| ch33ta |
I need a low pass filter for my TDA7294 amplifier, found one and it looks very simple
LOW PASS FILTER
please tell me if you have a better schematic (but simple, not too complicated), or if you have a suggestion for the low pass filter above |
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| Dxvideo |
| That works on the same theory but simpler, |
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| sek |
| Depending on what you're aiming for, the website of SL can also never hurt. :D |
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| ch33ta |
tnx
can I use TL072 ???
or if you have a better solution tell me
btw. I need to put this on a single power suply if it is possible? (+12V) |
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| AndrewT |
Hi,
why do you want a low pass filter?
In my opinion it will remove some of your low bass information.
If you are planning to run with large amounts of equalisation to extend the low frequency response of a speaker, then a low pass will protect the speaker from excessive cone travel and the power amplifier from excessive output voltage.
If you are running the speaker near flat then I suggest you use a DC blocking capacitor on the input to your amplifier and set the RC time constant of this filter (-6db/octave- single pole) to about 80mS to 90 mS. That will let all the bass and sub-bass through and get the best out of the low frequency response in the speaker.
BTW
the circuit in post2 will not work with the late information supplied in post4! nor will the linked circuit in post1. |
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| ch33ta |
| quote: | | Depending on what you're aiming for, the website of SL can also never hurt. |
it's like this:
I need a 24dB/oct lowpass filter with changeable frequency (up to 200Hz)
and if it's possible a tested one :smash:
I don't like when to build something that probably won't work or if it hasn't been tested :D |
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| AndrewT |
Ah!
a low pass to stop the bass getting to your speakers.
I'm afraid your link confused me.
A pair of 2pole Sallen & Key filters cascaded to give 24db/octave.
Do you want Linkwitz Reilly or Butterworth roll off characteristic or something else?
There's a Group Buy and a few spares may be available for a suitable filter (but it's not adjustable). |
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| ch33ta |
| quote: | | If you are planning to run with large amounts of equalisation to extend the low frequency response of a speaker, then a low pass will protect the speaker from excessive cone travel and the power amplifier from excessive output voltage. |
There is definetly huge amount of equalisation :D
I have a two-band tone control, bass control range is from -19 to +17dB (I love that little button :D )
So i need a low pass filter because the range of bass control is from 20Hz to 500Hz, and I don't want anything above 150Hz on my subwoofer. |
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| ch33ta |
| quote: | | Ah! a low pass to stop the bass getting to your speakers. I'm afraid your link confused me. |
:eek:
low pass
This is a simple low pass filter with changeable frequency (30-150Hz).
I just want to know what do you think about this schematic (will it work, and would you make any changes to it ?) |
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| ch33ta |
I must say I am kind of new at all this, so if you know some better filter please give me a link.
btw. tnx for answering on my newbie questions ;) |
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| richie00boy |
| Low pass will let only bass through... is this what you want? It won't protect speakers. |
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| sek |
Well, the link you posted shows a tested and ready project. Just what you're looking for.
It will work, although it can be done differently. But the recommendations in the project description are okay.
It's 12dB/Oct., though! Implementing an adjustable filter of 4th order (in this case: with four adjustable resistors) is difficult. Depends on what you need exactly.
Lars Clausen of then LC-Audio (now Olive Audio) made one, but it's a little more complex (albeit a lot more sophisticated and capable). It contains remote power control, gain adjustment, adjustable low cut for protection, and variable bass boost, adjustable 24dB/Oct low-pass filter and variable phase alignment 0-180 degree. He recently pulled it from his website for updating the project, but you can always send him an email and ask how far it is progressed.
I have the schematic of the first version that I could send you by email, if you like. But as it contains only the schematic (and no board layout or manual) you should perhaps contact Lars first.
Cheers,
Sebastian. |
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| Dxvideo |
I tried it with a TDA2050 amp and 6,5" 4ohm in a ported box (28lt). It works ok, but i cannot say its the best subwoofer i ever heard. A linkwitz citcuit will work better.
And if you want to do it really, its for TL072 or other audio op-amps, but for single supply you must use TDA2320A it can work with +12v. |
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| ch33ta |
to explain my situation a little better:
I have a 100WRMS amplifier, and a two-band tone control, but on the tone control low signal amplification is from 20Hz to 500Hz, and I don't want anything above 150Hz on my subwoofer so I need a low pass filter.
Amplifier runs at ±40V and tone control at +12V, so i thought of placing the low pass filter on the same power supply as the tone control, but it is not too important.
I mentioned TL072 for low pass filter because it is low noise, and very cheap, but it's not too important, if you know a better OP Amp tell me.
Sebastian, please send me the schematic if you can, I would like to see it.
diy_ch33ta@yahoo.com |
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| Dxvideo |
If you will use it with a real subwoofer like 12 or 15" in a sealed box (~50lt) then you can use the Rod Elliots Linkwitz circuit. I use a circuit very like it and very happy with it. Read it carefully and design a good PCB. You will like its sound.
http://sound.westhost.com/project48.htm |
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| ch33ta |
| I have a 10" subwoofer, but it's in vented box, not sealed, does it matter, or is this for sealed box only ??? |
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| sek |
Rod Elliot's project 48 works for closed boxes only - what you need is really only a low-pass filter and maybe some gain in the low end.
You got mail, the "official" location of LC Audio's Subwoofer filter is here. ;)
Cheers,
Sebastian. |
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| AndrewT |
Hi,
you can apply a sixth order alignment to a vented box.
BUT
the box and driver and EQ and filter MUST all be designed to work together. |
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| ch33ta |
| quote: | | Rod Elliot's project 48 works for closed boxes only - what you need is really only a low-pass filter and maybe some gain in the low end. |
This is exactly what I need, nothing else, cutoff frequencies higher than 150Hz and a little bass boost.
tnx, Sebastian for the schematic - I'll build it as soon as I find some time. :smash:
The schematic is simply beautiful, a little more complex, as you said, but it's worth building. :D |
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| sek |
Great! ;)
Please keep us posted with your progress.
I'm planning to do something like that for my subwoofer(s), too. But at the moment I'm stuck with the satellites' crossover filters and EQs. :cannotbe:
Cheers,
Sebastian. |
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