Re: Stereo Guys: amp question
 

Now you're over my head too! Were just throwing an amp in a boat not building a system to win competitions! :D

But, I will take a stab at it. I would guess that the headroom will depend on the amp. I never understood it. But some amps only put out 35% or so more RMS power at 2 ohms and others put out 100%! But, I would guess that if the peak power goes up less than rms, you lose headroom. If peak goes up more, you gain headroom and if it goes up the same the headroom stays the same? Just a guess. :D

Re: Stereo Guys: amp question
 

Alright-

one last question, im going to use two 4 ohm speakers to the one channel of the amp, tied in parrallel, im using 16ga speaker wire to go from the speakers to the tie in, i plan to make each lenght of wire from the speakers to the tie in equal, roughly 5-6 feet, at which point i will tie both of the pos together, and then run 1 single wire to the amp, repeat with negs, the one single wire will only run about 2-3 feet from the splice to the amp, should i use 14ga wire to run from the tie in to the amp or stick with the 16ga??

is it important to keep the length of wire equal from each speaker to the tie in?

second, i know this shouldnt be done, but im not sure why, how come i cant just run both my positive wires right to the one channel of the amp, and both my negative wires right to the one channel of the amp

thanks for your help,

Steve

Re: Stereo Guys: amp question
 

In case you haven't seem my PM you CAN tie the wires right at the amp terminal. 16 gauge is ok, 14 gauge is better over all. Try to keep the lengths of the wires the same because the wires have resistance as well and having one a lot longer than the other will actually make one speaker sound a little different and not quite as loud as the other although it usually takes a trained ear in the right situation to hear this. Did that diagram come through that I sent you?

Re: Stereo Guys: amp question
 

Yep, what Unsane said. Just tie them together at the amp connection/terminal. I don't even really understand what you were trying to say! :confused:

I always use 12 guage for the speakers and 10 gauge for my subs.

Re: Stereo Guys: amp question
 

Just got your PM Boomer, you're all good:

Now on to the headroom and ohms thing. Some amps will only gain a little bit of power from halving the ohms because that's all the circuits can take (HEAT MON!!!) So there is an internal automatic gain reduction circuit in most amps that compensates (turns down) so you don't cook the goods. Some home receivers have a switch for 8 or 4 ohm operation. The switch actually "downshifts" the amp. On a Technics receiver you hold the A and B speaker buttons together until it clicks and reads "low impedance" in the window. Now some amps will double from 8 to 4 or 4 to 2 ohms like the calculator says (Ohm's Law) These are usually larger PA amps like the ones I use. These amps have big circuits or "pipes" as I like to say. An average PA amp will nearly double from 8 to 4 but gain only a little more from 4 to 2 ohms. A bigger PA amp will gain about 50% from 4 to 2 ohms. These amps weigh on the order of 90 pounds. A company called Crest used to make an amp that doubled from 8 to 4 ohms, doubled again from 4 to 2 and gained another 50% from 2 to 1 ohm making a massive 7500 watts per channel! It weighed 140 pounds too! Now some car amps are using Class D technology. This is a switching type amp that makes a lot less heat but sacrifices some sound quality, mainly on high freqs, but for subs, their "nastiness" isn't as pronounced, so car SUB amps are usually Class D or in the case of JBL's monster 8000 watt amp, Class I ( a relative of Class D) There have been many classes of amps out there broken down into 2 groups: Analoge and switching. Analog being Class A, B, AB, G and H. These types' circuits "tracks" the incoming signals and tries to make an accurate but larger "xerox" of it. Class A is the best sounding but a furnace, this is because you have 2 circuits a push and a pull (for speaker movement) and in a Class A amplifier while one circuit is using "all" of its energy, the other circuit is sitting there but it's not asleep, its Power supply is feeding an unused grid giving off a lot of heat, but when it's its turn to work, it is ready for anything making a very accurate reproduction of the signal. Here's another way to look at it: put 2 engines in a car, leave the throttles wide open and use the 2 clutches to drive it. Forget the hurting of parts but you're wasting a lot of energy, but it reacts quick. So curb heat, the Class B amp was invented. The push side will "shut down" when the pull side is in use and vica versa, not making as much heat. But wait a minute, it sounds like DONKEY! That's because each circuit board takes time to start up and as the soundwave crosses over to the other side, it's briefly demanding more energy than is present. Using the car analogy, you would have to start each engine up. Soooo a compromise was created, Class AB. When the wave crosses from the push to the pull side, the push side will actually stay on for a little bit longer giving some of its energy to the pull side to give it a chance to "warm up". Most PA amps are like this and most good, Full range car amps, but they still make some heat and have power limitations. Classes G and H use mulitple power supplies, kind of like that Hemi engine that goes from an 8 cyl to 6 and 4 etc.. G is really not used, but H is found in a lot of med level home theatre receivers. But the switching amps are a different story. Unlike Class A that wastes 80% of it electricity or AB which is about a 40 to 50% waster, Class D wastes about 10%, remember that waste is heat, all the rest goes to the speaker. A Class D amp switches its circuits off and on about 500,000 times a second 250 for push and 250 for pull. When the waveform gets bigger, they stay on a little longer to make more energy (get louder) These amps can make a lot of power with very little heat and they don't weigh a lot. However their drawback is sound quality for 2 reasons. First they switch on and off taking a "picture" of the soundwave. The lower the frequency, the bigger the soundwave, the more pictures it can take, the more accurate the reproduction. But the higher the frequency, the less pix per wave are taken and more errors happen called distortion and it sounds like donkey doo doo. (those little home theatres in a box use Class D amps) Secondly, as the switching takes place, it takes a little time for the circuits to turn off and on so it does miss some stuff once again translating into distortion, but they have found a home with boom boom machines. they can deal with lows a lot better, with less heat making more power. Most well made car sub amps are Class D or a variant like Class I which actually sounds a little better because it has less errors than D. So these kind of car amps will double their power from 4 ohms to 2 ohms and gain another 50% from 2 to 1 ohm because to do so will not overheat its circuits like a traditional non swithing amp. Whew, I need a drink! Hope I really haven't confused anybody further, I tried to make it as simple as possible, I don't speak EE, nor do I want to!

Re: Stereo Guys: amp question
 

http://www.crutchfield.com/S-J9Febce...ech/kb334.html maybe this will help what i meant noboat- i was refering to the 2 speaker parrallel set up, the way they tied both the -'s into one, and both the +'s into one, then into the amp

im just going to bring both negs from each speaker( and same with pos) and screw them right in on the one channel of the amp, but i also thought about doing it the above way

unsane, i have no idea what you said above, and im not even going to try to understand it, but youve been extremely helpful with my situation and i appreciate it, you too noboat

thanks

Re: Stereo Guys: amp question
 

I did a lot of checking. I am running 4 sets of Polk audio sepertates in the new boat. The newest amp with great power for a good price is the new Rockford t4004. I ordered 2 of them for my mids. This will run them with no problem. This amp is getting great reviews.

Re: Stereo Guys: amp question
 

I was just going to say the exact same thing but you beat me to it!! :D

Re: Stereo Guys: amp question
 

Buy a 4 channel 80 watt rms amp, or get 2-2channel 80watts amps. If your radio has front and rear RCA output jacks, use the fader in your radio. If not, get a separate fader. I wouldn't start splitting channels...ohms...series...etc.. Thats a pain in the ass. Im not sure if you can still purchase separate fader controls. Im old school. Sony used to make one. You may have to use a equalizer with a fader control, but I could be wrong.

Re: Stereo Guys: amp question
 

Ah, got ya! I don't think they are literally tying them together i think they're just tring to make it clear they are both going to one spot. :D