New amp setup

SanPhire · Post by **SanPhire** » Mon May 16, 2005 11:44 am

I'm currently hauling around a set of Kenwood HQ 7x10s with 340W on tap, a set of Infiniti 180W 6x9s and some Alpine S-Range 13cm + tweeter pods up front (I think these will handle about 100W)
I'm also looking to get a 10" or 12" sub to bring the bass in.

What I'm hoping to get hold of is a 3 channel amp to drive the sub and a low-passed version of the rear-speaker signal to run the 7x10s
Then a 4 channel amp to run the rest of the rear signal and the front.
I has some questions which are:

How does the 480s altenator stand up to running ICE - what sort of current can I place on demand without having to worry about the battery not getting enough charge or burning the altenator out?

Does anyone make an ammeter that will show the current pulled by the car on a dash display?

Who make nice amps?

Who make nice cross-overs? (I'm studying filter design at uni - but I don't want to have to think!

)

rpruen · Post by **rpruen** » Mon May 16, 2005 9:30 pm

Nice amps?

Alpine, Rockford.

Crossovers?

Go for an active crossover, you won't regret it

I'm guessing you have access to white / pink noise and some test kit

The alternator.....

The 480 alternator is a bit sad at only 70A, and 40A of that is needed to run the car electrics.

Ammeters are fairly easy to do. Best to use one that has a remote resistor, or that uses the earth strap as the resistor. That way you have minimum extra resistance in the circuit.

Richard

480_rocket · Post by **480_rocket** » Tue May 17, 2005 9:11 am

I think every thing should be run active crossover'ed. Are there on the market than can set up a passband for the sub? I'd like to run a steep high pass slope at say 25Hz-30Hz.

rpruen · Post by **rpruen** » Tue May 17, 2005 3:24 pm

Yes there are.

Mine does that for the subwoofer, and also for the woofers. The midrange and tweeters have a fixed rolloff though.

It's sadly not fitted at the moment. Mostly due to lack of space, and also that I keep having to fix the car.

Richard

Jamo · Post by **Jamo** » Wed May 18, 2005 3:08 pm

If you want good bass get a seperate mono amp for the subwoofer, preferebly class D.

It will make a huge difference on bass output.

Also what budget limit are you looking for on the sub?

You must get a sub matched to the correct sized box, don't buy a pre made box if you have the skills to make one yourself.

i've got a pioneer 9400 head unit with built in adjustable x overs so i don't run them seperately.

robkendall · Post by **robkendall** » Wed May 18, 2005 6:32 pm

would a capacitor help with the draining (or not as the case would be!)
i think i saw some that can be set to provide power on demand (starting car, deep bass bits?)
that way, the power wouldnt all be drained from the battery/overload the alternator?

rgrds
rob

Jamo · Post by **Jamo** » Wed May 18, 2005 7:27 pm

robkendall wrote:would a capacitor help with the draining (or not as the case would be!)
i think i saw some that can be set to provide power on demand (starting car, deep bass bits?)
that way, the power wouldnt all be drained from the battery/overload the alternator?

rgrds
rob

Yes, connect the cap as close to the amp as possible, also be wary of cheap caps as they have a a low surge voltage limit of about 16-17v ideally waht one 20v plus to be safe.

rpruen · Post by **rpruen** » Wed May 18, 2005 9:06 pm

Yes the cap will help with sudden heavy loads. It however won't help stop the battery going flat, since the alternator / battery still need to supply the total power requirement.

The capacitor is just a storage device for electricity. Being close to the amp it means that there is a store of power close by (and very quickly available), so surge loads don't have to travel over the supply cables 'as is' but are smoothed out. That helps to stop the resistance of the cables, and (internal) resistance of the battery causing volt drop.

You will find that the battery will not last quite as long with a large capacitance connected, as it smooths out the slightly bumpy output of the alternator. The battery actualy likes it charging current to be lumpy, rather than smooth.

Richard

JohnTurbo · Post by **JohnTurbo** » Thu May 19, 2005 12:44 am

Yes funny that, same with nicads...have a very expensive pulse charger for them.

SanPhire · Post by **SanPhire** » Thu May 19, 2005 2:40 pm

Ok - cheers for the advice guys - so a few more thoughts and Qs!
1st up 30A isn't much to play with - I do have a 440 air-con altenator in, but its a bit battered off a scrappy. I think its rated at 80A which gives me 40A to play with... I'm going to need something that will either cap the power heading to the boot, or an ammeter into the dash.
Does anyone make automative ammeters? I haven't been able to find them yet, and asking an ammeter to watch over 30/40 amps seems a lot to ask! <feelin dumb - should know how to do this!>

Thinking about active x-overs... but they're damn expensive (even on e-bay) for what they are. I guess you pay for someone else working out the component values - - - ok, so I'll have to go hunting for my lecture notes and my MATLAB cd and remember how to do switched-capacitor filters - at least I can tune them the way I want them that way!

The sub is looking to be the Alpine 12" S-range beaut. Double-stacked magnets and a genuine 18Hz response - - - now we're talkin!

Hmm... mono-blok D-class is tempting me - - - shh.. listen, you can here it call to me... but this has all got to go onto a summer wage slip!!!

Will be getting a good dude I know to do the sub box as I want it to be ported in-phase properly to get the best out of it.

Also jumping two 24V 0.8F capacitors in the boot with everything else. I just happen to have some lying around..........

480_rocket · Post by **480_rocket** » Thu May 19, 2005 3:51 pm

Active crossovers for PA equipment are dead cheap, maybe something like that could be used if you're handy with electronics.

You can get hundreds of amp ammeters. Most will have a lump of metal acting as the shunt resistor, and the actual meter being just a voltmeter measuring the milivolts of drop across the shunt.

Do some calcs in WinISD Pro to check that speaker will work well in a ported box, I used a PA speaker in my car - not ideal for the harsh humidty but still OK after 3 years.

Other designs to look at are 4th or 6th order bandpass, or even using the rear hatch screen as a super scooper design. These designs, escpeailly the latter if it works well will create some insane SPL with only hundreds of watts.

Jamo · Post by **Jamo** » Fri May 20, 2005 8:56 am

480_rocket wrote:Active crossovers for PA equipment are dead cheap, maybe something like that could be used if you're handy with electronics.

You can get hundreds of amp ammeters. Most will have a lump of metal acting as the shunt resistor, and the actual meter being just a voltmeter measuring the milivolts of drop across the shunt.

Do some calcs in WinISD Pro to check that speaker will work well in a ported box, I used a PA speaker in my car - not ideal for the harsh humidty but still OK after 3 years.

Other designs to look at are 4th or 6th order bandpass, or even using the rear hatch screen as a super scooper design. These designs, escpeailly the latter if it works well will create some insane SPL with only hundreds of watts.

I dont like WinISD, i use Bass Box Pro 6, it's goes into more detail and is simplier to use, although it's only a guide tool, you really need to fine tune the F values to get some good box designs.

I'm a SQ man over SPL, even though i need SPL for my type of music taste.

6th Order band pass is the daddy but takes up some space, currently have a project coming on (when i can get some of Lee's time

)

rpruen · Post by **rpruen** » Fri May 20, 2005 9:26 pm

SanPhire wrote: 1st up 30A isn't much to play with - I do have a 440 air-con altenator in, but its a bit battered off a scrappy. I think its rated at 80A which gives me 40A to play with... I'm going to need something that will either cap the power heading to the boot, or an ammeter into the dash.
Does anyone make automative ammeters? I haven't been able to find them yet, and asking an ammeter to watch over 30/40 amps seems a lot to ask! <feelin dumb - should know how to do this!>

You can fit two alternators, as I did in my Honda. The seccond fitted onto the aircon bracket using a little threaded bar, and some 10mm plate to make a mounting. It took some time to find a sutable longer poly-v belt, but any industrial drive specialist will be able to source one for you. I had 2 100A amp alternators, and that was just about enough for the 1.2KW sound system (input power is more than output, it needed about 150A).

Ammeters are dead easy, you can make one out of a mV meter and a shunt, or from an op-amp and mV meter (so it can use the earth strap on the battery as a shunt, that way no extra resistance or volt drop is created). The op-amp version is better, and requires simple calibration, usualy using a known wattage, such as the headlamps.

Failing that you can just buy an ammeter with a remote shunt. The shunt fits into the engine bay to keep the wires short, and has a pair of connections that go to the meter itself.

Richard

Murf · Post by **Murf** » Sat May 21, 2005 2:04 pm

it needed about 150A

SanPhire · Post by **SanPhire** » Sun May 22, 2005 9:39 pm

Many thanks for the advice guys!!!

- have checked out WinISD - very handy!
Will be thinking about removing the aircon (leaks anyway -

)
and putting in some more current to the beast of doom.

Transimpedance op-amp - - - I'm thinking "I" heads to one end of the earth strap and "Gnd" to the negative post - then calibrating Vout to a voltmeter with R1.
If I'm wrong - someone shout at me for bein dumb!

Looking forward to an ICE install of much beauty.
Will have some UV-activated Quinine solution sloshing around somewhere too... Well - the 480's boot is used to having water isn't it? Might as well make it look pretty!!

rpruen · Post by **rpruen** » Sun May 22, 2005 10:56 pm

SanPhire wrote:Transimpedance op-amp - - - I'm thinking "I" heads to one end of the earth strap and "Gnd" to the negative post - then calibrating Vout to a voltmeter with R1.
If I'm wrong - someone shout at me for bein dumb!

That's it!

Be aware that you need a dual supply. A dc-dc converter would be handy there. If you then use a center zero meter then you can have charge and discharge displayed. Charging current into the battery will produce a -ve voltage from the output, and a discharge +ve.

R1 allows you to set the gain to suit the meter you are using, simply calibrate it to a known value. Handily two 60W lamps (high beams) is exactly 10A at 12V. So if using an 80 mV FSD meter (and the scale is -80 - 0 - 80) then setting 10 mV for a 10A load will make it read in amps.

Hope that helps

Richard

dragon · Post by **dragon** » Sun May 22, 2005 11:03 pm

After reading this thread, I am minded to remind you that the offical language of this forum is English, not gibberish!!!!

--Dragon, not understanding at least 40% of this convo...

rpruen · Post by **rpruen** » Sun May 22, 2005 11:05 pm

It's not gibberish!

It's technobabble.

Right I'll just be off then before I get banned

Richard

martinholmesuk · Post by **martinholmesuk** » Mon May 23, 2005 8:09 am

Where does the flux capacitor go?

Jamo · Post by **Jamo** » Mon May 23, 2005 8:56 am

dragon wrote:After reading this thread, I am minded to remind you that the offical language of this forum is English, not gibberish!!!!

--Dragon, not understanding at least 40% of this convo...

Dude thought you was a Techy?

SanPhire, be careful mate or else your bonnet will end up looking like this