W124 sound system/engine performance drop!

[Niks]

On monday I spent half the day installing my sound system in the car. I had to fit in a amp wiring kit to run from the battery to the boot for the amplifier to drive a subwoofer.

I have a 1800W amp driving a 1000W subwoofer, used a 4 Gauge power cable from the battery to the amp. Ive also grounded the amplifier to the chassis of the car too.

I noticed today on the way home from work that if I crank the volume up with the bass going, the engine feels like its lacking some power compared to before I installed everything. It has a slightly "lazy" feel to it.

Im not sure whats going on here. Does this mean that the sound system is taking too much power from the battery or alternator so there isnt much left over going to the engine? Or have I done something seriously wrong?

 

[Sp!ke]

What rating is your alternator, how many A/H is your battery and did you fit a capacitor in line with the amp?

It sounds like you're sapping your battery to the extent that it is effecting your spark.

 

[Niks]

Hi Spike,

I have no idea what rating the alternator is, how do I find out?

The car has an original white Mercedes Benz battery in it, it has the part number written on the top of it. If there is a specific one for a 1995 E280, then that would be it.

No I didnt fit a capacitor in line with the amp as I couldnt push my budget far enough to get a good high quality one. What I did though was fit in a Rockford Fosgate power splitter block which will enable me to add a second amplifier if I chose to at a later date for future speaker upgrades.

 

[bolide]

Does the car drive OK with the system off?

I'd park up, crank up the system and check the DC voltage at the amp terminals with the engine off and then with it on. Have another voltmeter on the battery & record both voltages

I suspect you'll see a decent voltage drop at the back of the car. If you do, run 0 guage cable instead with a good fuseholder up front. Then do the Big Three

You might be better off with a second battery in the back and a split charge system. I'd also bypass the splitter till you need it - it's just another source of voltage drop

I'd forget a cap. It won't hold enough charge to make any real difference

Nick Froome
www.w124.co.uk

 

[grober]

Have you checked the flux capacitor?

Sorry couldn't resist. Bolides advice is good.

 

[MBK]

i'd go with boldie's advice on the double battery wth split charging. i used to have the same problem with the sound system drawing too much power. I just dont crank up the sub so high anymore lol. (i can change the amp level from driver seat so its easy)

 

[Niks]

Thanks for the input guys, I tested it again this morning on the way to work. With the volume down, the car drives fine and the power delivery was back to normal. With the volume cranked up and the sub going around 60% of power (probably 600W rms), there was a slight power loss.

I think i'll need to check out this split charging system as it might be the only way to go.

Even if I put a 0 Gauge cable in, the power cable from the alternator itself is no where near 0 or even 4 Gauge so there is a limit on how much power it will allow to be extracted from the alternator itself as that would be the source right?

Maybe another alternative would be to try a new Bosch high power battery and see if that makes any difference. If it doesnt then it will have to be the split charging system route.

Kully, what amp and how much power are you running?

 

[MBK]

Hi Nik,

Im runing two Phoenix Gold Qx Amps, my mono is 900watt powering a JL Audio 12w6v2 and my stereo amp is 350.4 its powerings two sets of Phoenix Gold Tantrum components front and back. i normally run the sub at 10% just so it accompanies the music but when i'm cruising i whack it up to 80% theres not really a power loss in the engine as such just on idle when the bass line drops the revs dip a little. but once your moving no real loss in power. If your local to Greenford drop me an PM and i'll help you set it up.

Also try a Dry cell battery like odyessy or a yellow top these help alot.

 

[pupsi]

If you're gonna try a new battery, then just wire it in as your second battery with a split charge relay. They are around £20.

And do as bolide said regarding the big 3 and running 0awg.

You can pick up a 0awg wiring kit for £35 off eBay which is a good price.

 

[Number_Cruncher]

I find these quoted power figures a little odd.

If the alternator can produce, say, 60 Amps at 14 Volts, that's 60x14=840W

So, there's no way to continuosly run at thousands of Watts without discharging the battery, or two batteries, or ten batteries, or ten batteries and ten capacitors!

This electronic amplification must be seriously inefficient.

The total sound power from a packed Wembly crowd is just about sufficient to boil an egg! Or, phrased another way, even small sound powers can produce very large sound pressure levels.

 

[Niks]

Kully, Im guessing this system is in your W124 right? You mentioned component sets up front, did you get custom door builds/pods to put them in? This is something im looking to do as well as I want to put in a decent set of Components in up front and back running of a separate 4 channel amp. At the moment im just using the standard speakers as the Alpine coaxial ones I bought ended up being the wrong size at 5.25".

Also, im not really a fanatic bass head, the sub needs a lot of power to be heard properly as the car is a saloon and the petrol tank is right behind the rear seats.

 

[MBK]

Yeah this is all in the 124 Coupe, if i remember correctly you can get 5.25" to fit in the front oem spaces, i've thought about door pods too, AKA$H has some really nice ones on his coupe.

 

[Howard]

How about cutting a bass port under where the first aid kit goes ?

 

[MBK]

thats what i've done or was already done to the car when i got it. bass sounds full bodied.

 

[Howard]

In my old coupe i could only get 10 cm Infinity References in the front dash mounts ...

The rears take 5 1/4 inch IIRC , but i had to make 1/2 inch MDF spacers for mine as the speakers were too deep.

 

[MBK]

i done some moddding to the oem dash speaker holes while my front screen was being replaced so i squeesed in 5.25" but looks OEM when you put the speaker covers back on.

 

[Howard]

Good skills !

 

[MBK]

yeah i was just lucky i needed the windscreen replacing. Howard was the Whale yours? it looked a really nice motor.

 

[Howard]

Yep , the Whale was mine .

I loved that car . Simon has it now in Guildford , so it went to a good home.

 

[Niks]

I tried to put in the 5.25" in the front dash but the holes arent big enough. If you managed to do it in yours then maybe I might have a shot at modifying them instead of selling the speakers.

Jenhert do door cards for the W124 saloon and coupe. They are also available without the speakers which works out cheaper but they have 2 holes in them for 6" drivers and need a little modifying to fit them onto the door. I got told the dealer for Jenhert closed down so now they are trying to find new dealers to distribute their products.