I could have posed this question in my build thread, but I figured this board could use more discussion about car audio in general.

How many watts do you think is necessary to provide your front stage with enough power to faithfully reproduce the transient peaks in the music you listen to?

I know it's a very general question, but I'm curious to see what other people's opinions are given their different listening habits, the type of music they to, and equipment they are using.

I'm currently planning to run 500watts per channel to my mids and I'm wondering if most people would consider that extreme overkill. I saw a thread on DIYMA from a guy who was looking for a two-channel amp that would do 500x2 @ 4ohms and he was berated heavily, but mostly for other reasons besides the fact that he wanted to run that type of power to his front stage. No one really weighed in on whether it was a good idea from a headroom standpoint.

Opinions?

 

As much as you can afford!

 

I have found out that headroom makes a big difference in dynamic range and speaker control... but how much is to much, i dont know... I noticed a big difference going from 100 to 200 per side... is there a difference from 200 to 500, probably but how much really....

 

It depends on the amp, but the ability to dig deep for more power when a transient note comes can really make a system sound great. With some amps, you need to do headroom with RMS. With others, you can match RMS to RMS and the amps will reach down and find the watts when they need them because they slew so fast (and might be underrated).

I loved my JL slash amps, but you need to find headroom with those in RMS... about double was fine for me. If you take a higher end amp like a Zapco or ARC (just 2 of many that come to mind), you can literally take a 50-75 watt amp that will produce sound levels like a 200 or 250 watt JL, Fosgate, etc. amp.

Also, most amps sound better at lower wattage levels. The THD and noise go up as power goes up. ...so the lower in the RMS range the better. This is especially true of lesser quality amps and less true of really good sounding amps.

I guess the easier way to answer this question is to ask which amps you are looking at? I am not a betting person, but I can almost bet that the output from an older Zapco 350.2 at 100w per side would produce more "sound" (and probably sound better) than a lot of amps at 500w.

Bottom line: I think that it is really important, but how you go about it will depend on the equipment.

 

Oh, I forgot, and this is just me talking... and keep in mind that I am a 100% douchebag dogmatic dinosaur most of the time, but I have personally found that amps that have a linear output offer the best transient response. These usually have bipolar output transistors instead of MOSFET. Perhaps this is anecdotal since most bipolar amps are also very well designed. Your results might/will vary...

 

Lol, well the amp in question is a Zapco. I picked up a DC 1000.4 yesterday. I currently have it bridged @ 500x2 to my mids (ID XS-65). I'm wondering whether I should continue to run it bridged or if I should just run all four channels @ 150 watts so I can take advantage of the built-in processing for my tweeters.

 

You be the judge, but the 50 watts that my DC650.6 puts out to my Focal 6.5s will drive them to the edge - we have measured over 200 watts on a transient note at 110hz going to them. I have tons of amps sitting around that I could put in for more power and the 50x6 watts that go to my 4-way set is PLENTY.

That DC1000.4 takes a 80 amp fuse for a reason - it is a bad ass.

IMO, you don't need any more headroom than what each one of those channels has to offer. Even if you used the fronts to power the whole comp set (on the crossovers), you could use the rear to power your subs and I don't think that you would lose a bit of loudness and probably would pick up a pile detail. Of course, active is fun... for a while.

If you ever hate that amp, I will buy it from you. My guess is that you will have it for a lifetime.

 

Long term, you'll prolly toast those ID crossovers with 500w.

It is good having that much power on tap, though.

 

Sweet. If my wife finds out that I bought it you'll probably be getting a PM

I'm actually running them active with the little Fosgate amp sending 75 watts per channel to the tweets and then 500 to the mids from the 1000.4.

 

Several people I know run 2x rms, some even more. A very famous vehicle that most of you have heard about runs 2.5x more than the speakers rated rms. I *think* he has 3x the rms on the subs but he's also running all Dyn which can take transient peaks like no other. I tried mine out briefly with 300w to the midbass vs 150 and it has a more effortless, dynamic sound. I'm getting ready to change processors so I'm not getting too deep when it's getting ripped out anyway. I say let your common sense be the judge. I run 150w on my mids which are pretty efficient for a car audio driver and they only see 750hz and up so 150w is probably a ton of headroom. 150w on my 9" midbass that's going from 65hz to 750hz is more than adequate but I wouldn't say it's as much headroom as I like. I've got 100w for the tweeters, way more than enough. I have no problem going with 300w on the midbass but I think it would be money wasted for more than that. Maybe 2x rms is a good rule, I have no idea. So many variables.

 

I guess you could get a rough idea by doing the math. For example, my X-65's have a 92dB 1w/1m sensitivity rating so you'd have:

1 watt - 92db
2 watts - 95db
4 watts - 98db
8 watts - 101db
16 watts - 104db
32 watts - 107db
64 watts - 110db
128 watts - 113db
256 watts - 116db
512 watts - 119db
1024 watts - 122db

From what I've read, most music has a crest factor (the difference between the average level and the peak level) between 10-20dB depending on the dynamics of the music and the amount of compression used. Most modern recordings will probably be on the lower end of this range.

Whether your amplifier has enough headroom will largely depend on how loud you typically listen to your music. OSHA regulations state that you should not be exposed to SPL levels of 100dB for more than 2 hours per day and 105dB for more than 1 hour per day. Based on these guidelines it would be reasonable to use either of these figures as a maximum reference for average listening levels under normal circumstances.

So, if you want to listen to your music really loud (~104dB) and you listen to dynamic recordings (~18-20dB crest factor) you're looking at around 1,000+watts to accommodate for transient peaks.

Of course this is oversimplified and you would need to take into consideration things like the extra SPL added by using more than one speaker, how much additional power the amp can provide in short bursts compared its average power rating and probably many other factors I haven't thought of, but interesting either way. Not really trying to make a point, just rambling.

 

I think that list makes the point that 300w on a midbass is not as crazy as a lot of people think. To accurately reproduce the music with an average SPL of 104db and 16w you could easily require 300w on transients. My midbasses are only 89db efficient to begin with so it's even worse.