Capacitors....Interesting discussion!

[Holland]

I was having some .... noise when the trim was going up and down he he he... anyway, Al and Eds in Ontario set me up with some PAC's RCA Ground loop isolators... solved that and many other issues.... They are directional when inline with the rca cables.
Worked for me...

[Havasu Hangin']

I was having some .... noise when the trim was going up and down he he he... anyway, Al and Eds in Ontario set me up with some PAC's RCA Ground loop isolators... solved that and many other issues.... They are directional when inline with the rca cables.
Worked for me...
Once again...a band-aid for bad wiring. If you run the wires correctly, you should not have a ground loop. Of course, most shops will not tell you that, since it involves extra work.
Try disconnecting the isolator and make sure your bass notes don't change...

[ROZ]

Like HH said, have them relocate the power and grounds for the stereo. Another cause would be the gains are too high on the amplifiers, thus they are amplifying the noise that is being induced into the power cabling of the amp (in a round about way, it's a bit more complicated then that).
Yea, what he said

[Havasu Hangin']

Standard lead cell batteries do not plate fast enough to deliver power for deep bass.
What is "do not plate"?
What is "deep bass"?

[Tom Brown]

Since Cap's add more resistance and are not a power supply source, they are actually a negative.
The resistance a cap adds is across the supply rails and if the cap is even modestly decent quality, the resistance will be extremely low. The cap will be able to source current during times of heavy load and that current is coming from a shorter distance, reducing the cable length/resistance, and hastening the slew rate of the amplifier's power supply. I would think that's a positive.
I still don't bother with them. Decent amps with good quality wiring will kick the crap out of cheap equipment, poor wiring, and a band-aid.

[Tom Brown]

Tell Magic to stop being so lazy and isolate the stereo power/ground from the rest of the boat.
Installing a cap as a noise suppessor is like putting a band-aid on yer leg after the surgeon cut you foot off because he didn't want to take the time to remove your sock to fix a hangnail.

Does anyone remember back in the early 80s when Ford ran the alternator gauge wire across the top of the dash, right above the stereo? Those things buzzed like dragon flys.
I have fixed tons of installations where they had a bunch filters chained together by simply re-routing the charging gauge wire on the outside of the firewall.
One day, I'll put a little extra poli-dent on my top plate and share some good stuff with you kids.

[rivercrazy]

The resistance a cap adds is across the supply rails and if the cap is even modestly decent quality, the resistance will be extremely low. The cap will be able to source current during times of heavy load and that current is coming from a shorter distance, reducing the cable length/resistance, and hastening the slew rate of the amplifier's power supply. I would think that's a positive.
I still don't bother with them. Decent amps with good quality wiring will kick the crap out of cheap equipment, poor wiring, and a band-aid.
The problem is when say a 40 farad cap is used it creates quite a bit of resistance. Say your alternator is putting out 13.8V into a cap that large. The downstream voltage will be less than 13.8V. So its useless and actually a power robber....

[h2oski2fast]

Standard lead cell batteries do not plate fast enough to deliver power for deep bass.
So that means a battery wouldn't be concidered a capacitor?
Also, you mean to tell me that lead cell battery that can handle the draw of a starter (400 to 500 amps), but can't handle the draw of "deep bass" (whatever that is)?

[Havasu Hangin']

The purpose of doing so is to provide a sort of reserve power source from which the amplifier can rapidly draw power when it needs it (such as during a deep bass note). The electrical theory is that when the amplifier attempts to draw a large amount of current, not only will the battery be relatively slow to respond, but the voltage at the amplifier will be a little lower than the voltage at the battery itself (this is called line drop). A capacitor at the amplifier which is charged to the battery voltage will try to stabilize the voltage level at the amplifier, dumping current into the amplifier. Another way to think about it is that a capacitor in parallel with a load acts as a low pass filter, and the voltage level dropping at the amplifier will appear as an AC waveform superimposed upon a DC "wave". The capacitor, then, will try to filter out this AC wave, leaving the pure DC which the amplifier requires.
Stolen from MobileAudio.com
The theory behind capacitance is correct...it's the execution that creates confusion. Like Tom mentioned, amplifiers have (and need) caps to regulate the voltage across the power supply.
Where the marketing hype comes into play is the "more is better" theory behind external caps. The bottom line is that they do not store enough energy to regulate the voltage of a system to make an audible difference. Add to the fact that they have a high ESR value (which means some energy is lost as heat), and their trade-off value becomes non-existent.
From Car Sound:
The main point for those who point out the obvious differences between the Red (cap installed) and yellow (cap not installed)…how much of a dB difference is .1-.4 volts in terms of music? And do you feel you are going to hear this within a car?
On with the explanation:
http://www.caraudiolounge.com/upload...1076374639.jpg
Dark Blue curve---
For our first test we played the system with the engine off and no cap. The result was the purple trace at the bottom. We played the system as loud as we could get it that seemed to produce no audible distortion. This was track 30 of the IASCA disc. It starts off with fairly low level sounds for the first 34 seconds. In order to insure the electrical system was stable we did not start the measurement until we were 20 seconds into the song. This means that our 0 starting point is :20 on the CD counter.
The battery was able to maintain it's voltage just below 12.5 until the loud bass hits at 34 seconds (14 seconds into our chart) At this time it dropped to about 11.5 and had a few large variations due to the music. According to the computer calculations (third chart) the average voltage for this test was 11.7volts. This test was done as a baseline for the following tests.
Yellow curve—no cap
For this test the volume was left as it was for the baseline test. The engine was started. Notice that at low volume the alternator was able to maintain about 14 volts. When the loud music hit the voltage dropped to about 12.5 where it remained except for a few short moments where it actually climbed back to over 13.5 volts. The computer averaged calculations for the average voltage during the 100 seconds of this test was 12.973 volts.
Red curve—cap added
This test was identical to the previous test except the cap (15 farad type) was added 6 inches from the amp with 4 gauge wire—no relays or fuses. The red curve seems to overlay the yellow except that the actual peaks don’t rise as fast or as high during the brief quiet moments. I feel this would be due to the alternator having to recharge the cap. The voltage on loud passages hovered around 12.5 volts. The computer averaged calculations for this test show the average voltage to be 12.878 volts. I see no meaningful differences with or without the cap. I certainly don’t see the voltage sitting solid at 14 volts.
One note I might add is that this was a two thousand watt system driven right to clipping and the average voltage stayed above 12.8 with a stock 80 amp alternator. Under these conditions the battery would never discharge!The green and light blue curves were done just for kicks while we had the system set up. In both these tests we turned the volume up until the system was very distorted.
This placed a severe load on the alternator and caused the voltage to dip as low as 12 volts. The curves seem to follow each other so closely that unless you have a good monitor it is doubtful you can tell there are two curves. The average voltage for these two curves were both 12.277 and 12.295 volts. If this volume were sustained for very long periods of time this battery would discharge.
Like HCS said, the only way to truely take advantage of caps would be to build an array of many small, low-ESR caps...which just isn't practical in cars or boats.
It seems the only people these days touting the benefits of caps are those who are selling caps....and talking about the power draw of a "deep base note"...and how the battery can be "slow to respond"...
...whatever that is. :idea:

[Havasu Hangin']

Answer my question about Soundstream Van Gogh amps, you're the expert.
Don't listen to my opinion...I'm just an "internet wire jockey".
:notam: