MickMad

Re: Nyan 1073 EQ =^x^= (formerly Cheap's73 / Poor Man's 1073)
« Reply #60 on: February 18, 2020, 05:13:59 PM »
Hey there, great project! I was myself looking at gyrators and eq designs to make my own dream eq and I stumbled upon this, you did a nice job, especially so for being a "noob" in DIY electronics! Keep it up!

If I may, I'd suggest using a Teensy 3.2, it's much more powerful and faster than an Arduino Uno; it also has the possibility to change USB functionality (like USB MIDI) by just choosing an option in the IDE :) It may make your life easier!



Rocinante

Re: Nyan 1073 EQ =^x^= (formerly Cheap's73 / Poor Man's 1073)
« Reply #61 on: February 18, 2020, 07:34:12 PM »
I agree with using the teensy. You can still use arduino coding with it too.
If there's a harder way to do this, I haven't found it yet.

krabbencutter

Re: Nyan 1073 EQ =^x^= (formerly Cheap's73 / Poor Man's 1073)
« Reply #62 on: February 19, 2020, 04:41:56 AM »
Hey there, great project! I was myself looking at gyrators and eq designs to make my own dream eq and I stumbled upon this, you did a nice job, especially so for being a "noob" in DIY electronics! Keep it up!
Hey, thanks a lot :)

About the teensy: I know everybody loves them, but take a look at my current main:
Code: [Select]
void loop() {

  val1 = analogRead(analogPin1);
  val2 = analogRead(analogPin2);
  val3 = analogRead(analogPin3);

  Serial.println(val1);
  Serial.print(val2);
  Serial.print(val3);
 
  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
 
  display.println(val1);
  display.println(val2);
  display.println(val3);
 
  display.display();
 
  delay(1);
}

The arduino is mostly busy doing nothing and a teensy would just do 'more nothing' but for double the cost.
Although I'm having a couple small additions to the code in mind, it would still be just very basic stuff.
So from my current perspective, a cheap arduino nano clone is all that is needed.

However ... higher resolution ADCs could of course be a benefit but there's a catch:
although I'm using ALPS pots, there's still quite a bit of variance between the channels. So unless you know how to carefully measure & calibrate each potentiometer and input, a better ADC will just give you incorrect values at a higher resolution ;D
And remember, whatever you do, somebody will eventually come along and shout "use your ears!" anyway  :P

krabbencutter

Re: Nyan 1073 EQ =^x^= (formerly Cheap's73 / Poor Man's 1073)
« Reply #63 on: March 03, 2020, 05:30:31 PM »
Quick update:
- I've finally re-built my PSU and the voltage regulators are now inside the EQ case
- while reworking the power supply I've also put some more thought into the grounding layout. The output of the voltage regulator PCB is now the common point where Chassis/Signals/Power/Earth come together

'Unfortunately' this EQ is so quiet now, that I can't accurately measure THD+N with my audio interface anymore :P (Presonus Studio 26). THD+N is at minimum -75dB but if I increase the input signal even further, I'm ending up at the same -90dB as my audio interface.
« Last Edit: March 04, 2020, 02:31:55 AM by krabbencutter »

krabbencutter

Re: Nyan 1073 EQ =^x^= (formerly Cheap's73 / Poor Man's 1073)
« Reply #64 on: March 15, 2020, 11:28:34 AM »
Thing's are looking good  8)

The case is complete, although a bit sketchy. I might build a new one someday, but for now it's sturdy enough and sufficiently protects against any outside interference. The OLED display has been moved to the front, which taught me an important lesson about shielded cables ;D

Yesterday, I've updated the arduino sketch. Potentiometer readings are now smoothed and calibrated to compensate any 0dB offsets in my unit. Display readout is now in dB, the values however are just basic approximations.
Given that the advertised gain values of a real 1073 are all over the place anyway, I'm fine with that for the time being :P

Now that everything's in place I've also uploaded new measurement data. If you look at the mid band, you'll notice that all frequency settings are actually reaching full +/-18dB.
This is because each frequency setting has a trim-pot, which makes it possible to calibrate the maximum available gain for each band (and of course it would be just as easy to recreate the default behaviour).

Next up:
- I'm going to order some new knob caps
- If I ever re-build the case, I'll add the frequency selectors & the HPF switch to the arduino as well
- I'm thinking about doing a eurorack compatible 'light' version called tiny73 (single PCB, no HPF, 2 selectable frequencies for mid & low)


 

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