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Old     (norcalmalibu)      Join Date: Jun 2004       02-02-2007, 11:31 AM Reply   
I have a question most JL Audio subs are wired for 3ohms.. If you wired it up to an amp that is running 4ohms bridged will it do any damage to the amp? Or will it just supply less power to the sub?

I am confused, please help!
Old     (cyclonecj)      Join Date: Jul 2001       02-02-2007, 11:39 AM Reply   
my JLs are dual 4ohm coils, but as for your question, it is 25% bigger load on the amp. If it is rated for 4 ohms bridged and you put three on it, your amp may not be able to keep up. It may, or it may get hot and go into protection. What amp are you running?
Old     (norcalmalibu)      Join Date: Jun 2004       02-02-2007, 12:02 PM Reply   
hifonics # RMS Power Ratings:
HIFONICS XX-COLOSSUS II
* 600 watts x 2 chan. @ 4 Ohms
* 1100 watts x 2 chan. @ 2 Ohms
* 1600 watts x 2 chan. @ 1 Ohm
* 2000 watts x 1 chan. @ 4 Ohms
* 3200 watts x 1 chan. @ 2 Ohms

The subs are actually TCSounds, I used JL sense most people don't know about Tcsounds...
http://www.tcsounds.com/tc3000.htm
I was going to wire them at 2.8ohms sense I am pretty sure it wont be stable at .7
Old     (grant_west)      Join Date: Jun 2005       02-02-2007, 12:03 PM Reply   
Nate: It will just supply less power to the sub

Example: Most amp's are rated this way.

500 watts at 4 ohm's
750 watts at 3 ohm's
1000 watts at 2 ohm's

JL amps are suposedly diffrent
JL says their amp's produce the same wattage at what ever ohm's. They say a JL 500-1 will produce 500 watts in what ever Ohm load you show the amp. I have never tested a JL amp with a Load or Watt meter so I dont know if what they are saying/selling is true.

BTW: The speaker tell's the amp what load it pushes. Not the other way around. Example
1 4 ohm speaker will make the amp push a 4 0hm load.
2 4 ohm speakers will make the amp push a 2 ohm load
Old     (pickle311)      Join Date: Oct 2005       02-02-2007, 6:40 PM Reply   
an Ohm is a mausurement of resistance, the less resistance you have the more current you can flow in an electrical circuit. The more current there is flowing though the circuit, the more heat it produces. Heat is electronics worst enemy. Most amplifiers are built to withstand a certain ammount of heat. The heat is controlled by the ammount of resistance within the circuit, the amp and speakers. If there is no resistance, the circuit sees that as a direct short. It's the same as going out to your car, popping the hood, and placing a peice of large wire between the two terminals of your battery. If you decide to try this, I recommend doing it in the dark. It makes some really pretty lights. If your amp sees no resistance on the output, it will fry. If you're lucky you may have a protection circuit built in, but don't test it to see. Most of them don't work that well anyway.

Now for the JL Subs, here's why they have 3 ohm coils. It started with dual 6 ohm coils. The point was to series the coils giving you a 12 ohm load. With that, you could then take 3 12ohm speakers and parallel them together giving you a total of 4 ohms. You then had the option of having 3 subs on one amp without overheating or frying it. JL then went with 3ohm coils for the same principle with double the speakers. Get the point?

The bottom line is,, if you are running a class AB amp, I wouldn't go below 4 ohms. Generally speaking though, 3ohms is within the tolorence of the components inside a good amp, just make sure it has very good ventallation and use fans. It will probably decrease the life of the amp a bit though.


As for JL saying their amps produce the same power reguardless of the ohm load, that could only be done with a digital amp and I don't know how. I would have to see the schematics and it seems like it would be extremely expensive and a waste.
Old     (05mobiuslsv)      Join Date: Apr 2006       02-02-2007, 7:52 PM Reply   
Shane pretty sure JL says their amps will put out the same power regardless of voltage not ohm load.
Old     (joe_crawley)      Join Date: Jan 2007       02-02-2007, 7:58 PM Reply   
The enclosure the sub is in will have a large impact on the impedance the amp sees. If you have the sub in a small box, you'll be running just fine. If it is running free air, you may see the amp shutdown. The amp will go into shutdown a few times (maybe even a few dozen times) before it blows up, so you should be safe to try it out and see if the amp will cooperate. The smaller the airspace of the sub enclosure the higher the impedance the amp will see.

Shane- an amp with a strictly regulated power supply will produce the same power regardless of load- this is absolutely not a question of digital vs. analog.
Old     (sea_ray_dave)      Join Date: Dec 2004       02-03-2007, 7:24 AM Reply   
Nate, That amp won't work at a .7 load but will do excellent at 2.8, it is a beast!! I won't be surprised if it melts the voice coils. I have been wondering about tcsounds using 4 voice coils crammed into 3 inches but have not heard a set to form an opinion. You will have way more than enough power going to them. Let me know how you like the subs and give a review.
Old     (mikeski)      Join Date: Aug 2003       02-03-2007, 9:39 AM Reply   
Nate,

Just run a monoblock class D dedicated amp to it and you should be fine. Send me a PM if you need any help or suggestions.

Mike

ps I need some CV joints...
Old     (norcalmalibu)      Join Date: Jun 2004       02-03-2007, 12:15 PM Reply   
Thanks for the input guys, I have learned a tremendous amount of information over the last year because of this board.

thanks
again

David, I will let you know how they sound, ive been waiting to order my set. They just switched from an aluminum cone to a titanium one. I know they had problems before on the aluminum ones separating from the cones. One thing that is nice about TC is the warranty.
Old     (pickle311)      Join Date: Oct 2005       02-03-2007, 6:35 PM Reply   
Joe, I'm going to have to strictly disagree with you. Here's why. A regulated power supply is designed to put out the same ammount of power with a given input range. Meaning that the input voltage will not drastically change the output. Regulated power supplys generally have a operating range and if the voltage falls out of that range it will then turn itself off. The resistance in that loop will determine the ammount of current flowing and it has a direct effect on the wattage put out by the amp. More resistance, less current flow. Current is power. An unregulated power supply output directly dependant on the input voltage. If you look at the specs, most of your amps give you a rating with the input voltage at 14.4 volts. There's 2 reasons for this. 1, the company can legally pad their specs and make it look better. 2. A lot of alternators put out over 13 volts. Here's the design flaw of an unregulated power supply. When the input voltage dropps, the power supply will not shut itself off. It will continue to try and produce power. It does this by supplimenting the lost voltage with more current and inevitably self destructs. If I'm wrong, please prove it. I'm an Electrical Engineer by the way.
Old     (cyclonecj)      Join Date: Jul 2001       02-04-2007, 6:17 PM Reply   
JL amps change the rail voltage on the output transistors to keep the output constant within a range (1.5-4 ohms) yes it's a regulated supply but that alone won't do what JL amps are designed to do.

you need to go back to school and learn power supply design. A non-regulated power supply won't eat itself.

Every amp made that can produce over 12 watts average power has a regulated PWM switching power supply in it.
Old     (pickle311)      Join Date: Oct 2005       02-04-2007, 8:01 PM Reply   
haha, ok it won't, I've seen it happen several times. Clarion amps had a huge problem with it for a couple of years. I even had one of their engineers on the phone discussing it. There's several companies running unregulated power supplys in their amps, even Kicker. Or Kicker was a few years ago. I've been out of the industry for a while so this may have changed.

That explains it on the JL amps, I haven't done any research on them.

Why would you need a PWM (Pulse With Modulation) power supply when you are dealing with DC? all it takes is a couple of capacitors and resistors to filter out any deviation on the input voltage. Sure, it's filtered better but is it really needed. Maybe in really high end applications, but for the average consumer it's a waste. I mean it takes DC and chops the hell out of it, feeds it to a transformer that converts that chopped DC signal to a high frequency AC signal and then goes through a rectifier to convert it back to DC. Funny, it does the same thing that your altenator does, runs AC through a full wave rectifier and gives you a clean DC voltage. Really not relevant to the conversation, but I don't see the real benifit of all the conversions. I know power supplys and I'm sick of school, I got my degree and went back for more. I finished that and said I was done. I don't want any more education haha.
Old     (cyclonecj)      Join Date: Jul 2001       02-05-2007, 6:04 AM Reply   
Because of physics. You can get 12 clean watts from 12vdc without putting it through a DC to DC converter. Any stereo amp over 24 watts RMS needs a switching power supply to boost DC and to create a double ended supply. A big amp needs 50vdc +/- or more on its supply rails. THat only happens with a switching, PWM power supply.

Sure, car amps fail. But they have regulated supplies in them. Car stereo people don't really understand what regulation is, and what JL does is way more than power supply regulation.

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