SLC Infotainment Option

[Roger]

Drop the ohm load, and power output and draw go up.

The current draw might, but the speaker power output won't. Maximum speaker power will be achieved when the external load (the speakers) matches the internal impedance of the amplifier.

The caps would be run in series ( if wiring multiple caps) on your battery lead to the amp.

Edit- here is a drawing of a multiple cap install. Not sure if you would call it parallel, or series, or a combo of both.

The capacitors are wired between the positive and negative terminals of the battery, just as the amplifier is. They're therefore in parallel with each other and the amplifier.

 

[Scott Rowland]

Dropping the ohm load on the amp (wiring 2 4ohm speakers in parallel to get 2ohm load) most certainly raises output of amp. With the couple amps I have shown, they are stable and can handle the heat (may want to add fan though) of dropping all the way to 1/4ohm loads. Thats why the output would raise so drastically. Not every amp can do this, but the ones I used as examples can. I am under the assumption, that as that ohm load drops, and output raises, draw would raise also.

The multiple cap arrangments i have done, were already prewired inside of a type of mounting box or body. I was under the understanding it was in series, like multiple batteries are normally done. So parallel it is.

My main point was atleast getting out there some of the numbers people should be looking at when buying a piece of equipment, and not going by the big sticker that says "1000 watts!" in a 6"x6" amp with a single 20a fuse and expecting it to sound good.

 

[Roger]

Dropping the ohm load on the amp (wiring 2 4ohm speakers in parallel to get 2ohm load) most certainly raises output of amp.

That depends upon the internal impedance of the amp. Below the internal impedance of the amp, output power will fall. See Maximum Power Transfer Theorem for more detail.

The multiple cap arrangments i have done, were already prewired inside of a type of mounting box or body. I was under the understanding it was in series, like multiple batteries are normally done. So parallel it is.

The link that you gave earlier showed only capacitors wired in parallel, which is what you have to do to be able to sum the capacitances.

The higher the voltage across a capacitor, the more energy it stores (cv^2/2), so the longer the current gap that it can fill is. If you put them in series, each has less than 12V across it, so stores less energy.

My main point was at least getting out there some of the numbers people should be looking at when buying a piece of equipment, and not going by the big sticker that says "1000 watts!" in a 6"x6" amp with a single 20a fuse and expecting it to sound good.

Agreed. The power numbers quoted are often pure marketing BS, with no basis in physics.

 

[Scott Rowland]

Subwoofer Wiring Diagrams Understand Ohms Law

 

[Roger]

Subwoofer Wiring Diagrams Understand Ohms Law

I assume that you're referencing your earlier comment:

Dropping the ohm load on the amp (wiring 2 4ohm speakers in parallel to get 2ohm load) most certainly raises output of amp.

Whilst reducing the impedance (note: not resistance - speakers have inductance) of the load causes more current to flow, it also reduces the voltage across it. As power is the product of voltage and current, you reach a point where reducing the impedance of the speakers causes the speaker power to drop.

If your amplifier is designed to hit its maximum power output with 2 Ohm speakers, then your comment is true. If you reduce the load to 1 Ohm, or increase it to 4 Ohm, on that amp, the speaker power will decrease.

If the amplifier is designed for maximum power with 4 Ohm speakers, using 2 Ohm speakers will reduce its power output.

 

[Roger]

Let's take a simple example of a 12V source with an internal resistance of 4 Ohm. Your amplifier has an internal impedance - it cannot drive infinite current.

If we connect a 2 Ohm load, we get a current of 12/(4+2) = 2A, for a load voltage of 4V and a power of 8W.
If we connect a 4 Ohm load, we get a current of 12/(4+4) = 1.5A, for a load voltage of 6V and a power of 9W.
If we connect an 8 Ohm load, we get a current of 12/(4+8) = 1A, for a load voltage of 8V and a power of 8W.

 

[Scott Rowland]

I assume that you're referencing your earlier comment:

Whilst reducing the impedance (note: not resistance - speakers have inductance) of the load causes more current to flow, it also reduces the voltage across it. As power is the product of voltage and current, you reach a point where reducing the impedance of the speakers causes the speaker power to drop.

If your amplifier is designed to hit its maximum power output with 2 Ohm speakers, then your comment is true. If you reduce the load to 1 Ohm, or increase it to 4 Ohm, on that amp, the speaker power will decrease.

If the amplifier is designed for maximum power with 4 Ohm speakers, using 2 Ohm speakers will reduce its power output.

This is why I get very high quality amps that are designed to run 1ohm or less. In my opinion, it is where the money should be spent in a sound system.

I am catching on to your point though now. And yes, buying a 4ohm rated amp, that can run 1/4ohm, will be putting out more watts at that 1/4ohm than it did at 4ohm. We are pretty much saying the same thing, I am just saying the outcome, while you are saying the process. Luckily, most only need to know the outcome in order to properly wire their speakers and get their ohm loads where they want them.

 

[Scott Rowland]

Here is some specs I found on an old school U.S.Amps amp. It basically is showing what both of us are trying to say. You are saying that an amp made to run at 1/2 O, will not make more power at any other ohm, thus, not increasing. I am saying, that since the baseline of car audio is 4ohm, that is where they will get rated at. That is where these "cheater" amps shine. Being made to work at 1/2 ohm, output will go from 100w @ 4ohm, to 800w @ 1/2 ohm. So, we are basically saying the same thing, from different angles. Notice the 225a rating on fuse, while advertising only 100watts.
If you run them at only 4 ohm, you will have tons of headroom and your distortion levels will be at a minimum. All the other numbers I mentioned are there also. This is one bad ass little amp!

Us Amps USA100HC specification:

2 x 50W @ 4 ohms (THD <0.006%)
2 x 100W @ 2 ohms
2 x 200W @ 1 ohm
2 x 400W @ ½ ohm
1 x 800W @ 1 ohm bridge
1/2 ohm stable
S/N Ratio: 115 dB
Damping Factor: >1000 (at 4 ohms)
Fuse: External 225A

 

[Yos]

Here you go guys...think I've finally found my audio solution! Should work perfect with any interior designs. (4" wide...3" deep) :thumbsup:

PMX-2 - Punch Marine/Motorsport Compact AM/FM/WB Digital Media Receiver 2.7" Display | Rockford Fosgate(R)

As far as I'm concerned...it was designed just for our cars! Might be as popular as my gold foil chassis! Haha :laugh:

 

[Jack]

I knew that you would get "round, round" to it!

 

[Rich Kruger]

I dont know.....that display is kinda small. Especially for my age challenged eyesight!