View Full Version : Going active on a MB Quart DSC4125 - too much power?

02-25-2011, 12:35 AM
I am about to purchase a dsc4125 (125x4 @4ohms) and was considering running active to my current DLS MS6a components (currently fed 75 RMS passive with 80hz HP at source). With running active, I can control crossover frequencies at the source. It seems like the woofer is rated to 100 RMS and should be fine, but the tweets are only rated to 50 RMS. Will I blow them with this much power? Should I leave the physical crossover in place for the tweeters and just run active to the woofers?

On the same note (and this may be a silly question), while running passive to the comps, do you have to use a high pass filter on the amp/source or does the speaker crossover take care of all those low frequencies?

02-25-2011, 12:40 AM
You still need to use a crossover either at the amp or at the HU to keep the low frequencies away from your mids, regardless if you're running passive crossovers. The passives on split the frequencies between the mid/tweet.

As far as your main question goes, there's no such thing as too much available power, so long as you're smart with it. More often than not, with quality speakers, you're going to hear the driver stress out or distort badly before you reach the thermal limits of the voice coils.

02-25-2011, 12:50 AM
but how can i ensure the tweeters are not getting too much power? even with my current amp supplying 75 RMS passive, the gains are almost all the way down. so with 125 RMS, even with the gains at zero, won't it still be hella loud? maybe i'm not understanding this correctly...

02-25-2011, 01:16 AM
^^^^ what headunit are you using?
you can go active with that amp.
1-First off you need a Lowpass xover that will reach high enough to xover the top end of the mids,2.5-4k.
Then you can use a highpass on the lowend of your mids.
2-For the tweeter you can use the passive until you can learn about slopes & xovers.
3-That amp doesn't allow you cross your tweeter high enough. I'm guessing your tweeters are x-over at around 3-4k
The amp highpass only goes up to 1.2k.
4-If you do get a external x-over or deck that will allow you to go active will let you have control of your speakers.
Do you know what the slope & x-over pionts on the passive are?
you might be able to go there web-site & they may have some info or you can call up the company for info.,
you want to ask them what are slope & x-over pionts are on those tweeters.
There is so much much to learn about caraudio, it take time.
Read all you can about speakers

02-25-2011, 11:19 AM
thanks for your reply. i actually have been lurkng for a while and have a good idea of how to manage crossover frequences and slopes and understand the frequency ranges for the woofer and the tweets. the passive crossover is 12db HP at 4k for the tweets and 6db lowpass for the mids. i have a carpc that allows me to pick any HP, LP, and BP filter at the source per channel, so i can run the amp on full range and bypass the amp crossovers altogether. my question was more for POWER. with the amp putting out 125 RMS per channel, even with the crossovers set properly at the source, wont this blow my tweeters? Does the passive crossover that comes with the speakers attentuate the power of the signal before reaching the tweets to prevent blowing them?

02-25-2011, 11:32 AM
The amp doesn't "only" produce 125watts per channel, it can do 0-125 watts. Keep your gains down on the tweeter channel and/or keep you HU volume down.

Its not that big of a deal, I had a 3000watt amp on a 300watt sub with no problems. I also have a DSC4125, the input sensitivity isn't that high.

02-25-2011, 12:02 PM
ok that's what i was hopng for. looks lke i'll pull the trgger. thanks!!