Passive crossover before amp on speaker level

[OVLDULVEBIOAB]

Hi all, 

New to the forum - doing my 2nd install, upgrade to a Chevy Bolt. 

Generally, one puts passive crossovers after the amp, but is there anything preventing me from putting the between amps? 

I will be running speaker level outs into my aftermarket (Sony) amps. Seems like it would be more efficient to block the bass before it gets amplified a second time. 

If the signal is already amplified by the head unit, it should be okay to apply the High pass filter, no? 

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[Talontsi90]

The only passive xover networks ive seen for line level are the F-mods by Harrison Labs. Im not sure it would be advisable to put them on a high level input as it will diminish the signal too much.

 

[n2audio 5,000+ posts]

Logically, it seems like it should work, but when you choose a speaker level cap you calculate the cap's value using the impedance of the load.

With amp inputs typically being several thousand ohms I'm not sure this would work.

I will try to come up with a definitive answer...

After consulting an expert -- apparently impedance on speaker level inputs can vary drastically, so unless you have that value from the mfg there's no way you could size your filter.  DC resistance measurement wouldn't be much help because the inputs will not behave like a speaker.

 

[keep_hope_alive Premium Member]

I totally agree with n2audio above.  Amp input impedance vary and a passive crossover is built for the specific load.   Even the FMod assumes an input impedance.

You are correct that it's somewhat more efficient to put a crossover before an amp.  That's why we use electronic crossovers.  We let the electronic crossover accept the factory signal and handle routing.  Nowadays, we use a DSP for this task and gain a ton of other features at the same time.  With the price of DSPs reaching the cost of electronic crossovers, it's becoming a standard practice.