How loud does it need to be, in terms of SQ

[beak81champ]

As most of you know by now, I am the new guy that will ask a million questions, not only because I've never installed this equipment before, but because I want to learn everything I can before I tear into the 2nd largest investment I own. When I look at some of the system diagrams in the signature area of some peoples posts, I am amazed at the number and size of the amps everyone is running for SQ purposes. I totally understand the SPL enthusiasts need for thousands of watts and tons of subs, but how much do you need for SQ?

Is it just as loud as you can afford, or is there another reason to have tons of wattage available to go to each speaker? If you are in competitions, how loud do the judges want your system to be? Is there an SPL number that SQ guys shoot for, and the judges expect to hear your system at that level, or is it just having the headroom in your system for before and after competitions to crank it up?

I think I will only have like 90 watts per channel for my system, and judging from the systems I've seen on these sites, it seems like I won't have enough money invested to sound good. Am I totally off the mark here? Could my system sound anywhere in the same ballpark as other's systems with the right install and tuning, or do I need to continue buying stuff until I have like an amp for each speaker, and multiple DSP's, etc.

I am not planning on doing any competing, but it might be nice to have that option, if my system mistakenly turns out to sound halfway decent...lol

[BigAl205]

Most competitors just like having overhead...IOW, more power than the speaker needs. This allows the amp to run the heck out of the drivers without even breaking a sweat, plus you have the added benefit of less noise because you aren't running the gain wide open.

According to the MECA rulebook

6. Judge’s listening level will vary (70-115 dB) during judging to assess all system criteria.

[naiku]

I think I will only have like 90 watts per channel for my system, and judging from the systems I've seen on these sites, it seems like I won't have enough money invested to sound good. Am I totally off the mark here? Could my system sound anywhere in the same ballpark as other's systems with the right install and tuning, or do I need to continue buying stuff until I have like an amp for each speaker, and multiple DSP's, etc.

90 watts is plenty, the way I see it is that if you are listening and can turn it up as loud as you want it to be, without it distorting, then you are good. If you find you turn it up as loud as you can, but want more, then yep, you may want to look into additional power. Trust me you don't need to spend a fortune for it to sound decent, my system is the very definition of budget but I like to think it sounds good. Which at the end of the day is what is most important.

[Babs]

Might also depend on the amps you're running.. An example might be would a Rockford class A/B T600-4 100 watts be the same 100 watts out of something like a class-D PDX F4, or a clone amp such as the NVX JAD800.4 at 125 watts per. Might be, might not. Not to get into any amp class debates, but I could certainly tell the F4 had more "control" as well as SQ over the NVX (cookie cutter build-house amp), which was immediately evident after the swap. I suspect, if I did the same "100 watts" out of something like a Zapco, JL XD or HD, Mosconi, Sinfoni or other pricier amp, the results would be different. Back in the day (we're talkin' '94 or so) when I sold stuff at Circuit City, I'd frequently demonstrate this by A/B test swapping a low-end Technic's or Kenwood rack-system receiver with a similarly rated Onkyo or HK separate amp such as "the big pig" M-504 Onk.. Not all 100 watts are the same.

Point being, if you're reasonably sure you're running a quality amp setup, you're good.. I'd rather have 50 very clean watts per channel with good headroom than mediocre watts from some amp rated at 100 watts but with no real guts in dynamics and mediocre fidelity and seems to strain at your personal "reference level". Which is why I'm glad I finally heard Erin's car with the JL XD's.. Always liked their layout and size, and hearing is proving.. They sounded fantabulous.

[Notloudenuf]

I think people are running entirely too much power and I think that has made others think 150 watts per tweeter is "required"
I had 40w/ch on my original install and it got plenty loud and sounded great doing it.

All of the above is IMO and YMMV.

[erinh]

the wattage means nothing without knowing the sensitivity of the driver and the distance of the speaker(s) from the listener.

for example, consider a high efficiency midwoofer with 97dB @ 1w/1m sensitivity vs a standard midwoofer with a sensitivity of 87dB @ 1w/1m. Let's call these Midrange 1 and Midrange 2, respectively.
if you want to hit 97dB at 1khz from 1 meter away, then with Midrange 1 all you need is 1 watt. But to hit that with Midrange 2 mid you'd need 10 watts.

if you wanted to listen at a consistent 97dB (which is pretty dang loud) but have 'headroom' for transients found in modern records of +6dB then you'd need:
midrange 1: 4 watts
midrange 2: 40 watts

let's say you listen to older music with as much as +12dB transients. to achieve those transients while maintaining the 97dB nominal output, you'd need:
midrange 1: 16 watts
midrange 2: 158 watts



This is where the legitimacy of 'headroom' and 'power' become apparent. Now, how realistic is it to think you're going to rock out at music at a consistent 97dB? Ehhh... maybe not. But you get the point.

Then you have to factor in the listening position of a car, where the passenger side distance from speaker to listener is 1.5-2x the driver's side distance from speaker->listener. taking the +6dB example above, and using 1.5 meters distance from the speaker you get:
midrange 1: 9 watts
midrange 2: 90 watts

Crown's site has a good writeup on this:
http://www.crownaudio.com/how-much-amplifier-power

then you can use their calculator here:
http://www.crownaudio.com/en-US/tools/calculators


And obviously the above was all made on the assumption that your drivers are the same sensitivity rating and distance away. But, let's say your midrange is 3dB less sensitive than your tweeter and they're the same distance from you. Let's say the tweeter is 90dB @ 1w/1m and the midrange is 87dB @ 1w/1m. You'll need double the power on your midrange to make them play the same level. Or you simply attenuate the tweeter output 3dB to match the midrange. Either way, you're limited by the lowest sensitivity driver.

[chithead]

Just a random thought based on your last example ^^^ If building a single seat car, do you need more power for the passenger side, versus the driver's side speakers?

[Babs]

Just a random thought based on your last example ^^^ If building a single seat car, do you need more power for the passenger side, versus the driver's side speakers?

Erin can certainly answer better than I on that, but I do remember in one of his threads, maybe a tuning thread, there was mention of using left and right side amps so left and right gain settings were independent from each other, so to allow adjust-ability for side level matching. That might not be stated accurately, but just touching on the idea. I might try this when I get the car back together with 3-way.

In any case, plotting them will tell you how many db's difference to level match. I noticed as much as 2-3db on the lever in the Helix in my sides.

[erinh]

Just a random thought based on your last example ^^^ If building a single seat car, do you need more power for the passenger side, versus the driver's side speakers?

six of one, half a dozen of the other. take a look at my post again:

if you wanted to listen at a consistent 97dB (which is pretty dang loud) but have 'headroom' for transients found in modern records of +6dB then you'd need:
midrange 1: 4 watts
midrange 2: 40 watts

-snip-


Then you have to factor in the listening position of a car, where the passenger side distance from speaker to listener is 1.5-2x the driver's side distance from speaker->listener. taking the +6dB example above, and using 1.5 meters distance from the speaker you get:
midrange 1: 9 watts
midrange 2: 90 watts

So you can see that if you want to match the output of the passenger side (because it's further away) to the driver's side, then you can expect you'll need more power OR you attenuate the nearer speakers. So, it really depends on how you look at it: more power on one side or less power on the other. The safe answer is to set up the further side for the volume you need (not forgetting to factor in what the speakers can handle) and then just level match the near side output to that.

[chithead]

Interesting. I see now why these fancy processors are becoming more of a priority. My level of tuning capability in the past was strictly via the head units, and did not have individual attenuation ability available in them.

I'm digging it. Carry on, wise gentlemen!