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Old 5th June 2010, 08:46 AM   #1
AuroraB is offline AuroraB  Norway
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Question Volume / Source selector - open source project ?

This forum contains a very large amount of projects, more or less ready to build or tweak, ranging from good to extremely good for the amplifier part. There is one system part that we all need, though, that is rarely presented in more than a half-finished way - the volume / source selector.

Quality pots and switches are slowly becoming extinct or economical unobtanium, as uP / remote control rules the commercial market. A good selector setup can be built with relays and common switches, but quality volume control is just another hurdle.

As for myself, I used to write programs for 8/16 bit uP using assembly and compiled BASIC , later some PASCAL, but never got around to learning C, as other work and tasks needed focus. Thus it will take me a looong time to build an write a stable control system. It seems that my situation is comparable to a lot of folks around here

OTOS - there's a few guys (gals?) around here that do master this "art", - Danzup seems to be one to mention, and there are a few others..
Maybe obvious by now, but what I'm looking for , is a sort of an open "group project" to develop a sort of "universal DIY-Audio" volume/selector system around a given set of parameters - say 5 to 8 inputs, 8 bit volume, and remote control, just for starters (!)........
The project should contain files for programming, PCB files etc, for anyone to copy and use. PCB group buys are of course also possible, but there will always be late comers and basement tinkerers.....

For reasons given above, my own contribution can only be in the area of ideas, surrounding circuitry, PCB etc....
Anyone interested?????

EDIT: Just another idea on the same foot - this project, along with e.g. various PSU designs could be part of a new sticky section - a sort of "ancillary" refrence designs...?????
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Old 5th June 2010, 10:08 AM   #2
danzup is offline danzup  Romania
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If this project will use Atmel Atmega I'm in for hardware and software design ( software in Bascom and source commented for easy modifying by diy-ers with a lot of support from me , if you want... ).
What type of volume method do you want to use ? I think this is the most important choice to be made .
As for 8 bits are more than enough, no matter what type of volume is choose .
About the other parts everything else can be adjust.....
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Old 5th June 2010, 10:48 AM   #3
AuroraB is offline AuroraB  Norway
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Hi Danzup - I sort of expected you to chime in...

Whether one uses Atmel or PIC, which to me seems the two most logical alternatives, doesn't really make a difference.......?
Both types have extensive support and free software, and can be programmed with very simple tools. Personally I prefer Atmel, but that's another story.

At the moment, I'm fiddling with a P1.7 clone, which uses an 8 bit output attenuator, but input or output attenuators mostly needs different resistor values.

I just started reading through your thread again, and I think you mostly have it covered already, although I do have to sort through which files belong to which version. There's quite a few of them already - and BTW - thanks for your open minded support.

Maybe we should give this a few days, just to see who else chimes in with ideas.

Somehow there should be some established commongrounds and limits. Otherwise there is the danger of endless permutations.....

How about max 7 inputs and 1 output ...= 1 port - or I2C....
8 bit volume - 1-2 lower bits can always just be left out...
LCD display
RC5 remote protocol....
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Old 7th June 2010, 08:27 AM   #4
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I'll watch this with interest, maybe add some input and definitely grab some ideas and suggestions.

I'm building a combined 2CH/HT with biamped mains, and triamped surrounds and would like to include the potential for 6 subs. All VC's will be on the outputs of 4 DCX2496's. It'll also have input selection and gain (mains only) and maybe a few other functions beyond the scope of what you guys are talking about, but I'm not trying to make mine a universal project, just suit what I need to do.

I got a big bunch of PGA2310's last week and have access to a Mikroe AMTEL development board at times until I get my own and I have the Bascom compiler. I've programmed in BASIC before but not for a few years so capability is rusty.

Whenever I mention this to others I get a 'wow, I'd like a 2CH + input selection version' response, but I'm not interested in designing PCBs or supporting it, so it would be nice to have something to refer them to.
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Old 17th June 2010, 09:04 AM   #5
maxw is offline maxw  United Kingdom
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This is a very good idea and something I thought was always lacking too. I thought Twisted Pear filled this gap very well with the Joshua Tree and Darwin but they have been out of stock for a long time and mainly focus on digital these days.

The main barrier for most DIY people I think is the PIC/software side of a good relay based input/volume controller. There are a few options available from DIY sites or Ebay but for me they are always lacking in some respect. They are not customizable and using PIC etc is not a very beginner friendly option....

So how about using an arduino for control? They are cheap, available everywhere, come in many shapes and sizes and are all very easy to write software for, even for a complete novice. With arduino it would also give flexibility to use switches, rotary encoders, pots, remotes and any displays too. Not to mention all the other off the shelf accessories you can get like bluetooth control, wifi etc.

If we had separate volume and input selector PCBs that are controlled via I2C one could use an arduino or anything that does I2C. One PCB for single ended or just double them up for balanced.
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Old 17th June 2010, 10:06 AM   #6
danzup is offline danzup  Romania
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Quote:
Originally Posted by maxw View Post
This is a very good idea and something I thought was always lacking too. I thought Twisted Pear filled this gap very well with the Joshua Tree and Darwin but they have been out of stock for a long time and mainly focus on digital these days.

The main barrier for most DIY people I think is the PIC/software side of a good relay based input/volume controller. There are a few options available from DIY sites or Ebay but for me they are always lacking in some respect. They are not customizable and using PIC etc is not a very beginner friendly option....

So how about using an arduino for control? They are cheap, available everywhere, come in many shapes and sizes and are all very easy to write software for, even for a complete novice. With arduino it would also give flexibility to use switches, rotary encoders, pots, remotes and any displays too. Not to mention all the other off the shelf accessories you can get like bluetooth control, wifi etc.

If we had separate volume and input selector PCBs that are controlled via I2C one could use an arduino or anything that does I2C. One PCB for single ended or just double them up for balanced.
Arduino is based on the same atmel AVR , but why to pay extra when you need only the atmel chip ?
The flexibility to interface to anything you want : switches, rotary encoders, pots, remotes and any displays too is in software and not in platform .
No problems about writing for arduino for me , but I do not pay a dime never for arduino : it is only an atmel AVR chip with a lot of pins ! Nothing else !
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Old 17th June 2010, 10:22 AM   #7
maxw is offline maxw  United Kingdom
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Originally Posted by danzup View Post
Arduino is based on the same atmel AVR , but why to pay extra when you need only the atmel chip ?
The flexibility to interface to anything you want : switches, rotary encoders, pots, remotes and any displays too is in software and not in platform .
No problems about writing for arduino for me , but I do not pay a dime never for arduino : it is only an atmel AVR chip with a lot of pins ! Nothing else !
I can totally understand your point, and I agree, but then what is the difference between this project and every other AVR controlled relay/input system that has been and gone? It will just be the same again with 50 or so PCB and then forgotten.

The way I see it, is that the reason why no volume/selector project has been very popular is that every wants something different in a preamp but very few have the skills (or motivation to learn) to code for their own requirements like displays, buttons, encoders, remotes etc.

If each module was I2C controlled then at least it opens up options for more beginner users which will get more interest, perhaps?

Quote:
Originally Posted by danzup View Post
I do not pay a dime never for arduino : it is only an atmel AVR chip with a lot of pins ! Nothing else !
Maybe to you, but for other people an arduino is a very easy platform to use, with lots of accessories and support via forums, thousands of code examples and a huge community

Last edited by maxw; 17th June 2010 at 10:25 AM.
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Old 17th June 2010, 10:33 AM   #8
danzup is offline danzup  Romania
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Quote:
Originally Posted by maxw View Post
I can totally understand your point, and I agree, but then what is the difference between this project and every other AVR controlled relay/input system that has been and gone? It will just be the same again with 50 or so PCB and then forgotten.

The way I see it, is that the reason why no volume/selector project has been very popular is that every wants something different in a preamp but very few have the skills (or motivation to learn) to code for their own requirements like displays, buttons, encoders, remotes etc.

If each module was I2C controlled then at least it opens up options for more beginner users which will get more interest, perhaps?
Of course it will be with i2c modules this project !
I have something like this on my desk :
Google Traducere

All I was saying was why to use arduino as a platform .
I am intended to help everyone ( how easy is ) to write modification in Bascom firmware
I will write for this project in a way as everyone to alter the firmware for his own needs .
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Old 17th June 2010, 10:39 AM   #9
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Hi there,
this is something that I am also looking for.
To start off we need to set basic characteristics.
I would like a controller board that can control:
  1. LCD Display
  2. 1-2 Relay boards for input and volume control.
    1 board if using single ended
    2 boards if balanced. Normaly these can be hook up parallel. One could use more boards for instance for multi channel control.
  3. Pass labs type attenuator 1dB steps wit 8 relays.
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Old 17th June 2010, 10:40 AM   #10
danzup is offline danzup  Romania
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For the beginning I will suggest something like in attached files .
The project was designed modularly so that:
- Who wants to make only volume controller plate and plate volume only.
- Who wants to make only source selection board controller and only source selection board.
- Who wants only the volume and selection make controller board and the two boards.
- Who wants to make all facilities will make one controller card and all cards.
Beauty lies in the fact that the draft boards volume / source selection / control bass / treble controls are universal wiring modules with the same chip PCF8574 only address each plate will be different.
Micro-controller at start scan his bus I2C and see which modules are present and will change on the fly to display and settings and facilities.
On the volume pcb can be used to a max of 8 relay , so everyone can test : r2r , shunt , decade , hybrid ladder or combination of that !
Only the routine with volume part must be altered according with what type of volume you implement
It is an idea of mine .
Waiting for your input !
Attached Images
File Type: jpeg module i2c.jpeg (28.8 KB, 751 views)
File Type: jpg Volume_R_2R_PCF8574P_.JPG (31.5 KB, 745 views)
File Type: png 30segw6.png (48.6 KB, 736 views)
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Last edited by danzup; 17th June 2010 at 10:45 AM.
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