Anyone know anything about car audio?

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deuce42

Well-known member
Joined
Dec 31, 2008
Messages
645
Location
Sydney, Australia
Hi guys

I think I asked a similar question a year ago but cant seem to find the post - am hoping one of you guru's can offer some insight into my rather lame and anaemic car speakers.

So in a nutshell:

1) my car came with a pretty dull sounding audio system.

2) Figured I would replace the speakers. This turned out to be a huge job just to get access to the panels, -  but I put in some 6.5 inch splits into the doors. The splits were Rockford Fosgate "Punch" series splits with a 6.5 driver and 1" tweeter. They seemed from my research to be pretty good and the range stated was 60hz-22khz.

3) Only space for small speakers in the back and I put in a pair of Pioneer speakers which appeared to be 85-22k.

4) Turn on the sound, - absolutely no bass - like I mean you cannot even hear a kick drum in a song. The sound gets marginally better when you turn up the volume, but me thinks this may just be that common phenomena that most people think anything "louder" sounds better.

5) Didn't replace the head unit as I presumed the stock BMW head unit would be ok with decent speakers,  and in previous cars having had speakers changed made huge improvements to sound without having to change the head unit.

So my questions:

* Am I needing a subwoofer? I really have no space for it and had hoped that 6.5" splits and 4"back speakers would sound decent, at least to the extent of hearing so much as a kick drum or bass guitar in a song?

* Is there a problem with my installation? I mean two wires to each speaker doesn't exactly seem like high level electronics and room for any error but have I perhaps done something totally stupid? 

* Did I just buy the wrong speakers?

* Is  the problem the head unit maybe?  It functions fine and people I know with the same car have similar trebly thin and "distant" sounds although none of them have ever changed speakers.

Any advice greatly appreciated.
 
Is the head unit set flat?  There should be some bass. Did they make a good seal when you installed?If the head has a mp3 jack input you can shoot the car with a sig gen or if you are iSomething enabled you cant go wrong or broke with AudioTools.  You can test polarity for an extra $8 or so.
I would look to the install if there is less bass then from the factory.
Sub?  You can drive yourself crazy trying to make a control room in a car!
Mike
 
The head unit is most likely the weakest link... even in some cars with factory installed Infinity/JBL systems I've found that an aftermarket CD player with a Mosfet amp of ~50W x4 will make dramatic difference.

Even better is dedicated amps to component speakers/subwoofers.

If your head unit has RCA outputs, you can opt for a standalone 4way amp to power the drivers which will make considerable improvement.

 
Just as in the world of Engineering, "no bass" can point to inverted polarity issues.

Can you isolate the front/rear and see if the bass gets louer when fading F/R, and further isolate each speaker by L/R balancing to one at a time?  If the bass gets LOUDER as you remove other speakers, then you've got a simple polarity issue.  As absolute polarity is not crucial for Car Audio IMO, just get them all working together by flipping the +/- on the ones that seem to detract from the bass.

Aside from that, most factory radios have all kinds of dynamic EQ and "Loudness" type "enhancements" along with variable volume with speed and other processing, and these can really screw up the audio - but I doubt the end result should be even less bass than the stock speakers pumped out...

There are numerous devices meant to "learn" the Head Unit's non-linearities and correct them in order to present a "corrected/flat" signal to an external amp while retaining the stock Head Unit's aesthetics and functionality.  If your radio is doing such things, I would highly recommend looking into these units.  I believe Alpine, JBL, and Audio Control make such boxes.

8)
 
What model BMW?
Have you looked at this site? http://www.bimmerboard.com/

As Randyman posted check for inverted polarity issues.

If you have a different brand of speakers in the back maybe they move opposite?
 
If polarity is not your issue, the next place I would look is at the volume of air behind the woofers. If the woofers are not mounted to a very stiff panel, the panel can absorb a lot of the bass. Sometimes this is not the problem, and it's actually an air volume issue. The woofer may need more mechanical resistance. An inexpensive way to check this is to pick up a pair of those foam baffles. XTC makes them. What I do to experiment is to cut out a quarter sized hole in the back to vent it, because without a hole they create too much back pressure (in most cases). I keep adding holes if necessary. If it sounds good, you can take it a step further then and fiberglass it to stiffen it.

Most of the time though, the factory head units are tweaked in ways for the factory speakers and don't sound right with aftermarket speakers. The other thing is, some factory head units now come with a subwoofer option. When that is on with no sub hooked up, it may be crossing over the low end to a sub that isn't there.
 
Thanks for your responses guys

So used the front and rear fader and left write balance extensively so hear if there were bass frequencies returning but sadly not. Each speaker in isolation is as thin. I am taking this to mean that polarity is not the fault then.

As for the head unit, its pretty basic without any real frequency adjustable parameters other than treble and bass.

Perhaps it is about mounting with "airtight issues", although I thought I had done this correctly and even the back speakers have no bass. Like I say, i am not looking for a mobile nightclub on wheels, just to hear the kick and bass guitar in any song.

Will maybe look to the mounting again of the whoofers.


 
Post what make/model of speakers you installed, as well as the make/model of head unit (or make/model of auto if it's factory)

I'm betting if you were to stick any recent make pioneer (or other) head unit equipped with ~40-50W (per channel) Mosfet you'd see a huge improvement.

Factory head units suuuuuck from my experience.  Check your old speakers for a W rating and compare to those you installed.

Something else to check, sometimes aftermarket speakers have passive HPF installed near the terminals. 
 
Okay thanks

So here is the link to the speakers:

http://www.rockfordfosgate.com/products/product_details.asp?item_id=112892&locale=en_US&p_status=

The head unit is sadly just a standard BMW "business CD" unit - doesn't seem to have much info available other than its manual here:

http://www.bimmerfest.com/forums/attachment.php?attachmentid=89006&d=1161410207


Maybe the head unit really is that terrible - I am just stunned since even the most basic of hynundai or nissan car head units sound a complete millenium better. I mean a whole new world better. 

Couldnt locate any hpf's near the spearkers.

I guess I could get a new headunit just was more concerned about the aesthetic of the interior to match and the steering wheel controls. The dash is a strange shape and the headunit fits with its contours. The steering wheel buttons control the audio and worried aftermarket head units may present problems.

Tried to do a search on the headunit on car forums and some people even seem to say they didn't mind the head unit!  I am just so lost!

Thanks once again
 
Assuming you have the polarity correct...my uncle got 4 new 6 inch speakers for his truck that he put in, and his complaint was not nearly enough bass. So, we went out and got a 50-100? watt amp and a decent little dedicated sub(10 inch)..., wiring, proper car audio power connectors, etc...dialed in a nice mix of sub on the amp...boom, problem solved.  8)
 
deuce42 said:
4) Turn on the sound, - absolutely no bass
That is pretty much typical of this type of set-up. I've had several american cars (Corvette, Cadillac, all sorts of Chryslers) fitted with the best audio factory options of the time. They all rely on heavy EQing and some sort of dedicated bass speakers. To this day, the best car audio system I owned was in a Chrysler Voyager, had 2x6.5" in the front and 2x 6x8" in the rear. The 6.5" were driven directly from the head, but the elliptics were fitted with a booster with tons of EQ.
In the Corvette, I had the Bose system, which is pretty good sounding. The only problem is the electronics that die  - very unreliable. I bought aftermarket replacements, that are supposed to be much more reliable, but they are flat - no EQ. The sound is horrible.
5) Didn't replace the head unit as I presumed the stock BMW head unit would be ok with decent speakers,  and in previous cars having had speakers changed made huge improvements to sound without having to change the head unit.
Problem there is you need some serious bass boost. Your head may be capable of providing this bass boost, but may not have enough power to sustain the resulting power demand. 15dB boost (which is quite typical there) requires 100W@LF to match 4W@midrange.
Am I needing a subwoofer?
Sub is one solution, not the only one.
Is there a problem with my installation?
That's always a possibility. Other posts indicate fault-finding methods.
Did I just buy the wrong speakers?
It is a possibility. The paucity of specs makes no conclusive evaluation
Is  the problem the head unit maybe?
I don't think the frequency response could be that bad. What happens when you crank bass? Basically, I have the same problem in my Mercedes Vito. The head is quite good, but delivers only about 15W per channel. Since it is the ute version, it only has two 5" speakers in the front doors. Sounds like diluted piss. If I crank the bass control I am gratified with instant level drop - there is a limiter in the amps!
The personal version of Vito, the Viano, has a much better system, with the same head and a 4-channel booster with built-in bass boost.
I have tried to find one on the aftermarket but haven't found one that met my demands in terms of specs, price and ease of integration.
 
Speakers are fine. Q=0.7 at 60Hz

On infinite baffle it would be down 3db at 60Hz which is plenty good (better in car).

In small sealed box the bass limit is:
10"x10"x10" Q=1 at 84Hz
6"x6"x4" Q=1.8 (5db bump) at 150Hz

So it isn't a box-volume issue. But do you have a baffle or is it wide-open front to back? Door speakers are usually in a hole in a cardboard panel which covers all the holes in the metal on the inside of the door. If you are driving around with the upholstery off and seeing all the window mechanism, that's your bass leak. If the trunk-shelf has extra holes for defroster etc, or your rear seat back is dropped/missing, that's a bass leak. A Six with no baffle will fall below 1KHz.

I hate to come back to the radio, because it really "should" be fine in a basic-car way. But.... bring your 3rd-best home speakers out to the car and hook them up. Standing on the ground the bass is thin (no room support); inside the shut car should boom (small-room bass support). I bet this is fine; R-F Kickers are quite OK unless you got some defects.

My '02 Accord EX setup, I can't complain. Four channels at ~~18W. Could use more bass. Door speakers are semi-cheap, and too hard to get out. Deck speakers, I replaced with the most butt-kicking 6x9s I could find. I can hear deeper bass in the car than I could in my DAW room. Does run out of raw power on the highway. My next trick was gonna be two 12"s firing through the drop-armrest in the back seat and 400W behind it... but I got to a point where I didn't need any more music in my life than what I got in my day-job.

I *HATE* the controls on many car radios. The designers clearly don't use them. Your radio has a bass knob cleverly hidden as a musical note; be sure it is set flat or maybe +2. (Don't depend on radio bass-boost: most CPU-ed radios will dial-out bass as volume is dialed-up.)
 

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These are amazingly detailed responses and I am really very grateful. Thanks everyone, its given me a lot of info to go on.

Will work at finding "seals" near the speakers and them maybe consider the sub from there.
 

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