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hello / sub oscillator

hello / sub oscillator

2008-04-12 by Bauke van der Wal

first of all, hello from the netherlands. i'm recently new to the
list and this is the first message i write. i've started building
modules a few months ago as a next step to my childhood love of
smelling the fumes ;-)

and somehow i hope to make a nice big droning system ...

i'm working on the sub oscillator at this moment (Rev2) and i have a
small question. i have plenty of 25K pots from an old mixer here and
i want to use them as replacement for the 50K's. question is (quite
simple i guess) how the 47K and the 22K resistors around the mixer
(first part of the 358) should be changed to keep the amplification
rate. should i just 'halve' them (approx. 25K for the 47's and 13K
for the 22 ?)

greetings and many thanks in advance,
bauke

--
http://www.darkambient.net

Re: hello / sub oscillator

2008-04-12 by sasami@hotkey.net.au

On the REV2, there are no changes that need to be made to use different
value pots.

Ken
Show quoted textHide quoted text
>i'm working on the sub oscillator at this moment (Rev2) and i have a
>small question. i have plenty of 25K pots from an old mixer here and
>i want to use them as replacement for the 50K's. question is (quite
>simple i guess) how the 47K and the 22K resistors around the mixer
>(first part of the 358) should be changed to keep the amplification
>rate. should i just 'halve' them (approx. 25K for the 47's and 13K
>for the 22 ?)
_______________________________________________________________________
Ken Stone sasami@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

sub oscillator low volume

2009-02-14 by casperelectronics

just built the sub osc. great module. there seems to be something
like a 50+% volume drop from pre to post sub osc. Am I missing
something?
why is this? it looks like the first amp stage increases the volume
of each input considerably.. . . should I just change the value the
last 47K resistor in the final inverting amp to amplify the signal?
Thanks!!!!!!
-pete

Re: sub oscillator low volume

2009-02-14 by otherunicorn@gmail.com

You would be better increasing the 22k on the previous stage to 47k to add
more gain. Don't forget that when you mix a lot of signals together, the
output will clip as the sum of the signals will now be greater than the
available voltage.
Show quoted textHide quoted text
>just built the sub osc. great module. there seems to be something
>like a 50+% volume drop from pre to post sub osc. Am I missing
>something?
>why is this? it looks like the first amp stage increases the volume
>of each input considerably.. . . should I just change the value the
>last 47K resistor in the final inverting amp to amplify the signal?
>Thanks!!!!!!
>-pete
>
>
>
>
>
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> <p>just built the sub osc. great module. there seems to be
something <br>
>like a 50+% volume drop from pre to post sub osc. Am I missing <br>
>something?<br>
>why is this? it looks like the first amp stage increases the volume <br>
>of each input considerably.<wbr>. . . should I just change the value the <br>
>last 47K resistor in the final inverting amp to amplify the signal?<br>
>Thanks!!!!!!<br>
>-pete<br>
><br>
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_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

Re: sub oscillator low volume

2009-02-15 by casperelectronics

thanks for the response. I don't think it's a matter of clipping.
I'm sending a 4 volt saw wave to sub osc. channel A. I have 1, /2, /
4, & /8, turned all the way up and I'm getting an output of .25 volts.
It has the same ratio on channel B as well.
I've switched out the op amps with no change.
-pete
Show quoted textHide quoted text
On Feb 14, 2009, at 5:21 PM, otherunicorn@... wrote:

> You would be better increasing the 22k on the previous stage to 47k
> to add
> more gain. Don't forget that when you mix a lot of signals
> together, the
> output will clip as the sum of the signals will now be greater than
> the
> available voltage.
>
> >just built the sub osc. great module. there seems to be something
> >like a 50+% volume drop from pre to post sub osc. Am I missing
> >something?
> >why is this? it looks like the first amp stage increases the volume
> >of each input considerably.. . . should I just change the value the
> >last 47K resistor in the final inverting amp to amplify the signal?
> >Thanks!!!!!!
> >-pete
> >
> >
> >
> >
> >
> ><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
> "http://www.w3.org/TR/html4/strict.dtd">
> ><html>
> ><head>
> ></head>
> >
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> >
> >
> ><body style="background-color: #ffffff;">
> >
> ><!--~-|**|PrettyHtmlStartT|**|-~-->
> ><div id="ygrp-mlmsg" style="width:655px; position:relative;">
> ><div id="ygrp-msg" style="width: 470px; margin:0; padding:0 25px 0 0;
> float:left; z-index:1;">
> ><!--~-|**|PrettyHtmlEndT|**|-~-->
> >
> > <div id="ygrp-text">
> > <p>just built the sub osc. great module. there seems to be
> something <br>
> >like a 50+% volume drop from pre to post sub osc. Am I missing <br>
> >something?<br>
> >why is this? it looks like the first amp stage increases the
> volume <br>
> >of each input considerably.<wbr>. . . should I just change the
> value the <br>
> >last 47K resistor in the final inverting amp to amplify the signal?
> <br>
> >Thanks!!!!!!<br>
> >-pete<br>
> ><br>
> ></p>
> >
> >
> > </div>
> >
> > <!--~-|**|PrettyHtmlStart|**|-~-->
> > <div width="1" style="color: white; clear: both;"></div>
> > <!--~-|**|PrettyHtmlEnd|**|-~-->
> > </body>
> > <!--~-|**|PrettyHtmlStart|**|-~-->
> > <head>
> ><style type="text/css">
> ><!--
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> > border: 1px solid #d8d8d8;
> > font-family: Arial;
> > margin: 14px 0px;
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> > font-weight: bold;
> > line-height: 122%;
> > margin: 10px 0px;
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> > </style>
> > </head>
> > <!--~-|**|PrettyHtmlEnd|**|-~-->
> > </html><!--End group email -->
> >
> >
> __________________________________________________________
> Ken Stone sasami@... otherunicorn@...
> Modular Synth PCBs for sale <http://www.cgs.synth.net/>
> Australian Miniature Horses & Ponies <http://www.blaze.net.au/
> ~sasami/>
>
>
>



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