Question for audiophiles- car speakers

I'm trying to choose some rear car speakers for my 91 Saab 900 and need some help.

The stock grilles are for 4x10 speakers (ack) and had some Ford 5x7 speakers fudged in place before I bought it. So I planned on making some adapters for what I initially thought would be 5.25" speakers.

But now that I compare some speaker specs I'm not so sure.

The speaker line I'm looking at is the Polk Audio db series. The 5.25 I had picked out is the db521. But I wonder if I should go with the 5x7 db571.

The 5.25 frequency response is 60-22 kHZ, whereas the 5x7 has 52-22kHz. I always thought round speakers made better sound, but the 5x7 has a wider frequency range.

Will the 5x7 actually sound better, or am I splitting hairs for no reason?

The lower number (52hz) of the 5x7 means it will produce a lower bass note than the 5.25 is able to. Round speakers tend to produce better sound quality than oval. The oval speakers are usually a compromise based around space and frequency response.

AIUI, while a round driver has inherent sonic advantages over an oval one, the differences aren't so huge that they can't be out-weighed by the other details of the speaker construction.

To produce a low note, you need to move a lot of air. For drivers with equivalent travel, this means that the one with a larger surface area will have more bass response. A 5x7 driver has 20-30% more surface area, so it's not surprising it goes lower.

Cars are actually a really awful environment in which to try to accurately reproduce sound. The space constraints are really significant, the drivers are usually aimed in the wrong directions, there's lots of bad resonances, and the noise floor in most cars is quite high, so anything with a lot of dynamic range is hopeless.

I suggest a LS400 with the Nakamichi stereo option. It would probably be cheaper than trying to get as good sound in any other vehicle. That stereo is literally the best I have ever heard. Something like some obscure percussion instrument will be on the radio or on a CD and I turn to look because it sounds like it literally was inside the car.

Otherwise, JBL makes good speakers. I'd find the biggest JBL speaker that fit in the hole and get it on Amazon or eBay.

codrus wrote: AIUI, while a round driver has inherent sonic advantages over an oval one, the differences aren't so huge that they can't be out-weighed by the other details of the speaker construction. To produce a low note, you need to move a lot of air. For drivers with equivalent travel, this means that the one with a larger surface area will have more bass response. A 5x7 driver has 20-30% more surface area, so it's not surprising it goes lower. Cars are actually a really awful environment in which to try to accurately reproduce sound. The space constraints are really significant, the drivers are usually aimed in the wrong directions, there's lots of bad resonances, and the noise floor in most cars is quite high, so anything with a lot of dynamic range is hopeless.

This is really interesting to me. Here I thought the frequency response of the speaker was influenced more by the shape of, in this case for the lower notes, the speaker cone. When in reality it is the surface area.

Makes sense in terms of the amount of air that needs to be pushed. Which is why you get more bass response from a 6" speaker than a 3" speaker.

Thank you for the explanation!

@Dr. Hess- I'll check out the LS400 with that option, maybe it will end up on my bucket list! For now I'm trying to make some noise that is more respectable than the marginally working stock-ish stuff that came in the car

I made the mistake of purchasing some kenwood 4x10 speakers for my old c900. In the future if I'm not installing a full system with front 4" separates and a sub, then the next best bass option would be these: 4x10 to 6x9 adapters

As an explanation, the 4x10 speakers are excursion - limited by their 4 inch across dimension. Therefore, you have the driver of a four inch speaker attempting to push the cone area of a larger speaker, with wildly different compliance from the surround at its narrow dimension vs its long dimension. A speaker with inherent distortion, that you can't really drive to get any bass reponse from, and that will easily be smoked by head unit wattage levels. The worst of all possible worlds.

travellering wrote: As an explanation, the 4x10 speakers are excursion - limited by their 4 inch across dimension. Therefore, you have the driver of a four inch speaker attempting to push the cone area of a larger speaker, with wildly different compliance from the surround at its narrow dimension vs its long dimension. A speaker with inherent distortion, that you can't really drive to get any bass reponse from, and that will easily be smoked by head unit wattage levels. The worst of all possible worlds.

Put in these terms it makes sense why the 4x10s are so horrible, thank you for the explanation. I bought a pair of 4x10s a long time ago to put in a 1980 blazer I had and they were miserable!

On those 6x9 adapters, do you think they would fit in the C900? I had seen them before but thought for some reason they wouldn't fit. I think a pair of nice 6x9s and a small wattage amp would do very nicely for me.

I believe they will, and my search pulled up a number of responses from saabnet.com , so I'd imagine someone there has tried it. I believe you may have to angle the speakers oddly (firing toward the outside of the car) but am not certain enough to say.

Take the load off whatever drivers you install by installing a small sub and crossing them over at 80 HZ

Another thought.
I don't know how cheap you're trying to be, but junkyards can turn up nice speakers. Ford used JBL speakers in it's premium stuff for a long time, Chrysler/Jeep used Infinity, GM and Saab used Bose, but I'd shy away from Bose. They are hard to use in anything other than the factory systems due to individual amps, bizarre impedance ratings, and cost. I was always blown away by the Infinity stuff from Grand Cherokees and Chrysler cars.

travellering wrote: I believe they will, and my search pulled up a number of responses from saabnet.com , so I'd imagine someone there has tried it. I believe you may have to angle the speakers oddly (firing toward the outside of the car) but am not certain enough to say.

Thank you travellering, I will check into those again. I'm not sure why I dismissed them so quickly.

DrBoost said: Take the load off whatever drivers you install by installing a small sub and crossing them over at 80 HZ

This is exactly what I had been thinking, because in my mind I was so set on using the 5.25" speakers in the back. Phase one was to be bass blockers on the front dash speakers, the 5.25's in the rear with a lower wattage four channel amp. Phase two would be using the second set of channels to add a small sub down the road, at which time I would install another (different) set of bass blockers on the 5.25" speakers.

My budget for this stuff is modest to say the least. But it's been fun to nerd out and research some DIY ideas. Despite having a very lay knowledge of electronics, I really enjoy messing with them. Plus I can afford to do a little more now than when I was a teenager. But now I'm more interested in quality than volume

codrus said:

Cars are actually a really awful environment in which to try to accurately reproduce sound. The space constraints are really significant, the drivers are usually aimed in the wrong directions, there's lots of bad resonances, and the noise floor in most cars is quite high, so anything with a lot of dynamic range is hopeless.

^ This. The listening room is actually the most significant factor in good audio reproduction. Even the best car is pretty bad.

Don't worry about trying to get an actually nice audio setup. It's not going to happen in a car. Really your goal is just "pretty decent" which isn't that tough of a hurdle to clear.

Decent 5x7's will make a world of difference in the car and you will be very happy. The exception to this is if you like really bass-heavy music like electronica or hip hop. In which case you need a decent sub. Then get the 5's and cross the sub and mains at 70-80hz.

That said... sometimes you can set up a listening space to be so bad it's good. One of the best listening experiences I ever had was in the brewery with speakers pointed with massive toe-out. So, speakers aimed almost randomly in a huge space with a lot of curved and angled REALLY reflective surfaces. I was listening to Radiohead's "Everything In It's Right Place" and sitting on the brewhouse sculpture stairs and... holy E36 M3. Instead of an accurate soundstage, what I got was a crazy sonic sculpture. The sound was three dimensional with different instruments appearing to hover all around me in 3-dimensional space. It was trippy and awesome and PERFECT for that song.

But that was a special situation, and you are NOT going to get an experience like that in a car.

Audiophile and car speakers don't really belong in the same sentence. You could have the best of the best equipment but it's still in a hollow cavity made of thin steel. You do you, but point of diminishing returns shows up in a hurry. Round better than oval, soft tweeter domes better than hard. Most specs are exaggerated. Alpine Type S used to be a good benchmark of cost vs sound.