Question about hooking a 2 subs to a box (Car Audio)

[zumbo]

Read this my friend.

I have to say, It is a honor to finally win one with you.

 

[mulester7]

.....question.....to Professors Annunaki and Zumbo....and let's bring Professor Markw into the mix as a consultant....Iron Chefs, wait a minute, this ain't the food channel....Audio Professors Three, what is the overall ohm load presented to a NON-STRAPPED amp section with four, 8 ohm, speakers wired, in effect, from the output terminals with two parallels after the mains, and a series wiring on the fourth speaker?....Clint, begin the 5 minute clock.....

 

[zumbo]

.....question.....to Professors Annunaki and Zumbo....and let's bring Professor Markw into the mix as a consultant....Iron Chefs, wait a minute, this ain't the food channel....Audio Professors Three, what is the overall ohm load presented to a NON-STRAPPED amp section with four, 8 ohm, speakers wired, in effect, from the output terminals with two parallels after the mains, and a series wiring on the fourth speaker?....Clint, begin the 5 minute clock.....

SCV or DVC? And I don't quiet get the wiring. Can you draw a diagram?

If I understand this, two speakers are paralled. And two more are paralled. That makes two 4ohm speakers. Now series those two sets and you have one 8ohm load.

 

[Buckeyefan 1]

Wow, a few posts since I left. I have my 2 subs wired in parallel. Don't forget, they are dual voice coil 4 ohm subs, which makes each a 2 ohm load. Two of them yields a 1 ohm load in parallel. I do all my own installations and have never blown a sub or amp. The mono (not stereo) amp I am using has the following rating:

Channels: 1
Frequency Response: 20Hz-250Hz
Fuse: 80A
Crossover: Low Pass
Protection: Thermal, Short Circuit, Overload
RMS Power:
625W RMS x 1 @ 4ohms
924W RMS x 1 @ 2ohms or 1ohm
Max/Peak Power: 1200W
Battery Voltage Range: 10.5-14.4
Low Level Input: 200mV-6V
Crossover Freq. (Variable) 40-200Hz 12dB/Oct
Bass Boost: 0-12dB

The two subs I am using have an RMS rating of 300W each, and a peak power rating of 500W burst level. Since the amp is putting out 924W at 1 or 2 ohms, I am getting 462 watts to each sub. Almost a perfect setup at an extremely low ohm level. I've always wired two subs in parallel, never in series. It's a waste of power not to if the amp can handle it. You need to use a large capacitor, otherwise the large drain on the alternator will drain the battery. I think you need a constant 14.4 volts+ to run an amp at those levels.

 

[zumbo]

Wow, a few posts since I left. I have my 2 subs wired in parallel. Don't forget, they are dual voice coil 4 ohm subs, which makes each a 2 ohm load. Two of them yields a 1 ohm load in parallel. I do all my own installations and have never blown a sub or amp. The mono (not stereo) amp I am using has the following rating:

Channels: 1
Frequency Response: 20Hz-250Hz
Fuse: 80A
Crossover: Low Pass
Protection: Thermal, Short Circuit, Overload
RMS Power:
625W RMS x 1 @ 4ohms
924W RMS x 1 @ 2ohms or 1ohm
Max/Peak Power: 1200W
Battery Voltage Range: 10.5-14.4
Low Level Input: 200mV-6V
Crossover Freq. (Variable) 40-200Hz 12dB/Oct
Bass Boost: 0-12dB

The two subs I am using have an RMS rating of 300W each, and a peak power rating of 500W burst level. Since the amp is putting out 924W at 1 or 2 ohms, I am getting 462 watts to each sub. Almost a perfect setup at an extremely low ohm level. I've always wired two subs in parallel, never in series. It's a waste of power not to if the amp can handle it. You need to use a large capacitor, otherwise the large drain on the alternator will drain the battery. I think you need a constant 14.4 volts+ to run an amp at those levels.

Cool. So you are roughly getting 462watts to each with peaks of 600watts each provided a constant 14.4v current. Nice.

Are you using ferrod caps and a couple of Optima batteries?

 

[annunaki]

Hold on there Zumbo. I do not give up that easily. Check this first as well as the whole article in the link below before you declare a "winner". We are all winners here as we are all learning something.

2 Ohm Stereo vs 4 Ohm Mono Loads

There seems to be some confusion as to why a 4 ohm mono and a 2 ohm stereo load are the same, as far as the amplifier is concerned. When two 4 ohm speakers are connected to each channel of a 2 channel amplifier, the amplifier is capable of driving the speakers with half of the total power supply voltage. If the amplifier has a power supply which produces plus or minus 20 volts, it will not be able to drive the speakers on a single channel with any more than 20 volts at any point in time. If we have a 2 ohm load on each channel, at the highest point on the waveform the amplifier will apply 20 volts to the speaker load. Remember that we are only considering a single point in time for this example. If we go back to ohms law...

I=V/R
I=20/2
I=10 amperes

If we take a single 4 ohm speaker and bridge it on that same amplifier, the amplifier will be able to apply twice the voltage across the speaker. This is because while one speaker terminal is being driven positive (towards the positive rail), the other terminal is being driven towards the negative rail. This will allow the entire power supply voltage to be applied to the speaker's voice coil. It will now be able to drive the 4 ohm speaker with 40 volts instead of 20 volts in the previous example. Back to Ohm's law...

I=V/R
I=40/4
I=10 amperes

The same amount of current flows through the output transistors whether the amplifier is driving a 4 ohm mono load or 2 ohm stereo load. As far as the amplifier is concerned, they are the same load.


--------------------------------------------------------------------------------


NOTE:
Some people say that when an amplifier is bridged onto a 4 ohm load, it 'sees' a 2 ohm load. While it is true that the same current flows whether the amp is bridged on a 4 ohm load or a 2 ohm stereo load, the amplifier is driving a 4 ohm load across its outputs. A single 4 ohm speaker can never be a 2 ohm load.


http://www.bcae1.com/bridging.htm

 

[zumbo]

I have never tried the caps. They were just coming out when I got out of it. I did, however, have a dual battery set-up. I could run a constant 13.8 at 2500 rpm.

 

[mulester7]

.....Zumbo, if the terms SVC and DVC apply to 5, 6, or 7 channel surround receivers, I am fishing in Lake Ingorance.....let's say for a wiring diagram you have four speakers wired individually, in line, progressing, from one set of output terminals with the cross wiring to the fourth speaker, ANYWHERE, except the first wiring and it could possibly be first, I'll have to think about that....guys, I'm not trying to be coy....I'm searching for answers also....Clint, reset the 5 minute clock....

 

[RecLodossWar]

Ok, so you now already know only one of my subs is hooked parallel to the amp. Would any of these setups do the better jobs?

http://www14.brinkster.com/meweb01/setup1.gif
http://www14.brinkster.com/meweb01/setup2.gif
http://www14.brinkster.com/meweb01/setup3.gif

Thanks.

 

[zumbo]

Hold on there Zumbo. I do not give up that easily. Check this first as well as the whole article in the link below before you declare a "winner". We are all winners here as we are all learning something.

2 Ohm Stereo vs 4 Ohm Mono Loads

There seems to be some confusion as to why a 4 ohm mono and a 2 ohm stereo load are the same, as far as the amplifier is concerned. When two 4 ohm speakers are connected to each channel of a 2 channel amplifier, the amplifier is capable of driving the speakers with half of the total power supply voltage. If the amplifier has a power supply which produces plus or minus 20 volts, it will not be able to drive the speakers on a single channel with any more than 20 volts at any point in time. If we have a 2 ohm load on each channel, at the highest point on the waveform the amplifier will apply 20 volts to the speaker load. Remember that we are only considering a single point in time for this example. If we go back to ohms law...

I=V/R
I=20/2
I=10 amperes

If we take a single 4 ohm speaker and bridge it on that same amplifier, the amplifier will be able to apply twice the voltage across the speaker. This is because while one speaker terminal is being driven positive (towards the positive rail), the other terminal is being driven towards the negative rail. This will allow the entire power supply voltage to be applied to the speaker's voice coil. It will now be able to drive the 4 ohm speaker with 40 volts instead of 20 volts in the previous example. Back to Ohm's law...

I=V/R
I=40/4
I=10 amperes

The same amount of current flows through the output transistors whether the amplifier is driving a 4 ohm mono load or 2 ohm stereo load. As far as the amplifier is concerned, they are the same load.


--------------------------------------------------------------------------------


NOTE:
Some people say that when an amplifier is bridged onto a 4 ohm load, it 'sees' a 2 ohm load. While it is true that the same current flows whether the amp is bridged on a 4 ohm load or a 2 ohm stereo load, the amplifier is driving a 4 ohm load across its outputs. A single 4 ohm speaker can never be a 2 ohm load.


http://www.bcae1.com/bridging.htm

Hmmm.
I still don't think a 2ohm stable amp can handle a 2ohm load bridged. I have always been tought the theory I linked.

 

[annunaki]

RecLoDossWar,

Your links do not work, it says you must be a member of Brinkster.

 

[zumbo]

Ok, so you now already know only one of my subs is hooked parallel to the amp. Would any of these setups do the better jobs?

http://www14.brinkster.com/meweb01/setup1.gif
http://www14.brinkster.com/meweb01/setup2.gif
http://www14.brinkster.com/meweb01/setup3.gif

Thanks.

Links don't work!

 

[annunaki]

Hmmm.
I still don't think a 2ohm stable amp can handle a 2ohm load bridged. I have always been tought the theory I linked.

It CAN'T if it is only 2 ohm stable in STEREO. It would have to be 1 ohm stable in stereo to be 2 ohm stable in MONO.

 

[zumbo]

So we have come to the conclusion I had in the beginning. His amp can't drive those two 4ohm subs in parallel. Or, provide enough power in stereo to drive both. However, it can drive one fine.

 

[annunaki]

I never disagreed with that conclusion. We are more or less arguing semantics.

 

[zumbo]

I never disagreed with that conclusion. We are more or less arguing semantics.

When it comes to the technical part, you certainly have me there. I do enjoy it VERY much when a thread gets to this point. I love learning.

 

[Buckeyefan 1]

Cool. So you are roughly getting 462watts to each with peaks of 600watts each provided a constant 14.4v current. Nice.

Are you using ferrod caps and a couple of Optima batteries?

1 xlg ferrod cap, and only one truck battery (over 900 cca's??). My F150 extended cab puts out a constant 14.4 volts. Truck alternators and batteries are much larger than cars, so I didn't have to worry as much about it as the guys with the tiny Civics.

 

[annunaki]

I agree with you on that point.

 

[zumbo]

1 xlg ferrod cap, and only one truck battery (over 900 cca's??). My F150 extended cab puts out a constant 14.4 volts. Truck alternators and batteries are much larger than cars, so I didn't have to worry as much about it as the guys with the tiny Civics.

Yep. I had mine in a Silverado. It had the upgraded towing package with the boosted alternator and an extra battery slot under the hood. I just added another battery.

 

[annunaki]

I hope you used a dual batter isolator. Alternators do not last long without them.

Later,

and have a good weekend guys.