microcontrolled pre for a GC power amp

demogorgon · 26th November 2004, 06:14 PM

Hey guys!

I have a bit of a dilemma here.
I'v made the descition to have an active pre for my GC and need the input selector to be controlled my a micro controller.
this because the amps are my term-asignment and i have to include cerain things.

It would altso be preferable if i could get away with using transistors to controll the line-ins, relays are so damn expensive, and my budgette is already blown with aboute 70 euro.

If anyone has some tips, links or other thing i might find usefull i would be eternally gratefull!

regards
marius

demogorgon · 26th November 2004, 06:30 PM

[IMG]www.home.no/demogorgon/scetch.JPG[/IMG]

her is the atempt i made, thinking i was sooo clever, tehn all of a sudden it struck me as lightning from the sky, those things wont let AC through!

and here i am again, back to square zero, but it show the sort of layout i planed, and still hope to use thoug.

regards

edit: and again the picture does not appear, mystical..
well, clic in at www.home.no/demogorgon/ and you should come to a apache server index and there se a picture named scetch.JPG.

nuppe · 26th November 2004, 06:46 PM

Maybe an analog mux would work for input selection like a 4051 or 4351? I know they are not exactly Hifi but they are cheap and easy to use. An SSM2404 is higher quality but might be harder to find. For the microcontrol i can't give you any clues as i have no experience with this yet, but i can give you a couple of links:

Mark Hennessy's preamp and Devil_H@cks preamp

I got some great inspiration from these two sites for an integrated amp i'm planning, but haven't had the time to get started yet.

Edit: i saw your second post after i posted mine. I'm a complete dummy when it comes to analog transistor level stuff, but won't the transistors in your sketch need to be biased to pass AC?

Good luck with your project!

/Andreas

demogorgon · 26th November 2004, 07:10 PM

mux? would this be short for what at least i know as a multiplexer?

if it is i have thought of it, but i do have to use a microcontroller =<
(or something containing assembler code anyways :P)

nuppe · 26th November 2004, 07:35 PM

Yep, a multiplexer was what i was suggesting. You could still use a mux controlled by a microcontroller, it's a bit over the top, but it would work. Or do you need the microcontroller to control the inputs directly?

/Andreas

squadra · 26th November 2004, 10:05 PM

Quote:

Originally posted by demogorgon
[IMG]www.home.no/demogorgon/scetch.JPG[/IMG]
edit: and again the picture does not appear, mystical..
well, clic in at www.home.no/demogorgon/ and you should come to a apache server index and there se a picture named scetch.JPG.

To solve at least one of your mysteries...
you need to prefix the image with http:// otherwise your url will be appended to the current location ( http://www.diyaudio.com/forums/ )

Regards,

Pj

demogorgon · 26th November 2004, 10:09 PM

well, to have the microcontroller controlling the "gate medium" in lack of a better term, was the original plan, and would have saved me a lot of truble, but if that should prove to be an impossibillity, then i have to offcource consider other options.

I really dont know that mutch about multiplexers to judge if it is a actual choise or not, making this thing as easy as possible and having as few components in the signalpath as possible are high priorities.
the gainclone certainly sounds bad enough allready, so decreasing the sound quality further would ultimatly mean i would have to go solid state!

I'l have to google a litle on the subject and consider the pros and cons of the mux. But if it turns out that the mux is not suited for the task at hand, any other tips?

regards
marius

Squadra: Thanks! I'l keep that in mind the nexttime i post image links!

squadra · 26th November 2004, 10:25 PM

Quote:

Originally posted by demogorgon
Hey guys!
It would altso be preferable if i could get away with using transistors to controll the line-ins, relays are so damn expensive, and my budgette is already blown with aboute 70 euro.

regards
marius

There used to be an IC DG212 that contains 4 switches.
If you only require 2 inputs you can use the attached schedule.
Or you might create 4 inputs with 1 IC like that, so only 2 IC's for stereo.

Maybe that IC can still be found, it was pretty cheap.
Otherwise look for a replacement.
No transistors, but close enough, I hope

regards,

Peter

squadra · 26th November 2004, 10:28 PM

The IC is still available, and this is the datasheet:
http://pdfserv.maxim-ic.com/en/ds/DG202-DG212.pdf

demogorgon · 26th November 2004, 11:10 PM

well, I'l have a look at it then..

dont quite grasp how to controll them with a microcontroller yet, but i'v got all weekend.

regards
marius

26th November 2004, 06:14 PM	#1
demogorgon diyAudio Member Join Date: Jul 2004 Location: Behind you.	microcontrolled pre for a GC power amp Hey guys! I have a bit of a dilemma here. I'v made the descition to have an active pre for my GC and need the input selector to be controlled my a micro controller. this because the amps are my term-asignment and i have to include cerain things. It would altso be preferable if i could get away with using transistors to controll the line-ins, relays are so damn expensive, and my budgette is already blown with aboute 70 euro. If anyone has some tips, links or other thing i might find usefull i would be eternally gratefull! regards marius

26th November 2004, 10:28 PM	#9
squadra diyAudio Member Join Date: Dec 2003 Location: only in your mind.	The IC is still available, and this is the datasheet: http://pdfserv.maxim-ic.com/en/ds/DG202-DG212.pdf __________________ I'm ready to prove everything I have said, for I can find good witnesses.

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26th November 2004, 06:30 PM	#2
demogorgon diyAudio Member Join Date: Jul 2004 Location: Behind you.	[IMG]www.home.no/demogorgon/scetch.JPG[/IMG] her is the atempt i made, thinking i was sooo clever, tehn all of a sudden it struck me as lightning from the sky, those things wont let AC through! and here i am again, back to square zero, but it show the sort of layout i planed, and still hope to use thoug. regards edit: and again the picture does not appear, mystical.. well, clic in at www.home.no/demogorgon/ and you should come to a apache server index and there se a picture named scetch.JPG.

26th November 2004, 06:46 PM	#3
nuppe diyAudio Member Join Date: Aug 2003 Location: Gothenburg	Maybe an analog mux would work for input selection like a 4051 or 4351? I know they are not exactly Hifi but they are cheap and easy to use. An SSM2404 is higher quality but might be harder to find. For the microcontrol i can't give you any clues as i have no experience with this yet, but i can give you a couple of links: Mark Hennessy's preamp and Devil_H@cks preamp I got some great inspiration from these two sites for an integrated amp i'm planning, but haven't had the time to get started yet. Edit: i saw your second post after i posted mine. I'm a complete dummy when it comes to analog transistor level stuff, but won't the transistors in your sketch need to be biased to pass AC? Good luck with your project! /Andreas

26th November 2004, 07:10 PM	#4
demogorgon diyAudio Member Join Date: Jul 2004 Location: Behind you.	mux? would this be short for what at least i know as a multiplexer? if it is i have thought of it, but i do have to use a microcontroller =< (or something containing assembler code anyways :P)

26th November 2004, 07:35 PM	#5
nuppe diyAudio Member Join Date: Aug 2003 Location: Gothenburg	Yep, a multiplexer was what i was suggesting. You could still use a mux controlled by a microcontroller, it's a bit over the top, but it would work. Or do you need the microcontroller to control the inputs directly? /Andreas

26th November 2004, 10:09 PM	#7
demogorgon diyAudio Member Join Date: Jul 2004 Location: Behind you.	well, to have the microcontroller controlling the "gate medium" in lack of a better term, was the original plan, and would have saved me a lot of truble, but if that should prove to be an impossibillity, then i have to offcource consider other options. I really dont know that mutch about multiplexers to judge if it is a actual choise or not, making this thing as easy as possible and having as few components in the signalpath as possible are high priorities. the gainclone certainly sounds bad enough allready, so decreasing the sound quality further would ultimatly mean i would have to go solid state! I'l have to google a litle on the subject and consider the pros and cons of the mux. But if it turns out that the mux is not suited for the task at hand, any other tips? regards marius Squadra: Thanks! I'l keep that in mind the nexttime i post image links!

26th November 2004, 11:10 PM	#10
demogorgon diyAudio Member Join Date: Jul 2004 Location: Behind you.	well, I'l have a look at it then.. dont quite grasp how to controll them with a microcontroller yet, but i'v got all weekend. regards marius

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