A question on LC Audio active crossover.
The active crossovers gain popularity recently, so I was looking at your active crossover http://www.lcaudio.dk/com/xover.htm and the circuit seems interesting enough to build it.
My question is, what was the main reason to go IC route in LP filter and do you really think that NE5532 offers best performance here?
The active crossovers gain popularity recently, so I was looking at your active crossover http://www.lcaudio.dk/com/xover.htm and the circuit seems interesting enough to build it.
My question is, what was the main reason to go IC route in LP filter and do you really think that NE5532 offers best performance here?
I think for low frequencies up to say 500 Hz, the NE 5532 is very good. However i realise now that many use our filter at higher frequencies, up to 3-4 kHz. Therefore we now have switched to LM6172 for the low pass section. This opamp is much faster, and sounds good even at the highest frequencies.
Best regards
Lars
Best regards
Lars
Thanks for reply.
I would be using a cross frequency around 3k, so indeed using better IC should be beneficial. Why not going the same way as in HP section with discreet circuit?
Also, the schematic pictured on your site shows two different capacitor values, while calculator provides the same value for both caps. Any prticualr reason for that inconsistency?
I would be using a cross frequency around 3k, so indeed using better IC should be beneficial. Why not going the same way as in HP section with discreet circuit?
Also, the schematic pictured on your site shows two different capacitor values, while calculator provides the same value for both caps. Any prticualr reason for that inconsistency?
Also, do you think the Burr-Brown chips would perform OK in your circuit? I've got a bunch of them, and I need to put together an active x-over for some new speakers.
Thanks,
Zach
Thanks,
Zach
Peter:
I am not so keen on SE circuits for the bass, because they have a tendency to warm up the deepest sounds. In the filter i wanted to keep the bass at neutral, but since the coloration of even harmonics from the SE circuit only has a positive effect on the higher frequencies, i found this circuit's absence of time delayed feedback loops to be purely beneficial.
All the best from Lars
I am not so keen on SE circuits for the bass, because they have a tendency to warm up the deepest sounds. In the filter i wanted to keep the bass at neutral, but since the coloration of even harmonics from the SE circuit only has a positive effect on the higher frequencies, i found this circuit's absence of time delayed feedback loops to be purely beneficial.
All the best from Lars
One last question. It is mentioned that LP section implements integrated Bass Correction (or bass boost) circuit using just 2 resistors. However it doesn't seem to be pictured on a schemaic. Would you mind sharing how it's done?
> the schematic pictured on your site shows two different capacitor values, while calculator provides the same value for both caps.
There are two ways to build this type of 12dB/oct filter.
* Unity-Gain, un-equal values
* Equal Values, gain of about 1.5
The Unity-Gain design leads to awkward parts values, and complicates parts-picking and part-stuffing. But it allows use of simple unity-gain buffer instead of a gain-amp with precise gain.
Most texts and calculators focus on the Equal Value version, assuming you can use an amplifier with precision gain (2 resistors). The math and the fabrication is easier.
If you try an Equal-Value Unity-Gain filter, you will get a very soft corner. You need to add a "bump". That's why you need a little gain, or alternatively an unequal value design that relies on impedance interaction to bump-up the corner.
> LP section implements integrated Bass Correction (or bass boost) circuit using just 2 resistors.
There are more op-amps on the board than schematics show. There seems to be an input buffer. That has two caps at its input, and optional resistors. Without the resistors it probably gives a 6dB/oct slope at some very low frequency. With resistors the frequency is raised, and proper offset of resistor values gives a "bump".
There are two ways to build this type of 12dB/oct filter.
* Unity-Gain, un-equal values
* Equal Values, gain of about 1.5
The Unity-Gain design leads to awkward parts values, and complicates parts-picking and part-stuffing. But it allows use of simple unity-gain buffer instead of a gain-amp with precise gain.
Most texts and calculators focus on the Equal Value version, assuming you can use an amplifier with precision gain (2 resistors). The math and the fabrication is easier.
If you try an Equal-Value Unity-Gain filter, you will get a very soft corner. You need to add a "bump". That's why you need a little gain, or alternatively an unequal value design that relies on impedance interaction to bump-up the corner.
> LP section implements integrated Bass Correction (or bass boost) circuit using just 2 resistors.
There are more op-amps on the board than schematics show. There seems to be an input buffer. That has two caps at its input, and optional resistors. Without the resistors it probably gives a 6dB/oct slope at some very low frequency. With resistors the frequency is raised, and proper offset of resistor values gives a "bump".
Peter
It is done with a normal Sallen Key (High Pass) stage, where the Q is raised to above 1, and therefore the signal makes a bump.
You might see how it works, looking at our subwoofer filter (not a product) here: http://www.lcaudio.dk/subfilter.pdf
The values of the caps are both 100n the values of the resistors can be found using the calculator on the website.
All the best
It is done with a normal Sallen Key (High Pass) stage, where the Q is raised to above 1, and therefore the signal makes a bump.
You might see how it works, looking at our subwoofer filter (not a product) here: http://www.lcaudio.dk/subfilter.pdf
The values of the caps are both 100n the values of the resistors can be found using the calculator on the website.
All the best
Re: A question on LC Audio active crossover.
NE5532 is a feature -- allows all us tweakers to play with other op-amps that are better 🙂
dave
Peter Daniel said:
NE5532 is a feature -- allows all us tweakers to play with other op-amps that are better 🙂
dave
Hi there! Greetings from Serbia!!
I'm kind of new here , and I've been looking through this post and this one caught my attention. I think that this is a great sub filter, but I cant find printed circuit board for it. Does anybody have one, and would he be so kind to send it to me?
Thanks in advance!
my e-mail is : godaboss@bankerinter.net
thank you again!🙂
I'm kind of new here , and I've been looking through this post and this one caught my attention. I think that this is a great sub filter, but I cant find printed circuit board for it. Does anybody have one, and would he be so kind to send it to me?
Thanks in advance!
my e-mail is : godaboss@bankerinter.net
thank you again!🙂
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