JBL to power 3 subs?

[Mark_ab 5,000+ posts]

I'm thinking of getting a 3rd Perfect 12 when I get my new car. A couple of questions here. Can the JBLBP1200.1 run 3 of them, or should I get another amp for the 3rd? And how would I have to wire them to get a 2 ohm load, if it's possible. Also, I was thinking of facing them inside, towards the cabin, and doing a stealth install. The car is a (probably) 91 Z34, which has a fairly sizable metal plate behind the rear seats. I'll probably port this, somehow. Any suggestions? Zane?

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[zane 10+ year member]

So long as you are running the SVC 4 ohm models- you should be able to do this.

You will be a a 1 ohm mono load, which the BP1200.1 will handle. You will likely need to add a fan to the amp to increase airflow, as this is usually necessary in any situation where the impedence is below 2 ohms.

Basically you will need to wire the subs together in paralel. Two 4 ohm subs in paralel yields a 2 ohm mono load, adding the 3rd will yield a 1 ohm mono load.

Just wire the 3rd sub in to your setup the same way the others are and you should be good to go!

take it easy,

-zane

 

[Mark_ab 5,000+ posts]

Okay, thanks. That was the original plan, however, I wasn't sure if the JBL could handle a 1 ohm load. Will this be sufficient power for the subs? I'd imagine so, 400 a piece. What about the direction the subs are facing? Are there advantages to each, front or back?

 

[zane 10+ year member]

If you look in the .pdf file for this amplifier on http://www.jbl.com it notes a 1 ohm load minimum. I have also verrified this and had no problems.

Concerning the direction your subs face- this is a matter of trial and error unfortunately. Each car has its own acoustical properties, some hinder and some improve sound. I can only say that the best thing to do is try the enclosure in several different positions and go with the one that sounds best. Most cars generally respond to bass better with the subs facing to the rear. This is mainly because they immediately have a surface to bounce sound off of and send it back into the car. This at times can cause some cancellation, so it is best to just find a location that you are happy with and then incorperate your install arround it.

take it easy,

-zane

 

[Mark_ab 5,000+ posts]

Okay, thanks Zane, much appreciated. Hopefully the car will warrant the subs facing in, as I'd really prefer that stealth install.

 

[RangerMan Premium Member]

Even though the 1200.1s say that you can only run them and a 2 ohm minimum. I have seen some running at 1.5 ohms fine but I have never personally tried one ohm.

 

[Unregistered]

Basically you will need to wire the subs together in paralel. Two 4 ohm subs in paralel yields a 2 ohm mono load, adding the 3rd will yield a 1 ohm mono load.

Not trying to be an ass, but wouldn't (3) SVC 4 ohm subs make a 1.33 load? (4) SVC 4 ohm subs would be a 1 ohm load. Take the impedance and divide by the number of circuits (subs in this case) in parallel to determine the load.

 

[dr. no 10+ year member]

hey, the 1200.1 don't say they have a 2 ohm min. All the amps in that seriesare 1 ohm stable.

 

[zane 10+ year member]

Originally posted by Unregistered Basically you will need to wire the subs together in paralel. Two 4 ohm subs in paralel yields a 2 ohm mono load, adding the 3rd will yield a 1 ohm mono load.

 

Not trying to be an ass, but wouldn't (3) SVC 4 ohm subs make a 1.33 load? (4) SVC 4 ohm subs would be a 1 ohm load. Take the impedance and divide by the number of circuits (subs in this case) in parallel to determine the load.

This is correct in many circumstances, however, measure many a speaker rated at 4 ohms and it will read anywhere from 3.4 to 3.7 ohms on an ohm meter.

Just depends on the manufacturer, the material, and design of the speakers VC.

take it easy,

-zane

 

[Jeff 10+ year member]

Yeah, that is true Zane. I guess a subs impedance is nominal. It would be better to calculate actual.

 

[RangerMan Premium Member]

Originally posted by dr. no hey, the 1200.1 don't say they have a 2 ohm min. All the amps in that seriesare 1 ohm stable.

Both of mine says "slams into 2 ohms" on an orange sticker on the front. I should know, I have 2.

 

[Jeff 10+ year member]

My bp600.1 also had the "slams into 2 ohms" sticker, but the owners manual says, "The total impedance of the speaker system connected to a BP Series amplifier must be at least 1 ohm".

 

[RangerMan Premium Member]

Neither of mine came with a manual.