<html><head></head><body><div style="color:#000; background-color:#fff; font-family:verdana, helvetica, sans-serif;font-size:13px">Yes. Very good point, Richie.<br><div id="yui_3_16_0_1_1451658254564_83126"><span></span></div><div id="yui_3_16_0_1_1451658254564_83066"> </div><div id="yui_3_16_0_1_1451658254564_83069" class="signature"><div id="yui_3_16_0_1_1451658254564_83068"><font id="yui_3_16_0_1_1451658254564_83067" size="2">Sincerely, <br> </font></div><div id="yui_3_16_0_1_1451658254564_83112"><font id="yui_3_16_0_1_1451658254564_83111" size="2">Chris Juried <br>Audio Engineering Society (AES) <var id="yui-ie-cursor"></var>Member <br>InfoComm-Recognized AV Technologist</font><span id="yui_3_16_0_1_1451658254564_83115" class="postbody"><br><a rel="nofollow" target="_blank" href="http://www.juriedengineering.com/">http://www.JuriedEngineering.com</a> (Juried Engineering, LLC.)<br><a id="yui_3_16_0_1_1451658254564_83123" rel="nofollow" target="_blank" href="http://www.tubeequipment.com/">http://www.TubeEquipment.com</a> (Tube Equipment Corporation)<br><a id="yui_3_16_0_1_1451658254564_83114" rel="nofollow" target="_blank" href="http://www.historyofrecording.com/">http://www.HistoryOfRecording.com</a> (History of Recording)</span><a rel="nofollow" target="_blank" href="http://www.linkedin.com/in/chrisjuried"></a><font id="yui_3_16_0_1_1451658254564_83121" size="3"><font id="yui_3_16_0_1_1451658254564_83128" size="2"><br><br>This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any distribution or copying of this email, and any attachments thereto, is strictly prohibited. If you have received this email in error, please immediately notify me at (954) 478-4355 and permanently delete the original and any copy of any e-mail and any printout thereof.</font></font><br></div></div><br> <div class="qtdSeparateBR"><br><br></div><div style="display: block;" class="yahoo_quoted"> <div style="font-family: verdana, helvetica, sans-serif; font-size: 13px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div dir="ltr"> <font face="Arial" size="2"> <hr size="1"> <b><span style="font-weight:bold;">From:</span></b> Richie Burnett <rburnett@richieburnett.co.uk><br> <b><span style="font-weight: bold;">To:</span></b> Tom Wiltshire <tom@electricdruid.net> <br><b><span style="font-weight: bold;">Cc:</span></b> synth-diy@dropmix.xs4all.nl<br> <b><span style="font-weight: bold;">Sent:</span></b> Saturday, January 2, 2016 4:12 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [sdiy] VSM201 Vocorder Question<br> </font> </div> <div class="y_msg_container"><br>With carrier frequency of 50kHz, 0.01% duty ratio (for 80dB attenuation) represents a pulse width of just 2ns! That's getting near the sort of time mismatch you can get in turn-on and turn-off times for the switches. So the switch might not turn on at all, or might stay on twice as long!<br clear="none"><br clear="none">-Richie,<br clear="none"><br clear="none">Sent from my Xperia SP on O2<br clear="none"><div class="yqt4170598947" id="yqtfd02771"><br clear="none">---- Tom Wiltshire wrote ----<br clear="none"><br clear="none">>+1 totally agree<br clear="none">><br clear="none">>If you can produce a 1% pulse width, you still only get -40dB. You need to get a 0.01% pulse wave to get -80dB. Tough to do. Not impossible, but awkward enough to make it stop seeming like such a great solution.<br clear="none">><br clear="none">>I've thought about this a bit because of using the PIC's PWM module so much. The best case output from that is either 8-bit or 10-bit, which means that -60dB is about as good as I'd get using it for a VCA, and that implies having a switching frequency which is much too low (31KHz) for many jobs.<br clear="none">><br clear="none">>Tom<br clear="none">><br clear="none">><br clear="none">>On 2 Jan 2016, at 19:42, <a shape="rect" ymailto="mailto:rburnett@richieburnett.co.uk" href="mailto:rburnett@richieburnett.co.uk">rburnett@richieburnett.co.uk</a> wrote:<br clear="none">><br clear="none">>> <snip><br clear="none">>> Control range of PWM'd CMOS switches acting as VCAs isn't that great though.<br clear="none">>> <br clear="none">>> -Richie,<br clear="none">>> <br clear="none">><br clear="none">_______________________________________________<br clear="none">Synth-diy mailing list<br clear="none"><a shape="rect" ymailto="mailto:Synth-diy@dropmix.xs4all.nl" href="mailto:Synth-diy@dropmix.xs4all.nl">Synth-diy@dropmix.xs4all.nl</a><br clear="none"><a shape="rect" href="http://dropmix.xs4all.nl/mailman/listinfo/synth-diy" target="_blank">http://dropmix.xs4all.nl/mailman/listinfo/synth-diy</a><br clear="none"></div><br><br></div> </div> </div> </div></div></body></html>