Hello everybody!
Is a simple first order lowpass filter "good enough" in front of an amplifier that drives a subwoofer?
Or do I need a higher order LPF?
I am not talking about "getting the best sound" from the system, I just don't want to damage my new subwoofer.
I am also not asking about optimizing the crossover point or phase issues and stuff like that.
Just preventing damage from occuring.
Shouldn't the inductance of the subwoofer itself cause low frequencies to be "cut off"?
Or would passing an unfiltered high frequency signal into a subwoofer cause it to heat up and burn itself out?
Is a filter needed at all?
I know a bit about electronics but almost nothing about speakers and how to drive them.
To me they are just "magic inductors that turn current into air-movement" ;-)
Usually I just try stuff to see if it works but I don't want to scrap my new subwoofer.
A bit more information about my setup:
This is what I want to do:
Yes, it is a badly drawn sketch but it explains what I want to do.
Use a subwoofer "in parallel" with an existing system that will be set to only do mid and high frequency.
The subwoofer I have is a Behringer VP1800S (please no anti-Behringer rants, thanks).
It is rated for 1600W maximum and has a frequency range from 40Hz to 200Hz.
The amplifier is built for the full audio range and can output 400W stereo, I will use it in "bridged mode" to get 800W and a single "channel".
I will never actually push 800W through the subwoofer, that would probably destroy everything around the subwoofer ;-)
Of course I tried to search online about using simple first order lowpass filters in fron of subwoofers but I couldn't find any proper information about the topic.
Any answers would be appreciated.
Is a simple first order lowpass filter "good enough" in front of an amplifier that drives a subwoofer?
Or do I need a higher order LPF?
I am not talking about "getting the best sound" from the system, I just don't want to damage my new subwoofer.
I am also not asking about optimizing the crossover point or phase issues and stuff like that.
Just preventing damage from occuring.
Shouldn't the inductance of the subwoofer itself cause low frequencies to be "cut off"?
Or would passing an unfiltered high frequency signal into a subwoofer cause it to heat up and burn itself out?
Is a filter needed at all?
I know a bit about electronics but almost nothing about speakers and how to drive them.
To me they are just "magic inductors that turn current into air-movement" ;-)
Usually I just try stuff to see if it works but I don't want to scrap my new subwoofer.
A bit more information about my setup:
This is what I want to do:
Yes, it is a badly drawn sketch but it explains what I want to do.
Use a subwoofer "in parallel" with an existing system that will be set to only do mid and high frequency.
The subwoofer I have is a Behringer VP1800S (please no anti-Behringer rants, thanks).
It is rated for 1600W maximum and has a frequency range from 40Hz to 200Hz.
The amplifier is built for the full audio range and can output 400W stereo, I will use it in "bridged mode" to get 800W and a single "channel".
I will never actually push 800W through the subwoofer, that would probably destroy everything around the subwoofer ;-)
Of course I tried to search online about using simple first order lowpass filters in fron of subwoofers but I couldn't find any proper information about the topic.
Any answers would be appreciated.
The subwoofer driver doesn't care about H/F signals. It will try to reproduce them (badly) if it can. Your low pass filter will only affect sound, stopping the sub and mains both playing in the 100-500hz range.
So subwoofers gernerally don't get damaged by getting regular amplified audio that is not inside their working frequency range?
If that is the case, I would not need a filter at all (for protection reasons), right?
How would the filter affect the main signal path?
If it is completley passive then yes, but if I use operational amplifiers configured as voltage followers to "decouple" the input signal before it goes into the mixer (because it is a stereo signal and I only have one sub, so I need to mix the L&R signals together) and the LPF then it will not affect anything else..
I am 99,99% sure about that (at audo frequencies).
If that is the case, I would not need a filter at all (for protection reasons), right?
How would the filter affect the main signal path?
If it is completley passive then yes, but if I use operational amplifiers configured as voltage followers to "decouple" the input signal before it goes into the mixer (because it is a stereo signal and I only have one sub, so I need to mix the L&R signals together) and the LPF then it will not affect anything else..
I am 99,99% sure about that (at audo frequencies).
How you choose to convert a stereo signal to mono is a different question. But there is no energy in H/F signals. In a typical music program 80% of the power goes to the bass. A tweeter in a 100w 3-way system likely handles 5w full range.
I already built a stereo to mono converter box that will be placed before the input of the subwoofer amp (and before the LPF).
Just a simple summing amplifier with buffered inputs so it doesn't load down the inputs.
Like I said, I knów a thing or two about electronics ;-)
Just a simple summing amplifier with buffered inputs so it doesn't load down the inputs.
Like I said, I knów a thing or two about electronics ;-)
How about a pair of FMod passive crossovers? 2nd-order BW2, I would recommend 50Hz.
https://www.hlabs.com/products/crossovers/
A sub playing high frequencies sounds bad.
https://www.hlabs.com/products/crossovers/
A sub playing high frequencies sounds bad.
Thanks for the recommendation, but I will probably build an active crossover or just buy a proper one (sometimes I am lazy).
I need to do some more research about that topic first.
This "simple lowpass" was just meant for quickly testing if everything basically works as I intended (the wiring, speaker placement, etc.).
Which it did.
Nothing burnt up or was destroyed without the filter, I was worried for no good reason.
But it is better to ask then to break a shiny new piece of equipment.
I need to do some more research about that topic first.
This "simple lowpass" was just meant for quickly testing if everything basically works as I intended (the wiring, speaker placement, etc.).
Which it did.
Nothing burnt up or was destroyed without the filter, I was worried for no good reason.
But it is better to ask then to break a shiny new piece of equipment.
It would be better in my opinion to have a high pass filter for the crappy stereo that doesn't like low frequencies doesn't get it in the first place.
Yup. Putting a HP on the main speakers is more important. Choosing the best frequency for the HP filter is also important. Choosing the type of HP filter is also important. It's much better for it to be a line-level HP filter, for example.
Subwoofers are not typically designed to run with a LP filter, but doing so will not damage them, even at high power levels. The exact opposite is true for main speakers.
Subwoofers are not typically designed to run with a LP filter, but doing so will not damage them, even at high power levels. The exact opposite is true for main speakers.
"He ain't lyin" That is what makes the Harrison Labs little plug-in filters so handy, even if you use something else in the end. They are set at 12 db per octave at the frequency given and the input impedance of the amplifier itself. There is a chart to help with this. So, first I chose 100 hz high pass filter, but it was higher than I wanted, so swapped them out with 70 hz. Might even try 50 hz just to see where that lands me.