(Another) Loudspeaker controller

[dirtyhanfri]

Hi, I`d like to give back to this forum a bit of what it gives to me, and I`m trying to build a monitor controller that could be useful for someone, also I`d like to get some feedback and advice from more experienced people, this is my first attempt to build something "new". Actually I`ve been looking around for a couple of weeks and found a lot of interesting ideas, but I try to keep it as simple as I can, unbalanced inputs (I`m restricted here by my inteface) and only a pair of balanced outputs by the moment.

I`ll use Rotatory switches for input, attenuation and out, DPDT for pad and mute. About the pad, I`ll try out various resistor values, any advice on this?. For the mute I`ve thinked in derivate signal to ground is it ok?. For input and output switches I`ve left one position unplgged between each for another way of mute and avoid clicks and pops, stupid? useful? The rotatory are shorting Alphas, should I use non-shorting?

I`m working also in a x-over circuit for a 2.1 system, but by the moment I`d like to be sure with my first steps.

So, this is the controller part schematic. I`d like to now what do you guys think about, maybe there are critical mistakes, please, point me in the right direction. I don`t know much about electronics (well I`m gonna start studying the Electronics and Design course this month). I`ve omitted the attenuator switch for lazyness... :-[

P.S. Dont be to hard with the messy schematic, second time I use Eagle ever.

Thanks

 

[dirtyhanfri]

Also, Is 10K ok for the attenuation switch?

 

[dirtyhanfri]

Well, I´m going on with this project

"Output A" will go to my main 2.1 system, so I have to split low freqs (below 100Hz) and Mid-High Freqs

The idea is split the signal for stereo and sub and then balance the stereo signal.

The schematic for the filters is easily found in the web, as calculators for cap and resistor values. I don´t post it because I found it in a guy´s web where he sold the pcb´s so I´m not sure about posting it.

I have some schematics for a x-over, with tl072´s, HPF and LPF, but I need 2 inputs per channel (one for lpf and one for hpf) Could I just wire it parallel? Will I have impedance problems?

I just realized it when I started drawing my pcb´s for self-etching...

Hi guys, and thanks for your time!

 

[dirtyhanfri]

I have some schematics for a x-over, with tl072´s, HPF and LPF, but I need 2 inputs per channel (one for lpf and one for hpf) Could I just wire it parallel? Will I have impedance problems?

Hi guys, and thanks for your time!

Could somebody help me with this please? I´m not sure about, and don´t know how to search about in the web and i´d like to start building this...

I think I`ve read something about a buffer before paralleling the signal, would this be ok?

I know the best way to know it is trying myself, but would be hard to etch my first pcbs, drill and populate them just for learn it doesn´t work propperly...

Thanks.

 

[erikb1971]

Hey Hanfri

I found that for questions on amplifiers an monitors you get a lot of goo feedback on www.diyaudio.com.

Good luck!

PS Iam going to be working on a similar project in a few months, so keep us posted!

 

[dirtyhanfri]

Great!, thanks for the link, let´s see what can I find in.

For sure i´d like to keep this posted, I think it could be useful/inspirational for some people

 

[fazer]

I like simple passive designs.  The only thing I was going to add is something mastering consoles have. 

Left Right Reverse can help you compare your mix balance.  Also a left only, Right only, mono,  monitor out.  These are great when your mixing. 

There are plug ins that can do this on the DAW master mix,  but I find the sound changes with the simple insertion of the plug in.  So I always get rid of it before the final mix.  I would rather have it on my monitor controller.  Just a couple of extra switches for an unbalance monitor out.

 

[ruffrecords]

Also, Is 10K ok for the attenuation switch?

Depends. 10K is fine as a load for your average pro gear. But with a 10K pot switch your output impedance can be as high as 2.5K (pot at -6dB). This has two main consequences.

1. If you feed this to a 10K input powered monitor you will lose nearly 2dB of level (pot divider of 2.5K and 10K).

2. You need to watch cable capacitance (and hence cable length) to ensure you do not lose high frequencies. Many cables have 300pF/metre capacitance and 300pF and 2.5K has a turnover frequency of just over 200KHz - doesn't sound too bad until you remember that phase starts shifting at a tenth that frequency i.e 20KHz. 5 metres of such cable with have an HF 3dB point of 42KHz and be 1dB down at 20KHz with significant phase shift. I advise using low capacitance cable.

Cheers

Ian

 

[dirtyhanfri]

Ruffrecords: I´ll use low capacintance cable, I´m not so worried about the cable lenght, it will be less than 2m, so I think I won´t have HF loose, anyway, thanks for the explanation, very instructive, great!

fazer: L-R Reverse ands single mute could be added to my design easily I think, just some dpdt switches, but, really, I´m not using these functions a lot, and when used I can insert a plugin in
Logic, wich (for my ears) is transparent, anyway, this seems to be a long term project so I´ll have time to think about it.

I´m stucked with the X-over, don´t know if just parallel the signal and then wire it to HPF and LPF or it will be bad.. some advice on this?

Thanks for your replies