Anderton VCF (Super Tone Control) Op-amp question

[snk]

Hello,
A couple years ago, I built an Anderton Super Tone Control, and I like it a lot (it is a multimode filter, with a dedicated output for LPF, BPF and HPF).
I recently used it on my electric piano, and it sounds amazing (much better than a regular eq, cleaning unwanted frequencies and giving a nice coloration). However, it's a bit noisy and I wish I could get a better signal to noise ratio.

My questions are the following (I am trying to understand if the noise comes from an already highly boosted output stage, or from poor opamp perforamnces):
1 - the BandPass volume is set to full, LPF and HPF set to minimum, and the global output volume is set to 3'o clock : with such settings, is it normal to get quite some noise? Am I amplifying the signal a lot?
2- As far as I remember (I built it 3 or 4 years ago), I am using TL072. Would a 5532 or a Burr-Brown opamp give me a cleaner signal?

[snk]

Ooops! I forgot the links to ressources 

Original circuit is on page 135 of this pdf: http://www.adjutojunior.com.br/eletronica_basica/ELECTRONIC_PROJECTS_FOR_MUSICIANS_by_Craig_Anderton.pdf

I have used this layout : https://tagboardeffects.blogspot.com/2012/09/anderton-super-tone-control.html
https://www.diystompboxes.com/smfforum/index.php?topic=96510.0

[Mark Hammer]

1) What is the output impedance and bandwidth of your keyboard?  Many processing circuits allow for MUCH greater bandwidth than their anticipated source provides.  For instance, there might be much greater treble bandwidth in the filter than your piano requires.  In which case a fixed 2-pole lowpass filter (e.g., rolloff at 14khz) at the input OR output could remover a lot of the hiss that serves no one.

2) I assume you're powering it with +/-9V?  Why not +/-12 or even 15V for a little more headroom? 

3) Is there proper buffering between the piano output and filter input?  And how noisy is the piano itself?

[antonis]

I'd try "pure" linear dual power supply..

[snk]

Thank you, Mark

1) What is the output impedance and bandwidth of your keyboard?  Many processing circuits allow for MUCH greater bandwidth than their anticipated source provides.  For instance, there might be much greater treble bandwidth in the filter than your piano requires.  In which case a fixed 2-pole lowpass filter (e.g., rolloff at 14khz) at the input OR output could remover a lot of the hiss that serves no one.

1/ I don't know the output impedance (it's a Hohner Pianet T, a passive electric piano somewhat like a Rhodes... or like an electric guitar), but I have several pedals between the piano and the filter (a tremolo, a compressor, sometimes a booster), so I don't think that in that case the piano impedance matters much?
1 bis / I should have talked about the noise timbre : it isn't a buzz or a hum, and it isn't just hiss either. It's just amplified broadband noise. So a low pass filter in front of it isn't a solution, because I can hear the noise in medium frequencies also.
1 ter / Also, the pedal is setup in Bandpass mode, with the frequency pot set around 900Hz-1kHz. So, it's already killing bass and treble.
1 quatro / I must add that if I bypass the Anderton SVF, the pedal chain is dead quiet : i can't hear noise coming from the combo piano + compressor + tremolo. It's only when I engage the filter that I can hear some noise. It's not hell on earth, and good enough for rehearsals, but I have recordings to do in a studio and I wish I could improve the signal to noise ratio (but I'd like to keep that Anderton VCF in the chain).

2) I assume you're powering it with +/-9V?  Why not +/-12 or even 15V for a little more headroom? 

2/ Yes, I am powering it with a +/-9V power supply. I haven't tried with higher voltage, because the symmetrical power supply is included in the circuit layout.
I don't hear any clipping (the signal is clean, without audible distortion), would higher voltage give less noise?

3) Is there proper buffering between the piano output and filter input?  And how noisy is the piano itself?

3/ the piano itself is dead quiet since I restored it (I have shielded the inside, and I am using cables with very good shelding).
I do not use a dedicated buffer, but I think that the other pedals in the chain feature a buffer. I will try adding a buffer (I have some). Can buffer lower the noisefloor? I thought it would "only" fix impedance issues (tone loss, etc)?

[snk]

I'd try "pure" linear dual power supply..

You mean instead of the chargepump?

[snk]

For what it's worth, it sounds like this :
https://whyp.it/tracks/181515/pianet-anderton-vcf-01?token=Qx4nf

0:00 to 0:04 = bypassed FX
0:04 to 0:11 = engaged FX
0:13 to 0:22 = piano playing, bypassed FX
0:23 to 0:34 = piano playing, engaged FX

[antonis]

You mean instead of the chargepump?

Yes.. ΄

(like an old bike  repairman used to say: "When you're sure something is going wrong with your carb, take a look at your distributor..)

[snk]

You mean instead of the chargepump?

Yes.. ΄

(like an old bike  repairman used to say: "When you're sure something is going wrong with your carb, take a look at your distributor..)

Your bike repairman was right : I tried the pedal with another power supply... and it is dead quiet 
(that's a bit strange, because the power supply i was using was really quiet and noiseless with every other pedal I have... until this one !)
So, problem fixed, thank you everyone for the help !

Also : lesson learned : chargepumps are prone to make circuits noisier, and are not always reliable. It's very handy and convenient, but sometimes you need something of higher quality and reliability.

[Mark Hammer]

First, thank you for your earlier post in response to mine.  Very thorough and informative. Much appreciated.

Second, glad you solved the issue.  Charge pumps are both a blessing and a curse.  They solve problems but introduce others.

Just out of curiosity, what value decoupling caps were you using between the charge pump and circuit?

[antonis]

Charge pumps are both a blessing and a curse.

Ceramic caps might be efficient exorcists for the later..
(combined with series resistors for Vin & Vout electros could make an effective banishment team..)

Also, op-amp general precautions, like Vcc & Vee series resistors and ceramic decoupling caps between Vcc & Vee (not to GND), should always be taken..

[snk]

First, thank you for your earlier post in response to mine.  Very thorough and informative. Much appreciated.

Thank you Mark for your kindness and all the knowledge yo share.

Just out of curiosity, what value decoupling caps were you using between the charge pump and circuit?

I haven't opened the enclosure for a while (and the circuit inside is wrapped), but as far as I remember, I used the values suggested in this layout : 100µF, 10µF, 47µF.