2 12" dual 8 ohm subs?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=48315
Printed Date: June 09, 2024 at 6:44 PM
Topic: 2 12" dual 8 ohm subs?
Posted By: onyx21
Subject: 2 12" dual 8 ohm subs?
Date Posted: January 22, 2005 at 1:37 PM
I have 2 12" dual 8 ohm subs that need about 500w RMS. This is probably a dumb question but is there any way to wire them to get a 1 ohm load on the amp? I f not what is the lowest load I can get on an amp and what amp would you recommend?
Replies:
Posted By: audeogod
Date Posted: January 22, 2005 at 1:42 PM
The lowest ohm load you can achieve with them is a 2 ohm load, with all coils and woofers wired in parallel. See my post entitled "Look! Parallel subs ohms formula" for more info. I just posted it yesterday so it shouldn't be too hard to find. Page 1 or 2. As for the 500w RMS, is that per woofer, or a total between them??
Posted By: onyx21
Date Posted: January 22, 2005 at 1:43 PM
I appreciate it, and thats per woofer
Posted By: audeogod
Date Posted: January 22, 2005 at 1:49 PM
Ok, I don't have a specific amp recommendation, but what I would do is look for a monobloc amp that can deliver 1000 watts RMS(500 per sub) at a 2 ohm load. Because you will be wiring them in parallel and no 2-channel amp that I know of can handle a 2 ohm load bridged mono. You need a mono amp. Other than that you can wire each coil on each sub in parallel for 4 ohms per sub, and then run them on any regular 2-channel amp with one per channel at 4 ohms. Then you will need to find a 2-channel amp that delivers 500 watts RMS into a 4 ohm load per channel. It's still a 1000 watt amp, only at 4 ohms, and in stereo. That might be big bucks.
I can't really say which would be cheaper, mono or 2-channel. Just look around. As for 2-channel, I have heard some people whom I trust recommend the USAcoustics brand because they are rated to perform at 12.9 volts, not the more common 14.4 volts. That means that you may actually get a little more out of them than what they say you will.
Posted By: onyx21
Date Posted: January 22, 2005 at 1:51 PM
Posted By: audeogod
Date Posted: January 22, 2005 at 1:53 PM
From what they told me, the USAcoustics is supposed to be a good "bang for your buck" amp. Affordable, and dependable. I've never used one, but the guys who recommended them have used them for awhile, and I've known them for years from just internet posts of course, but they have never been people to just run their mouths about stuff they don't know about. Always told me reliable information.
Posted By: onyx21
Date Posted: January 22, 2005 at 2:06 PM
What If I wanted to do 1 amp one each sub? Could I do the memphis MC1000D ?
Posted By: haemphyst
Date Posted: January 22, 2005 at 2:11 PM
YES, YOU CAN GET A ONE OHM (EFFECTIVE) LOAD! 8 oms/4 voice coils=2 ohms. 2 ohms on a BRIDGED stereo amp, the amp will "see" one ohm per channel. The total load is STILL 2 ohms, BUT the amplifier, bridged, "sees" twice the load or one half the impedance when bridged. Since you didn't say what amp you had (or had in mind), you will need to make certain your amp/purchase is indeed one ohm stable. The spec you will be looking for is a stereo amp, around 500 watts per channel at one ohm. Thas amplifier, bridged to a two ohm load will net one ohm load per channel for the amplifier,with approximately 1000 watts of total output.
audeogod, any one ohm stable, stereo amp will run two ohms bridged.
USAmps are good products, a little expensive, but good, most are one ohm stable, OR look for an old-school Orion red HCCA250. Bridged to this load, you would get around 800 watts RMS. I happen to have one of these amps, in great shape, and I would probably be willing to let it go for about 200 bucks. Let me know.
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: onyx21
Date Posted: January 22, 2005 at 2:19 PM
FYI: The subs are 12" 8 ohm DVC Diamond audio Mac Daddy
Posted By: onyx21
Date Posted: January 22, 2005 at 2:19 PM
FYI: The subs are 12" 8 ohm DVC Diamond audio Mac Daddy with 800w peak
Posted By: audeogod
Date Posted: January 22, 2005 at 2:40 PM
Yeah, I know if it is 1 ohm stable stereo, then it will be 2 ohm stable mono. Just like 2 ohm stable stereo is 4 ohm stable mono. That's confusing to think of it being a 1 ohm load when it's not really. I also know they make 2-channel bridgable amps that can be 2 ohm stable bridged, but I don' t know of any specifically. I think Soundstream made some a while back. I never messed with any of them.
When you bridge an amp, you no longer have two channels, but rather just one now. And that "new" channel behaves differently than the two did independantly by combining the stereo signals into one signal, and power output changes(not always linearly either) and the lowest ohm load it can safely handle goes up from what each single stereo channel would handle. The new channel is being shown a 2 ohm load by the way you wire the subs up. Some say that that's just 1 ohm per channel, but I disagree. The ohms don't divide up and go different directions. They are a characteristic of the speaker circuit itself and remain where they are(so to speak) I believe that it's 2 ohms on an entirely new channel(same output devices though).
Posted By: onyx21
Date Posted: January 22, 2005 at 3:01 PM
Thanks, audeogod and haemphyst both of ya'll have been extremely helpful
Posted By: haemphyst
Date Posted: January 22, 2005 at 3:21 PM
Nope. Wrong. (But to some extent, still partially correct.) When you bridge an amplifier, you are inverting the output phase of one of the channel, so when one phase is swinging, say 10 volts positive, the other channel is swinging 10 volts negative for a 20 volt potential across the speaker. Twice the voltage across a given load (according to Ohms law) will mandate twice the current, to maintain that voltage. Twice the voltage times twice the current equals 4 times the power. Because the amplifier is making twice the current, it is the same as the amplifier running twice the load on two separate channels, thus an "effective" one ohm load per channel. Yes, the actual load DOES NOT CHANGE, it is still two ohms, but the EFFECTIVE LOAD PER CHANNEL is twice the load, thus the amp "seeing" one ohm per channel. It is still two ohms, but because the amp is working harder, it is EXACTLY the same as halving the impedance in stereo mode.
The power output will continue to rise, YES IN A PERFECTLY LINEAR FASHION - IT MUST, until the amplifier power supply can no longer make enough current to maintain the voltage across the load. This is the reason why you do not see amplifier always offering as much power as you might think it would, in either bridged mode or a 2 ohm power rating vs. a 4 ohm power rating... (i.e. a non-linear output power curve.)
You can disagree with the above information all you would like, but you would be wrong to do so. Please check out this website, and read all ofit. There is a WEALTH of information there. On the left, you will scroll down and find the amplifier bridging secion. ------------- It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: onyx21
Date Posted: January 22, 2005 at 6:12 PM
Now I'm trying to choose between the old skool Orion HCCA 250(Used) and the Kenwood Excelon KAC-X811D(new). Both are in my price range and both put out 800w RMS. I have a kenwood excelon head unit also. Any opinion on whci to get?
Posted By: onyx21
Date Posted: January 22, 2005 at 11:34 PM
Also the Hifonics BX1500D
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