will this setup blow my amp??
 

hello all,

can anyone tell me if i use a jl 300/4 amp to power 2 focal speakers up front and bridge 2 channels to a JL 12w3v2 sub.. will it blow the amp? I usually dont blast my music but like it loud enough.. someone told me that this setup is not enough power for my sub and that the amp will overheat.. just wanted to know if anyone has tried this before with this amp??

thanks!

No, it won't blow the amp. According to the spec sheet for this subwoofer the 150W you're feeding it is towards the minimum of its recommended RMS range.
The only issue I could see, is if you're turning the gains all the way up on the amplifier to try and force it to drive that sub more. If you're using what you have correctly, no you won't have a huge amount of bass, but you shouldn't be damaging anything either. You're just not using that subwoofer to its full potential.

yes you can damage your amp with this sub. It is within the power requirements as mentioned above. However that sub has dual voice coils and if you have the dual 2 configuration and it's hooked up in parrallel(1 ohm load) you CAN damage the amp. If you have the dual 2 config. you will have to hook the voice coils up in series.

i just took out the sub and at the back it does say its a D2, just curious.. if i do end up going with the jl 300/4 amp.. and its really not enough power then does it really matter if i go with a JL amp for sound quality? or can I just go with a cheaper alpine or phoenix gold amp that has more power.. and it will sound just as good or better.. i am really on a budget.. its just someone told me that i should go with a brandname amp like JL.. but dont really want to spend that much $$ any advice would be appreciated.

was just reading up on the JL 300/4 amp.. apparently if i use 2 ohm speakers on 2 channels (my sub) and then 4 ohm speakers on other 2 channels then, the 4 ohm speakers will only get 37.5 watt rms for the front speakers.. i guess this amp is no good for me.. do all amps work like this?

Why not just buy an appropriate amp for the sub and use a separate amp for your speakers? Or just buy a five channel amp? By not buying JL you could probably afford to do it.

i really want to avoid using 2 amps.. if i just want to power the fronts and a sub.. then i will have 2 channels not in use with a 5ch amp.. is the 5th channel usually made specifically for subs? i did see a phoenix gold 5ch amp for sale in the classifieds.. maybe that will do??

Your amp is too tiny for double duty.

Yes, the 5th channel is designed to power a subwoofer. I can understand your logic, seems like a waste of money if you're not using the rear channels.

I've done some quick snooping around...

According to the Focal website, chances are you are using 4 ohm speakers, which have an RMS of about 60-80W. That range seems to be constant throughout their speaker line up, unless you're using 4" speakers.

The JL sub has an RMS wattage of 300.

In my humble opinion, you should consider this amp.
Pioneer Premier PRS-D4200F <<< click the red text
It'll give you 75W x 2 @ 4ohm for your Focals. And 300W x 1 (bridged) @ 4 ohms for your subwoofer.
On the Pioneer site it states that their suggested retail price is $500USD. On Crutchfield, the JL 300/4 amp is $550USD.
I was already looking at the D4200F at a local shop in town. He'd let is go for $450CDN. He also suggested a Hertz HP4 4ch amp.
The Hertz amp puts out 130W x 2 @ 4 ohm, and 440W x 1 (bridged) @ 4 ohm. I have an email from this shop where they say the HP4 would be $400. I'm not sure if putting that much power to your Focals would be a cause for concern though. Someone else could shed some light of what doubling the RMS would do.

Hope that helps.

hmm.. ic not bad.. my sub is 2 ohm though.. doesnt that mean the power doubles or something?

anyone know which amps can be bridged at 2 ohm? so far all i can find is a Rockford Fosgate t4004.. anything else?

You can bridge the 4 channels into 2, and run the 5th channel for the sub, and it will be wicked!!!

http://www.the12volt.com/12voltimage...m_dvc_1ohm.gif

or

http://www.the12volt.com/12voltimage...m_dvc_4ohm.gif

So as you can see, depending on which way you wire your voice coils together, you're either creating a 1 or 4 ohm load for whatever amplifier you choose to get. But I've never come across an amp that is capable of running bridged channels at 1 ohm. If there is one, I'll assume it wouldn't be cheap.

DLS A3 Ultimate 2-channel amp is 1 ohm stable bridged, and 1/2 ohm in stereo. Just for info sake. Not too cheap, but deals can be had. I have one in my collection.

If he is planning on using that amp, he can run the sub at 4 ohms and get full power. Slash series are regulated fully, and make full power at 1.5-4.0 ohms.

thank you so much for the diagrams.. but just a bit confused as my version of the sub is D2 meaning 2ohm.. how does it turn into a 4ohm if it says its 2ohm version? If it does turn into a 4ohm then i can pretty much use any 4ch amp because most when bridged support minimum 4ohm.. correct? i noticed someone selling a phoenix gold r-9 5xchannel amp. with this amp would i be able to bridge the 4 channels and run it to my 165cv Focals and then use the 5th channel on my JL sub? assuming i have the setup like your last diagram?

The 'D' stands for "Dual". So you have two voice coils that are 2 ohms each. Wiring the voice coils gives you the 4 ohm total load. Wiring them in parallel gives you a 1 ohm load.

Yes, most amps will be capable of operating at 4 ohm when bridging channels. Like I said, there'll be some that are 1 ohm stable when bridged. They just won't be cheap.

I have to make a retraction on the Hertz amp I suggested. The HP4 is a $1500 amp. The EP4 is a $400 amp.

tragicmagic thank you for the clarification.. just noticed that you reply to alot of people questions.. you must be the audio guru lol .. big ups to you for your help!

anyone have a decent USED amp for cheap they wanna get rid off that will power my system??? only want to spend about $100.. yes i am poor right now :(

you'll be fine.
run the fronts off the front channels
run your sub off the rear channels (bridged@ 4ohm) D2 in series will give you a 4ohm load.

DJchinky, thanks. But no sir, I am not an audio guru. Just an enthusiast. To be honest, my knowledge pales in comparison to most of the guys on here. The reason I try to be so helpful is so that I can learn about all the stuff that's out there, and the most efficient way of stringing it all together. When I see a message posted by newer users, it gives me an opportunity to do some research. The more we know, the wiser we are when it comes to making a purchase. With that said, you have to listen to the equipment to find what really sounds great to you.


You'll find that some of these guys have a "go big, or go home" attitude. Just an observation. While their input and suggestions are all with good intentions, its important to realize that what they're suggesting may be a whole lot more than you're looking for.

Go around to audio shops. Start small. Then gradually listen to more powerful, higher end equipment until you reach the point that you're most satisfied with. It never hurts to buy equipment that has more capacity than what you're using it for, at first, in case you want to push your system further in the future, you'll already have some headroom.

If I were you I'd take that sub, wire it for 4 ohm, then go around hooking it up to amplifiers with different outputs at 4 ohms. You might find that a less expensive 300W amp is enough. Or you might find that you want to have 600W available for it.

Well, I think the reason a lot of guys say go big or go home, cause everyone went through many upgrades, which costs money. If you go big and expensive as soon as possible, you will save money at the end on multiple upgrades which will inevitably cost more. Experience speaks volumes. On the flip side of the coin, upgrades are half the fun.

upgrades are fun if you have the cash! If he's only got a $100 he should hook it up at 4ohms and save up some money cause $100 don't go far.As for used equipment it's a roll of the dice, usually no warrenty and the equipment may have been abused. Do you're research, save your money and make the right purchase the first time. It will save you a lot of headaches.

definitely!! but ill roll the dice.. i usually have good luck.. well not sure how long it will last tho.. keep my fingers crossed!
thx!

I would not start anything if I only had a $100, I would buy essentials like bread and milk.

well i can spend a bit more.. i think im gonna try looking for a used alpine mrp-f450, f550, f600.. what do you think? i will prob have to spend about $200

If my financial situation was so bad, that I was wondering whether to spend $100 or $200 on something trivial, I would not waste my time on garbage gear, and put my money towards making more money, and then consider getting something better, which may actually bring me joy. Right now, you are looking at spending so little money, that you may feel that you actually wasted your money after you buy it, run it, and decide that this is crap. We are trying to help do the right thing, if not, then dont waste your time and efforts. And going from something that is worth $100 to something that is worth $200 is hardly an upgrade, as you gotta count on variables like actually getting ripped off by someone. Man, think about what you want to have at the end, and work towards it, I would not suggest getting gear piece by piece without a plan. Just make sure you will be content with your decisions, as the bitterness of poor quality remains long after the sweetness of low price has faded.

i hear ya.. im not that picky with audio.. originally i was just gonna replace headunit and use headunit power to run speakers so i can any amp would make a difference.. i also havent heard the best audio yet.. so i have nothing to compare too.. lol.. but appreciate the advice.