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.

After reading all of the posts above (thanks everyone) I'm wondering if the issue is not power, or speaker selection, but installation.

I'm using an enclosure sold by Pelican (Moch-1 underdash). Here's the link: Pelican Parts - Product Information: PEL-MOCH-2000S

The enclosure does not completely seal around the edges, and the back of the speakers, the magnet, may actually be in contact with the structure of the car. Would this cause me to lose mid-range and overall volume, forcing me to push the volume to the point of distortion in order to hear the tunes over the open-roof road noise?

Are there installation instructions or does anyone have any guidance to help me improve the job I've done?

I had one and sold it - put the speakers in the door. Best place to mount the tweeters is in the corner where the windshield, dash & A-piller all come together.

That may not solve your top off noise issue, but will be better than the mock-1 (no, I did not mis-spell it).

Yes exactly. Overstating the obvious but the closer you get speakers to your ears, the better you will hear them, especially tweeters.

Not simply closer, but also line of sight. The higher the frequency the more directional it is, so pointing the speakers towards your ears especially the tweeters will give you better results and better 'staging' of the sound.

To appreciate what you have you need a Lexus LS4XX and a 120A alternator upgrade. Or you could settle for the more than satisfactory LS4XX sound system. But given the overall tone of your post you probably already have coffee can extensions on the exhaust tips and that doesn't look good on a 911, let alone an LS400.

There is NO audiophile worth their salt that would go to the EXTREME sound level you are touting, certainly not, NEVER, in a 911. Sorry this previous statement is just WRONG. There is NO car venue would that would justify your extreme.

Absent having a concert hall no TRUE, actual, audiophile would go to those EXTREMES.

But good luck with your hearing once you reach your seventies, or even sixties.

Oh, my '78 Targa has a Kenwood "head", a Kenwood multi-CD player under the passenger seat aong with a Kenwood 5 channel 250 watt Amp. 4 upgraded dual cone speakers (6.25" front, 6X9" rears) with integrated crossovers (polarized capacitors GONE!). Kenwood Amp. includes a DC-DC voltage up-converter, ~200 volts for PEAK drive to those speakers.

NOT a RICER or teenager (72) so sub-woofer NOT required.

Nice system if/when I'm going slow enough, say in a rresidentual area or city stop and go traffic. On the road "at speed", top on or off, system OFF.

Oh, QUIETEST summer use only tires that are available for a 911, and a spray can (4) of undercoat discharged into each wheelwell.

To each his own... I mean that's coming from a guy with a completely removed stereo in his 911 but what's the difference between an extreme audio system and an extreme engine build or an extreme suspension build?

The most valid point in your post and the one thing I do hope he takes your advice on is the hearing loss.

wwest's posts must be read with a generous helping of salt.

How many us would tackle an extreme engine rebuild, 800 HP, say, without KNOWING that ancillary issues (suspension?) would have to be addressed in order to take advantage of that 800 HP.

Op, in effect, is building a 1000 HP engine without addressing some very obvious ancillary issues, like the WRONG car to begin with.

That depends on tires, roadbed type/condition, top on/off, wheelwell/carpet insulation, and.......

SPEED (wind noise)!

Basically there is NO audio sound system that will be functional fidelity wise in a 911 "at speed". Well, maybe the 996 and beyond.

But even my '01 C4 benefitted greatly from "quiet" summer use only tires and a spray can of undercoat into each wheelwell.

if the amp really has an output of 250rms per channel bridging channels 3 and 4 will be more than enough to drive about 95% of the subs available today. i run a pair of 8" subs that are seeing less than 200rms each and it is overpowering if i want it to be.

no aftermarket headunit in the world puts out 100rms. the average is 18w per channel and if you get certain alpine units you can buy a very small add-on to the hu amp that ups it to 45w per channel.


your front stage distorts for one of 3 reasons:

1. you are sending them too much power
2. you are sending them a clipped signal
3. your crossover point it not high enough for the speaker

i currently run an active system consisting of a pair of 1" tweets, a pair of 6.5" midrange in the door and a pair of 8" subs in a rear seat delete i made. they are powered by an alpine pdx5 (roughly 120x4, 400x1) but i am by no means using all of that power. my system is more than adequate for open top driving on any road.

OP, i would suggest moving the speakers into the door to start, but also adding some vibration control of some sort. that will dramatically increase the output of your front stage. see my audio build thread for detailed pics on how i treated my doors. i would also suggest crossing your front stage at 100 at a minimum, maybe even 120. let your sub handle the sub duties, that is it's job. low frequencies are omnidirectional, and in the small cabin of a 911 you should be fine without any time alignment.

what are the specs on your subs and the enclosure? installing them with too much, or too little, airspace can make any sub sound like garbage.

another problem with the Mock-1 'enclosure' is that speakers should be rigidly mounted & that thing is flimsy & flexible

I am waiting for the ebay pic of the spray can of wheel well undercoat next to his SPAL fans... Welcome WWEST, I am glad to see you are the resident expert on this as well...

Yup I meant total power, the amount of power being talked about here just surprises me unless we're building a competition audio system here to blast away everyone in a parking lot, but especially if it's hard to hear. I was actually incorrect about my headunit too, it's 50x4 peak (how they advertise it of course), 22x4 continuous, or 14x4 RMS and I've found this to be more than adequate for my two 6x9's in back and 6.5's w/ tweeters in front.