Part 1: 1ohm amp load to two dvc 4ohm subs how is wattage affected? Part 2: Would I use 1ohm or 4 ohms when using ohms law to set my gain?


Archer3545

CarAudio.com Enthusiast
Jan 3, 2020
20
0
Oklahoma
Part 1 TLDR: My question: I bought two 400w rms DVC 4ohm subs. I have a 800w at 1 ohm stable amp. If I wire the subs to a 1 ohm final load on the amp, that should mean that the amp is putting out 800 watts in total, but wouldn't the 4ohm resistance from the subs them self reduce that 800w to something lower therefore meaning if I want to hit that 800w rms total for both subs I should either buy another one of those amps or just get a new one alltogether?

Part 2 TLDR: When setting gain for sub with multimeter if the amp load is 1ohm but the speakers are 4ohm do I use 1 or 4 in the ohms law equation? The best I could find was to use the amp load so in my case 1ohm, which means to hit 800w rms I should set the gain to 28.28v, but on the manufacturer website for my amp it says RMS Power at 1 Ohm: 800 Watts x 1 Channel (14.4v) Does that mean with the gain set to 14.4v it's pushes 800 watts and if so why even use ohms law if it could ultimately be way off?

Part 1: So I bought a new amp for my sub the amp that I bought is a
Skar Audio RP-800.1D Monoblock Class D MOSFET Amplifier with Remote Subwoofer Level Control, 800W
https://www.skaraudio.com/products/rp-800-1d-car-amplifier

and the sub is a Skar Audio SVR-8 D2 8" 800 Watt Max Power Dual 2 Ohm Car Subwoofer
I've had the sub for a few months now and it's wook great for a little 8" sub, the previous amp I had was a good pioneer one that has worked well for about 6 months now, It matched my sub well and the reason I bought a new amp is mostly because I wanted something more reliable with a slightly smaller profile. Now for a long time I have been wanting to get more bass out of my system and I don't have much experience with subs, because this has been my first attempt and I live in a small town and there isn't really a way I can test different stuff out to fit my personal preference without buying it, so it's been a lot of trial and error to get to this point. I was really on the edge between getting a second 8inch sub identical to the one that I have, and I would buy the same skar amp that I just bought again as well. Know my intial thought process was if cone area is what makes 12" subs sound better than 8's and 12's aside from the fact that 12's can do lower frequencies, than maybe two 8" subs would be bette than a single 12" sub because more it has more surface area. I know I'm stupid give me a break it's been a few years since I have taken geometry. So I did reasearch and found that two 8" subs don't have more surface area than a sing 12 that actually have slightly less. That coupled with the fact that the sub I currently have is out of stock and I would have to wait an unknown amount of time to get it, drove me to semi-impulsivly buying two
Rockford Fosgate P2D4-12 Punch P2 DVC 4 Ohm 12-Inch 400 Watts RMS 800 Watts Peak Subwoofer
https://rockfordfosgate.com/products/details/p2d4-12/

Now the reason I said semi-impulsively is because I did my reasearch and I have looked at those subs in the past. Now to get to the point. The amp I bought is 1 ohm stable at 800w I have heard that higher ohms while yes have more resistance and therefor it is harder to get a lot of power at that ohm, but it is more stable and clean sounding. Regardless for the time being I want to run this amp at one ohm and I couldn't of done this if I went with the two 8" subs because they would of been D2 and you can't wire that down to 1 ohm at least not on a mono amp, but you can wire two DVC 4 ohm subs to one ohm and that's what I plan to do.
My question: I bought two 400w rms DVC 4ohm subs. I have a 800w at 1 ohm stable amp. If I wire the subs to a 1 ohm final load on the amp, that should mean that the amp is putting out 800 watts in total, but wouldn't the 4ohm resistance from the subs them self reduce that 800w to something lower?

Part 2: the best way I have to set the amp gain is to use ohms law and a multimeter. So V= the square root of (desired rms wattage x resistance of speaker load) But what is the resistance of speaker load for me? Do I use 1ohm because that's my amp load or do I use 4ohms because that's my speakers resistance? Now I googled what is resistance of speaker load in car audio and it came up with "Each voice coil has an impedance of 4 ohms which results in a 2 ohm impedance for each speaker. One speaker is connected to each channel of the amplifier. This is a 2 ohm stereo load." While that specific example is not related to my setup my best guess would be to use the amp load. so for it would be the square root of (800w rms x 1) = 28.28v but on the manufactures website for my amp under specifications it's lists each rms wattage at different omhs and it lists a voltage with it. https://www.skaraudio.com/products/rp-800-1d-car-amplifier
  • RMS Power at 2 Ohms: 600 Watts x 1 Channel (14.4v)
  • RMS Power at 4 Ohms: 370 Watts x 1 Channel (14.4v)
  • RMS Power at 1 Ohm: 800 Watts x 1 Channel (14.4v)
  • Peak Power at 1 Ohm: 1,200 Watts x 1 Channel (14.4v)
So what does that 14.4v mean? Does that mean with a 1ohm load and the gain set at 14.4v it's pushing 800w and with a 2 ohm and the gain set at 14.4v the amp is pushing 600w? If so then how does that work if it doesn't follow ohms law? Is the 14.4v something else and I'm just overthinking it or is ohms law just a general way if the manuafacturer doesn't give you a specific voltage?
 

Lasherž

CarAudio.com VIP
Apr 27, 2020
312
31
United States
Part 1 TLDR: My question: I bought two 400w rms DVC 4ohm subs. I have a 800w at 1 ohm stable amp. If I wire the subs to a 1 ohm final load on the amp, that should mean that the amp is putting out 800 watts in total, but wouldn't the 4ohm resistance from the subs them self reduce that 800w to something lower therefore meaning if I want to hit that 800w rms total for both subs I should either buy another one of those amps or just get a new one alltogether?

Part 2 TLDR: When setting gain for sub with multimeter if the amp load is 1ohm but the speakers are 4ohm do I use 1 or 4 in the ohms law equation? The best I could find was to use the amp load so in my case 1ohm, which means to hit 800w rms I should set the gain to 28.28v, but on the manufacturer website for my amp it says RMS Power at 1 Ohm: 800 Watts x 1 Channel (14.4v) Does that mean with the gain set to 14.4v it's pushes 800 watts and if so why even use ohms law if it could ultimately be way off?

Part 1: So I bought a new amp for my sub the amp that I bought is a
Skar Audio RP-800.1D Monoblock Class D MOSFET Amplifier with Remote Subwoofer Level Control, 800W
https://www.skaraudio.com/products/rp-800-1d-car-amplifier

and the sub is a Skar Audio SVR-8 D2 8" 800 Watt Max Power Dual 2 Ohm Car Subwoofer
I've had the sub for a few months now and it's wook great for a little 8" sub, the previous amp I had was a good pioneer one that has worked well for about 6 months now, It matched my sub well and the reason I bought a new amp is mostly because I wanted something more reliable with a slightly smaller profile. Now for a long time I have been wanting to get more bass out of my system and I don't have much experience with subs, because this has been my first attempt and I live in a small town and there isn't really a way I can test different stuff out to fit my personal preference without buying it, so it's been a lot of trial and error to get to this point. I was really on the edge between getting a second 8inch sub identical to the one that I have, and I would buy the same skar amp that I just bought again as well. Know my intial thought process was if cone area is what makes 12" subs sound better than 8's and 12's aside from the fact that 12's can do lower frequencies, than maybe two 8" subs would be bette than a single 12" sub because more it has more surface area. I know I'm stupid give me a break it's been a few years since I have taken geometry. So I did reasearch and found that two 8" subs don't have more surface area than a sing 12 that actually have slightly less. That coupled with the fact that the sub I currently have is out of stock and I would have to wait an unknown amount of time to get it, drove me to semi-impulsivly buying two
Rockford Fosgate P2D4-12 Punch P2 DVC 4 Ohm 12-Inch 400 Watts RMS 800 Watts Peak Subwoofer
https://rockfordfosgate.com/products/details/p2d4-12/

Now the reason I said semi-impulsively is because I did my reasearch and I have looked at those subs in the past. Now to get to the point. The amp I bought is 1 ohm stable at 800w I have heard that higher ohms while yes have more resistance and therefor it is harder to get a lot of power at that ohm, but it is more stable and clean sounding. Regardless for the time being I want to run this amp at one ohm and I couldn't of done this if I went with the two 8" subs because they would of been D2 and you can't wire that down to 1 ohm at least not on a mono amp, but you can wire two DVC 4 ohm subs to one ohm and that's what I plan to do.
My question: I bought two 400w rms DVC 4ohm subs. I have a 800w at 1 ohm stable amp. If I wire the subs to a 1 ohm final load on the amp, that should mean that the amp is putting out 800 watts in total, but wouldn't the 4ohm resistance from the subs them self reduce that 800w to something lower?

Part 2: the best way I have to set the amp gain is to use ohms law and a multimeter. So V= the square root of (desired rms wattage x resistance of speaker load) But what is the resistance of speaker load for me? Do I use 1ohm because that's my amp load or do I use 4ohms because that's my speakers resistance? Now I googled what is resistance of speaker load in car audio and it came up with "Each voice coil has an impedance of 4 ohms which results in a 2 ohm impedance for each speaker. One speaker is connected to each channel of the amplifier. This is a 2 ohm stereo load." While that specific example is not related to my setup my best guess would be to use the amp load. so for it would be the square root of (800w rms x 1) = 28.28v but on the manufactures website for my amp under specifications it's lists each rms wattage at different omhs and it lists a voltage with it. https://www.skaraudio.com/products/rp-800-1d-car-amplifier
  • RMS Power at 2 Ohms: 600 Watts x 1 Channel (14.4v)
  • RMS Power at 4 Ohms: 370 Watts x 1 Channel (14.4v)
  • RMS Power at 1 Ohm: 800 Watts x 1 Channel (14.4v)
  • Peak Power at 1 Ohm: 1,200 Watts x 1 Channel (14.4v)
So what does that 14.4v mean? Does that mean with a 1ohm load and the gain set at 14.4v it's pushing 800w and with a 2 ohm and the gain set at 14.4v the amp is pushing 600w? If so then how does that work if it doesn't follow ohms law? Is the 14.4v something else and I'm just overthinking it or is ohms law just a general way if the manuafacturer doesn't give you a specific voltage?
That's the most well-organized giant mass of text I've seen on this site so far, kudos lol.
Part 1 TLDR: My question: I bought two 400w rms DVC 4ohm subs. I have a 800w at 1 ohm stable amp. If I wire the subs to a 1 ohm final load on the amp, that should mean that the amp is putting out 800 watts in total, but wouldn't the 4ohm resistance from the subs them self reduce that 800w to something lower therefore meaning if I want to hit that 800w rms total for both subs I should either buy another one of those amps or just get a new one alltogether?
Each coil is 4 ohm still, but when they're all wired to parallel your amp sees 1 ohm. It's easier to think of it from your amp's perspective not your subs. Your 800W 1 ohm stable amp is very well matched for a parallel load on two DVC 4 ohm subs so you're just fine doing that. It will effectively be [email protected] ohm to each coil if you must think about it from the subs' perspectives. The amp you have is exactly what you want, no need to swap unless you don't like how it sounds.
Part 2 TLDR: When setting gain for sub with multimeter if the amp load is 1ohm but the speakers are 4ohm do I use 1 or 4 in the ohms law equation? The best I could find was to use the amp load so in my case 1ohm, which means to hit 800w rms I should set the gain to 28.28v, but on the manufacturer website for my amp it says RMS Power at 1 Ohm: 800 Watts x 1 Channel (14.4v) Does that mean with the gain set to 14.4v it's pushes 800 watts and if so why even use ohms law if it could ultimately be way off?
You go by the amp load for that equation, you're overcomplicating it by thinking of the voice coils separately when they're connected to the same terminals on the amp. So you would use 1 ohm. The 14.4v thing is the battery voltage of your car. What they're saying is that when the car is running and the alternator is keeping it at a healthy 14.4v it will deliver 800w RMS. Current kills amps, so lower voltage on the battery will lower the power handling of it proportionately from 14.4v. I wouldn't worry about it beyond just not running the amplifier at full tilt with the car off. That's not good for your battery anyways.
 

Lasherž

CarAudio.com VIP
Apr 27, 2020
312
31
United States
I have heard that higher ohms while yes have more resistance and therefor it is harder to get a lot of power at that ohm, but it is more stable and clean sounding.
It is more stable, but I don't think the sound quality will be better. The reason why people sometimes prefer higher ohm loads to low ohms is because it's easier on the amp, primarily because the lower the ohms the more current flow there is whereas higher ohms only mean higher voltages. Voltage rarely kills equipment in car audio, it's usually current (the heat it causes). Current also raises resistances whereas voltage doesn't.

All of that being said, I go with the lowest stable ohm rating. If the manufacturer says it can do it, then I expect it can do it for a long time without worrying about it. Being 1 ohm stable is a feature, you may as well take advantage of it if it's at the manufacturer's blessing. The only reason I'll run higher ohms is it my speakers aren't matched with the subwoofer but a higher ohm configuration is.
 
OP
A

Archer3545

CarAudio.com Enthusiast
Jan 3, 2020
20
0
Oklahoma
It is more stable, but I don't think the sound quality will be better. The reason why people sometimes prefer higher ohm loads to low ohms is because it's easier on the amp, primarily because the lower the ohms the more current flow there is whereas higher ohms only mean higher voltages. Voltage rarely kills equipment in car audio, it's usually current (the heat it causes). Current also raises resistances whereas voltage doesn't.

All of that being said, I go with the lowest stable ohm rating. If the manufacturer says it can do it, then I expect it can do it for a long time without worrying about it. Being 1 ohm stable is a feature, you may as well take advantage of it if it's at the manufacturer's blessing. The only reason I'll run higher ohms is it my speakers aren't matched with the subwoofer but a higher ohm configuration is.
Ok thanks and yeah I get a little carried away sometimes, I like to over explain and give more then enough information. That's why I do the TLDR otherwise people get annoyed. Anyway thanks that helped clear some things up and gave me peace of mind. Something else that concerns me is the heat and I have been thinking about this for a while. I live in Oklahoma, and our summers are rough like it's about to start being 100F+ everyday. My amps are all in the trunk open air nothing covering them, but my trunk doesn't get any air from the AC and it stay much hotter than the rest of my car. Should I be worried about that, and do you think getting some sort of active cooling like fans for both my amps to keep them from reaching retardedly hot temps?
 

Lasherž

CarAudio.com VIP
Apr 27, 2020
312
31
United States
Something else that concerns me is the heat and I have been thinking about this for a while. I live in Oklahoma, and our summers are rough like it's about to start being 100F+ everyday. My amps are all in the trunk open air nothing covering them, but my trunk doesn't get any air from the AC and it stay much hotter than the rest of my car. Should I be worried about that, and do you think getting some sort of active cooling like fans for both my amps to keep them from reaching retardedly hot temps?
It's fair to be concerned about it. Basically all mainstream company amps have a thermal cutoff though and so if it doesn't work due to heat you'll know it. Some people end up having to put cooling fans on their amps, but until it overheats there's no reason to assume you'll have to. A general tip to avoid heat build-up is to keep it off the carpet and more importantly do not let anything sit on top of the amp. The nice thing about heat build-up in an amp though is that even though it may be too hot to touch, it doesn't mean any of the parts inside the amp mind. All that means is that the heatsink chassis is functioning as intended. The only indicator that the amp is getting too hot is the thermal cutoff protection circuit. Silicon is surprisingly robust to heat and won't start taking permanent damage until over 100 degrees centigrade.
 

Create an account or login to comment

You must be a member in order to leave a comment

Create account

Create an account on our community. It's easy!

Log in

Already have an account? Log in here.


Users Who Are Viewing This Thread (Users: 0, Guests: 3)



Latest posts

Trending topics