Power Capacitor???

[Waldo]

I am installing my own stereo system in the boat and have read some things about power capacitors. Does anyone here use one or more for their systems depending on the amperage?
Here is the breakdown of the power that is going in the boat:
*One 4-channel 600watt (65W x 4 RMS), powering 4 - 6 1/2 alpines.
*One 2-channel 800watt (200W x 2 RMS), powering 2 - 10" RF Punch HE subs (separate boxes).
My boat has a dual battery setup and a 65 amp alternator. I don't plan on running the stereo super loud when the boat is not on, but maybe on occassion. What do ya'll think??? I think it is just more $ to spend but have never used one. Any suggestions would help.
Thanks in advance!!!

[ROZ]

It would be to your benefit to have 2 batteries to dedicated to the stereo on onside of a perko, and another battery dedicated to start and accessory on the other side of the perko.
While I believe there is a use for capacitors, I believe that your money is better spent on upgrading the charging system....In a perfect world, your stereo would pull 50amps while the boat is running(stereo is mostly played when beached).....You have a 65amp alternator.
[ April 25, 2003, 04:01 PM: Message edited by: ROZ ]

[riverbound]

I manage the Al&Ed's in ontario. and rule of thumb is for every 500 watts use a one farad cap. but I run a very similar set up in my boat and dont use any caps. they are mainly used if you are having problems keeping the voltage constant in your vehicle.
If you have any more questions feel free to call me at (909)481-8411 my name is bill

[Frosty_pop]

I don't know about a cap, but I run a 110 amp alt. and everything is fine with the boat running, but on the beach if I play it loud, it clips ( shut's off and on ) Do you think I need some sort of cap?

[Tom Brown]

ROZ is the man but I'd like to add my $0.02...
If the amps are well designed and of decent quality, there won't be a lot of voltage fluctuation on the power rails under heavy loads. Of course, at the extreme end of the load spectrum, the power rails will be going wild if there is enough output ICs capacity to tax the power supply.
Adding external reserve current will not make up for a poor amp implementation. It may help a bit, though. Also, the capacitors will help more if you have poor quality amps than it will if you have good quality amps.
Another point I'd like to make is that by going to two batteries for the stereo, as ROZ has said, you will double the amount of current your batteries can peak source to the stereo. This effect is not completely unlike adding the capacitors. Sure, a battery will never be able to discharge anything like a capacitor but I'm just saying it will help.
-- Tom

[ROZ]

Frosty_pop:
I don't know about a cap, but I run a 110 amp alt. and everything is fine with the boat running, but on the beach if I play it loud, it clips ( shut's off and on ) Do you think I need some sort of cap? Protection mode usually happens when you're running them too hot, low voltage, sometimes unssually low impedence, or defective gear.
How long after you turn off the engine do you run into problems?
Are the amps hot?

[Tom Brown]

Frosty_pop:
I don't know about a cap, but I run a 110 amp alt. and everything is fine with the boat running, but on the beach if I play it loud, it clips ( shut's off and on ) Do you think I need some sort of cap? It clips at lower levels on the beach because you're running the system at a lower voltage. A cap will buy you absolutely nothing in that regard.

[ROZ]

Damn! Tom has been keeping little 12v secrets from us! :cool:
[ April 25, 2003, 04:28 PM: Message edited by: ROZ ]

[Tom Brown]

Hey, take what I say with a grain of salt. I'm of the opinion that $40/ft speaker wire and windows on sub boxes are for primadonas. In the case of the windows they can really shit on the performance of a sub box. I guess that's what it takes to win shows, though.
So you see... I'm not really 'into it' in the way everyone else seems to be. :cool:
[ April 25, 2003, 05:04 PM: Message edited by: Tom Brown ]

[Waldo]

Thanks for the input guys!

[Frosty_pop]

Well I am running 2 300 watt amps, one is a Kenwood 300 watt 4 channel that drives 4 6 1/2 in round speakers. The other is a 300 watt 4 channel Sony that drives 2 6 1/2 in round speakers and 1 12 in. pyle sub. It doesn't start to clip till it's been running about an hour on the beach. My brother in law has the same problem with totally different set up.

[Tom Brown]

Frosty_pop:
Well I am running 2 300 watt amps, one is a Kenwood 300 watt 4 channel that drives 4 6 1/2 in round speakers. The other is a 300 watt 4 channel Sony that drives 2 6 1/2 in round speakers and 1 12 in. pyle sub. It doesn't start to clip till it's been running about an hour on the beach. My brother in law has the same problem with totally different set up. Get a volt meter and watch what's happening as you play your stereo. You may find it interesting. :)

[Frosty_pop]

I'm sure it will be interesting, but the question remains... How do I fix it?

[ROZ]

Tom Brown:
Frosty_pop:
Well I am running 2 300 watt amps, one is a Kenwood 300 watt 4 channel that drives 4 6 1/2 in round speakers. The other is a 300 watt 4 channel Sony that drives 2 6 1/2 in round speakers and 1 12 in. pyle sub. It doesn't start to clip till it's been running about an hour on the beach. My brother in law has the same problem with totally different set up. Get a volt meter and watch what's happening as you play your stereo. You may find it interesting. :) Yup. The play time for your setup is an hour before your voltage poops out and the amps kick off.....Some amps shut down at 11.5volts. Some go all they way to 10.5v before they shut down. Most are somewhere in between. Your amp's spec. sheet may have that information....
If you don't want to run the boat to charge the battery(s)every hour, you need to add more juice.

[Havasu Hangin']

All amps have capacitance built in...
Need external caps? Why? If a cap discharges, you need to re-charge it, right? That's just another load on the system.
Caps don't store enough energy to make a difference, and they can only discharge about 50% of it's energy before it drops below 10.5 volts...a battery can discharge over 85% of it's potential before dropping below 10.5 volts.
Caps cost money...audio shops love em.
My 2 caps.

[Tom Brown]

I'd like to point out the other side of extending battery life... efficiency.
The vast majority of the power should be going to the subs. There's no way around this power requirement. Every 3 dB of additional bass efficiency will roughly cut the bass power requirement in half to play at the same volume. A properly boxed and installed sub with an efficient driver is the key to efficiency.
Also, high-pass all satellites in the system. Sending bass information to them will just make them run hot, use more power, and sound worse. This base is working against the sub in a component system. The odds of even modest phase coherency is approximately zero. A high-pass will reduce clipping too.
It's not a good idea to use the same amp for both sub and satellites. At max volume, the sub channels will wreak havoc on the power supply rails causing distortion on the satellite channels (and also making the satellites run hotter, operate less efficiently, and increase the likelyhood of blowing them).
The last thing I'll mention is to stay away from class AB amps for the satellites as they tend to draw a lot of power regardless of the drive requirements. Everyone wants a billion watts on all amps but properly configured satellites should draw very little power.
In my opinion, it usually pays to have a professional configure and install a system when it calls for a lot of equipment and installation choices.
-- Tom :)
[ April 25, 2003, 07:19 PM: Message edited by: Tom Brown ]

[Infomaniac]

A cap is for the "BIG" bass note from the sub. Depending on how big your subs are. It is possible for there to not be enough instanteneous current for that big boom. The cap has it available if needed. Buy them online and they are not that much. My Okie system has 2 1 farad caps. 1 for each sub. Lightning audio brand. Not expensive at all. The cap will not discharge unless needed.
To each his own preference.
I did have a professional look over my installation intentions. Wiring schematic.
Ended up with an Okie installation and way cool sounds after a few changes from his recommendations.
[ April 25, 2003, 07:28 PM: Message edited by: Infomaniac ]

[Waldo]

Both amps have high pass and low pass options...they will be used accordingly.

[Infomaniac]

I have the same subs but 12". An amp for each one and a cap for each one.
I wanted to make the boat system similar to the home theatre system. Descrete amps. 1 for each speaker. Works out much better for sound.
IMHO :D
[ April 25, 2003, 07:53 PM: Message edited by: Infomaniac ]

[Fat Chance]

I'm using my for 4 Channel Kenwood to power 4 Boston 6 1/2's, and 4 Boston 6x9's (at 2 ohms obviously), so I'm beat'n the shiat outta that amp. It doesn't clip, but after awhile at volume, it does shut down..thermal protection. The thing is hotter then a pistol. I'm trying some fans on a relay to keep 'er cool this season. I do run 2 JL 10's bridged to a PPI 2 Channel, all powered by 2 Trojan 6 volt batteries. (a big thanks to Froggy for that one). The system will run for ever, great base, very releiable outside of cook'n the Kenwood after an hour or so...No Cap though, don't think it would do a thing for me.
[ April 25, 2003, 09:33 PM: Message edited by: Fat Chance ]

[Stupid Fast]

Tom Brown:
I'd like to point out the other side of extending battery life... efficiency.
The last thing I'll mention is to stay away from class AB amps for the satellites as they tend to draw a lot of power regardless of the drive requirements. Everyone wants a billion watts on all amps but properly configured satellites should draw very little power.
-- Tom :) Here is a quetion:
What is the difference between an A, AB . And D class amplifier? I have never ben able to find something that said what makes the amp a certian class. Just Use __ for X type install. Even that depends on who you ask( and which amp they have the most mark up on) :D
Thanks
Stupid(thirst for knowledge)Fast
P.S. Tom I was kinda shocked by you serious post. I am still kinda waiting on the punch line. :D
[ April 26, 2003, 04:21 AM: Message edited by: Stupid Fast ]

[beyondhelpin]

Look at the lights on your dash or stereo. If the flicker or dim while the stereo is thumping you probably need a cap. If they stay on without dimming or flickering you do not need a cap.
You problem is probably low battery voltage or poor quality-defective amp with the shutdowns. It could also be bad wiring or a damaged speaker. Unhook each speaker at the amp to isolate the wiring and speaker individually. If it still shuts down after you have isolated each speaker out of the system. It is probably the above problem.
It is also possible for it to also the thermal shutdown. Feel your amps are they hot enough to cook breakfast? If you have two amps powering separately your sats and subs do they both shut down at the same time or just one of them.?
PS If you are running lots of power I would run two batteries isolated from your starting and accessory battery. One more thing don't take your boat home and just park it with the batteries not fully charged. Keep them in good charge state or they will quickly loose their umph. Get one of these.....I have the Pro III with remote. Fifteen amps to each battery! I leave it hooked up constantly at the house and at night when camping.
onboard charger (http://www.cabelas.com/cabelas/en/templates/product/horizontal-item.jhtml?id=0000963013401a&navAction=jump&navCount=2&indexId=cat600056&podId=0000963&catalogCode=ID&parentId=cat600056&parentType=index&rid=&_DARGS=%2Fcabelas%2Fen%2Fcommon%2Fcatalog%2Fitem-link.jhtml.2_A&_DAV=http%3A%2F%2Fa1460.g.akamai.net%2Ff%2F1460%2F 1339%2F6h%2Fwww.cabelas.com%2Fcabelas%2Fen%2Fconte nt%2FPod%2F00%2F09%2F63%2Fp000963ii02.jpg)

[ROZ]

Stupid Fast:
Tom Brown:
I'd like to point out the other side of extending battery life... efficiency.
The last thing I'll mention is to stay away from class AB amps for the satellites as they tend to draw a lot of power regardless of the drive requirements. Everyone wants a billion watts on all amps but properly configured satellites should draw very little power.
-- Tom :) Here is a quetion:
What is the difference between an A, AB . And D class amplifier? I have never ben able to find something that said what makes the amp a certian class. Just Use __ for X type install. Even that depends on who you ask( and which amp they have the most mark up on) :D
Thanks
Stupid(thirst for knowledge)Fast
P.S. Tom I was kinda shocked by you serious post. I am still kinda waiting on the punch line. :D I could give you the "in a nut shell" explaination, but HH turned me onto this website a couple years ago... eatel.net... It's a great information based car audio website. For those of you that just want the breakdown, here it is:
CLASS 'A'
Many class A amplifiers use the same transistor(s) for both halves of the audio waveform. In this configuration, the output transistor(s) always has current flowing through it, even if it has no audio signal (the output transistors never 'turn off'). The current flowing through it is D.C. A pure class 'A' amplifier is very inefficient and generally runs very hot even when there is no audio output. The current flowing through the output transistor(s) (with no audio signal) may be as much as the current which will be driven through the speaker load at FULL audio output power. Many people believe class 'A' amps to sound better than other configurations (and this may have been true at some point in time) but a well designed amplifier won't have any 'sound' and even the most critical 'ear' would be hard-pressed to tell one design from another.
NOTE: Some class A amplifiers use complimentary (separate transistors for positive and negative halves of the waveform) transistors for their output stage.
CLASS 'B'
A class 'B' amplifier uses complimentary transistors for each half of the waveform. A true class 'B' amplifier is NOT generally used for audio. In a class 'B' amplifier, there is a small part of the waveform which will be distorted. You should remember from an earlier page, that it takes approximately .6 volts (measured from base to emitter) to get a bipolar transistor to start conducting. In a pure class 'B' amplifier, the output transistors are not "biased" to an 'on' state of operation. This means that the the part of the waveform which falls within this .6 volt window will not be reproduced accurately. The output transistors for each half of the waveform (positive and negative) will each have a .6 volt area in which they will not be conducting. The distorted part of the waveform is called 'crossover' or 'notch' distortion. Remember that distortion is any unwanted variation in a signal (compared to the original signal). The diagram below shows what crossover distortion looks like.
CLASS 'AB'
As we said earlier, a class 'A' amplifier is very inefficient. This is not good for a car audio amplifier. We also said that a class 'B' amplifier will cause a signal to be distorted, which is not good in any audio amplifier. A class 'AB' amplifier is the best compromise. A class 'AB' amplifier is a class 'B' amplifier which has a small amount of "bias" current flowing through the output transistors at all times. This eliminates virtually all of the crossover distortion. The bias current is flowing because the output transistors are always conducting current (even without an audio signal). This differs from a pure class 'A' amplifier in the amount of current flow. A pure class 'A' amplifier has an enormous amount of current flowing through its output transistors with NO audio signal. A pure class 'B' amplifier has NO current flowing through its outputs with no input signal. A class 'AB' amplifier is much more efficient than the class 'A' but without the distortion of the class 'B'. MANY of the car audio amplifiers which claim to be a class 'A' amplifier are just a high bias class 'AB' design. These amplifiers are only class 'A' at very low power output levels. At higher power levels, one of the output transistors will switch off while the other output transistor is conducting. I don't want you to think that I am telling you that there are no class 'A' amplifiers. There are a few high quality mobile amplifiers which are a true class 'A' design.
CLASS 'D'
We said that class 'A' amplifiers were VERY inefficient. Class 'AB' amplifiers are also inefficient but are more more efficient than class 'A' amplifiers. Class 'AB' mobile amplifiers are generally 60% efficient when driving a 4 ohm load at maximum power (just before clipping). The reason that these amplifier configurations are inefficient is because there is a difference of potential (voltage) across the output transistors and current flowing through the output transistors. When you have voltage across the device and current flow through the device, there will be power dissipation in the form of heat. The power needed to produce this heat is wasted power. When there is (virtually) no voltage drop across a device (such as a large piece of wire or a transistor), there can be a significant amount of CURRENT flow through the device with (virtually) no power dissipation. This means that there is virtually no heat given off (highly efficient). The inverse is also true. If you have a significant amount of VOLTAGE across the device (transistor, wire...) but no current flow through the device, again, there will be no wasted power.
OK, now to the point. A class 'D' amplifier, which may also be known as a switching amplifier or a digital amplifier, utilizes output transistors which are either completely turned on or completely turned off (they're operating in switch mode). This means that when the transistors are conducting (switched on) there is virtually no voltage across the transistor and when there is a significant voltage across the transistor (switched off), there is no current flowing through the transistor. This is very similar to the operation of a switching power supply which is very efficient.
:cool: