i have a small 4 channel amp and i wanted to run my gf's subs off it for just the time being. they are duel 4 ohm vc's and i wanted to know what the risk is or running my amp at 2 ohm bridged, when its only 4 ohm stable ? i would put a speaker on each side.
thanks guys
Replies (6)
swez on 05/31/2008 06:38:24
Chances are good that the amp will get hot and shut down with a 2 ohm load. The safest way to do this is not to bridge the amp and run one sub per channel @ 2 ohms. The power per sub may not be what you want for the long term, but it won't fry the amp either.
In the future, consider a solid 2 channel amp that will power these subs to whatever potential you desire. If you wire each sub for 8 ohms and then run them in parallel, that's a solid 4 ohm load and most 2 channel amps will take that just fine when bridged. (net 4 ohm load)
The other option is a 1 ohm stable MONO Class D amp. Here, you can wire all coils in parallel and the amp will see a net 1 ohm load. HiFonics makes a few Class D amps that handle 1 ohm loads. They are well priced and seem to stand up to the task well enough for the price. The Brutus Series is a good bet.
The main issue is matching the amp to the RMS level of the subs used. It's better to go a bit higher on the amp power levels so the amp signals remain clean and the subs will love the extra wattage when the signal is not clipping. Most quality subs can handle 20% more than rated RMS power and be just fine.
Swez
ckoscin2 on 05/31/2008 09:56:24
thanks swez, would it help at all if i ran a fan on the amp. i picked up the amp from a friend who needed money, a crossfire vr404 50x4 rms for 30 bucks. wont be out much if the amp goes.
if i bridged the amp with the subs at 8 ohm there wouldnt be alot of power going to them...im just looking for a lil more bump to hold me over till i get my other stuff..
i have the 4 channel right now with two 10's but they are 8ohm svc. so i wired them in parallel to bridge them on the amp at 4 ohm. but i am only using half the amp.
Ash on 06/1/2008 01:16:29
That Crossfire amp is rated to do:
50 rms @ 4 ohms stereo x 4 channels
100 rms @ 2 ohms stereo x 4 channels
200 rms @ 4 ohms bridged x 2 channels
Not a bad budget amp at all, it's just a matter of matching up power handling requirements to get the most out of the setup like Swez stated. You don't want to run it below it's ohmic capabilities.
The dual 4 ohm or single 8 ohm subs will work with a final 4 ohm load on the amp, but what do they require power wise? You can get away with pushing at least half of the required rms wattage, but no less. Just watch for clipping and know the system's limitations.... If the subs only require about 150 watts rms, it would be close enough to keep.
As far as the other 2 channels that aren't being used, you can put them on the front stage and make the amp run pretty much the whole system with the rear speakers fed by the headunit. That is fairly a standard system. Could be better with a single 4 ohm woofer with matching 200 rms, but if you need more, a dedicated bass amp will be needed as well as some subs that can do either 2 or 1 ohms.
By the way what are the subs that you have?
swez on 06/1/2008 07:24:32
I too resonate with your comments there Ash. Less is more in some cases and feel the same way... get rid of the clutter or make a storage system to hide away all the favorite treasures for future use as needed is the goal when work slows down very soon. (June 13th or so) Yippie Skippy!
Pops and I share a common bad habit. We are both "Pack Rats" to a large degree. The garage and basement are so cluttered w/ junk we don't need or use, so I can see a few garage sales in the future too. I know I'm a "PR", but Pops has taken this to a new level. He's got me beat 10:1. GRIN MAD
Some say a good rule of thumb is: "If you have not used something for more than 2 years and it's cheap to replace later, sell it, give it away or toss it". That really works and regular prunning is a good idea.
Swez
ckoscin2 on 06/1/2008 12:57:02
i have an crossfire cfa-404s (special edition 1 of 500) on my door speakers already with diamond audio m6 componets up fron with infinity kappa 5x7's in the back.
i picked up the other crossfire cheap so i borrowed my friends RF 10's.. i think they are p1's with single 8 ohm vc's. my gf has diamond m3 12's and they are dvc with 4 ohm vc's, i wanted to parallel the vc's of the 12's and bridge the amp at two ohm(one on each side). i figured the amp would get a lil hot maybe but i only bump from my house to my work, its only about a 4-6 min drive.
im looking into gettting a kicker L7 12" and a new amp, but the local shop is about an hour drive. gas here is $4.20 a gal so im not looking forward to going just because of the gas. i just want to know if they amp could handle the lil extra, and what i can do so i dont see any smoke ? but for short time would it not hurt ?
Ash on 06/1/2008 13:26:25
I don't recommend it... Even for a short trip, a strain is a strain. When it will finally blow, no one can tell for sure, but the fact remains that it isn't made to do beyond what it is designed.
The P1's are a decent match. At least better than your other option. The only other way to get more output is to run a ported enclosure. This will net another 3db off rip, but you will have to watch excursion below the port tuning frequency. Won't really be a problem too bad since you're already down about 50 watts each, but still possible.
There really isn't any other option besides getting a stronger bass amp to run with. Cooling fans or short runs won't help, and you definitely don't want the amp to shorten it's life from overheating. If you want more output, then you're going to have get more power sub & amp wise.
thanks guys
Replies (6)
swez on 05/31/2008 06:38:24
Chances are good that the amp will get hot and shut down with a 2 ohm load. The safest way to do this is not to bridge the amp and run one sub per channel @ 2 ohms. The power per sub may not be what you want for the long term, but it won't fry the amp either.
In the future, consider a solid 2 channel amp that will power these subs to whatever potential you desire. If you wire each sub for 8 ohms and then run them in parallel, that's a solid 4 ohm load and most 2 channel amps will take that just fine when bridged. (net 4 ohm load)
The other option is a 1 ohm stable MONO Class D amp. Here, you can wire all coils in parallel and the amp will see a net 1 ohm load. HiFonics makes a few Class D amps that handle 1 ohm loads. They are well priced and seem to stand up to the task well enough for the price. The Brutus Series is a good bet.
The main issue is matching the amp to the RMS level of the subs used. It's better to go a bit higher on the amp power levels so the amp signals remain clean and the subs will love the extra wattage when the signal is not clipping. Most quality subs can handle 20% more than rated RMS power and be just fine.
Swez
ckoscin2 on 05/31/2008 09:56:24
thanks swez, would it help at all if i ran a fan on the amp. i picked up the amp from a friend who needed money, a crossfire vr404 50x4 rms for 30 bucks. wont be out much if the amp goes.
if i bridged the amp with the subs at 8 ohm there wouldnt be alot of power going to them...im just looking for a lil more bump to hold me over till i get my other stuff..
i have the 4 channel right now with two 10's but they are 8ohm svc. so i wired them in parallel to bridge them on the amp at 4 ohm. but i am only using half the amp.
Ash on 06/1/2008 01:16:29
That Crossfire amp is rated to do:
50 rms @ 4 ohms stereo x 4 channels
100 rms @ 2 ohms stereo x 4 channels
200 rms @ 4 ohms bridged x 2 channels
Not a bad budget amp at all, it's just a matter of matching up power handling requirements to get the most out of the setup like Swez stated. You don't want to run it below it's ohmic capabilities.
The dual 4 ohm or single 8 ohm subs will work with a final 4 ohm load on the amp, but what do they require power wise? You can get away with pushing at least half of the required rms wattage, but no less. Just watch for clipping and know the system's limitations.... If the subs only require about 150 watts rms, it would be close enough to keep.
As far as the other 2 channels that aren't being used, you can put them on the front stage and make the amp run pretty much the whole system with the rear speakers fed by the headunit. That is fairly a standard system. Could be better with a single 4 ohm woofer with matching 200 rms, but if you need more, a dedicated bass amp will be needed as well as some subs that can do either 2 or 1 ohms.
By the way what are the subs that you have?
swez on 06/1/2008 07:24:32
I too resonate with your comments there Ash. Less is more in some cases and feel the same way... get rid of the clutter or make a storage system to hide away all the favorite treasures for future use as needed is the goal when work slows down very soon. (June 13th or so) Yippie Skippy!
Pops and I share a common bad habit. We are both "Pack Rats" to a large degree. The garage and basement are so cluttered w/ junk we don't need or use, so I can see a few garage sales in the future too. I know I'm a "PR", but Pops has taken this to a new level. He's got me beat 10:1. GRIN MAD
Some say a good rule of thumb is: "If you have not used something for more than 2 years and it's cheap to replace later, sell it, give it away or toss it". That really works and regular prunning is a good idea.
Swez
ckoscin2 on 06/1/2008 12:57:02
i have an crossfire cfa-404s (special edition 1 of 500) on my door speakers already with diamond audio m6 componets up fron with infinity kappa 5x7's in the back.
i picked up the other crossfire cheap so i borrowed my friends RF 10's.. i think they are p1's with single 8 ohm vc's. my gf has diamond m3 12's and they are dvc with 4 ohm vc's, i wanted to parallel the vc's of the 12's and bridge the amp at two ohm(one on each side). i figured the amp would get a lil hot maybe but i only bump from my house to my work, its only about a 4-6 min drive.
im looking into gettting a kicker L7 12" and a new amp, but the local shop is about an hour drive. gas here is $4.20 a gal so im not looking forward to going just because of the gas. i just want to know if they amp could handle the lil extra, and what i can do so i dont see any smoke ? but for short time would it not hurt ?
Ash on 06/1/2008 13:26:25
I don't recommend it... Even for a short trip, a strain is a strain. When it will finally blow, no one can tell for sure, but the fact remains that it isn't made to do beyond what it is designed.
The P1's are a decent match. At least better than your other option. The only other way to get more output is to run a ported enclosure. This will net another 3db off rip, but you will have to watch excursion below the port tuning frequency. Won't really be a problem too bad since you're already down about 50 watts each, but still possible.
There really isn't any other option besides getting a stronger bass amp to run with. Cooling fans or short runs won't help, and you definitely don't want the amp to shorten it's life from overheating. If you want more output, then you're going to have get more power sub & amp wise.
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