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synthesist
Joined: Feb 17, 2011 Posts: 79 Location: austria
Audio files: 2
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Posted: Tue Feb 22, 2011 6:44 am Post subject:
Volume Buffer Subject description: my op amp is way too loud |
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Hey there!!
I've been watching this forum for a few weeks now and I really like it a lot.
I am glad that there is actually a real forum for cmos synths.
So, I've build a few modules and they all hang on a single 6 volt supply.
Some VCOs, LFOs, 4-Step Sequencer, a WSG- Filter, Atari Punk Console and a Cacophonator.
The main- problem is that the sound output of the cacophonator (Art Harrisson design) is very low. Also the output of the WSG- Filter. You can almost not hear it.
I made an op- amp circuit to raise the volume to line level using the LM 386. Of course it is way too loud now. The LM 386 I guess is made to drive speakers only.
Of course I can use some resistors to lower the volume now, but isn't this a waste of power? (Sorry but indeed I have no idea of electronics.)
And does it matter if I put the resistor after the amplifier or before the signal gets into the amplifier, to save some power?
Or does someone have a better idea how to buffer the volume to line level?
This is the shema of the amp
circuit:http://www.hobbielektronika.hu/forum/files/30/30b186a707557adee3a4c5300efdc80c.gif
(00)
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egasimus
Joined: Feb 11, 2011 Posts: 113 Location: Bulgaria
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richardc64
Joined: Jun 01, 2006 Posts: 679 Location: NYC
Audio files: 26
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Posted: Thu Feb 24, 2011 12:24 am Post subject:
Re: Volume Buffer Subject description: my op amp is way too loud |
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synthesist wrote: | Hey there!!
I made an op- amp circuit to raise the volume to line level using the LM 386. Of course it is way too loud now. The LM 386 I guess is made to drive speakers only.
Of course I can use some resistors to lower the volume now, but isn't this a waste of power? (Sorry but indeed I have no idea of electronics.)
And does it matter if I put the resistor after the amplifier or before the signal gets into the amplifier, to save some power?
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You're on the right track. Decreasing the signal level going in won't waste power: it will reduce the '386 power consumption.
Internally, the '386 input has a 50k resistor to ground. A resistor in series with the input will form a voltage divider with that, reducing the input level: 47k or 51k will cut it roughly in half. Increase or decrease as needed. _________________ Revenge is a dish best served with a fork... to the eye |
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