I realize that this may seem off topic, but since it is rare that anyone ever mentions the use of two pots in this manner, I just have to ask... Would this or could this pot arrangement be used as a coarse/fine sort of volume control. Not talking about the loudness thing, just as a volume control. I have been curious for quite some time about this.
Definitely 2.2uF. If 22uF the shelving action would be way too low in frequency.
Dave.
OnAudio,
Thank you for posting those schematics. Could you please explain how your 'Bloom and emphasis control' works? It's obvious to me to realize that R6 an R7 make up a 10K linear pot but which are the adjustment pots in the bloom and emphasis section? You have posted an interesting circuit and I would like to better understand it.
Thank you for posting those schematics. Could you please explain how your 'Bloom and emphasis control' works? It's obvious to me to realize that R6 an R7 make up a 10K linear pot but which are the adjustment pots in the bloom and emphasis section? You have posted an interesting circuit and I would like to better understand it.
This is how my preamp is set up. It uses Walt Jung's precision shelving controls. Low boost frequency @200 Hz, high boost frequency @2 kHz. This is cascaded with Rod Elliott's 36 dB/octave high pass filter tuned to 18 Hz.
This setup is the best I've ever heard by a long shot.
It's nothing earth shattering. It uses separate op amps for bass and treble. One control has no effect on the other, unlike conventional bass/treble controls. And the math is way simpler too; it's much easier to juggle the parameters and Jung explains exactly how to do that.
Use low noise precision film resistors. Use high quality, 5% film capacitors.
I've been using it since 1975. It's the best there is but only as good as the parts you use. It works excellent with OPA2134; 5532 has too much input bias current for bass control but it's fine for the treble control. You can scale down the pots and resistors too; the original circuit was designed to work with ancient devices like the CA3140.
Last edited:
Use these capacitors. https://www.mouser.com/ProductDetail/WIMA/MKP2F033301M00JSSD?qs=ISKKXg98%2B1mCc2/9XeTiAw==
Use these resistors. https://www.mouser.com/ProductDetail/Vishay-Dale/CMF50680R00FKEB?qs=qQSrJSM1sVe47NCIlYa4Bg==
You won't be sorry.
Use these resistors. https://www.mouser.com/ProductDetail/Vishay-Dale/CMF50680R00FKEB?qs=qQSrJSM1sVe47NCIlYa4Bg==
You won't be sorry.
There is a long thread about options for implementing the Cello Audio Palette on this forum. This was a product of the 80's and based on a prototype by Dick Burwen. Burwen's prototype had 4 peaking filters and two shelving ones, based on opamps. Lots of them. When Cello (in the shape of the late and very great Tom Colangelo) implemented the design, it had 6 peaking filters only, and used discrete buffers and opamps. Really focused on recording studios as a program equalizer, there was a significant high end audio market too.
https://www.diyaudio.com/community/...e-eq-design-was-high-end-tone-control.209644/
When the Audio Palette occasionally comes up for sale they seem to go for 10 grand plus. What units for the 10 grand? Doesn't matter - USD, UKP and Euro are so similar now.
On loudness control, this was a thing of the late '70s to mid '80s, largely but not uniquely in Japanese amps. It dropped of the audio perch around 35 years ago. There is a view that the loudness control was driven by marketers looking for product differentiation.
There is also the Quad-style Tilt control. That is a mild shelf pivoted around 800Hz, and appeared in the 44 and 34 preamps, and now after a long hiatus in their current Artera Pre. This is switched in decibel steps to a maximum/minimum of +/-3dB. There is an excellent detailed set of measurements of the 34, including the action of the filters including the tilt here https://www.kenrockwell.com/audio/quad/34-preamplifier.htm . It's effect is subtle, but can compensate for mild recording imbalance.
https://www.diyaudio.com/community/...e-eq-design-was-high-end-tone-control.209644/
When the Audio Palette occasionally comes up for sale they seem to go for 10 grand plus. What units for the 10 grand? Doesn't matter - USD, UKP and Euro are so similar now.
On loudness control, this was a thing of the late '70s to mid '80s, largely but not uniquely in Japanese amps. It dropped of the audio perch around 35 years ago. There is a view that the loudness control was driven by marketers looking for product differentiation.
There is also the Quad-style Tilt control. That is a mild shelf pivoted around 800Hz, and appeared in the 44 and 34 preamps, and now after a long hiatus in their current Artera Pre. This is switched in decibel steps to a maximum/minimum of +/-3dB. There is an excellent detailed set of measurements of the 34, including the action of the filters including the tilt here https://www.kenrockwell.com/audio/quad/34-preamplifier.htm . It's effect is subtle, but can compensate for mild recording imbalance.
Thanks Sawyers, they do have quite a collection there with different permutations, however most of the target curves are in the same ball park. Post https://www.diyaudio.com/community/threads/tone-and-loudness-controls.405853/post-7517764 here is probably what that thread was waiting for. The Cello has quite interesting filters with lower Q, The German filter is interesting too.