small tweeter amp with integrated highpass ?

[tinitus]

hi, looking for a design, but is there any ?

btw, does not need to be very high quality

 

[sreten]

hi, looking for a design, but is there any ?
btw, does not need to be very high quality

Hi,

Very easy to arrange for 1st order high pass by reducing the input
coupling capacitor. More complicated for 2nd order high pass and
not much more complicated for 3rd order high pass as all you do
is reduce the input coupling capacitor over 2nd order.

rgds, sreten.

 

[tinitus]

and btw, I only need one channel(mono)

wonder if other part of the chip could do the highpass ?

 

[tinitus]

Hi,

Very easy to arrange for 1st order high pass by reducing the input
coupling capacitor.

unfortunately not enough for a compression driver

 

[andrewlebon]

http://discovercircuits.com/PDF-FILES/hipass.pdf

 

[sreten]

Hi,

Assuming a standard chip amplifier the gain at the inverting input is one.

For noise reasons the feedback resistors should be fairly low impedance.

You can take any unity gain active high pass filter circuit, 2nd or 3rd order
and use it, only changing the circuits connection from the op-amps output
to the amplifiers inverting input, to get any 2nd or 3rd order filter function.

rgds, sreten.

 

[tinitus]

ok
if I understand you correctly it is possible to convert one half a of chip amp into active xo, if connected inverting/unity gain

 

[tinitus]

ah, i see, it needs at least a double chip like the LM4780
but wasting a complete poweramp to have just 12db high pass
might not make much sense
other than having a few less components, and connections

 

[tinitus]

ok, sounds like I would need not only unity gain, but a unity gain stable chip, for the highpass filter part
means either a pure buffer chip, or a low gain one, configured as buffer, right ?

 

[tinitus]

maybe with Baxandall feedback

 

[tinitus]

hmm, LM1875 seems to be hot

would it be ok with the Baxandall neg feed back tone control ?

 

[sreten]

Hi,

Any active filter circuit designed for unity gain can be used with a amplifier
with gain by moving the unity gain point from the output to the inverting
input, the only caveat being the inverting input should be low impedance,
and it will be if you optimised the power amplifier for low noise.

I don't see what baxandall has to do with it. You can still incorporate
tone shaping in the gain feedback network without changing any of
the details of of the high pass network.

rgds, sreten.

 

[tinitus]

in this direction ?

just a fast sloppy drawing

not sure about the single supply, but whatevr

 

[tinitus]

found another one
though a bandpass, its for use with non unity gain amp

maybe it would for high pass

hmm, bandpass means small amount of gain, I suppose
well I see the issue/trouble of both having gain and trying to filter at the same time, I guess

 

[tinitus]

hmm, 2sk170 might just survive the 24V, and I have some

 

[tinitus]

 

[abraxalito]

Looks like a fairly sure-fire way to get a chipamp to oscillate - fix it up with 100% feedback.

To build a highpass in the Sallen-Key style you do need to ensure the chipamp's noise gain remains in the stable region - i.e. >26dB typically.

 

[Kjeldsen]

You can get small class d chips ranging from 3 to 25 watt with build in DSP (eq, crossover, limiter etc.).

D2audio, conexant, Texas Instruments and Infinion make such chips.

 

[tinitus]

Looks like a fairly sure-fire way ......

ok, I forgot a few components around the power chip
better now ?

 

[abraxalito]

How about something like this - component values not totally optimized but you might get the general idea.