My new preamp design: Arduino, 6 input selector, MDAC attenuator, IR etc

maxw · 13th November 2016, 10:57 AM

I've made a new design where the MDAC attenuator, input selector and RCA board all sandwich together into a nice compact unit:

My last preamp project had only 3 inputs which was a little annoying so I designed a new one with 6 inputs and mute:

I've written the initial Arduino code for two rotary encoders, one for volume and one for input selection, infrared and start up mute. The code is here:
https://github.com/FutureSharks/preamp-two

For now I'm using an Arduino Pro Micro 5V but I think I'll switch to something more modern like a NodeMCU or something that uses an ESP32.

PCB layout files are here:
https://github.com/FutureSharks/prea...ee/master/PCBs

The power supplies I'm using are these two:
A simple LT1763 based 5V PSU
Compact DIY friendly dual TPS7A3301 power supply

maxw · 13th November 2016, 11:02 AM

Here it is in a temporary "enclosure" made from Makerbeam

maxw · 13th November 2016, 11:05 AM

And measurement taken with Arta

maxw · 13th November 2016, 11:10 AM

A couple questions:
1. Can anyone recommend a company for machining small quantity aluminium parts in Europe? I would like to get a front panel made from 20mm thick aluminium.
2. Has anyone used a bluetooth 4.0 / BLE remote with an Arduino?

thimios · 13th November 2016, 11:14 AM

Great job,i like it!

rainwalk · 13th November 2016, 02:08 PM

Hi Maxw,
it's also seemed great project! What type of the display for this amplifier?
Still neopixel?? I hope the LCD or FND!!

also more cheaper encoder is profer

ed.

maxw · 13th November 2016, 03:38 PM

Quote:

Originally Posted by rainwalk

Hi Maxw,
it's also seemed great project! What type of the display for this amplifier?
Still neopixel?? I hope the LCD or FND!!

also more cheaper encoder is profer

ed.

Thanks. For display I don't know yet. I think LCDs look cheap so not so keen on that idea.

You can definitely use cheap encoders! I don't know what problem you had in the other thread but I've used many cheap encoders before without issues. Sometimes they need some hardware of software debouncing but it's definitely possible

rainwalk · 13th November 2016, 03:42 PM

Quote:

Originally Posted by maxw

Thanks. For display I don't know yet. I think LCDs look cheap so not so keen on that idea.

You can definitely use cheap encoders! I don't know what problem you had in the other thread but I've used many cheap encoders before without issues. Sometimes they need some hardware of software debouncing but it's definitely possible

Okay. I'll try again and let you know.
Thanks!!

maxw · 13th November 2016, 03:47 PM

Quote:

Originally Posted by rainwalk

Okay. I'll try again and let you know.
Thanks!!

Try the code in this post here:
https://forum.sparkfun.com/viewtopic.php?t=13956#p65052

AlanElsdon · 22nd November 2016, 10:27 AM

Max,

Files downloaded, I will let you know how I get on.

Alan

13th November 2016, 10:57 AM	#1
maxw diyAudio Member Join Date: Jun 2004 Location: Berlin	My new preamp design: Arduino, 6 input selector, MDAC attenuator, IR etc I've made a new design where the MDAC attenuator, input selector and RCA board all sandwich together into a nice compact unit: My last preamp project had only 3 inputs which was a little annoying so I designed a new one with 6 inputs and mute: I've written the initial Arduino code for two rotary encoders, one for volume and one for input selection, infrared and start up mute. The code is here: https://github.com/FutureSharks/preamp-two For now I'm using an Arduino Pro Micro 5V but I think I'll switch to something more modern like a NodeMCU or something that uses an ESP32. PCB layout files are here: https://github.com/FutureSharks/prea...ee/master/PCBs The power supplies I'm using are these two: A simple LT1763 based 5V PSU Compact DIY friendly dual TPS7A3301 power supply

13th November 2016, 02:08 PM	#6
rainwalk diyAudio Member Join Date: Jun 2007	Hi Maxw, it's also seemed great project! What type of the display for this amplifier? Still neopixel?? I hope the LCD or FND!! also more cheaper encoder is profered.

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13th November 2016, 11:10 AM	#4
maxw diyAudio Member Join Date: Jun 2004 Location: Berlin	A couple questions: 1. Can anyone recommend a company for machining small quantity aluminium parts in Europe? I would like to get a front panel made from 20mm thick aluminium. 2. Has anyone used a bluetooth 4.0 / BLE remote with an Arduino?

13th November 2016, 11:14 AM	#5
thimios diyAudio Member Join Date: Aug 2009 Location: Agrinion	Great job,i like it!

22nd November 2016, 10:27 AM	#10
AlanElsdon diyAudio Member Join Date: Jun 2003 Location: Surrey/Hampshire borders	Max, Files downloaded, I will let you know how I get on. Alan