i don't recommend buying power for less than $0.25 per Watt. Great amps are still >$1 per Watt. Most decent amps are around $.50 per Watt.

since most amps at that price range are unregulated - meaning power output decreases as supply voltage decreases - most people will never achieve rated power since they can't maintain 14VDC.

 

What keep-hope-alive has said can most likely be taken as truth. Obviously this amp (stax 1600) is overrated because my fronts are rated at like 60 watts RMS handling, but no clipping occurs even at reasonably high volume. But do not worry, the amp was cheap but it will still give you enough power. My speakers can get LOUD, and they handle the power well so whatever amount of wattage they are getting, its workin out just fine for them. If you've got a good pair of aftermarket front and rear speakers, this amps perfect. I keep my gains at about one half the way up, you may not want to go much above that just in case.

 

Thanx austinman3214,
I got some decent looking 6.5 Boss up front and some Polk 5.5 coaxial in the back(neodymium magnet due to very limited rear dash space in my 2007 Civic) that should handle the power just fine. The amps were a decent weight and felt beefy enough out of the box. I will let you know how it all sounds when I finally get my dash kit and get the thing hooked up and bumpin.
I checked out the PA amps on ampguts and their insides look very respectable compared to the others shown.
Also-keep_hope_alive thanks for your breakdown on the ratings, very interesting stuff. I checked out the fuse rating on the Alpine PDX amp you used as an example and it's only 30ampx2. According to your calcs. wouldn't this limit it to under the listed 100wpc 1% thd at 4ohm?

 

the PDX amps boast very high efficiency, greater than 80% and are rated at 14.4VDC. That means they can input almost 860W and output 690W RMS, making a 100x4 rating very doable. Additionally, PDX are regulated to make their rated output at any impedance - so you get 100x4 at 2ohm and 4ohm. The power acoustic makes half as much power at 4 ohm as 2 ohm.

I'm not knocking Power Acoustik. They have a market they serve well, and they've been at it for a while - regardless of who actually owns the company name. For the price, they are a fine amp.

 

spirit man, let me know what kind of noise you get from your headunit when you amp those speakers up, i used to get a nasty white noise. Fixed that with a JL cleansweep. Sounds amazing now, but can get better.

I've a couple questions for you keep_hope_alive;

I'm now getting a low volume alternator whine when the car is on (of course). Can a simple grounding improvement eliminate this, or will it always be there? My power and RCA wires are on separate sides of the car, so that's an unlikely remedy. Let me know if there's anything else that can be done to combat that whine, all i can think of atm is grounding.

Also, my rear speakers sound muddy, not like its that bad, but it is noticeable. Can it just be the fact that they are 6x9s? or are these speakers of lower quality? I'm fairly confident they're getting a good amount of power, maybe a little too much, and polarity should be correct. I just am at a loss of why they don't sound as crisp as my polks in front.

 

austinman3214 and keep_hope_alive,
Hope you are enjoying two of the finer things in life such as Hondas and car audio. I also love coasters and extreme rides but that's for another forum. I ain't over the hill yet at 45!

I almost wish I would have went for the Alpines amps keep_hope_alive but I am confident I will be happy with the PA as I am seeing lots of happy owners positive feedback on them as well.

Hope you get your sq issues worked out austinman3214.

Guys check out this article on related issues we have been discussing.
I thought it was quite interesting.


http://www.monstercable.com/mpc/stab...Efficiency.pdf

 

the issues with your alt whine is certainly associated with grounding - that's how noise gets into the system. i always ground all components to bare metal on the floor, and i avoid any brackets, if possible, and keep grounds as short as possible - sometimes even using larger wire (like 10awg for head units).

if that doesn't work, you can start grounding the rca shields (input or output, not both).


as far as clarity of 6x9's, i haven't heard clear 6x9's under $400. Also, with any rear speakers, any subs in the trunk will immediately distort them. Best thing to do is just remove them from the rear deck (letting more bass through), or build enclosures for them in the trunk so they are sealed. Either will solve your clarity problem, but the latter lets you keep rear speakers. of course, if you get polarity wrong, they will sound very poor.

 

Richard Clark is a legend. That is a good article, though the efficiency discussion is different with new amplifier topology and technology - 80% is actually achievable nowadays.

However, the amps tested were Class A/B, similar to the PA STAX amps (full range), so similar efficiencies are more likely. I typically use 50-60% for modern Class A/B and 80% for modern Class D.

Musical power is completely different from sine wave power, as those graphs clearly show. fuses have a time-current curve associated with them, meaning they can handle a lot more than their rating for a short duration - allowing for musical peaks.

One good thing to take away from that article, as it pertains to the discussion, is that adding up fusing to determine maximum output power is legit, but you'll NEVER even see that much power without sine waves at near clipping levels - not music. For musical average power, take the calcs above and assume 20-30% of that is musical average power. not very much, eh? still loud? it doesn't take a whole lot of power to be loud. the real reason we buy high power amps is so we are operating much lower on the THD scale (since distortion increases as power output increases).


My xtant amps have recommended fusing of 60A for two of them, and 100A for the third. I use 30A fuses for the pair and a 60A fuse for the bigger one. I listen to music as loud as I want, it's always crystal clear, and i never blow those fuses. I know what my impedance load is, I know how my gain is structured, and I know what kind of power I can expect - thus I know what fusing is adequate. I have a 100A fuse on the 1/0 wire at my battery (despite having a combined, recommended fusing of 220A derived by just adding up the amp fuses as Richard explains).

When listening to music, the current demand is usually pretty low. But those short duration, high output bass notes are what put a strain on your system - in the form of voltage drop, regulator lag, and amplifier heating.

 

hey Keep_hope_alive, another quick clarification question for you. or maybe two.

so I've got a new amp which will make my car a two amp system. question of mine is what cables can i y cable to share the signal? i assume i run new power and ground wires, but can i steal the turn on lead and rcas? otherwise I've only got 4 rcas which im using for my front and rear channels, the cleansweep does not give me a subwoofer out.

I've been thinking of sealing my rears for a little while now but loking in my trunk there is no way a box will fit. i can provide a picture if needed but are there some creative ways to enclose them in such limited space?

 

you have to buy a separate module for Cleansweep sub out (with remote level control). otherwise you can use two y-adatpers on the front output. yes you can share the same remote lead (up to 3 amps on one) are common - depends on the source. I don't know what the Cleansweep has for remote turn-on capability - it should be in the manual.


the easiest way to seal the rears is with a fiberglass enclosure - just make a MDF base plate that mounts to the bottom of the rear deck around the speakers, staple some fleece to it and let that hang down and make a bowl - whatever shape is required to fit around the torsion bars, etc. make sure you could actually remove this once it is hardened. soak the fleece with resin while it's mounted up there. then remove the hardened enclosure and line the inside with 3-4 layers of fiberglass matte and resin (one layer + resin at a time). include resin and matte along the seam of the hardened fleece and the MDF mount.

include T-nuts in the MDF mount so you can secure it from inside the car through the rear deck, and use weatherstripping foam to seal the mount to the rear deck metal.

this will be fast and cheap - assuming you're capable of some fiberglass work. it's certainly and excellent start with FG.