VST equalizer demo.

[tor]

Im trying to put my first EQ together. All bands are 8 pole. I used Shifrin's RBJ modules and tweaked them to get a more silky sound and hopefully to minimize quantization errors.

So far it is a CPU consumer of dimensions. But I would be glad if some of you guys gave it a shot and tell me what you think of the sound of this baby. I am most of all concerned about how it affects the highest frequencies. Is it only my wish-thinking that like the sound up there or am I on to something here?

Do not mind the GUI

Please let me know what you think

[aliasant]

Im trying to put my first EQ together. All bands are 8 pole. I used Shifrin's RBJ modules and tweaked them to get a more silky sound and hopefully to minimize quantization errors.

So far it is a CPU consumer of dimensions. But I would be glad if some of you guys gave it a shot and tell me what you think of the sound of this baby. I am most of all concerned about how it affects the highest frequencies. Is it only my wish-thinking that like the sound up there or am I on to something here?

Do not mind the GUI

Please let me know what you think

That actually sounds very good!
Nice work

[tor]

Coming from you, I take that as a big compliment.

I guess I have to check if I really managed to reduce quantisation errors as well. And then there is optimization of the plug that is the biggest challenge for me.

Thank you!

[bootsy]

"8 pole"? Ain't this standard biquads?

If you are concerned with the sound in the top frequency range then you should avoid the curve warping near Nyquist frequency. Both, shelving and LP filter has this behaviour in your implementation.

peace,
bootsy

[tor]

If you serie connect 4 biquads you get a 8-pole right? Or have I misunderstood something? Would I call this something else than if I actually had a function with 8 poles?

That said... if it is a little warping i do not actually care. My concern is EQ how it sounds in the high frequencies and that it should be quite accurate due to the data showed in the GUI. My impression is that alot of EQs sound a bit harsh and metallic when pushed hard. Even on high quality program material. Probably a result of quantization errors. May be my try to workaround this issue create some minor warping. But I guess it is not that significant.

What do you use to measure the warping Bootsy? I can not see any in VSTpluginAnalyzer...
Do you find warping in the peak filters as well? If not that's strange.



Thank you for the feedback Bootsy

[bootsy]

If you serie connect 4 biquads you get a 8-pole right?

Yes but why 8-pole? You can get the same curves with just one biquad and the cascaded filter design won't give you a better phase nor a better impulse response - but correct me if I'm wrong of course.

What do you use to measure the warping Bootsy? I can not see any in VSTpluginAnalyzer...
Do you find warping in the peak filters as well? If not that's strange.

The VST Analyzer clearly shows the warping for both, LP and peak filters (measured at 44.1kHz). This is one of the major problems of digital EQs which are not oversampled.

[tor]

If you serie connect 4 biquads you get a 8-pole right?

Yes but why 8-pole? You can get the same curves with just one biquad and the cascaded filter design won't give you a better phase nor a better impulse response - but correct me if I'm wrong of course.

What do you use to measure the warping Bootsy? I can not see any in VSTpluginAnalyzer...
Do you find warping in the peak filters as well? If not that's strange.

The VST Analyzer clearly shows the warping for both, LP and peak filters (measured at 44.1kHz). This is one of the major problems of digital EQs which are not oversampled.

Why 8-pole:

Because it opens up for more creative tweaking due to sound and quant-errors.

VSTanalyzer:

Guess I have to zoom in some more. Actually never thought of that. Stupid me Thanks!

[tor]

I just deleted two posts... me crying over green trouble. I have sorted it out now. Kind of... not really sure what caused trouble but it is gone. Almost

[tor]

@ Bootsy: I really cant see the warping you refer to. What exactly do you do in VSTanalyzer?

I thought you meant ripple... sorry.

[tor]

I would love if someone could help me turn this two codes into an optimized asm. It is quite small codes. But in multiples it makes a huge difference I think. Credit will follow

Cheers and thanks in advance!
Tor

[Mo]

Hi Tor.

I gave it a quick look. Not much to optimize thought. Only a few unnecessary moves and floats removed.

Here it is:

[tor]

Thanks a lot Mo

Hello to you!
Don't think I have seen many post of you in here before. Nice to get feedback from new people (for me).

He he I have just uploaded a simple noise generator as well... want to give it a go while you're at it?

Again thanks.

[Mo]

I can't see much to optimize there too, but here you go:

Note the cvtps2dq opcode is way faster but make it only run on SSE2 machines (No pentium4/AMD equivalent or older).

[tor]

cvtps2dq opcode

he he.. thats like greek to me

But again.. thanks a bunch

ehm.. sorry but I have changed the noise gen a little. If you have more time....

Could you?

[Mo]

he he.. thats like greek to me

In the ASM code, i used cvtps2dq opcode to make the float to integer. This may be the fastest way to do it but will only work for newer processors. If you need it to be compatible with older hardware, you will need another way to convert the float or not use ASM for this.