Audio question - hardly a 911 tech question, but still...
 

I've got a 78 911SC Targa. I fitted it with an aftermarket subwoofer enclosure with a pair of 10" woofers. The front speakers are Boston Acoustic separates. The power comes from an alpine 1000w (250 per each of the 4 channels). The sub is using channels 3+4 bridged and bypassed for low-end, and the fronts are stereo and filtered for high-end. The problem is, I don't get enough punch from the bass NOR do I get enough clean volume from the front. It all sounds great in the garage, but at speed, with the top down, I find myself pushing to the point of distortion. One more detail - the front speakers are installed above my knees in one of those aftermarket speaker enclosures that cover all the mechanical stuff in that area (from the edge of the lower dash lip to the firewall.

Do I have enough power? Am I expecting too much from the fronts, given the way I've installed them (not in the doors, and therefore no cavity to reverberate). If I added more power (another amp) and dedicated 1000w to the front and another 1000w to the sub, would that do it with fidelity?

Open to all suggestions.

The stereo is fine, it's the car that's the problem.

Thank you for the reply...I guess the only suggestion I'm not open too is forgoing the car. :)

By that reply I guess you're saying, volume, fidelity and speed in a targa are not going to exist in harmony. I suppose I'm asking for too much, still, I think I can do better.

Anyone out there have some comparative data on wattage you're pushing in a targa or cabrio?

Excellent pun. :)

You are correct. *Coupes* are too loud to deliver really good sound, even when they have sound dampening installed. I can't even imagine a targa with the top off. LOL.

Ok let's break this down a little and make sense of the problem.
In a typical listening room the background noise level is around 50db. A quality sound system can generate about 110db cleanly so your effective S/N ratio is 60db. (Nice!) In a Targa with the top off at 70mph on the highway your background noise level is around 100db in the cabin. A quality sound system can still generate 110db but your effective S/N ratio is only 10db. (Sucks!) You have two choices. You can install a stadium array sound reinforcement system to generate 160db and quickly go deaf, or you can get studio reference quality sound in your Targa with these:
Amazon.com: Shure E2 Sound Isolating Earphones: Electronics

Two things are required for excellent sound: An excellent sound system and an excellent acoustic environment. The Targa simply won't go there, sorry.

The 944 is the same,you find speakers that fit finally without chopping the car around ,and believe me the end result is somewhat disappointing,even tried a variety of high end speakers with little improvement.

hmmmmmmmmmmm.

not giving up that easy. and headphones are like kissing [one's] sister. the passenger has to enjoy too, no?

come on, engineers. don't give up that easy.

That was a nice explanation by Cajundaddy. One of the disadvantages of Targas but I wouldn't trade mine.

Thanks John W.
I prefer top down driving as well but I am usually content with the symphony coming from the tailpipe. My Boxster and the Targa run in similar acoustic circles. After considerable thought on this subject I decided that building the ultimate sound system might be fun but it probably wouldn't ever overcome the fundamental physics of top down driving. Only on long straight highway drives do I resort to the IEM solution. As always, YMMV.

Consider using bass blockers on your smaller speakers if not already installed, so you can push your highs w/o distortion on the smaller speakers due to bass issues. In effect allowing you to increase the volume of your system w/o distorting your smaller speakers (aka the highs) while at the same time providing more power to your subs, if that make since:confused:, it's late and I have already had a few cold ones. SmileWavy

Using 3+4 channels bridged is not suffisant to have a good subwoofer level.


You should buy an amplifier .


Just my 2 cents.

Show us a pic of your speaker installation. I'd like to know more about your stated power specs and load arrangements (ohms)......

You certainly CAN increase the power amps' rating and buy yourself a tad bit more in the dB world,..but the numbers are the numbers (one helluva noise floor to overcome, providing you the marginal S/N when at speed, top off). Should you opt for more power, be damned sure that you've speakers that can handle it.

As to the passenger, get them an earbud setup, as well!!!!!

BEST!

Doyle

Great reply thanks for the tech.

I was being a bit tongue in cheek with my original response, but seriously, you can engineer anything you want, but there is a cost to implement all of that. As everyone has chimed in, you're throwing everything plus the kitchen sink to the problem, Targa, at speed, and the inherent poor location and baffling of the speakers in the first place.

I have a vintage modded Carver amp at home, with a pair of Kef reference speakers that I paid some ungodly amount of money back in the the early 90's for. It still sounds fantastic because it's sitting in my very quiet living room.

My Porsche has no audio, the radio, speakers and wiring has all been ripped out. It has RS carpeting and most of the sound insulating material has been removed. So I listen to the sweet sweet sound of the engine.

Before you go rocking down the road with your headphones on, check to make sure it's legal in your state. Ever Wonder If It's Actually Legal to Wear Headphones When You're Driving?

I've got a Targa as well, and I tried everything I know (within my budget limits) to get decent sound, and I finally gave up. Now I'm just gonna get the loudest legal muffler I can find and enjoy the revs.

Is the sound in a targa that much worse than a coupe? And 1000w? Seriously? That just seems ridiculous, I've never pushed anywhere near that much power thru a car stereo... cheap amp perhaps? My last car had a US Amps 250w bridged on 1 kicker comp 10" and I kept it turned down to 1/2 power for the entire 7 years I owned that car and I still never could turn the stereo up all the way without vibrating my ear drums out of my head.

In my 911 coupe right now I have yet to install a subwoofer, it's my first car in 20 years without one. I just have a 100w Pioneer head unit powering two Sony XPlod 6.5's w/ 2 tweeters in the doors and two 6x9's in a custom built deck under the back window and on the interstate with the windows down and the sunroof open I still can't turn it up all the way. The 6x9's bouncing off the back window are the loudest, I actually fade it back to them slightly to prevent the front speakers from distorting when I have to turn it up. If I end up installing bass, I've been thinking a powered, low-profile sub that will fit under the passenger seat will suffice. Granted that won't be shaking the car next to me at a stoplight, but I still don't expect I'll have any problems hearing and feeling it.

Yes, it is technically not legal in CA but essentially unenforced on the open highway. Around town I keep the ears open for safety reasons... and the car just sounds so good. :)

If I am going to get a traffic ticket it will likely be for reasons other than in-ear monitors. :D

is the background noise in a targa really 100 dB?


that is louder than being 20 yds from a jackhammer, and WILL cause hearing loss over time

I'm also curious about what the "real" background sound level of a Targa is (not so much for stereo stuff but for hearing preservation). Does anybody have real values?

You can use an SPL meter that is shielded from wind noise to get actual values. I have used one in my Boxster with top up and it's 93-95dbA at 70 mph. Top down on the freeway is much louder. (A weighted, slow response as per OSHA standards) There are even a few iphone apps that are reasonably close the the SPL meter up to 100db. Over 100 db the iphone mic is overloaded and inaccurate.