Car Stereo Experts...advice needed.

[djdrock]

My nephew is installing a JL 300/2 AMP, and a 12" Dual Voice Coil Bazooka Tube. His first installation attempt yielded a blown 10" single voice coil tube. He then purchased a 12" dual voice coil.

So, he has a couple of installation questions, and a couple of different options. His 10" is under warranty, so essentially, he will have the ability to use a 10" and 12". I think the 12" alone will be sufficient, but he may want both tubes installed.

Here are the specs of the components:

JL 300/2:

Rated Power: 150 W RMS @ 1.5 ohm-4 ohm (11V-14.5V)
Rated Power (bridged): 300 W RMS x 1 @ 3 ohm-8 ohm(11V-14.5V)
THD at Rated Power: <0.03% @ 4 ohm
S/N Ratio*: >108.5dB below rated power
Frequency Response: 5 Hz - 30 KHz (+0, -1dB)
Damping Factor: >200 @ 4 ohm per. ch./50 Hz
Input Range: switchable from 200mV-2V RMS to 800mV-8V RMS
Dimensions: 13.4"L x 9.25"W x 2.36"H
Differential-Balanced Input Topology: (1 pair of inputs)
On-board Crossover: fully-variable (50Hz-5 KHz), selectable-slope LP or HP (12 or 24 dB per octave)
Preamp Output: 2-channel (full-range, LP or HP)
Speaker output connections: accept up to 8ga. wire
+12V and Ground connections: accept up to 4ga. Wire


12" Bazooka Tube (Dual Voice Coil)

Power Handling --------------------------------- 600 watts (Max)
Impedance --------------------------------- Dual 4 Ohm
Sensitivity --------------------------------- 106 dB
Frequency Response --------------------------------- 30HZ-1000HZ
Recommended Power --------------------------------- 75-250 watts/channel
Voice Coil Size --------------------------------- 2" hi power/hi temp
Magnet Weight --------------------------------- 36 oz

I know there is a way to run things in series, parallel, bridged etc...

What are your recommendations for wiring the amp to the bazooka tube(s)? If he just runs the 12" Dual Voice Coil, how should that be wired to the amp?

If he chooses to run both the 10" single voice coil tube, and the 12" dual voice coil tube, how should that be wired to the amp?

Thanks!

 

[Gansan]

It's been many years since I've been into car audio, but here's my take:

I will only consider the single 12" scenario. You have two ways you can go.

1. Run the stereo output of the amp, and go one channel to each voice coil. This is kind of how the woofer is meant to be run.

2. Bridge the amp, and run the two voice coils wired in series. This means an 8 ohm load, which is pretty much equivalent to the stereo config of #1 of two 4 ohm channels.

You shouldn't wire the voice coils in parallel because at 2 ohms, that would drive the amp too hard in bridged mode. There may be other amps that can handle that, but I believe distortion goes up as the load goes that low.

I think ideally, the woofer should have had two 8 ohm voice coils, because then you can wire them in parallel and bridge the amp for a bridged 4 ohm load. That would have been the best combo of power and presenting a safe load for the amp.

 

[Hapa88]

It's been many years since I've been into car audio, but here's my take:

I will only consider the single 12" scenario. You have two ways you can go.

1. Run the stereo output of the amp, and go one channel to each voice coil. This is kind of how the woofer is meant to be run.

^I would go this route for a single 12" DVC scenario.


For wiring one Single Voice Coil 10" Tube, I would have the amp in "bridged" mode (300x1) and run it directly to the SVC tube.

If you really wanted to run both (which is overkill IMO), I would Series the 12" DVCs (giving you a 8ohm load), then parrallel that load with the 10" SVC 4ohm load. That, I believe, would give you an effective 6 ohm load which would go to your amp in "bridged" mode.

 

[TURBO2GO]

You are going to have to take my word that there is no good way to run both without some issues. You are going to wind up with more output from one sub than the other, and it just won't be a good balance. One will pop, one won't. I would not mix a DVC and an SVC in a parallel mode.

Your best bet is to run the amp in stereo, and run one channel to each voicecoil. Bridging amps in general is not as good as running them in stereo. Distortion levels go up as does heat output, it's like revving the engine at a higher RPM. Although you get more power, damping factor drops. That means less cone control which is really important here.

I know what I am recommending is not the "exotic" solution and some car stereo guy will think he is smarter than physics because all he will look at is output power thinking he has some sort of trick up his sleeve.... but it will ultimately sound worse.

Make certain the amp has a good ground and is fed well by a good 12V power wire. Placement of the sub also matters a lot, play with the orientation of the bazooka in the car. You can corner load it, have it face forward, rearwards, etc. Not knowing the car, I can't tell you but this makes a big difference.

 

[syndicate]

I do not recommend running differing sub sizes due to the frequency response differences. Long story short....don't do it. If a DVC 12 isn't enough, get a DVC 15 or a second DVC 12. Wiring the DVC 12 in series will yield an 8 Ohm load at the amp. You will then bridge at the amp to utilize the most power out of the amp. So in actual wiring speak:

Wire the 1st voice coil's (-) to the 2nd voice coil's (+). Connect the 1st voice coil's (+) to the (+) terminal inside the box or tube. Connect the 2nd voice coil's (-) to the (-) terminal inside of the box or tube. Now the amp should have it labeled which terminals are the bridging terminals. I will assume Left (+) and Right (-). Connect the left (+) from the amp to the (+) terminal on the outside of the box and connect the right (-) from the amp to the (-) terminal on the outside of the box.

Another important thing to note is to make sure the signal that communicates from the radio/cd player to the amp should be a mono signal like a dedicated subwoofer output. This should provide volume control of the sub independent of the highs and mids. If this is connecting to a factory radio, you can use a Line Output Converter to leech signal from the front or rear speakers in order to provide an RCA signal. Also, make sure to keep the bass on the radio/cd player as low as possible and let the sub take care of the bass. This will save your speakers from abuse.

I also recommend that you use 4 ga power and ground wire to hook up the amp. It may be a little much on a 300 watt amp, but it will help keep the amp cooler and if you ever need/want to upgrade, you won't have to redo the installation. Don't forget to scrape the paint and primer where you ground. Bad grounds are the number one cause of premature failure.

Hope this helps and if you ever need help, send me a pm.

Thanks,
Jay

 

[TURBO2GO]

I do not recommend running differing sub sizes due to the frequency response differences. Long story short....don't do it. If a DVC 12 isn't enough, get a DVC 15 or a second DVC 12. Wiring the DVC 12 in series will yield an 8 Ohm load at the amp. You will then bridge at the amp to utilize the most power out of the amp. So in actual wiring speak:

Wire the 1st voice coil's (-) to the 2nd voice coil's (+). Connect the 1st voice coil's (+) to the (+) terminal inside the box or tube. Connect the 2nd voice coil's (-) to the (-) terminal inside of the box or tube. Now the amp should have it labeled which terminals are the bridging terminals. I will assume Left (+) and Right (-). Connect the left (+) from the amp to the (+) terminal on the outside of the box and connect the right (-) from the amp to the (-) terminal on the outside of the box.

Another important thing to note is to make sure the signal that communicates from the radio/cd player to the amp should be a mono signal like a dedicated subwoofer output. This should provide volume control of the sub independent of the highs and mids. If this is connecting to a factory radio, you can use a Line Output Converter to leech signal from the front or rear speakers in order to provide an RCA signal. Also, make sure to keep the bass on the radio/cd player as low as possible and let the sub take care of the bass. This will save your speakers from abuse.

I also recommend that you use 4 ga power and ground wire to hook up the amp. It may be a little much on a 300 watt amp, but it will help keep the amp cooler and if you ever need/want to upgrade, you won't have to redo the installation. Don't forget to scrape the paint and primer where you ground. Bad grounds are the number one cause of premature failure.

Hope this helps and if you ever need help, send me a pm.

Thanks,
Jay

I have to respectfully disagree with some of the statements here. The main reason you do not want to run a DVC and an SVC sub together is mainly one of sensitivity and not frequency response.

"Then you will bridge the amp to utillize the most power out of the amp" is also not correct in this case. Not only are this amp's specs not any higher bridged at 8 ohms, but now you are increasing it's distortion levels and reducing the damping factor which is critical in controlling cone motion. It's like saying "rev it to 8000 because it has the most power" when it is the way power is delivered that is more important than how high it is. You have a perfect situation with the DVC at 4 ohms per coil and an amp that was DESIGNED to drive that load to begin with (this is not a mono sub amp, dont use it as one).

Jay does have a good point and we didn't ask... you should NOT be boosting the bass by an EQ or bass control too much, you are then increasing demand at one particular fequency and that is probably how he blew the sub. Leave it flat as much as possible. Adjust the amp's gain controls to get the level of bass that is desired. Use the amps "high pass" preouts to feed the amp that is feeding the main speakers.

4 gauge wire is overkill for this IMO, but it won't hurt. I think 6, 8, or even 10 gauge is fine.

My suspiscion is that it is not so much equipment failure that caused the damage, but an improper tune and installation. There is a lot more to that than people think.

 

[syndicate]

Well the manual for this amp does claim to put out 300 watts x 1 at 3-8 Ohms (which I totally don't believe). You would not be able to obtain this without bridging it. Honestly, the OP has the wrong sub for this amp or the wrong amp for this sub (however you want to look at it) as the ideal case when using a 2 channel amp for bass would be to have a single 12 inch DVC sub with 2 Ohm coils.

Not sure what you are trying to say by mentioning that it is not a mono amp and should not be used as such, but the only difference (basically) is that the mono amp will bridge internally and has the circuitry to be stable at 2 ohms. Two channels amps are designed to run 2 speakers and allow a separation of left and right channels. Sub woofers are not ever supposed to run in a true stereo mode off a true stereo signal. Doing this would cause some base notes to flatten out when signal is lost down that channel. Not really sure how to explain this better, but in stereo systems, different things will come out of the left but not the right or vice versa. Essentially the subs should play all base all the time, not just the right or the left signal only.

And to be brutally, honest, we can talk about this all day long, but the reallity is what the end user wants. Not sure how old your nephew is, but the THOUSANDS of customers I have had selling and putting systems in (usually 16 ish) want the most bass they can get. JL makes good stuff and should be fine to run bridged if you are running 4 ga. NEVER run 10 ga on ANY sub amp!!!

Djdrock, the absolute best option for longevity, quality and reliability would be for your nephew to return sub and get a single 12 with 2 Ohm DVCs OR return the amp and get a Mono amp.

On one last side note:
I agree with Turbo about not running the sub at 8 Ohms. I was just trying to give you actual wiring instructions to get (as the manual states) 300 watts at 3-8 Ohms. Personally, I dont see how it is possible mathematically for you to get 300 watts out of 3 Ohms and 8 Ohms, thats what the manual states. If it was my setup, I would try paralleling the coils on the sub (connect all (+)s together and connect all (-)s together and run them to the (+) and (-) termianls on the inside of the box respectively). This would yield a load of 2 Ohms which will give you the most power for you set up. You use the GAIN on the amp to control the actual amount of juice flowing through the amp to the subs. I would try it this way first and set the gain to a moderate level and see what the amp does. I have been running a Rockford 500 Punch A2 (2 channel) to run my Alpine Type R 15 with 4 Ohm DVCs for over 6 years. My amp is mounted under a seat and the vehicle used to be a demo car for 4 out of 6 of those years. The amp has NEVER shut down once. Just a real world example for you. Keep in mind that I had this stuff laying around and I would not have actively purchased this amp with this sub. A smarter decision would have been to get a mono amp, but I am just trying show you that it will work.

$0.02

 

[syndicate]

djdrock,
I think the concensus here that we all agree on is that (if he wants to keep what he has) he should run 1 sub (the 12 inch DVC) and wire it either way. Both ways will work and if you do it the way I was talking about (at 2 Ohms) and have amp problems, you can EASILY do the rewiring in the box and go the other route. Neither one of these ways are the RIGHT way though. The RIGHT way would be to pair up a mono amp to this system and get rid of the 2 ch amp or get a different sub.

Good Luck

 

[TURBO2GO]

Well the manual for this amp does claim to put out 300 watts x 1 at 3-8 Ohms (which I totally don't believe). You would not be able to obtain this without bridging it. Honestly, the OP has the wrong sub for this amp or the wrong amp for this sub (however you want to look at it) as the ideal case when using a 2 channel amp for bass would be to have a single 12 inch DVC sub with 2 Ohm coils.

The benefit of the DVC sub is that he actually doesn't have to sum the signal to mono. The sub essentially does this. Most music below around 80Hz is usually recorded in mono anyway. I wouldn't say he has the wrong sub for the amp or vice versa... this is actually a great way to do things if you don't want to run two subs and already own a 2-channel amp.

Not sure what you are trying to say by mentioning that it is not a mono amp and should not be used as such, but the only difference (basically) is that the mono amp will bridge internally and has the circuitry to be stable at 2 ohms.

A mono amp doesn't really bridge internally, it is a completely different design. Without getting too technical, a bridged amp is not the equal of a stereo amp with similar power that was designed as a mono amp. There is a lot to ampifier design and bridging is always a bit of a compromise. Since people look at the top power number, bridging seems the same or in some ways superior, when it is not. I can tell you for sure that you can achieve better sound with less rated power, even louder and tighter. Looking at the power output only is not a good way to do system design.

If he bridges the amp and runs the DVC sub coils in parallel he may even get a bit louder volume with the same relative gain settings, but that is not a good indication that this method is "better" or has any more headroom.

DJDrock, audio system design has been my full line of work for over 20 years now, so I have some experience. My work is in home and not car but the issues are the same. Presenting the JL amp with an 8-ohm load in bridged mode is inferior to letting it see 4 ohms on each channel. This is all nominal impedance anyway, you need to take into account what the amp sees at different frequencies and amplitudes.

In the car audio business it is a common mistake to just look at the power ouput and assume that it is better.

 

[syndicate]

In the car audio business it is a common mistake to just look at the power ouput and assume that it is better.

Understatement of the year!! I totally agree. I am not saying that more power is better AT ALL. I can just tell you that in 16 years of install, most customers would be furious with the bass output from a 12 in DVC at 150 watts. "I paid for this?"

Either way. I hope it works out.

 

[TURBO2GO]

Syndicate you are making a basic mistake here. Did you get enough sleep last night? LOL It's not 150 watts. It is 300. The performance would be similar to a single voicecoil running on a 300 watt amp. The amp is 150x2. Each is running a voicecoil. 150 watts aren't turning into vapor.

 

[syndicate]

Syndicate you are making a basic mistake here. Did you get enough sleep last night? LOL It's not 150 watts. It is 300. The performance would be similar to a single voicecoil running on a 300 watt amp.

I thought you meant only hooking up one voice coil. No wonder I was confused. Some of the DVC Bazooka tubes only have one terminal coming out of the back which may have led to my confusion. If the OP can wire each voice coil separatly then do that.

And no I didn't get much sleep last night :redface:

 

[TURBO2GO]

I thought you meant only hooking up one voice coil.

Absolutely not! why waste 1/2 the amp and 1/2 the sub?

Some of the DVC Bazooka tubes only have one terminal coming out of the back which may have led to my confusion.

I don't think so. I have never seen such a thing. I think you may have been in fact looking at an SVC and mistaking it for a DVC. The entire point of any DVC speaker is the fact that it can sum up two amp channels. In my 20 years I have never seen a DVC speaker with only one set of inputs.

Get some sleep... :biggrin:

 

[syndicate]

Absolutely not! why waste 1/2 the amp and 1/2 the sub?



I don't think so. I have never seen such a thing. I think you may have been in fact looking at an SVC and mistaking it for a DVC. The entire point of any DVC speaker is the fact that it can sum up two amp channels. In my 20 years I have never seen a DVC speaker with only one set of inputs.

Get some sleep... :biggrin:

I should have clarified.. The sub itself had 2 terminals, but the box only had one (+) and (-). Bazooka tubes make the subs so they don't come out easy. Essentially I think it was already wired in parallel from Bazooka. I was just trying to let the OP know to run the extra wire from the second coil if there was only one terminal on the box...........wow this is gettting confusing. LOL

 

[TANTO]

I'm a home audio guy who learned a lot trying to get of excellent components to sound good in a poor room. Just my non car audio guy comments: Would never consider running two different subs. The resonant problems(standing bass waves/booms/overhang/etc) are huge in 80% of rooms and will way overshadow things like bridging, cables etc. I would think that these issues would be an absolute nightmare in a small audio cabin, and thus should be measured with appropriate software first and then a sub chosen, retested and then corrected if possible. Probably one with built in EQ. Do they even make high quality subs? After wasting lots of money, quality vx quantity if an absolute rule. Just about all rooms need some sort of treatment. I guess (sigh) a full EQ is probably needed in a car. I was able to treat heavily in the home and use an Rives analog attenuator (got lucky). FWIW in my 60 years i have usually set up a room with 20% too much bass amplitude and then over the next couple of years have attempted to dial it down to 40%. I do like my bass though, but i'm getting that you guys your bass a bit more-he-he. No snob here, if it sounds good, do it!

 

[TURBO2GO]

Going off track here, but Tanto, a lot of stuff in a home doesn't apply in a car. Including all the standing waves and sonic reflections that you experience in a home. There isn't enough interior volume for some of the bass issue to appear like they are in a home, and the space itself is so assymetrical that it eliminates much of this right off the bat. At higher frequencies, the car's benefit is the proximity of the listener to the speakers, where he will receive a majority of direct sound compared to being 15 feet back in a home and getting more early reflections off the side-walls, floor and ceiling.

EQ'ing a car is no simple task either, much of what works in the home and studio can be tossed out the window in a car. The cabin interactions are incredibly complex and it needs some serious software with binaural microphones at moving the listener's head up or down a few inches with a short or tall driver makes a HUGE difference. This isn't the case in the home, and an equivalent to an overpriced Rives Audio unit :wink: wouldn't do a whole lot in the car.

The closest thing to what you speak of is actually pretty good right now and that is the Harman's piece sold by the JBL division (but with heavy input from Lexicon) called the MS-8:

MS-8 Demo

The smaller version of this is the MS-2, not nearly as good but good for an NSX with a portable audio unit I described in another thread. Right now this unit is being redone so we may not see new ones for a few months. The early ones had some issues.

<iframe width="560" height="315" src="http://www.youtube.com/embed/SS3Lf92z90U" frameborder="0" allowfullscreen></iframe>

 

[djdrock]

Going off track here, but Tanto, a lot of stuff in a home doesn't apply in a car. Including all the standing waves and sonic reflections that you experience in a home. There isn't enough interior volume for some of the bass issue to appear like they are in a home, and the space itself is so assymetrical that it eliminates much of this right off the bat. At higher frequencies, the car's benefit is the proximity of the listener to the speakers, where he will receive a majority of direct sound compared to being 15 feet back in a home and getting more early reflections off the side-walls, floor and ceiling.

EQ'ing a car is no simple task either, much of what works in the home and studio can be tossed out the window in a car. The cabin interactions are incredibly complex and it needs some serious software with binaural microphones at moving the listener's head up or down a few inches with a short or tall driver makes a HUGE difference. This isn't the case in the home, and an equivalent to an overpriced Rives Audio unit :wink: wouldn't do a whole lot in the car.

The closest thing to what you speak of is actually pretty good right now and that is the Harman's piece sold by the JBL division (but with heavy input from Lexicon) called the MS-8:

First, thank you to everyone for you valuable input. I will probably have a couple of questions. I need to sort through all of it.

Second, I am not to sure about the new MS-8 from JL. I have the Alipine Imprint in the NSX, and it is HORRIBLE. Similar technology.

 

[TURBO2GO]

First, thank you to everyone for you valuable input. I will probably have a couple of questions. I need to sort through all of it.

Second, I am not to sure about the new MS-8 from JL. I have the Alipine Imprint in the NSX, and it is HORRIBLE. Similar technology.

I wasn't recommending the MS-8 in your friend's situation. Sounds like he would be happy with a lot of bass and I am not sure that needs an expensive EQ like that.

BTW the Alpine only shares a goal with the MS8. They are very different and IMO the MS8 is FAAAAR superior.

 

[TANTO]

a lot of stuff in a home doesn't apply in a car. Including all the standing waves and sonic reflections that you experience in a home. There isn't enough interior volume for some of the bass issue to appear like they are in a home, and the space itself is so assymetrical that it eliminates much of this right off the bat.... and an equivalent to an overpriced Rives Audio unit :wink:

<iframe width="560" height="315" src="http://www.youtube.com/embed/SS3Lf92z90U" frameborder="0" allowfullscreen></iframe>

I did take this in the wrong direction. I obviously was not thinking about the wavelength needed for "my" issues. I was only mentioning EQ's as a bass problem mitigator. Thanks for the needed lesson.

I suspect i'm writing to a digital crowd , but in my home analog system the Rives unit is priceless! The online auction site audiogon.com saved me a ton. I plug Rives and audiogon whenever i can.

Sorry, back to the NSX