Going to triamped in my car, how much power for tweeters?

Right now I'm using a 4 channel amp, 2 channels for the sub, 2 channels for the mids and highs. I've got infinity 50cs components at the front (i think), with passive XO.

I plan to go fully active XO, here's rough overview on what I'm planning to do.

Sub = horn design with 2 x 8" drivers, each one getting 70Wrms.
Mids = 2 x 5.25" in the doors, each getting 70Wrms.
Tweets = They are 1" units, that's all I really know right now. I'm not sure how much power they will need to 'keep up' with the mids and sub.


I'm planning on going for tripath based amps all round, and I'm not really sure what amp to use for the tweets.

Would 25W rms per tweet be OK? Or could I get away with 15W? Or would it be best just to hook up and amp and see how well it works?
 
djQUAN said:
it will depend on the crossover frequencies you will use. you WILL use an active crossover, right?
Yep, I'm planning on keeping the same crossover frequency as the passive crossover, but I'm going to use 24db/oct LR.

I'm not sure what the crossover frequency of the components are, but I thought be able to find out with a voltmeter and sig gen. :)
y8s said:
you'll need to know the relative efficiency of the tweeters and mids.

if the mids are 87db @[email protected] (assuming 4 ohms for all drivers) and the tweeters are 90, you only need half the power of the mids.
All drivers are 4 ohm, but I haven't a clue about the efficiency... I'll have to dig up the specs... I've got the original box somewhere.

I thought that music often requires less power to the tweeters, even if the sensitivity of mids and tweeters are the same? Or is it normally a case of the tweeters being more sensitive?
 

jol50

Member
2007-11-08 2:14 am
One would think so, but does not always work out that way. I have some 2x35 that will wang on mid/highs with no bass....other amps distort at the same spot no matter if they are pushing bass or not (bass in the mids not sub). I am not sure why, I suspect the topology of the amp. I like to run plenty large amps on highs (if they fit) just to be sure unless it is a known amp to me. For smaller music systems I have often run 300w amps on sub and high (2x75rms). I really want them clean and that is easy way....I'd say if you don't have experience with the particular amps you will have to find out what they do. Better quality small amps seem to be better at doing highs in my experience.
 

jol50

Member
2007-11-08 2:14 am
Just put a cap on the tweeter with the active for some insurance.

I wish someone could explain it more. Bass certainly takes more power but I've had amps that will run tweeters very loud (& clean), and others that were larger that would not but would do bass better. Right now I have a kicker running highs and it will go to a certain point and clip. It does not matter if I have the subs on/off, or turn the HP up/down to vary the load on it. Last amp I had in there was a smaller wattage alpine that would go louder if the LP was higher, but broke up on the midbass if the HP was set lower.
 
If you run too small an amp on the tweeters they will get a distorted signal from the amp when it goes into clipping earlier than the rest of the system and this is a sure fire way to blow your tweeters.
Years ago I ran a Rockford Fosgate Punch40dsm to a set of splits using the supplied crossovers, in this system I blew 2 tweeters, I then upped the system to 2 Punch40dsm's 1 bridged per channel giving 4 times the power and no more blown tweeters.
So go for the biggest that you can afford/fit.....
 
Ok guys, I think I will wait until I've got a better amp for my tweeters before I go triamped... My passive XO is fine for now...
MartyM said:
What kind of tripath-based amps are you using, out of curiousity?

I thought the only ones for car audio were the now-defunct T-class full-range amps by Blaupunkt some time ago.

I'm very curious.
DIY :)
[IMGDEAD]http://img207.imageshack.us/img207/5145/n699581380370457679hx4.jpg[/IMGDEAD]

I'm using the Sure Electronics 4 channel class D module, which is pretty much the same as the amp9 kit by 41Hz.com

The only thing is it needs 24v to get the most out of it, so I butchered an old cheap "purple mosfet" amp for it's SPMS. I took 1 winding off the secondary and how it gives 26v out with 15v in, so I think it should all work well...

The only thing I'm not 100% sure if is if the SMPS is up to the task... I'll have to try some tones and see how much the rail sags...