<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Word 14 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-GB" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Is there no way of creating a ‘top octave generator’ and pitch-bending the master clock?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Maybe a second TOG would allow for detune effects?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Synth-diy [mailto:synth-diy-bounces@dropmix.xs4all.nl]
<b>On Behalf Of </b>Thomas Burdick<br>
<b>Sent:</b> 30 December 2015 09:58<br>
<b>To:</b> mskala@ansuz.sooke.bc.ca; Gordonjcp<br>
<b>Cc:</b> synth-diy@dropmix.xs4all.nl<br>
<b>Subject:</b> Re: [sdiy] Controller design<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif"">The reason for using VCOs instead of fixed-frequency oscillators is flexibility. The layout of the instrument is usually as follows: 10 buttons control 4 sets of reeds. Each set is tuned
diatonically like a harmonica, with different notes on push and pull, and some overlap, as you guessed. The usual tuning is for two sets of reeds to be slightly detuned, another to be an octave down, and another an octave up; sometimes the same-ocatave pair
are tuned a third off from one another, and there are other tunings as well. The bellows pressure not only controls volume, but also bends notes (and alters the color of the tone). Finally, because it's a diatonic tuning, you can play in two or three keys
with a single instrument, but like a harmonica, you'll need one tuned to a different key to play anything else.<o:p></o:p></span></p>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif"">So, I'd like to reproduce the peculiarities of the traditional instrument (diatonic tuning, bent notes, bellows pressure affecting tone), but also to get more flexibility from the electronics
than you can from metal reeds. If I use a linear CV, I can change keys by adding an offset voltage to the CV. And VCOs would let me adjust the amount of detuning between the two primary sets of reeds with a simple control, rather than retuning 20 different
fixed oscillators.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif"">I'm pretty happy with the VCO I have at the moment, which produces two triangle outputs offset by an octave. This means I can get four voices on four sets of reeds with 8 reasonable VCOs,
which seems tenable. Especially compared to 80 fixed oscillators.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif""><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-family:"Calibri","sans-serif"">As for Gordon's question of why not use digital oscillators: that's a reasonable question. I'm comfortable with analog circuitry, and it's fun to work on. I'm
less comfortable with microcontrollers, but I'll consider digitally generating the triangle core. That might make everything a little
<o:p></o:p></span></p>
</div>
</div>
</div>
<br clear="both">
_____________________________________________________________________<BR>
The information contained in or attached to this email is intended only for the use of the individual or entity to which it is addressed. If you are not the intended recipient, or a person responsible for delivering it to the intended recipient, you are not authorised to and must not disclose, copy, distribute, or retain this message or any part of it. It may contain information which is confidential and/or covered by legal professional or other privilege (or other rules or laws with similar effect in jurisdictions outside England and Wales).<BR>
<BR>
The views expressed in this email are not necessarily the views of Centrica plc, and the company, its directors, officers or employees make no representation or accept any liability for its accuracy or completeness unless expressly stated to the contrary.<BR>
<BR>
PH Jones is a trading name of British Gas Social Housing Limited. British Gas Social Housing Limited (company no: 01026007), British Gas Trading Limited (company no: 03078711), British Gas Services Limited (company no: 3141243), British Gas Insurance Limited (company no: 06608316), British Gas New Heating Limited (company no: 06723244), British Gas Services (Commercial) Limited (company no: 07385984) and Centrica Energy (Trading) Limited (company no: 02877397) are all wholly owned subsidiaries of Centrica plc (company no: 3033654). Each company is registered in England and Wales with a registered office at Millstream, Maidenhead Road, Windsor, Berkshire SL4 5GD.<BR>
<BR>
British Gas Insurance Limited is authorised by the Prudential Regulation Authority and regulated by the Financial Conduct Authority and the Prudential Regulation Authority. British Gas Services Limited and Centrica Energy (Trading) Limited are authorised and regulated by the Financial Conduct Authority. British Gas Trading Limited is an appointed representative of British Gas Services Limited which is authorised and regulated by the Financial Conduct Authority.<BR>
</body>
</html>