What was your reasoning behind substituting Opamps? <br><br><div><p dir="ltr">Best,</p>
<p dir="ltr">Chris <br>
http://www.JuriedEngineering.com </p>
</div> <br> <blockquote style="margin: 0 0 20px 0;"> <header style="font-family:Roboto, sans-serif; color:#6D00F6;"> <div>On Tue, Mar 8, 2016 at 1:58 PM, Joe</div><div><joe.frey@radioles.com> wrote:</div> </header> <div style="padding: 10px 0 0 20px; margin: 10px 0 0 0; border-left: 1px solid #6D00F6;"> <div id="msgSandbox_AGx2w0MAAfcQVt8iaQK7OCuHnb4_TEXT" class="msgSandbox" style="padding: 1.5em 0.5em 0.5em 1.2em; word-wrap: break-word;">No, it's not a boring question. Though, my answer may be. I recently<br clear="none">made an XY joystick from a TRS-80 game controller and I thought it would<br clear="none">be clever to use one axis to throw the audio around. It kept to the<br clear="none">oddballness of my sound processing rig. So, despite good advice to make<br clear="none">something else instead, I made this because I only needed one input<br clear="none">signal and one control voltage. By the way, I substituted a TL074 and<br clear="none">made a harness for a LM13600. The noise did not decrease.<br clear="none"><br clear="none"><br clear="none"><br clear="none"><div class="yQTDBase yqt2754562946" id="yqtfd97877"><br clear="none"> On Tue, 2016-03-08 at 11:25 +0100, Mattias Rickardsson wrote:<br clear="none">> Sorry for the potentially most boring question, but why not build it<br clear="none">> out of two OTAs instead? Giving a more trustworthy construction,<br clear="none">> identical behaviour for the two channels, proper offness by design, a<br clear="none">> choice of better pan laws than the linear one, and much much lower<br clear="none">> noise if using LM13700/NE5517?<br clear="none">> <br clear="none">> Might even be done quicker than getting the old circuit working<br clear="none">> properly. O:-)<br clear="none">> <br clear="none">> /mr<br clear="none">> <br clear="none">> Den 8 mars 2016 3:28 fm skrev "Joe" <<a shape="rect" ymailto="mailto:joe.frey@radioles.com" href="javascript:return">joe.frey@radioles.com</a>>:<br clear="none">> Hello all, I hope I am not becoming tedious with this project.<br clear="none">> I have<br clear="none">> built a panning vca using a single ota and I am having<br clear="none">> problems with<br clear="none">> noise. The circuit does what it is supposed to do.<br clear="none">> <br clear="none">> <a shape="rect" href="http://www.sdiy.org/richardc64/mmvca/index.html" target="_blank">http://www.sdiy.org/richardc64/mmvca/index.html</a><br clear="none">> <br clear="none">> The power supply I am using is here<br clear="none">> <br clear="none">> <a shape="rect" href="http://www.generalguitargadgets.com/wp-content/uploads/ggg_bipolar_ps.pdf" target="_blank">http://www.generalguitargadgets.com/wp-content/uploads/ggg_bipolar_ps.pdf</a><br clear="none">> <br clear="none">> I did as Tom suggested here:<br clear="none">> <br clear="none">> 10u to 220u between V+ and 0V and between 0V and V- where<br clear="none">> power comes in<br clear="none">> (filter caps) - watch polarity, of course.<br clear="none">> 100n between V+ and 0V and between 0V and V- as close to the<br clear="none">> power pins<br clear="none">> of each IC.<br clear="none">> <br clear="none">> So I unclipped the test leads I used to to put these caps in<br clear="none">> my circuit.<br clear="none">> So theses caps are not in my circuit any longer.<br clear="none">> <br clear="none">> I heard no appreciable change in the noise so I unclipped the<br clear="none">> test leads<br clear="none">> I used to to put these caps in my circuit.<br clear="none">> And, then I created a little custom socket and replaced the<br clear="none">> CA3080 with<br clear="none">> a LM13600 and heard no real change. I went back to the CA3080.<br clear="none">> Now I<br clear="none">> have it all boxed up and I am getting a HUGE amount of radio<br clear="none">> in the<br clear="none">> circuit. I tried to Google rf filter for audio circuits but<br clear="none">> have found<br clear="none">> nothing applicable, just lots of dissertations.<br clear="none">> Do that caps that Tom suggested above stop RF? Thanks in<br clear="none">> advance.JoeF.<br clear="none">> <br clear="none">> <br clear="none">> <br clear="none">> <br clear="none">> <br clear="none">> <br clear="none">> <br clear="none">> On Mon, 2016-02-29 at 23:08 +0000, Tom Bugs wrote:<br clear="none">> > 10u to 220u between V+ and 0V and between 0V and V- where<br clear="none">> power comes in<br clear="none">> > (filter caps) - watch polarity, of course.<br clear="none">> > 100n between V+ and 0V and between 0V and V- as close to the<br clear="none">> power pins<br clear="none">> > of each IC.<br clear="none">> ><br clear="none">> > On 29/02/2016 22:03, Joe wrote:<br clear="none">> > > Tom, No. As I stated I am strictly monkey see, monkey do.<br clear="none">> Trying to<br clear="none">> > > change that. I am going to get a book, now. Ray Wilson's<br clear="none">> "Make: Analog<br clear="none">> > > Synthesizers" was recommended.<br clear="none">> > > Can you tell me what to add where? Thanks.<br clear="none">> > > Joe.<br clear="none">> > ><br clear="none">> > ><br clear="none">> > ><br clear="none">> > ><br clear="none">> > ><br clear="none">> > > On Mon, 2016-02-29 at 21:34 +0000, Tom Bugs wrote:<br clear="none">> > >> Question - do you have filter & bypass caps on the<br clear="none">> circuits? They're not<br clear="none">> > >> shown in the original schematic.<br clear="none">> > >><br clear="none">> > >><br clear="none">> > >> On 29/02/2016 17:06, Joe wrote:<br clear="none">> > >>> Hello and thanks. My power supply is the bipolar power<br clear="none">> supply circuit<br clear="none">> > >>> provided by General Guitar Gadgets found here<br clear="none">> > >>><br clear="none">> <a shape="rect" href="http://www.generalguitargadgets.com/wp-content/uploads/ggg_bipolar_ps.pdf" target="_blank">http://www.generalguitargadgets.com/wp-content/uploads/ggg_bipolar_ps.pdf</a><br clear="none">> > >>> I have used it before but for other circuits that<br clear="none">> generate cv. There<br clear="none">> > >>> never seemed to be noticeable downstream noise in the<br clear="none">> audio in those<br clear="none">> > >>> circuits. Those circuits were the EFM pv-1 and an<br clear="none">> envelope circuit Harry<br clear="none">> > >>> Bissell sent me, also EFM I bet. I used 3080s in those,<br clear="none">> too. I find the<br clear="none">> > >>> same noise where the ground is connected from the<br clear="none">> bipolar power supply<br clear="none">> > >>> board to the panning vca board, by the way.<br clear="none">> > >>> My audio probe is a 0.1uf cap on the tip of an audio<br clear="none">> cable with the<br clear="none">> > >>> audio cable shield connected to ground.<br clear="none">> > >>> So, before I try to use a LM13700, is there some<br clear="none">> procedure I can use to<br clear="none">> > >>> determine the noise source. Removing ICs and powering up<br clear="none">> or something<br clear="none">> > >>> like that?<br clear="none">> > >>><br clear="none">> > >>><br clear="none">> > >>><br clear="none">> > >>><br clear="none">> > >>><br clear="none">> > >>><br clear="none">> > >>><br clear="none">> > >>><br clear="none">> > >>> On Mon, 2016-02-29 at 15:06 +0100, Rutger Vlek wrote:<br clear="none">> > >>>> The CA3080 is known to be a bit noisy, but if you find<br clear="none">> it everywhere (even in the ground) I'd do a more fundamental<br clear="none">> check on your power supply and measurement setup.<br clear="none">> > >>>><br clear="none">> > >>>> How do you supply the board with power? How do you do<br clear="none">> the audio trace exactly? Just to be sure that the noise is<br clear="none">> actually in the board, not in the measurement method :).<br clear="none">> > >>>><br clear="none">> > >>>> Rutger<br clear="none">> > >>>><br clear="none">> > >>>><br clear="none">> > >>>><br clear="none">> > >>>> On 29 feb 2016, at 03:46, Joe wrote:<br clear="none">> > >>>><br clear="none">> > >>>>> Hello there, I built this panning VCA and I am happy<br clear="none">> with how it sounds<br clear="none">> > >>>>> except there is a lot of background noise. I tried to<br clear="none">> audio trace the<br clear="none">> > >>>>> noise but I find it everywhere, even in the ground<br clear="none">> plane. Is there some<br clear="none">> > >>>>> advice that someone can give me about how to isolate<br clear="none">> it. Thanks.<br clear="none">> > >>>>><br clear="none">> > >>>>> On Sat, 2016-01-23 at 12:58 -0500, Joe wrote:<br clear="none">> > >>>>>> Thanks to all! You guys are the awsomest ever! Joe.<br clear="none">> > >>>>>><br clear="none">> > >>>>>><br clear="none">> > >>>>>><br clear="none">> > >>>>>><br clear="none">> > >>>>>> On Fri, 2016-01-22 at 16:13 -0500, Joe wrote:<br clear="none">> > >>>>>>> I am planning on building this single as a panning<br clear="none">> VCA by Richard<br clear="none">> > >>>>>>> Curcio.<br clear="none">> > >>>>>>><br clear="none">> > >>>>>>> <a shape="rect" href="http://www.sdiy.org/richardc64/mmvca/index.html" target="_blank">http://www.sdiy.org/richardc64/mmvca/index.html</a><br clear="none">> > >>>>>>><br clear="none">> > >>>>>>> I can source a CA3080 and since I am only building<br clear="none">> one I am not worried<br clear="none">> > >>>>>>> about expense. Here's the thing, I don't know what<br clear="none">> pot values to use for<br clear="none">> > >>>>>>> the trimmers and I am definitely thrown by the<br clear="none">> current controlling DC<br clear="none">> > >>>>>>> trimmer, though I understand how to wire it. Can<br clear="none">> anyone take a minute(or<br clear="none">> > >>>>>>> few) to help me figure them out? Thanks, Joe.<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="javascript:return">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">> > >>>>>> _______________________________________________<br clear="none">> > >>>>>> Synth-diy mailing list<br clear="none">> > >>>>>> <a shape="rect" ymailto="mailto:Synth-diy@dropmix.xs4all.nl" href="javascript:return">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">> > >>>>> _______________________________________________<br clear="none">> > >>>>> Synth-diy mailing list<br clear="none">> > >>>>> <a shape="rect" ymailto="mailto:Synth-diy@dropmix.xs4all.nl" href="javascript:return">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">> > >>> _______________________________________________<br clear="none">> > >>> Synth-diy mailing list<br clear="none">> > >>> <a shape="rect" ymailto="mailto:Synth-diy@dropmix.xs4all.nl" href="javascript:return">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">> > >>><br clear="none">> > ><br clear="none">> > ><br clear="none">> ><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="javascript:return">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"><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="javascript:return">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></div> </div> </blockquote>