Thomp

Here is my current setup:

Head Unit: Alpine 9827
Doors: Kenwood 1669S (powered by head unit)
Sub: Infinity 1030W (powered by amp, bridged)
Amp: Profile CA800

Yesterday on my way home from work I blew the fuse inline with the amp power to the battery. No big deal. So I look in the manual to get the recommended power fuse size and I can't find it. How do I calculate what the fuse size should be? Right now I've got a 25A in there.

While looking in amp manual, I see something about tri-mode wiring. I am pretty new at this so I have no idea if tri-mode wiring is good or bad. Right now my head unit is powering my 6 1/2" door speakers and my amp is dedicated to the sub. Do I have my system wiring in the optimal configuration?

So far I'm unimpressed with the Kenwood 6 1/2 drivers. They have a annoying brightness that I can't seem to get rid of in the high frequencies, and the mid range is also not that great.

This forum has been a huge help in fitting everything in the car, so a big THANKS for all the great info!

- Thomp

evan2

you are never going to be satisfied with the speakers unless you have some real power on them, no matter what your deck says you arent getting that much power to them

i really am not sure what size fuze should be in your inline box but i have like a 60 in mine
ive never had a issue with it on any of my cars...
id assume you should get the same size fuse that your amp has if it does, i have a jl 500.1 so it doesnt have a fuze internally

PJK3

i've never used tri-mode myself, but the concept is sound. whether it's right for you or not, i am unsure. what does Profile state is the output to each component in tri-mode? i'd be concerned you'll have too much power and might blow the fronts. if this really interests you, i'll try to run the power calcs for you. as it is, you've potentially got a ton of power on that sub... i doubt the Profile is actually outputing it's rated power, but even if it's in the ballpark, you're running pretty hot for that sub alone.


you may want to wander over to www.bcae1.com and read up on tri-mode and see if it's right for you. it's in the menu on the right as item 53.

that amp needs a 60 A fuse inline.

http://www.crutchfield.com/S-GkctBB6bSCv/c...pecs&i=489CA800

20A x 3 fuses are listed in the amp description.

NFRs2000NYC

For your setup, 60 should be plenty.....
We are talking about the inline fuses under the hood right, NOT the ones in the amp itself.....
Anyway, hijacking in progress....

Send me free money, beer, and supercharger if i am wrong, but isnt tri-mode simply an amp that is 4 channel, that has the ability to be used as a three channel?? (1 for each speaker and 2 for sub???)

Hijack over.

You may now continue to your scheduled destination.

Thomp

Yep, the one I put under the hood near the battery. The amp does have 3 x 20A fuses in the side of it, but I was guessing on the low side for the inline fuse just to be safe. I'll stick a 60A in there.

I'm thinking tri-mode will not work for me. The front speakers I have would go into melt-down. I'll just have to find small 2 channel amp to run them off of. I know the amp is too big for a single sub, but for $80 from Profiles web site, it sounded like a good deal. It's a refurb that comes with a warranty.

I would really like to go with components, but I haven't figured out where / how to mount the tweeter if I bought some (my car is an '01 without tweeter pods in the door).

Thanks for the advice about the fuse!

- Thomp

PJK3

Thomp -- that amp may or may not be bad for your front speakers... in tri-mode, power gets split up in all kinds of ways. so, whatever you are outputting when bridged, that power will get divided a few ways to each speaker, with different quantities of power going different places, depending on what the impedances (resistance) of the speakers are... are they all 4 ohm?
still -- based on what i'm guessing, you won't be able to run that setup in tri-mode b/c the impedence of the sub is going to drop you too low, and if you use a passive crossover in line w/ the speakers, i think you're going to get into a situation where you're overpowering the fronts.



Dave --
actually that isn't tri-mode. tri-mode is a bit more complex, and honestly it isn't a sector where i'm super confident. Dan might know more about this one...
either or - this is the concept as i understand it: you're using a 2 channel amp to drive a 3 channel load. two of those channels run in stereo and the 3rd runs in mono based on the other 2.

generally when you're running an amp in stereo, your power comes from the voltage potential between each channel and a neutral (or ground) signal. P = (E^2)/R

now, when you bridge an amp to make it mono -- what you're really doing is taking the same signal (it's mono right?) and running it normal in 1 channel and inverted (the opposite) in the 2nd channel. now, instead of using the voltage potential from the channel to neutral, you use the voltage potential between channel 1 and 2. (since signal 2 is the exact opposite of 1)
what you've done by doing this is double the voltage potential between the 2 signals. and in doing so, because P = ((2*E)^2)/R -- you've quadrupled the power, since 2^2 = 4.

example --
say your rms voltage potential from + to neutral across a 4 ohm speaker was 20 V. (stereo mode) that gives you 100 Wrms. 20^2/4 = 400/4 = 100
now, if you instead make your rms voltage potential from + to inverted + across a 4 ohm speaker, you'll have 40 V (bridged mono), which now gives you 40^2/4 = 1600/4 = 400 Wrms

of course this is in theory and doesn't account for the amps inefficiencies, so you generally don't get an exact increase of 4x's.


now, here's where i get a bit fuzzy...
w/ trimode, you're now running 1 set of speakers (stereo) off of the voltage potential to neutral, and another speaker (mono) off the voltage potential from + to inverted +. the loads add up a bit differently (and i'd have to spend some time remembering how to calc them) now b/c of the situation...

but basically, what you now have is the mono signal riding on the stereo signal. the tri-mode crossover helps sort out the mono and stereo signals...

does this help at all?

modifry

^ I think that's right.

To calculate impedance, it usually works best to "convert" the mono channel into it's equivelent stereo impedance.

4 ohms in bridged mode loads each stereo amp the same as a 2 ohm load on each channel. So running two 4 ohm loads (one on each stereo channel), then adding a 4 ohm load on the bridged channel is like running a 4 ohm AND a 2 ohm on each stereo channel. That's a 1.33 ohm load. Not good unless your amp is rated for 1 ohm loads in stereo mode. If not, you should run the mono channel into 8 ohms, giving a 2 ohm load on each stereo channel, which is probably legal for most amps.

PJK3

Bob -

thanks. not that you really were doubtful, but yup -- that's the way i remember to calc the loads. the mono impedance is split between the 2 channels in parallel...


and yup, a 2 ohm stereo load is legal for that amp, so 1.33 would be pushing it... you might be able to get away with it... but that is really pushing it, and it is pretty doubtful. it would really depend on the design of the amp. but that'd be the decision Thomp has to make.


given that the amp looks to max out at 600 Wrms when bridged mono (theoretically, it should hit just under 800 Wrms), i'm going to make the assumption that IF it will run or is stable at 1.33 ohms stereo (it probably isn't), the power spread would be something like 100 Wrms / main and 400 Wrms for the sub, which accounts for the total 600 Wrms output capability of the amp. (i THINK... boy, i'm more fuzzy on my EE classes than i thought... )

in the end? this amp isn't the best option for doing this.