So I was changing out all speakers in 2000 c4 non bose system. Dash and rear speakers are 4 ohm. I went to change the door speakers upon removal, saw that they are 2ohm. So now the new 5-1/4 speakers (4 ohm) sounds like crap. Is there a way to change this with the amplifier? Or am I having to replace the amp all together? Thanks

 

 

I think you'd be better off running a new amp, that will give you the best results. I don't think the amp is capable of changing any ohm settings but that's a guess.

 

You can't change the impedance of a speaker. It is a function of how it is made

If you look at amp specs, the power output increases as impedance decreases, however it is no louder with a lower impedance speaker even though the amp puts out more power

 

The simplest way to impedance match is with a 4 ohm in, 2 ohm out transformer. They aren't easy to find, but they are out there if you google-foo.

This will solve the impedance problem, but you have to be careful about core saturation. If you get too small transformer, you can put too much power in the transformer and overload it(core saturation).

This is low cost, low tech. Better is to replace the amp with a unit that has a 4 ohm output section to match the speakers.

 

Thanks guys. Now time for an multi channel amp and now sub since I'm upgrading again.

 

The main reason that the speakers "sound like crap" is because the door speakers are "subs" (ie: they're crossed over and should only be reproducing low end). Purring coax's in there is a bad idea, as the tweeters will give you that "poop" sound...

 

dporto is right. The Porsche door enclosures are bass reflex and not designed for full range output and that's the beauty of the Porsche 10 speaker/6 channel system. The mids and highs are handled by the front and rear speakers. The bass is handled by the door bass reflex enclosures.

Also, as a general rule of thumb you want to match the impedance of the amp's output with the impedance of the speakers. However, if your amp with handle different loads, then you should be fine but the fact is that most car systems are set for 4 ohms loads at the speaker level. Mixing impedance from the amp to the crossovers, to the speakers can get you into a world of hurt is not matched properly.

 

That is far too complicated and not needed.
An amp that can handle a 2 ohm load and also handle a 4 ohm load. With some amps, the other way might be a problem. A transformer is a complete waste of $, effort and space in this application

As others have pointed out, the door speakers are subs and driven from the amp as low frequency only

 

Here is a write-up for replacing the door speakers with new 5.25" subs:
http://www.6speedonline.com/forums/9...-speakers.html

 

Yes, I understand that soldering 4 wires, and mounting a small metal tab can be -- challenging for some. It is a solution, but not one that I recommended. As for what the amp can handle, you have it backward. an audio amp which is designed to handle n watts into a 4 ohm load will theoretically be able to produce way over n watts into 2 ohm(it's a log, and I don't want to mess with the math) load. However, for almost all retail analog power applications the amp will start clipping the signal anywhere near modest volume because once again, the audio amp amplifies as a log of the sine of the waveform. And, guess what - the 'sounds like crap' effect the OP mentioned. running a 4 ohm impedance output amp into an 8 ohm load will not clip, as the impedance of the sink(speaker coil) is greater than the impedance of the design of the source(amp). Thus, the ability of the same amp to produce n watts across an 8 ohm load will be -- unlikely. No clipping, but less volume of course.

Further, it's not really the power that's the only problem, but the mis-matched impedance of the output stage of the amp, and the speaker will produce an undesirable slight but noticeable ringing at the resonant frequency of the coil of the speaker. Usually depending on the size and winding of the speaker, it won't be an issue, but when the frequency is outside the range of hearing(speaker coil is very high inductance and very low capacitance), we can get the mutilplexed harmonics of the resonance freq at reduced levels which will be in the audio range of hearing(a design flaw of all speakers, but more of an issue when impedance is mis-matched).

Did you want to discuss audio technology more?

 

I'd love to. I did pro audio for more that 15 years

That's exactly what I was saying, output power at 2 ohms will be higher than at 4 ohms. I too don't want to mess with the math. More power at a lower impedance does not equate to more volume

Modern transistor based amplifiers generally do not have transformer outputs and are fine with loads at least 4-16 ohm and most 2-16 ohm so there really should not be a mismatch. Having an amp that can handle a 2 ohm load should not have any issues with a 4 ohm load.

In any case, we are talking about a car stereo, not a $50k audiophile home theater system. Most people can't really hear minute differences, perception becomes reality. Also as we age, our hearing gets progressively worse. When I was in my 20's, I could easily hear 18K and kind of hear 20k. No nearing 60, 10k would be a stretch.

Enough technical crap, what oil should I use?

 

Joey Ribbs DeeTee40 sold by Jack Rabies exclusively at Forsche Motorsports in Florida. Ask for Martin.

 

Call me when you get your EE degree. If that's "exactly what you were saying" then it's backwards to what you meant. But - no worries, we're all experts behind a keyboard.

I recommend some Kmart/target straight 30W. Pour it right in the CD changer cart slot next to the spare in the frunk.

 

2 or 4 wont make any difference in your system. Why it sounds bad is for you to experiment with. Wrong speaker selection is the problem , so put the old one back in