Super Low Distortion Ultra Pure Audio Oscillators Revisited

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psupine
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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by psupine » Thu Jan 18, 2018 5:33 pm

Yes, yes, I hear your mocking tone. I have a whole family who can sing that song for me. :lol:

It's a journey innit. I'd rather build something and learn along the way rather than buy a magic box that does stuff that I can't fix when it breaks.

I admit that surface mount thing is an arbitrary choice. My usual through-hole palette is AD797, LME49720, OPA2134, OP07, NE5532 and TL072, depending on where it is in the circuit. They are not the newest and greatest, but those first three are still pretty good chips, and the last three are pretty cheap for what they do. I've certainly built surface mount designs when I did this kind of stuff for a living, but at home without the microscope and rework station I really can't be bothered with it. I guess that limits the ultimate performance, but I'm ok with that.

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mediatechnology
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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by mediatechnology » Thu Jan 18, 2018 5:54 pm

I think the ambitious part of building the Cordell Analyzer are obtaining and wiring the multipole switches.
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psupine
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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by psupine » Thu Jan 18, 2018 6:30 pm

Since I have to re-roll the PCB anyway, I was going to use Elektro Bauelemente PCB mount wafers for S2 and S4 and NSF open wafers for S1, S3 and S5. All the switch parts I need are available from RS Components, rather than trying to track down NOS rotary switches from 1980. I'm also going to use balanced output and input. I managed to find some through-hole packaged LM1496 demodulators, but this is really off thread now. So back on thread ...

I am exploring the Cordell State Variable Oscillator with LTSpice, substituting Linear opamps to match the 5534 and 318 main features of BW and SR. It behaves nicely at 65Hz 650Hz 6500Hz but at 65kHz with the JFET fully off, the oscillator blows up. I'm sure it works fine in reality, but I've previously found that if LTSpice doesn't like circuit it's because I've done something wrong. My next step I suppose is to try to import the correct opamp models and explore that.

Or maybe I should just breadboard it ...

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JR.
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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by JR. » Thu Jan 18, 2018 7:40 pm

psupine wrote:
Thu Jan 18, 2018 6:30 pm


Or maybe I should just breadboard it ...
Not a bad idea... I didn't have spice, and couldn't trust it at first.

sorry I am not mocking, just reflecting where I am in my journey (far down the long road.).

JR

Jacko
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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by Jacko » Wed Feb 27, 2019 10:50 pm

Image

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mediatechnology
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Re: Super Low Distortion Ultra Pure Audio Oscillators Revisited

Post by mediatechnology » Thu Feb 28, 2019 6:11 am

Nice circuit. I wasn't familiar with the VCA810.

http://www.ti.com/lit/ds/symlink/vca810.pdf

I'm curious if I can make one with a 2180 and conserve an op amp.
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New Zealand Police Interviewed Mosque Shooter Before Granting Gun License https://www.zerohedge.com/news/2019-03- ... un-license
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