Jamie,

I'm deffinitely going to have to hear your car some time. These hints you keep dropping are pretty good teasers.

Just curious, what about the 2 secrets in the trunk Mr Efficiency?

Adam

 

Just one more comment.

Has anyone here ever seen a spectrograph in decibelwatts? It basically shows acoustical energy across the audible frequency spectrum.

Simply put, energy content in music increases as frequency decreases. But I'm sure most of you already knew that. So while putting lots of power on a tweeter seems sensable, it really doesn't need that much. 20 to 30 clean watts is all it takes for even the most dynamic of systems. Mids are a whole other story though. I've seen midrange drivers suck up over 200 watts to cleanly reproduce a soprano singing.

That said, I totally agree with Jamie on the power thing...and I practice what I preach.

Tweeters - 100+ watts each
Midranges - 100+ watts each
Midbasses - 200+ watts each
Subwoofers - 2000 watts

All that to achieve 105 db. [img]smile.gif[/img]

Adam

[ June 23, 2004, 11:19 AM: Message edited by: PEI330Ci ]

 

I too believe that the division of power through a passive doesn't happen, meaning that 75 watts would go to each speaker with a single 75x2 amp. But what Adam said is interesting and food for thought; and if I understood it right, he is saying that your 75 watts would get divided by the drivers you are using so simplistically each driver in a 3-way would get 25 watts each.

 

^thats how i see it, passive x-over or not. When you run 2 subs off 100x1, they get 50w each, not 100 each. Same principal no?

 

not the same principal, the crossover takes the power, and decides which driver gets which portion of the power. each driver may not get 100% of the power, but they will get the portion that they need to play the music properly. so 75 watts may be 55 watts to the woofer, and 20 watts to the tweeter, but there isn't a direct split.

that being said, if you played a sine sweep through the spectrum, it would be as if you were giving each driver 75 watts because you'd be feeding only one driver at a time.

 

Hmmm it would seem an easy way to test that out would be to play pink noise through the passive and the measure voltage at each speaker and at the amp.

 

I have 240 watts per set 2 sets.

[ June 23, 2004, 01:42 PM: Message edited by: Icon ]

 

Maybe you can fill me in on any secrets I had in that trunk ?

If your implying I had hidden amps then your way off.

The enclosure was a sealed design, with alot of air space in the enclosure. The design was that of a folded horn. Using the rear seat possition, and the rear window/hatch the enclosure loaded extremly well. Infact it did it so well that the cross over freq to those subs was a 12bd/oct at 35hz. This gave me a great balance of a crossover slope taking the upper sub bass down in level, and letting the low sub bass be more on level with the upper sub bass. Larry Chijner (Team JBL) still takes about the sub bass in that car today (5 years after it's last comp)