Need Help With Sound System

[Captain Obvious]

I recently put a newish radio in my Z. I've got a long list of "What I was looking for in a radio", and the best thing I found for the features I was looking for was out of a Kia (also used in Hyundai):

The mechanical install turned out great, and I really like the way it looks and feels. Problem is... It doesn't sound good. The system works as intended, but I want more bass, especially at low volume. It's like the bass is barely there at mid-volumes, and completely disappears at low volume.

I don't know if the problem is the head unit, the speakers or something else. Have we got any audiophiles in the braintrust that can bring me up to speed with theory stuff?

[Sean240Z]

I just installed a system in my Z. This was the first install I've done, but I am very happy with the results. To give you a hand, we're going to need some more info:

- what speakers do you have installed?

- do you have an amp installed?

[Captain Obvious]

The speakers are 6x9 Sony Xplods that came with the car from the PO:

They are mounted right behind the seats into the 280's false pressboard hatch area floor so there's plenty of volume on the back side of the speakers.. Location is such that the magnets hang right over the cargo hatch recesses.

The only amp I have is the one located in the head unit, and to be honest, I suspect that's my problem. My suspicion is that the factory head unit just doesn't have the balls to drive the low frequencies to the speakers and that's why I get no bottom end. However, before I simply start throwing money and equipment at the problem, I was hoping there was some way to confirm what's going on.

I know "doesn't sound good" is very subjective, but are there tests I can run? Questions that can be answered? Better descriptions of what I hear that can be provided? You know... The kind of stuff that the audio-geeks live for!

Edited October 13, 2013 by Captain Obvious

[djwarner]

I think the first question is whether the head was set up for a sub-woofer? Or whether the settings in the head have the capability of supplying a sub-woofer output even though none were installed in the previous car. When running a sub-woofer, low frequencies through the main speakers are attenuated. Also, if the front speakers were tweeters, low frequencies will also be attenuated.

Do you know about the particular installation the head came out off?

[Walter Moore]

Do you know how it sounded in the original car? I ask that because frankly the stereos in the Hyundais that I have rented in the past year or two were miserable.

[Captain Obvious]

Thanks much for the help guys!

djwarner, The head unit came from a Kia Spectra. Didn't make note of the year, but they used this radio (and like two others that are pretty much identical to it) in almost all the later model single-DIN Hyundai's and Kia's before they started going double-DIN. There are like three single-DIN models that all have the same faceplate functions, but the buttons are moved around to different locations. It's my assumption that the majority (if not all) of the electronics behind the faceplates are pretty much identical.

I do not know for sure if there was a subwoofer used in the original installations, but I doubt it. I can tell you however that there are no subwoofer specific connections on the back of the head unit. I can also tell you that if they did use a sub in the original application, it used high level inputs because there are no low level outputs from the head unit.

Walter, That's also a very good question, and I do not know the answer. I bought this model because it had the mechanical and human interface features I wanted, but I have no idea how it sounded. For all I know, it sounds just as good (bad) in my car as it did in the OEM installation. Kinda stupid, I know...

So if it's just a crappy radio, can I throw additional equipment at it to make it better, or am I back at square one looking for a different head unit?

[Mikes Z car]

An experiment might be to temporarily run wires to move the speakers to a different enclosure like an el cheapo large cardboard box or something more substantial (or headphones?). I noticed when I experimented with speakers many years back that it was critical for good bass for the front and back of the speaker to be isolated acoustically from each other (I think bass reflex ports work in spite of this) so that air flow coming out the front could not easily flow around the edge of the speaker to behind the speaker. I think this is one of the reasons the stock Z speaker has no bass, it doesn't have any material around the edge of the speaker to seal it up against the finisher on the inside of the car, hope that made sense. Take an old 2" speaker, connect it to a decent audio source with bass and cup your hands around it and use your knees to help it sound better. I notice Bose uses a long tube behind some of their speakers that zig zags back and forth to make the tube longer (can that idea be put in a Z?). Might try reversing the polarity of one of the speakers since they feed to a common volume, audiophiles wouldn't necessarily approve but I had that work well with two 6X9 speakers in the tail light finisher of a GT6 I once had to boost the bass, the finisher was similar to the finisher in the early Z cars.

Edited October 14, 2013 by Mikes Z car

[Captain Obvious]

Mike, Thanks for the thoughts. I did not install sealing around the edges of the board in which the speakers are installed, but it's a pretty tight fit even without seals. I understand the theory, but I believe that level of improvement is in the minutia. I'm no expert on the topic (obviously), but I think I'm looking for big steps first.

Short story on the speaker polarity is that I know it's correct. Longer story is that months ago when I did this install, I even went so far as to doubt the accuracy of the markings stamped onto the back of the speakers. So I took turns with each speaker hooked up to a DC source and verified the direction of the cone travel. I can guarantee that I've got the speaker polarities correct and they are all pushing in phase.

I've got a pair of pre-boxed speakers (ones with their own enclosure) installed in a different car. In that other car, they sound pretty good. Memory says I tried those boxed speakers in the Z and they didn't sound as good in the Z as they did in the other car, but maybe I should try that again...

[30 Ounce]

As mike said, try reversing one of the speakers + & - wires. If you connecting one of them backwards accidentally you will have no bass. Also try sealing the speakers to the box with silicone. That will make sure you have no air leaks.

[Mikes Z car]

I am actually thinking that the volume behind the speakers on the back deck is too small and flat but that is no help and assumes the radio itself is fine for bass. How can it be made better? I want something in my car that sounds good (good bass) and keep hoping a solution will show up. Cap'n if you solve the search for good bass please post it here. Would it help to have an event at various meets where sound systems could be evaluated by everyone? Just ideas. When I got my Z the sound system I thought sounded wonderful but to make the bass there was a large radio shack speaker box system with two 8" speakers and tweeters. I felt that it invited someone to break a window and swipe it so I gave it away (literally). Stealth is good?

Edited October 15, 2013 by Mikes Z car

[30 Ounce]

You could do what I did and use the spare tire well for a sub enclosure. I used 1 10" alpine sub and 300 watt amp and get a measured flat response from 20hz-200hz .sounds awesome. See my garage on this forum.

[240260280z]

Hey Bruce,

If you could install an EQ of some sort (Graphic or Parametric), you could tune the system's spectrum to your liking. Some radios have a provision of mid stage access at -10dBV or +4dBm levels for connecting an eq. If not, you can install a "pad" and load the power amp section of that radio appropriately then tap off this at the appropriate level to feed an EQ followed by a new and dedicated power amplifier to drive the speakers.

I am an old audio geek with applied physics and many years of recording experience and studio/room design. Good sound and car audio are difficult to say in the same sentence. The road noise, vehicle noise, speaker placement compromises, internal geometry, mix and proximity of highly reflective (glass and plastic) and highly absorptive (seats and carpets), and modal excitation of the confined space make it a difficult place for good sound.

All of the problems in the last paragraph will typically make the sound reaching your ears usually one or two of the following:

• bright and tinny
  
• mid-range and honky
  
• low and boomy
  
• peaky at certain frequencies
  

A parametric or graphic EQ can often lower the offending frequencies or enhance the missing ones, however it is a quick and dirty compromise but the best (cost and result) solution I have found.

Here are a few other tricks:

If you can move the speakers around to have the mid and highs aimed directly at your ears/head .... helps with clarity and definition. Using glass as a reflector to accomplish a nearly direct path with one reflection is the next best compromise that Bose typically has applied since the old 901 speakers. (Aiming mid and high drivers at windshield or rear glass to reflect at your head is an example).

The mids and highs travel as direct rays like light so you can aim these drivers easily and if you can see the driver with your eyes, it is a good placement. The secondary reflections will also travel straight lines, so if you can see the driver in a mirror that is held against a flat reflective (hard) surface, the sound will also travel that longer path and interfere with the earlier and direct wavefront. A typical example would be a tweeter on the left side of the dash with a direct path to your ear and the 2nd reflected sound hitting the glass beside your ear.... not much you can do unless putting foam on the reflection point is done.... not practical if you want to roll down or look out your window ..... so you have to compromise. Two tweeters in each headrest is one solution I have seen applied. Works great in a convertible with the top down too,

The low frequencies below 300Hz do not travel as waves but they excite the room/cockpit modally. These are difficult to treat w/o moving the drivers. Typical ways to adjust the lower spectrum are to move the bass driver into or away from a corner as the bass spectrum is often reinforced by corner placement. a neat experiment is to crank up your home stereo then walk your head into a corner of the room.... the bass really builds up! Putting a speaker there helps increase the bass. You can also do this at home by moving your speakers out into the room then into the corners... you will hear the bass increase (you can simply move a L speaker into a corner and an R speaker in the midlle of the room then use your balance control to A/B them if you want to be geeky and empirical for real time comparison...you can do the same in the car by having your son move the drivers while you sit in the drivers seat and a/b )

Some manufacturers install bass drivers in the foot wells to excite that area to enhance bass by taking advantage of modal buildup in the confined space. Others use the rear trunk. this can usually enhance the bass but can also make certain frequencies resonate. small bookshelf speakers typically have this problem. Usually it is not a problem but sometimes you can hear it....sort of like the horrible 2,400 rpm drone of the MSA turbo exhaust... the system sounds great until you excite the pipe at these frequencies.

Well that is enough of a dump to get you into and out of trouble. I'll ring you later this week to touch base.

Edited October 15, 2013 by Blue