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Car Forum / Driving, Maintenance, Tuning / Car Audio / November 2005Running 4 Ohms to 2 Ohm
I know its possible to run a 4 Ohm Woofer's to run 2 ohm... 1) How do u do this On a SVC and a DVC Woofer? 2)I Know is that you need 2 subs to do this and Better to go with Mono-Amp. Is it okay to use a 2-channel and bridge it? 3)Also, is it possible to run on 1 Ohm? If so, How -- jimbo_limited > I know its possible to run a 4 Ohm Woofer's to run 2 ohm... > > 1) How do u do this On a SVC and a DVC Woofer? to run a single 4 ohm speaker you would need a bridgeable 2 channel amp and run the single 4 ohm speaker on the bridged outputs. On the DVC you would need one with dual 8 ohm coils, then paralall the 2 voice coils the run it bridged. > 2)I Know is that you need 2 subs to do this and Better to go with a > Mono-Amp. Is it okay to use a 2-channel and bridge it? If the amp is bridgeable you can run a singel 4 ohm speaker on it and the amp will run at 2 ohms > 3)Also, is it possible to run on 1 Ohm? If so, How? It's possible, but the amp must be a 1 ohm stable amp or running it at 1ohm will cause the amp to over heat or short out the outputs and damage the amp > I know its possible to run a 4 Ohm Woofer's to run 2 ohm... > > 1) How do u do this On a SVC and a DVC Woofer? You can't do it with a single SVC sub. This is basic Ohm's Law: two 4-ohm loads in parallel will present a 2-ohm load to the amp. Two 4-ohm SVC subs wired in parallel, or one 4-ohm DVC sub with the coils wired in parallel, will achieve this. > 2)I Know is that you need 2 subs to do this and Better to go with a > Mono-Amp. Is it okay to use a 2-channel and bridge it? Sure, as long as it will handle the load. Remember that halving the impedance of the speakers will double the current draw on the amp, and bridging it will effectively quadruple the current it must handle. Lesser amps may run fine with 2-ohm loads un-bridged, but not handle the current when it is bridged, so be sure to check the specs on the amp you're using (or the ones you're planning to buy). > 3)Also, is it possible to run on 1 Ohm? If so, How? Four 4-ohm SVC speakers wired in parallel, or two DVC drivers with their coils wired parallel, then wired parallel with each other. Very few amps will handle this without releasing their magic smoke. --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 0546-5, 11/20/2005 Tested on: 11/20/2005 8:13:30 AM avast! - copyright (c) 1988-2005 ALWIL Software. http://www.avast.com Just wanted to add that running 1ohm bridged is nearly impossible, off the top of my head i don't know any amp that will handle that. Mono amp would be the way i'd go because of it handling a lower impedance and because of the increased efficiency of a class D. If you don't care about efficiency, go a/b. >> I know its possible to run a 4 Ohm Woofer's to run 2 ohm... 1) How do u >> do this On a SVC and a DVC Woofer? [quoted text clipped - 26 lines] > avast! - copyright (c) 1988-2005 ALWIL Software. > http://www.avast.com >Just wanted to add that running 1ohm bridged is nearly impossible, off the >top of my head i don't know any amp that will handle that. Mono amp would >be the way i'd go because of it handling a lower impedance and because of >the increased efficiency of a class D. If you don't care about efficiency, >go a/b. True. One-Ohm mono operation isn't very common, because it's simply not as important as it used to be. Back in the eighties and early nineties, you had people that wanted to compete in the low-wattage classes in IASCA and USAC, but still crank out huge SPL numbers. This led to the development of so-called "cheater amps", that had low power ratings at four ohms, but could be safely used all the way down to one-quarter or one-half Ohm. This meant that you could compete in the "1-50 Watt" class, but you could be getting 400 watts or more out of your amp by running ultra-low impedences. If you've ever seen a "50-Watt" amp that's two feet long, weighs about thirty pounds, has multiple cooling fans, four-gauge power inputs, an 80-amp fuse, and cost about $500 new, that's probably why.  SignatureScott Gardner "Oh look, things are going from bad to worse!" oh also, you might want to even consider some of the (i think its called) regulated voltage amps. They will put out the same power from 1-4ohm and stable anywhere between. Depending on your application this could be a much better choice. (you wouldn't have to find a way to wire the speaker to 2ohm, 4 would be just as good) >>Just wanted to add that running 1ohm bridged is nearly impossible, off the >>top of my head i don't know any amp that will handle that. Mono amp would [quoted text clipped - 17 lines] > thirty pounds, has multiple cooling fans, four-gauge power inputs, an > 80-amp fuse, and cost about $500 new, that's probably why. >oh also, you might want to even consider some of the (i think its called) >regulated voltage amps. They will put out the same power from 1-4ohm and >stable anywhere between. Depending on your application this could be a much >better choice. (you wouldn't have to find a way to wire the speaker to >2ohm, 4 would be just as good) The new JL Audio amps are like that (same power into different loads). There are also amps that may be stable at lower impedences, but don't produce any extra power by doing so. My old PPI Art Series amps are like this. For example, the A1200.2 puts out 1200 Watts into a 4-ohm mono load, but if you use a three-ohm or two-ohm mono load, the amp will work just fine, but it will reduce the output power to keep the current at a safe level. SignatureScott Gardner "Some mornings, it's just not worth chewing through the leather straps." (Emo Philips) > Just wanted to add that running 1ohm bridged is nearly impossible, off the > top of my head i don't know any amp that will handle that. Audiobahn makes several that do 1ohm bridged. Thanks for the response.. I knew u needed 2 SVC Subs to run on 2 Ohms. I just wanted to be sure. This is what I will be getting for my car audio system: Two 12" Rockford Fosgate Punch Stage 2 Model # P212S4 Class D Monoblock Amp w/400w+ RMS or 2-channel Bridgeable (2 Oh Stable) or Two 12" Rockford Fosgate Punch Stage 3 Model # P312D2 Class D Monoblock Amp w/1000w+ RMS Reason for asking if i can wire a 4 Ohm SVC to 2 Ohm is because i wan the P212S4 to run the most power i can get out of the woofers -- jimbo_limited :-P rockford subs don't put out any power, good luck with that p312d2-- dual 2ohm means it can run at 4 ohm or 1ohm, if you have two of them you can run at 8,2,or 1/2 ohm each sub needs 500W p212s4 -- single 4ohm runs at 4 ohms, if two subs, 8 or 2ohms. each sub needs 200W The P312d2 -- the t10001bd would match up to this perfectly, run it at 1 ohm for two subs or 4ohms for 1 sub. the p212s4 -- i'd go with the punch P6001bd and set my gains back a little. Odds are with impedance rise you'll be fine. The P312d2 would be the setup i'd go for. But more than likely you could get a better bang/buch system elsewhere. > Thanks for the response.. > [quoted text clipped - 13 lines] > Reason for asking if i can wire a 4 Ohm SVC to 2 Ohm is because i want > the P212S4 to run the most power i can get out of the woofers. > :-P rockford subs don't put out any power, good luck with that > [quoted text clipped - 3 lines] > p212s4 -- single 4ohm runs at 4 ohms, if two subs, 8 or 2ohms. each sub > needs 200W Speakers don't "need" power, they "draw" power. The rating on a sub is how much maximum power it can handle before melting down (actually it's a bit more complex than that, but that's what it effectively boils down to), not how much it "needs" or "makes". If you put a sub rated for 200W on an amp that provides up to 500W, you stand a better chance of blowing up the sub than if you put a 500W-rated sub on a 200W amp (there's a whole other argument about underpowering speakers, but we'll stay away from that for now). And remember, amp power ratings are TYPICALLY given for four-ohm loads, and are ostensibly a measure of the maximum power the amp CAN provide, not how much it "pushes" out. Running multiple subs on that amp does not "divide up" the rated power - the actual power output will depend on the actual impedance of the load, up to the maximum available. Example: you have an amp rated for 250W into 4 ohms. You hook up a 4 ohm sub, and with everything set at full, you'll get up to 250W out of the amp. If you hook up two 4-ohm subs in series, for 8 ohms, you'll get a maximum of 125W out of it. With two 4-ohm subs in parallel for a 2-ohm load, the amp will still max out at 250W. However, it will take a lot lower input to achieve that maximum output - at a volume level that will produce 100W output into 4 ohms, you'll get 200W into 2 ohms: the voltage level is the same, but under Ohm's Law, with half the load, you'll have twice the current draw, and thus twice the power consumption. Of course, all this assumes perfect efficiency, ignores the varying impedences a speaker presents at different frequencies, and completely disregards the many ways amp manufacturers fudge their specs... --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 0546-6, 11/20/2005 Tested on: 11/21/2005 8:39:29 PM avast! - copyright (c) 1988-2005 ALWIL Software. http://www.avast.com > Example: you have an amp rated for 250W into 4 ohms. You hook up a 4 > ohm sub, and with everything set at full, you'll get up to 250W out of the > amp. If you hook up two 4-ohm subs in series, for 8 ohms, you'll get a > maximum of 125W out of it. With two 4-ohm subs in parallel for a 2-ohm > load, the amp will still max out at 250W. umm, I don't think so...if it's a crap amp it'll die, if it's good, it WILL give you an approximate doubling of power. It won't stay the same unless it's specificly designed to output a certain power over varing loads; which most amps do NOT do. However, it will take a > lot lower input to achieve that maximum output - at a volume level that > will produce 100W output into 4 ohms, you'll get 200W into 2 ohms: the [quoted text clipped - 11 lines] > avast! - copyright (c) 1988-2005 ALWIL Software. > http://www.avast.com >>Example: you have an amp rated for 250W into 4 ohms. You hook up a 4 >>ohm sub, and with everything set at full, you'll get up to 250W out of the [quoted text clipped - 6 lines] > it's specificly designed to output a certain power over varing loads; which > most amps do NOT do. Actually, you're correct... that's what I get for mulling over an answer most of the day before finally getting to post it while I'm half-asleep :) --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 0547-1, 11/22/2005 Tested on: 11/22/2005 10:05:23 AM avast! - copyright (c) 1988-2005 ALWIL Software. http://www.avast.com >>>Example: you have an amp rated for 250W into 4 ohms. You hook up a 4 >>>ohm sub, and with everything set at full, you'll get up to 250W out of the >>>amp. If you hook up two 4-ohm subs in series, for 8 ohms, you'll get a >>>maximum of 125W out of it. With two 4-ohm subs in parallel for a 2-ohm >>>load, the amp will still max out at 250W. That 125 watts into two series woofers will play just as loud as 250 watts into one, and with less distortion. The 4 ohm parallel thing, will play even louder even with 250 watts in. There will be some variation since all the drivers usually will not be in the same plane. I just thought to throw that in. Some don't think about that. greg >> umm, I don't think so...if it's a crap amp it'll die, if it's good, it WILL >> give you an approximate doubling of power. It won't stay the same unless [quoted text clipped - 10 lines] >avast! - copyright (c) 1988-2005 ALWIL Software. >http://www.avast.com >>>>Example: you have an amp rated for 250W into 4 ohms. You hook up a 4 >>>>ohm sub, and with everything set at full, you'll get up to 250W out of [quoted text clipped - 11 lines] > > I just thought to throw that in. Some don't think about that. yeah, i think it's like +3 for doubling of subs and +6 if there in the same plane. > greg > [quoted text clipped - 14 lines] >>avast! - copyright (c) 1988-2005 ALWIL Software. >>http://www.avast.com please tell me you had another reason other than correcting me saying "needs". What i meant was to reach the sub's full potential you'll need X wattage. most of the time you can give a sub shitloads more power than its rated for, but that depends on the setup and how nice you are with the gains. For someone that doens't know much about car audio i def wouldn't say underpowering is better than overpowering. I'd say the other way around cause you know he'll be clipping in no time. >> :-P rockford subs don't put out any power, good luck with that >> [quoted text clipped - 40 lines] > avast! - copyright (c) 1988-2005 ALWIL Software. > http://www.avast.com > please tell me you had another reason other than correcting me saying > "needs". Yes: for the edification of all those who don't understand the difference. > What i meant was to reach the sub's full potential you'll need X > wattage. And how do I know that? I can't even begin to count the number of times I've heard someone wanting a high-wattage sub because they think it's automatically louder, or asking how much wattage a sub "makes", because they have no clue. Be more careful with your wording if you don't want to be mistaken for one of them. You'll note I used poor wording in my reply, was duly chastised for it and corrected, and I accepted that. Surely you can do the same. --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 0547-2, 11/23/2005 Tested on: 11/23/2005 8:33:15 PM avast! - copyright (c) 1988-2005 ALWIL Software. http://www.avast.com "You'll note I used poor wording in my reply, was duly chastised for it and corrected, and I accepted that. Surely you can do the same." Yes i can also note your mis-information. And,I don't think i'll be mistaken for one of "them" since i'm not wanting a high-wattage sub or asking what wattage a sub "makes" the first line in the old reply was sarcasm which isn't easily transferred over text. Mistaken for a newb that loves boss? eh you all can think i'm a crossdressing audiobahn fan as far as i'm concerned. In the end if you don't want to take my advice, don't, its not my equipment that will be blown. >> please tell me you had another reason other than correcting me saying >> "needs". [quoted text clipped - 23 lines] > avast! - copyright (c) 1988-2005 ALWIL Software. > http://www.avast.com > Mistaken for a newb that loves boss? eh you all can think i'm a > crossdressing audiobahn fan as far as i'm concerned. ouch....an Audiobahn dig... >>Mistaken for a newb that loves boss? eh you all can think i'm a >>crossdressing audiobahn fan as far as i'm concerned. > > ouch....an Audiobahn dig... Transvestite dig, too. --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 0547-5, 11/26/2005 Tested on: 11/28/2005 12:00:20 PM avast! - copyright (c) 1988-2005 ALWIL Software. http://www.avast.com |
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