Perfect!
Incorporate your intended 80Hz low pass into the subwoofer amplifier. When you do it at the signal level, you don't have to worry about wildly fluctuating impedances and the component sizes are much, much, much, smaller!
They have inline passive filters you might be interested in.
Here is a website that will interest you. They have a discussion forum dedicated to subwoofers.
The Subwoofer DIY Page - Audio Links
Currently there is a "passive crossover" thread going on over at the PartsExpress forum. Go take a look at the picture, pretty simple.
Inline Passive Crossover. - Techtalk Speaker Building, Audio, Video, and Electronics Customer Discussion Forum From Parts-Express.com
Subwoofer (12HZ-48HZ)+(28HZ-112HZ) preamplifier board - eBay (item 190511834547 end time Mar-20-11 08:06:08 PDT)
I'm wondering....If this preamp board that I am going to use has these frequency things going on...would I even need a filter at all? It seems that it may do just that...but perhaps I am wrong.
I'm wondering....If this preamp board that I am going to use has these frequency things going on...would I even need a filter at all? It seems that it may do just that...but perhaps I am wrong.
A little harsh perhaps? Using pre-built units may be a little hopeful...but when a passive crossover is done the right way there is very little to complain about.
Using 8" subwoofers, and maybe a little EQ, you can get response down to the twenties at reasoanble levels in a typical room, but this does tend to depend on your interpretation of 'reasonable levels'.
I've never heard a passive crossover for a subwoofer that sounded any good to my ears. Too much insertion loss and unpredictable frequency response.
A passive line level approach would be more effective and cheaper to boot.
More like a lot of EQ.
Regardless of the woofer size, if you want low twenties Hertz you still need a large enclosure, either that or a heck of a lot of power!
Some guy from Australia (Paul Sechi) was modeling double chamber reflex enclosures, he was able to get twenties Hertz with a 6 inch woofer, but the enclosure was refrigerator sized!
You may, one day. ...Insertion loss? Turn it up. Bad response? Room modes. Line level won't fix that, neither will passive.
I've been there, but more recently I used three 8" subs in 17 litre (0.6' ^3) boxes in a 2500' ^3 room. f3 was 28Hz (some EQ was used, mainly for room modes). Clean output at levels where you needed to speak up to hear each other.
Much easier to trim and tweak a line level passive than a full size passive. Passive line level costs way less. How much does a few small 1/4 watt resistors cost anyway? I already have drawers full of hundreds of small resistors and capacitors.
Significant series resistance is no good for your bass alignment either. Huge inductors if they are any good, aren't cheap!
No fun either trying to unwind your inductor to some in between or non standard value.
But if one day you decide to upgrade to a plate amp with its own crossover or a separate subwoofer amplifier with electronic crossover then you are stuck with a passive crossover of no use.
Did anyone look at that preamp board from eBay on had on the page before. There's zero documentation on it. I did order it, but mostly because I needed a stereo --> 1 mono board + preamp. The potentiometers are like EQs?
So anyone know how to calculate line level?
Anyone want to defend the crossover?
So anyone know how to calculate line level?
Anyone want to defend the crossover?
There has to be some documentation with it 😕
About the controls, we could assume one has to be the sub level. One may be the sub crossover frequency. It claims to have adjustable phase so we could assume one does that.
The fourth control could be any one of: overall level, high pass crossover frequency, mains phase, mains level.
This is not a hard and fast thing. Typically it is around 2Vpeak max. Sometimes higher, often lower.
The prebuilt one?? No.
With a subwoofer, you should always use a crossover, if there is no crossover then technically it is no longer truly a subwoofer. You need some kind of network to filter out the higher frequencies.
But I'm personally against large passive crossovers. My opinion is that line level active first, if not that, then line level passive.
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Oh alright then.
So suggestions on where to get starting building this line level crossover?
I don't know a clue about them. Never build speakers with a sub in them. In fact, these Sophomores are the first speakers I'll be using with crossovers.
So suggestions on where to get starting building this line level crossover?
I don't know a clue about them. Never build speakers with a sub in them. In fact, these Sophomores are the first speakers I'll be using with crossovers.
Um, the board from ebay says frequency can be adjusted. My understanding is that this is not as much a pre-amp as it is an active crossover. Perhaps you could mail this dude for a copy of the docs?
Here are some links, but I've got the feeling that it's way over your head.
TLS.org | Passive Line-Level Crossover
Crossove_Design
Low-pass filter - Wikipedia, the free encyclopedia
What you need is a subwoofer amplifier that has the crossover already built in, very typical of almost all subwoofer plate amps.
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