helotaxi

What kind of music? Long droning bass notes, or kick drum and bass guitar? If the former, the alt will probably have to be upgraded. If the latter, it actually might not. It comes down to average current draw, not peak. Likewise, even with a 200A alt, the batteries are going to be handling the peak current transients and the alternator is only going to replace the energy that was pulled from the batteries during the lulls. I wouldn't expect more than 100A or so over the run to the back, even if the amp draws over 300A on a musical peak. That peak current is coming from the rear batteries. The alt certainly can't provide it. As such, all you care about is the voltage drop caused by that amount of current. For 100A, 1/0 is more than enough to make sure that volatge drop is minimal.

Batteries are going to be a must. The alt will depend on your listening habits. One really big or two smaller batteries in the back near the amp in addition to the one under the hood. A single run of 1/0 from the alt will really be plenty since the run from the rear batteries to the amp will handle the majority of the current and the alt run will mostly be recharging the batteries.

It allows more current to flow and makes the amp less efficient. That's exactly the difference. More current and less efficient means that you're drawing proportionally more current from the vehicle electrical system compared to the power output. It also means that the amp is flowing more current at lower efficiency meaning that it is generating significantly more heat that it must get rid of to keep from failing. Considering the usually only marginal gain, running a lower than normal impedance isn't worth it daily.

Probably just a different model year. Memphis recycles model numbers even when making cosmetic changes.

Basic facts are that even HO alts will allow the lights to dim without good battery support. All the alternator needs to do is meet the average current draw of the system. Most people would be surprised at how low that actually is with actual music (i.e. not constant, droning tones). The battery or batteries handle the heavy transient loads (you know, the ones that cause the voltage to drop and the lights to dim) pretty much regardless of the peak capacity of the alternator. The alternator is only producing the amount of current demanded of it at any given time and it takes a finite amount of time for it to ramp up the output. That transition time is when the lights dim. If you've ever used an air compressor, the compressor itself is there to maintain the pressure in the tank and the tank handles the pressure spikes. If you're running a high constant demand tool (sprayer for example) then the actual compressor matters, but for low average but high peak demand tools (like a nailer) the capacity of the tank is more important. Think of the compressor as the alternator and the tank as the baterries. Music is normally high peak, low average in demand. The batteries are more important in that situation than the alternator. If you are one of those that listens to music with constant, droning bass notes, the average demand is higher and an alternator upgrade (supported by a good battery or two) would be wise. Regardless of what you do or need (batteries or alternators) without adequate wiring to carry the current none of the rest of it matters. You need adequate wiring size (it is impossible for it to be too big) and solid connections at every terminal distro block and amp. Bad connections will not only make wire size largely irrelevant, but can also be dangerous as the resistance of the bad connection will create very large amounts of heat during high current draw situations. Fuses won't protect from a fire caused be a high resistance connection.

Not an extra power source, an extra power reserve. The alternator is still the only source of electrical power in the car. The battery or batteries simply store that energy until it is needed in larger doses than the alternator can deliver in one shot. The larger the reserve, the less the voltage will dip when the reserve is tapped; however, the reserve can't make up for a higher average current draw than the alternator can deliver.

There comes a point where you're not going to get any louder without committing much more time (install, tweak and tune) and resources (space, money and utility) to the system. Power is a quickly diminishing return and frictional losses in the form of power compression make it even more so. You also have to invest in the electrical support (batteries, wire, alternator, etc...) to support that extra power. Cone area is slightly more reliable, but there are still losses in the form of phasing cancellation that keep you from realizing the full potential. That said, you can only fit so many drivers and so much cone into a given space, and once you begin sacrificing box volume to cram more drivers into the space, you start hurting system efficiency.

The problem that you're going to run into is that the body of the car isn't a very good conductor. To really have much benefit, you would want to run a negative wire from the battery back up to the engine. Seems like a pain, but otherwise you're not going to see the real benefit of the upgrade. You can run it right along with the battery (+) wire.

An extra battery (or a million extra batteries) will not prevent voltage drop from 14.xx to 12.xx volts. You'd be wrong there without qualifying that statement with a number of batteries, total battery capacity (Ah, not CCA) and total current draw. With enough batteries, or a small enough draw, the voltage won't dip hardly at all. You can completely compensate for amp draw with enough battery reserve (provided you give the alternator time to catch up and keep them topped off) and you can also overwhelm most any practical amount of reserve with huge amounts of current draw.The reality is that average current draw is what you really care about. That determines the duty cycle of the alternator. When you average out all the peaks in current draw with all the valleys (assuming normal music, not something with continuous droning bass notes) most people would be surprised by how little their system draws. That number is really all the alternator needs to handle. The rapid transients are covered by the battery reserve. A good reserve will keep the voltage from dropping appreciably (more than adequate wiring matters here as well), but the biggest alternator (discovered to many's consternation) won't keep the voltage from dropping on high draw, rapid transients.

In theory about 3dB. Real world something less than that becaues of power compression. Aubdible, yes. Distinctly louder? No.

If that is in fact what the problem is, a small spot of CA glue or epoxy will take care of it. If that is what's going on, you need to fix it since the sub will partially unload on the downstroke. The other thing that can cause a popping sound is the former hitting the backplate. The dust cap leaking could lead to that being more likely.

Sounds like the coil is venting through the spot where the dust cap has pulled loose on the "downstroke" and when the sub direction changes, the gap slams shut.

To answer your question...in a perfect world, yes it would be louder. In reality, it probably won't be and will likely end up sounding worse and possibly damaging one or all drivers. Since it seems you're hell bent on running 3 subs, make sure all are the same coil config and get rid of the amp that you have and buy a bigger amp that makes max power into 2 ohms. Build a box that it right for the 3 subs and wire them to 2.66 ohms.

They are more measureable than the difference in signal arrival time between 2 sections of wire with a foot difference in length. You'll see a bigger difference in phase from the slight differences in each driver's coil, motor and suspension.I know how to go about wiring subs so they don't interact. It isn't rocket science. And I'm talking about straight parallel wiring where you make a run from the amp to the + of the first driver and from there to the + of the second driver and so on, and do the same for the -.

That would also mean that the fairly standard method of wiring subs in parallel off the same amp (daisy chain) would have a significant effect. I would be more inclined to believe that the difference in speaker amplitude because of the resistance of the extra wire had an effect than believe that phasing was the issue.

So by that measure, surgery performed by the best "surgeon" in the darkest reaches of Africa must be good becuase he's the best in the area. False logic.

High sensitivity means less power required to get loud. Most SPL drivers have a higher sensitivity. Pretty misleading statement and really not in context in a car audio centric forum. When a pro audio guy starts talking about an SPL driver he's talking about a driver for sound reinforcement like a concert stack. The T/S sensitivity spec is for output @ 1kHz and for the frequency range desired for his application, a higher number there makes sense. The equation for getting that is pretty easy as well: large, light cone; light coil; minimal suspension; big motor. At higher frequencies, long excursion isn't critical. A 10mm Xmax is huge for those drivers. At 1kHz, sensitivity boils down to little more than (cone area x motor force) / (moving mass x suspension resistance). Compare that to a low frequency SPL driver as imagined by a car audio guy. For that kind of driver, 1kHz sensitivity means little because at lower frequencies, excursion means everything. To get low freq SPL, you have to move a lot of air, so swept volume matters. Additionally, the cone damping provided by the enclosure places huge stresses on the cone. That means that the cone has to be made heavier to withstand the strain. To counteract that heavier cone, you have to increase the strength of the motor so the coil gets heavier. You find yourself in this terrific catch 22: to get louder, you must increase mass which keeps you from getting louder. Going with a ported enclosure can reduce some of the need for Xmax and allow the coil to be shorter(and lighter), increasing BL right around the center point, but then you have to consider the cooling needs of a motor that is moving very little (and increase mass to compensate) and the incredible strain that is put on the cone and cone/former junction (and increase the mass to compensate). The result is a heavy driver that in fact DOES need a lot of power to get loud. There are large drivers in use in the car envirionment that have high sensitivities. Some of them are subs and they can often get pretty loud without a lot of power. That said, they are not the drivers that you see competitive in SPL comps. They simply cannot handle the rigors of generating very high levels of SPL. The reality is tha the qualities that lead high sensitivity in the middle to upper frequencies are not the qualities that you want in a lower frequency driver, especially one that you want to get really loud.

Anyone on whether the z140bh is worth the extra over the x940bt?

Been off pursuing other hobbies and raising a little girl... My DNX8120 is dying a rapidly accelerating death. First the XM receiver takes an intermittant dump over the last year. Then the disc transport died last month. Then some low life stole my in-car iPod. Long and the short I need to replace the HU because I'm basically down to listening to the local radio station. In a small town in the middle of nowhere, that is absolute torture. Requirements: Double DIN Nav DVD XM capable (NOT Sirius so the new Kenwoods are out) Parking brake lockout is easily bypassed Good Bluetooth (the 8120 has been spotty both with the phone and with A2DP streaming audio) Sound processing would be nice but not required. The RCAs will probably have to be on pigtails since the mounting depth in my truck is really limited and I doubt that there would be room for the RCAs to plug directly into the back of the unit. What's out there that's good these days? I'll be posting some of the vintage collection for sale on here and on eBay over the next week or two to finance the new HU so price shouldn't be much of an issue.

Watched the vids. Yep, looks quite simple. Not Kenwood simple but not nearly as bad as I was seeming to recall from previous units. Now I think it's just a matter of deciding between the X940BT and the Z140BH...

Thanks, Aaron.

Not a big fan of the Android devices AND 3G/4G service is skosch out here so Pandora isn't reliable. I could just stream it off my phone regardless. It looks like Audiovox makes an XM module for the newer Kenwoods (and most other radios) but I'm not finding any definitive compatibility info. I'm looking at the Pioneer AVIC-Z140BH plus the Pioneer XM module. Anything I should know about that unit? How much of a pain is the parking brake lockout? I know it was quite the process on some of the older AVIC units. Is there a particular reason to go with that unit ove the X940BT? It's about a $300 price difference online.

Pioneer aaaaand...Pioneer That only really narrows it down a little bit. What models are worth looking at? External tuners have been the way of things since the beginning. Even though SiriusXM is one company the hardware and accounts are still different between Sirius and XM. Pioneer and Alpine at least still support XM. Kenwood went to Sirius only.

I threw up in my mouth a little at the NPR thing. The one FM station in English is a country station, which isn't the problem. For every song that they play there are 5+ minutes of commercials for local businesses and another 5 min of a simple minded yokel droning on about what he thinks is worht talking about.

Different sources with different coding and different capabilities and the effect is different. The DVD is actually coded for more than 2 channels, music is not. The difference in movies will be that you can have actual surround sound (Dolby, DTS, whatever) but with music you will do nothing but confuse the soundstage and trash the frequency response unless you use some serious processing and have the time and know-how to correctly set it up. The difference will be audible and not an improvement if you care about fidelity.