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Discussion Starter #1
So I'm building a boom box with the extra car audio equipment I have laying around. The problem I'm at right now is that I have only 1 JL 10w3v3 and it is 8 ohms:(. The highest ohm rating of any of my available amplifiers is 4 ohms. Bridged at 4 ohms I am getting 300-350rms. I figure if I run the woofer directly into the amp at an 8 ohm load I will get 150-175 rms to the woofer. I am just curious if there is a way to wire the 8 ohm SVC woofer to be a 4 ohm load. Can I rewire it or instal something inline from the amp to the woofer that will change it to a 4 ohm load so I can utilize all of the power?
 

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Yeah, buy another 10w3v3 8 Ohm sub. The only correct way to reduce the Ohm load on the amp is by changing subs or by using parallel wiring. There are the oddball subs on the market with selectable impedance, but you don't have one of those.

edit: I'm referring specifically to changing the impedance with a switch, not dual voice coil subs.
 

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You can't use a resistor to cheat an amp into putting more power into the sub. It's going to send half the power as wasted heat into that resistor, and the other half will go to the sub.
 

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4 Ohm 200W Non-Inductive Dummy Load Resistor 019-025

this would bring the load down closer to 4 ohms, but honestly, that more than enough power, hell, heres a video of my GRANDFATHERS 15" on just 130w.
Look up Kirchhoff's Current Law. It explains why this is a bad idea, and how the extra power would just go into the resistor, which would just get wasted as heat.

A transformer can accomplish this but they are somewhat bulky, heavy and expensive for the part you'd need. And they aren't perfectly efficient or linear, either.

Get another sub either to replace that one or to use in conjunction with that one.
 

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Am pretty sure one of your amplifiers can do a single 8-ohm load. If your amplifiers have a spec lable as "----watts x 2 channels @ 4ohms" then you can bridge your amplifier at 8-ohms and expect the wattage to be the same as the 2channel 4-ohm spec. This will not fry your amplifier, if it has a protection circuit that prevents it from playing a single 8-ohm load then that amplifier is not made for high loads.
 

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Discussion Starter #7
I guess I'll just run it straight into the amp. I just wanted to get the full 300 to the woofer. I didn't know if there was a way the work around this

I really don't want to buy a new woofer. The goal was to use components that I already have
 

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I guess I'll just run it straight into the amp. I just wanted to get the full 300 to the woofer. I didn't know if there was a way the work around this

I really don't want to buy a new woofer. The goal was to use components that I already have
What amplifiers you have available to use, I can give you my opinion on which one to use for that single 8-ohm sub. Worse comes to worse all you will sacrifice is wattage/power but atleast you know the amplifier will run cooler and decrease THD.
 

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Just run the one, what u lose in spl will be gained in control and sq. It should sound just fine and the amp will run cooler.
 

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Discussion Starter #10
Option 1: fd2200 360 x 1 @ 4ohm on the subwoofer. Cadence z4000 75 x 4 @ 4ohm for the RF T152s woofers and the single scanspeak D3004 tweet. The Xover on the z4000 won't go past 1.6k so I will have to get a Xover or cap or something.


Option 2: use the Z4000 only. Bridge channel 3&4 for 300 rms at 4ohm and run the subwoofer off this bridged channel. Chs. 1&2 normal for the t152s woofers and no tweeter. I would use the Xover in the amp.


I will do some listening tests to see if the sub and 5.25s sound alright without the single tweet. The box would b considerably lighter to move without the extra amp. I will manage the added weight if it makes a considerable sound and power difference.
 

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Am pretty sure one of your amplifiers can do a single 8-ohm load. If your amplifiers have a spec lable as "----watts x 2 channels @ 4ohms" then you can bridge your amplifier at 8-ohms and expect the wattage to be the same as the 2channel 4-ohm spec. This will not fry your amplifier, if it has a protection circuit that prevents it from playing a single 8-ohm load then that amplifier is not made for high loads.
Since when does running an amp at a higher impedance fry your amp?
 

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Since when does running an amp at a higher impedance fry your amp?
I'd like to know the same thing. Lately this story has been spreading that 8 Ohm drivers are killing amps. :confused:
 

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I'd like to know the same thing. Lately this story has been spreading that 8 Ohm drivers are killing amps. :confused:
I've tried powering my woofers at a single 8-ohm load with my BP1200.1 and it was not able to do so. NO DAMAGE was done but 1200watts is just too much, right now I have a JL 500/1 and its more than enough.

If an amplifier runs a single 8-ohm load then it means it can do so for a long time with no problems. If it has some type of circuitry protection then the answer is simple it wont do so at all, BUT IT WILL NOT FRY your amp.
 

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I've tried powering my woofers at a single 8-ohm load with my BP1200.1 and it was not able to do so. NO DAMAGE was done but 1200watts is just too much, right now I have a JL 500/1 and its more than enough.

If an amplifier runs a single 8-ohm load then it means it can do so for a long time with no problems. If it has some time of circuitry protection then the answer is simple it wont do so at all, BUT IT WILL NOT FRY your amp.
Huh?
 

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Since when does running an amp at a higher impedance fry your amp?
I'd like to know the same thing. Lately this story has been spreading that 8 Ohm drivers are killing amps. :confused:
Some class D amps have the final filters set for moron.... They do not care for higher impedances and will resonate. This is mostly the case in car audio because the rest of the world knows how to make things work.

Remember in a class D amp the voice coil has the last "pole" in the final LPF included.

I'd still NEVER ad a resistor and simply rock it.
 

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I can't find an 8ohm version of the 10w3v3 anywhere on JL's site. I had no idea these things existed.

I say try what you have for now. I searched on the amp mentioned in this thread that supposedly won't work at 8ohms and found several cases of people running it at 8ohms with no problems. What kind of enclosure is this going in?
 

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Discussion Starter #20
if it's not a specific class D amp that's crude... :confused:Rock the bastard, put it in an efficient enclosure and have fun... no money down.
So which of the two options did you like? It's going into making a portable boom box that we can plug in for parties or take places with friends.
 
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