect your elders! Reg is right, actually. But it's not normally an audible factor in this type of problem.
-- "What is now proved was once only imagin\'d" - William Blake
Hmm. Reg never said matching was required or relevant. In fact, he has gone on record many times in this newsgroup saying that impedance matching is not a concept used by power amplifier designers.
In fact, I don't think you actually disagree with Reg at all. He said two things:
1) The impedance mismatch issue is a red herring. 2) Whenever speakers are connected to an amp there is a mismatch.If you do disagree, which statement do you disagree with?
Yeah, yeah, yeah. I mean, some amps can't drive 4 ohm loads, but I get the picture and I don't disagree.
--Mac
Absolutely not. More likely 100 milliohms max.
No - because 'matching' is not required or relevant. Any more than you 'match' a heater fan to a car battery.
Audio speaker circuits are *not* matched circuits. Thay are voltage driven LF circuits. If you stick a 4 ohm speaker on the end in place of 8 ohms then twice the current flows for the same signal conditions.
Graham
Matching is a total irrelevance for speaker circuits.
Graham
Did someone say it wasn't, then? I must have missed something!
-- "What is now proved was once only imagin\'d" - William Blake
If the amplifier is decent, it won't make any difference what the speaker impedance is over a large range. In fact ALL speakers have a rising impedance curve as frequency increases. A poor amplifier may be taxed in driving the larger current required for four ohms and that may be your problem but I doubt it. Most likely your problem is crappy speakers not impedance.
Clarity in speakers has to do with cone motion and cone breakup into various modes of vibration at audio frequencies. Woofers or low frequency drivers are notoriously poor at reproducing the mid range and high frequencies necessary for clarity and fidelity. Be sure to use speakers designed for the intended range of operation. Secondly speakers have design parameters like cone resonance, fs, Vas, Qm, Qe, R and a few others. In a proper speaker system, these parameters are accounted for and designed in just like with any other technical device. To ignore these parameters and grab a cheap replacement is to invite trouble and crappy sound. I guess that's what you've got. The best bet is to use the intended replacement speaker unless you want to do a custom design. Bob
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