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I assumed he was going active fronts with the Dsp 408.
However, Even if he was running active he would not want to use 15 microfarads. That would still be too close to the active crossover and would interfere.
Not according to my research on protecting my Morels in active mode. Please see video below, DH feel free to chime in. Doing the math, .0.159/2400*4 (true ohms, with meter)=.0000265 or 26uF rounding off to the closet and safest size 15uF. They make a 15uF and 50uF 100V Electrolytic Non-Polarized Crossover Capacitor
So the Morel Tempo's have a passive crossover of 3200hz and 6db/octave according to their site (If I am reading it correctly). Putting a 15 microfarad capacitor in there has a cutoff frequency of a 4 ohm speaker at 2600hz. That means that at 1600hz, the passive crossover only cuts 6db and is still within audible range. So your capacitor will start interfering with your speakers response i..e. you will be able to measure the acoustical difference between capacitor and no capacitor which isn't what you want. Having the capacitor within the audible range will also impact phase of the speakers and put the speakers 45 degrees out of phase, again not good. (Every 6db of slope shifts the phase by 45 degrees, hence why we like 24db/slope because the tweeter gets shifted by 180 degrees and the woofer gets shifted by 180 degrees so they are back to 360 or the same again).
A tweeter will be fine with a capacitor protector that is protecting it from 600hz and below or 68 microfarad. I like a little more so I go with a 47 microfarad capacitor or 800hz cutoff. Either way, my crossover is around 2500hz @ 24db/octave. An octave below this would be 1250hz and has cut 24db which means that by the time it reaches the 800hz, I have cut around 40db out of my tweeter. My capacitor is well outside of any measurable difference and doesn't impact the phase of the speaker.
I was going off of Morel's site, listing the RS of the Tweeter at 1200Hz and measured ohms at 4. Then I am guessing the information from CAF's site is incorrect? If so, then I guess I have been giving out bad advise from what I thought was a good source. Now I get to figure out what I need to change out my Caps to now!! that's sucks. But, it's my understand you really don't want to go below the RS of a tweeter as your risk damaging the unit. Is 800 Hz too low? One note, I am running an active setup and not a passive crossover.
So the Morel Tempo's have a passive crossover of 3200hz and 6db/octave according to their site (If I am reading it correctly). Putting a 15 microfarad capacitor in there has a cutoff frequency of a 4 ohm speaker at 2600hz. That means that at 1600hz, the passive crossover only cuts 6db and is still within audible range. So your capacitor will start interfering with your speakers response i..e. you will be able to measure the acoustical difference between capacitor and no capacitor which isn't what you want. Having the capacitor within the audible range will also impact phase of the speakers and put the speakers 45 degrees out of phase, again not good. (Every 6db of slope shifts the phase by 45 degrees, hence why we like 24db/slope because the tweeter gets shifted by 180 degrees and the woofer gets shifted by 180 degrees so they are back to 360 or the same again).
A tweeter will be fine with a capacitor protector that is protecting it from 600hz and below or 68 microfarad. I like a little more so I go with a 47 microfarad capacitor or 800hz cutoff. Either way, my crossover is around 2500hz @ 24db/octave. An octave below this would be 1250hz and has cut 24db which means that by the time it reaches the 800hz, I have cut around 40db out of my tweeter. My capacitor is well outside of any measurable difference and doesn't impact the phase of the speaker.
Most higher end sound quality cars run active networks. This just means every single speaker in your vehicle gets its own amp channel. So for a 4 channel amp, your speakers would be 1 drivers side woofer, 1 driver side tweeter, 1 passenger side woofer, 1 passenger side tweeter.
This allows you to individually control each speaker usually via DSP these days. You set what frequencies you want to cross the woofer and tweeter at via the DSP. You also have individual controls of EQ via the DSP for each speaker, since each has its own channel on the amp.
Passive means your tweeter and woofer share a channel on your amp. The amp goes to a passive crossover and that splits the signal. Any EQ impacts both the tweeter and the woofer.
Thanks! So the skinny is I don't need a capacitor with passive crossovers?
Nope because the crossover that came with your speakers already has this built in.
You can see in this, the white block things are resistors, the copper thing is the coil, and the yellow thing is the capacitor. Together these form the crossover network for you.
06-12-2019, 09:25 PM
