Question on amps, if anyone can help?

Just to clarify a couple of things.  First, the BP1200.1 has two sets of RCA inputs so that you can get bass even if you have your head unit faded to the front or to the rear.  If you always keep the fade in the middle though then you can hook up only one set of the RCAs and it will sound the same.

The amp has 3 dials for adjusting stuff:  input level ("gain") adjustment, bass boost adjustment, and low-pass filter frequency adjustment.  The LPF can be set as low as 32 Hz or as high as 320 Hz, and you will need to play around with it a bit to see what sounds best in your vehicle.

This amplifier does NOT have preamp outputs, so if you're going to be using a 4-channel amplifier in addition to the JBL amp you'll either need a 4-channel amp that has preamp outputs, or a head unit with 3 sets of preamp outputs (front, rear, sub).  If the head unit only has one set of outputs then you'll be better off using a crossover to direct the appropriate frequencies to the appropriate amplifier.  This also applies if you have a factory head unit and will be using a line output converter to get a single set of RCA outputs.

Technically the BP1200.1 can use high-level inputs and you could send the RCAs from the head unit to the 4-channel amplifier, but I always recommend using RCA type connections whenever possible, to give you the best sound quality and the highest S/N ratio.  What kind of head unit is in the vehicle right now?

150 watts per channel @  4 ohms RMS??????  That is a LOT of power you're talking about and I honestly don't know of any amps out there that will give you 150 watts RMS per channel when they're run at just 4 ohms.  A lot of them will do it at 2 ohms but not 4.

anyways, I saw from another post that your vehicle is a ford truck.  I'm pretty sure they have fairly large alternators in them so you might be okay as is. I'd say first try out the system and see how it sounds and see whether or not your lights dim at all with the system turned up, especially during a long loud bass note.

If the lights dim at the very beginning of the note but return to their original brightness before the note has ended, a capacitor would probably work pretty well for your situation.  It would mean that your alternator is capable of producing the required amount of current, but it's just slow to react to the additional demand.  The capacitor would provide energy to the amplifier during the split second that it takes for the alternator to react.  Make sure you try this test both with the truck parked/idling, and when you're out on the highway, just for comparison sake.

However, if during that long bass note your lights dim and stay dim until after the note is over, then most likely a high output alternator is a better way to go.  A capacitor would just make the alternator work harder and over time this can possibly lead to premature alternator failure.

Admittedly HO alternators are always gonna be better solutions than capacitors in either of the two above scenarios, but they are also much more expensive solutions and are not necessary for every vehicle.

And obviously if your lights don't dim at all even without a capacitor or HO alternator, then you don't need even need to do anything to it!

This was for a 97 F-150 right?? If thats right then you cant use 6X9's anyway, you will be using either 6X8's or 5X7's. An amp that i have ordered recently and am awaiting it to be shipped is this one from Crutchfield https://www.crutchfield.com/cgi-bin/S-m7imu7zfJ66/ProdView.asp?s=0&c=3&g=120&I=235USB4085&o=m&a=1&cc=01&avf=Y.

It is an 85X4 and by the specs is a real good, clean amp.

I am curious how you are going to install your 2 12's cause my wife drives the same truck. Are you going to take out the back seat??

esmith69 wrote:

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Just to clarify a couple of things.  First, the BP1200.1 has two sets of RCA inputs so that you can get bass even if you have your head unit faded to the front or to the rear.  If you always keep the fade in the middle though then you can hook up only one set of the RCAs and it will sound the same.

The amp has 3 dials for adjusting stuff:  input level ("gain") adjustment, bass boost adjustment, and low-pass filter frequency adjustment.  The LPF can be set as low as 32 Hz or as high as 320 Hz, and you will need to play around with it a bit to see what sounds best in your vehicle.

This amplifier does NOT have preamp outputs, so if you're going to be using a 4-channel amplifier in addition to the JBL amp you'll either need a 4-channel amp that has preamp outputs, or a head unit with 3 sets of preamp outputs (front, rear, sub).  If the head unit only has one set of outputs then you'll be better off using a crossover to direct the appropriate frequencies to the appropriate amplifier.  This also applies if you have a factory head unit and will be using a line output converter to get a single set of RCA outputs.

Technically the BP1200.1 can use high-level inputs and you could send the RCAs from the head unit to the 4-channel amplifier, but I always recommend using RCA type connections whenever possible, to give you the best sound quality and the highest S/N ratio.  What kind of head unit is in the vehicle right now?

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I can't say as if I agree with the post that says "I would not bother with a cap".  That is totally wrong.  Maximize all areas of your charging system by upgrading power and ground wires even from the stock alternator to the battery, battery to ground, etc.  An alternator is an expensive step that I have always done dead LAST due to the cost.  Your best bet IS a cap.  Maybe something larger than the typical "1 Farad" cap.  Look at something like Lightning Audio's 25 Farad cap...or maybe even the 40, 50, or 100 farad model depending on your budget.

What kind of vehicle is it going in again?

Are you even in this industry or do you get your information from magazines and friends?  And what is considered an expert anyway?  People that are "professional backyard installers" or people that do this for a living and know the technical side of it?  Don't get me wrong, I'm not saying a new alternator isn't important, because it is.  But not everyone needs to go out and buy one just because their lights dim.  Hell, lights will dim with a 200amp alternator, too.  And at idle, a "high output" alternator typically puts out less current than a stock alternator.  Alternators don't produce their rated output till about 2000 engine RPM (which is about 16,000 alternator RPM) ideally.  No vehicle is ever going to be able to supply all the current that some of these radical systems need to work perfectly, but in a vehicle environment, there is no "perfect".  We can only try to maximize what we have to work with and what an end customer is willing to spend on getting these upgrades.  If a salesman/installer knows Ohms Law and can apply it to make sense to the customer, then they can relay to them that they don't need that much power to get what they want in their system and won't kill his/her vehicle.  Plus you get into an amps' efficiency factor in that no amp will ever produce rated power in a vehicle, anyway.  Maybe one day when we step up to 42 volt electrical systems, we will definitely see some differences.

And, a cap is NOT like a battery.  There are TONS of differences in how they work and what they are there for.  Each serves its' own purpose in the system.  Resistance in a cap is far lower than a battery which gives it its ability to discharge/recharge faster than a battery.

I'm not here to argue with anyone, but the purpose of caps (in final) is to just maximize what we have to work with in our vehicles.  Each does what they feel is best.  But the SINGLE MOST IMPORTANT THING IN THE CHARGING SYSTEM IS TO HAVE PROPER SIZE CABLES AND CONNECTIONS!  Without this, all else is a waste.  The weakest link is what kills.

One of the great things about this forum is that you can get opinions from all sorts of people and everyone is free to express their opinions.  Opinions are by their very nature never "right" or "wrong."  Every little bit of knowledge helps though, and I know I learn new stuff on here every single day.

The alternator upgrade can be done after the stereo system is installed, and it will still take the same amount of time and money to do it then than it would if you did it at the same time as the rest of the stereo system.  With that in mind, i'll have to agree with tdsteele that you should at least get all the stereo stuff installed and play it and see how the charging system holds up.

First thing I would do if I were you (after all your gear is installed) would be to do that headlight test I decribed earlier because that will tell you right away what direction you need to be pointed in.

If that doesn't prove conclusive, drive the truck around for an hour or two at night, under different road conditions (highway, city, parked, etc.) and play around with the stereo.  Listen to different types of music.  If you only have the lights dim a couple of times during your entire drive, and you had been pushing your setup pretty hard the entire time, then I think a capacitor would suffice for your situation.  Clearly all you'd be needing is a little buffer of extra power to be used occasionally.

Just out of curiosity, what kind of music do you listen to?   Cuz if you listen to rap and plan to have your system slamming all the time and playing long bass notes at max power then I can tell you right now a cap will probably not be enough.  If you listen to something with a lot less bass then it might work okay, but the only way to know for sure is to try it all out first.

I never said the cap was an instant fix...just something to do BEFORE wasting money on an alternator you may not need.  And even then, the alternator may not help tremendously depending on the driving habits.  If you are at cruising speeds ( I mean cruising on a Friday night) then a lot of H.O. alternators produce the same or LESS than a stock unit.  It has to be at higher speeds to make more difference.  Everything done in a mobile system is for the benefit of the equipment.  It all works as a team.   But all this should be done after making sure ALL the other wiring tricks are done first.  Maximize the what's there before spending the big bucks.  Bottom line, there's only so much blood you can sueeze from the proverbial turnip.