Stereo install

[Ngueldner]

I am adding a small amp to my car to help me hear the radio with the top down.

Can someone offer advice on the best way to the power cable through the "firewall" fro mthe trunk into the cabin under the passenger's seat. I didn't see a good pass through such a large grommet with a little extra room. I don't want to drill any holes if possible.

Thanks,
Ng
88 cab

[89911]

There is a large grommet directly above your your clutch under the dash. You can speaker cable through there. I cut a small hole through the firewall hidden under the right kickplate for my amp preouts. Cut a 1" hole and then used grommet available at any electrical store to finish. Wasn't enough room to pull all this through the the other grommet.

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8 9 9 1 1, The last of the line.

[Serge]

On my 78 SC, there is a 3/4 inch hole under the dash, about three inches to the right of the brake master cylinder when viewed from the trunk area. There is also another similar opening on the passenger side, near the area where the trunk hinge rests. There are two or three others as well, but I've never had to mess with them. All of the holes I've mentioned are factory, grommeted holes, so you shouldn't need to drill any new ones.

When wiring your amp, try to keep the RCA and power wires away from each other to avoid noise, and make sure you ground the amp to the chassis. Before attaching ground wire, sand all paint and undercoating away to uncover an area of bare metal about the size of a quarter. I have had numerous amp problems in the past that have all ended up being caused by a weak ground.

I forgot to mention, you need to cut some rubber out of the center of the grommets to pass new wire through them. This is perfectly okay and does not harm the value of the car.

[This message has been edited by Serge (edited 07-04-2001).]

[TargaEuro]

I second what Serge said. Make sure you put a dab of clear silicone over the bare ground connections where they connect to the chassis to prevent corrosion and poor amp performance down the road....TargaEuro

[Eric Coffey]

If you can mount the amp in the front truck (like on the fresh air plenum cover),you can save the hassle of routing the thick power cable through the firewall, and won't have to route any RCA's under the seats/carpet. Just a thought.

-Eric

[MarkY]

The amp in my 1988 coupe is mounted on a piece of wood that is attached to the lid of the smugglers box in the front trunk. Saves the hassle of running a power cord through the fire wall. Also, you don't have to hassle with removing the seat.

A lot easier install IMO.

[Roland Kunz]

Hello

Rule Of all Rules: Whatever you add on be sure you work on a fused circuit or have a fuse within the first 10" after the battery.

Rule one: Use only factory grounds if possible. There is one under the passenger seat. ( 1979 on )

Rule two: Run all stereo groundwires to one point or run a small ground cable beetween the units.

Rule three: The ground cable should have the same size like the plus cable.

Rule four: Don´t buy big amps who will pull 20 amps to heat up your car without making music. Be smart and buy the Porsche under the Amps. ( For example JBL, a/d/s, AMA, Signat ).
Don´t get attractet by the power hype and buy amps that are good for welding but will not make music.

Look how much power they will deliver at 0,001% signal distorsion and how much they draw at idle versus full load.

Rule five: Avoid RCA/chinch cables use DIN or shielded cables. If you run RCA then always cross power cables but never run them parralel or at closer angle then 30-45°.

Rule six: never run RCA in a BMW except you don´t have to pay for the labour or just listen to pop music. Porsche are thank god not so cheap and craped full.

Rule seven: Silicone will not seal very long and it also contains sour elements who well start a batterie, use special electric clear coat or acryl, vaseline.

Rule eight: Don´t beleive in comercials and gold is not usefull on audio applications, except it is massive gold coatet.

Rule nine: The speakers make the music and are more important then the rest so 50-99% off your budget should go into them. If you buy effective units you will not need a seperate amp.

Rule ten: Sound needs a fundament witch is sound deadening and fiddeling. Material isn´t expensive and even the factory speakers will sound much better.

Rule 9eleven: Yes on the 911 the engine is the soundmaster. The engine uses the heatingsystem to generate low vibes witch will kill most bass insatallations while you drive. So you better get a Head unit wich will messure the car sound to equalize the speakers to it. ( Blaupunkt, Sony ES, Panasonic ).

A small amp will fit in the area abouve the passenger side glove box accesible from the trunk. You can run the wires using existing bulkhead holes. One is abouve the radio ( for AC and Cruise ) or at the other passenger side where the heating hose goes up ( two big ones one smaller )


Grüsse

[MarkY]

Originally posted by Roland Kunz:


Rule nine: The speakers make the music and are more important then the rest so 50-99% off your budget should go into them. If you buy effective units you will not need a seperate amp.

Agree with everything you say with the exception of the second sentence in the above rule.

A quality amp (PPI, etc.) will make a huge difference in sound regardless of what head unit / speaker combo you're using. There isn't a head unit made that can duplicate what a seperate amp will do.

PS - I'm not sure what "effective units" are, I'm assumming you meant 'efficient'. Even the most efficient head unit will be outperformed by a quality amp.

I couldn't agree more that crappy speakers will sound crappy no matter what is powering them.

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1988 black on black Coupe
www.cheaterswayside.com/911/gallery.asp?sort=0&userid=339

[nhromyak]

Check out
http://www.caraudioinnovations.com/tips.htm

for porsche installation tips.



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Nick Hromyak
'85 Carrera 7 & 9 Fuchs
Havin' Fun in Sacramento

[Roland Kunz]

Hello

OK basically then a big fuel tank with a big fuel pump will make a more powerfull engine ?


Don´t mix quality with quantity.

Said less controversal the big amp is comparabel to a big cubic engine.
If you compare it to a car then you should drive a small sportscar with a hughe 16 cyl 2000 cui diesel ?

There isn´t enough place to run a big engine in the head unit and so they have very little engines that will not delivery to much power to push the speacker. Then they get on there limit and sound bad.
The best high power head units have 40 Watt peak but will not push more the 5 Watt sinus with a unhaerable distorsion.


Now there are some speakers around who have very expensive drivers and will only need half the power from a normal speaker. Well Strontium, gallium and germanium are the key words.

The calculation is done by the costumer and depending on the usage. There is not one way to go but the mathematics are very simple.

3 dB is doubeling the volume.

Now we make a row.

We just compare three different effective speakers. A will make 85 dB at one watt input. B will make 88 dB at 1 watt and C will make 91 dB/watt

Lets see how much wattage you need to have the same volume from A and B.

I write down the volume and the wattage asfollows;

85dB / 1 / 0,5 / 0,25

88dB / 2 / 1 / 0,5

91dB / 4 / 2 / 1

94dB / 16 / 4 / 2

97dB / 256 / 16 / 4

100dB 65kW / 256 / 16

103dB/ 42mW / 65 kW / 256


OK this is very theoretiacl but gives a picture. ( I havn´t calculatet the below 1 watt numbers. )
Now before I invest into a 2x 1000 Watt monster that will suck 4000 Watt energy I invest the same money in the best speackers that will live with the radio amp and if my wallet is swollen again a get a REAL 15 Watt at 1 OHm with distorsion lower then 0,001%.

Just based on the abouve numbers and say you would like to have 97 dB volume in the car.

A will need a big amp, B can work with a small amp and C can run from the head unit.
Very simple calculation if you also count the big wires and all the other stuff you need for a big amp.
If you look at the 100 dB rating it is much more impresive.

In fact no speacker will withstand the needed power and the volume is not a easy
straight calculation. Music is not a sound generator and good sound isn´t a matter of the wattage or the size off the components. But if you will massage your body you will need some very heavy low end emitter witch will need much power to move the air or shake the body. That has nothing to do with realistic sound. ( Hi Fi )

I´m not interestet in amps that will have a 100 W peak at 0,1% distorsion or can put out 50 amp curency to rod weld my car.

Grüsse

[CamB]

Biggest problem in my experience is the nicest sounding speakers are usually 85-89db @ 1W/1m.

By the way, watch out for dodgy readings - eg Boston Accoustics have 92db efficiency at 0.5m - that is 89db.

Sneaky.

I figure a minimum of 30-50 (REAL, ie RMS into <0.5% distortion from 20-20k hertz) watts will be plenty for your ears.

But all bets are off to power subs.

Cam

[Serge]

Roland

I'm not sure where you got the idea that a higher quality speaker needs less power, but my experience seems to indicate the opposite. MB Quart, a very high quality German speaker company, is known for making speakers that are extremely power hungry. The Q series speakers (which I have) require a minimum of 70watts per channel, and sound better with 150-200 watts each. Try running any MB quarts with less than 50 watts RMS per channel, and they will clip like crazy (I know this from extensive trial and error).

A very decent system can be built with under a hundred watts total, but anyone who knocks the higher power systems quite simply hasn't ever listened to one. The emotional impact that comes from deep, deep base must be felt to be appreciated. Trust me, the higher wattage amps make music, much cleaner and more spatial than lower wattage systems.

To anyone contemplating a stereo sytem, I recommend the following- Don't listen to anybody's hype, but rather go to a store and audition systems in various price ranges to decide what you like best.

[89911]

Wow, this has really gotten off the topic of a hole in the firewall.

[Ted Stringer]

from someone who has done audio work as a hobby, get the best speakers and amp that you can buy. Also usually you will get the best sound if the speakers and amp are made by the same company. I have seen yamaha audio equip go to 180% or higher (the level indicaters were pegged and read to better than 140%) with out distortion. This system was a yamaha matched speakers and amp.

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Ted Stringer
nuke3@juno.com
'84 911 Targa aka pocketrocket

[Roland Kunz]

Hello

I know that the marked goes to what the costumer is asking for.

My numberchart was just out off the stomac to give a example for the physical law. In fact 3 dB is the difference beetween average and efficient units. And the amps made a very speedy development in boosting power. In the 80´s 15 W had been the limit ( Well and i modified the alternator to 13,5 Volt standard Voltage ). Today we have 1000 W if we pay for it. 0,5% distorsion is to much. At 1% cliping you destroy some high frequency emitters and normal people will hear 0,1-0,05 %. People with trained ears will hear even much lower rates. The bad thing is you get " nerved" by them.

On the other hand modern amps have signal to noise levels over 100dB witch is "useless" in any car and even in most home Audios.

I do know MB Quart very well as I had worked with them in the early 90´s. Also Tech Art uses MB Quarts. Other german brands are Canton, Mc Audio, Rainbow, Teufel, Heco, Magnat, Bakes & Müller ( Now Signat amp and T&A speakers )

Efficienty orientatet speackers where covered by Focal, Dynaudio, Mc Audio, a/d/s ( Braun ), Teufel, Bakes & Müller ( now T&A ), Panasonic, Alpine, Clarion, Polk audio, Nakamichi, Yamaha, ACR, Boston, JBL, Klein & Müller, Tannoy, Sony, Rainbow and MB Quart. ( Well shure there are more out there can´t know all )

Those speckers are sometimes not in the cataloges and for example MB Quart makes you every speaker you can pay and follow the phyiscal laws.

The low side and why those speakers are not sold to much is they need very solid and clean installations and they will not pump any bass compared to the "normal speakers.

Now this thread could be very long but to make it short my costumers came mostly from the music buiseness and payed for the "pure sound" and not for sound off scenarios.

Most of them used the time in there cars to listen to new music or to check how there mixes/productions sound in average ambient. They used the equipment as a tool for serious work.

Most off them came with speackers they would like to hear in there car ( Every producer has a typical "sound" ) and the Companys where willing to offer what they could to support them. ( Well thats a nice working situation spend some hours in soundfield labs, mybe this is why I´m so "snoby" on that object )
Mostly the speakers where full active driven without any passive parts. The amplifier for that wher costum modified, later with the full Digital units from Sony, Blaupunkt or Panasonic everything could be made without massive support. ( Well back then the first Soney ES was 10 000 $ or the Blaupunkt Berlin was 500 $ while a normal good car radio startet at 200 $ ).

But 12 speakers in a 928 where driven by 100 W and 80 W where neded for the bass.

This marked is nearly gone since Bose is in the car audio marked, the old W 140 S-Class was hard to beat.

BTW every Bose engennier must play a music instrument so Bose is shure he knows that the man knows what music and realistic sound is.

Good test music are pianos, acustic guitar, violines and women voices.

Pop Music or Techno is not my goal. ( The funny thing is the producers do produce Jazz, R&R, Pop, hard & heavy, trash metall, techno and ambient )

Now if everyone is interesstet in good audio I just have to tell him thet the most importent thing is the headunit that contains the own brain and that the highest sound improvment rates are some work on the car and a set average middle class speakers witch a good head unit and a medium amp.

Everything beyound that well only be need by special interessts and some like to hear pure music while other like to blow there windows out. The investet money is quite similar but it is like comparing a katana with a broadsword.
Both ar killing weapons but they must be handled different.


Grüsse