tag:blogger.com,1999:blog-8559314700259794131.post6738418660698214794..comments2024-03-16T17:35:18.893+01:00Comments on Eddy Bergman.com: Synthesizer Build part-29: VCA (Yusynth design).Eddy Bergmanhttp://www.blogger.com/profile/13286799069112368259noreply@blogger.comBlogger60125tag:blogger.com,1999:blog-8559314700259794131.post-90474629335293593292022-04-10T14:52:28.120+02:002022-04-10T14:52:28.120+02:00The AC or DC choise only affects the audio input(s...The AC or DC choise only affects the audio input(s) of the VCA. The CV input is not affected by this because the only difference between the AC and DC version is that with the AC version you have the 10µF caps on the inputs, which block DC voltages. So AC is for audio only, DC is for CV voltages and will also let through audio. So your best bet it to take out the 10µF caps. But again, this should not influence the CV input. Eddy Bergmanhttps://www.blogger.com/profile/13286799069112368259noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-40019669852492006652022-04-10T14:42:38.601+02:002022-04-10T14:42:38.601+02:00Hi Eddy, i was wondering. I made the AC version of...Hi Eddy, i was wondering. I made the AC version of the yusynth VCA i guess it would explain the adsr won't affect the CV input of the VCA right ? Debidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-13260160102118577212022-04-09T10:37:44.595+02:002022-04-09T10:37:44.595+02:00Ohh LM13700 from AliExpress are mostly fakes my fr...Ohh LM13700 from AliExpress are mostly fakes my friend. You should order them from a reputable source. I made that mistake too. Never order chips from AliExpress. I'm glad you're getting the system working! :) My paypal me = https://paypal.me/ModularEddyEddy Bergmanhttps://www.blogger.com/profile/13286799069112368259noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-35491230238835281572022-04-09T10:09:07.131+02:002022-04-09T10:09:07.131+02:00my bad, i meant vco into control input of the VCA....my bad, i meant vco into control input of the VCA.. but still when i tried the calibration process from Yusynth, i could see the sine wave being amplified by the gain pot, once the adsr connected to the "control input" which is obvisouly the "adsr in" on your build, the gain had no effect. I found that i have not much luck with the main chips i add to deal with since i bought only a few amount of them from Ali (lm13700 and tl074).. some of them are just wrong. Anyway, i m really close to get the whole rack working properly. Have you got a paypal/me ?Debidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-17950524074090894432022-04-08T11:10:12.253+02:002022-04-08T11:10:12.253+02:00No leave the comments up for now. I'll delete ...No leave the comments up for now. I'll delete them if it's neccesary later. What I find strange is: you say VCO into ADSR. The VCO has no connection with the ADSR. The VCO is connected to the VCA and the VCA is opened up by the Envelope Voltage which in turn is generated from the Gate pulses from the sequencer. So that is the correct order.Eddy Bergmanhttps://www.blogger.com/profile/13286799069112368259noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-14818339255186544832022-04-08T10:22:11.422+02:002022-04-08T10:22:11.422+02:00Do you want me do delete comments referring to the...Do you want me do delete comments referring to the sequencer because it s not the tidiest thing i did regarding to the fact we are on the vca section ?Debidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-72917881008740532622022-04-08T10:20:08.913+02:002022-04-08T10:20:08.913+02:00This comment has been removed by the author.Debidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-20644461814642050562022-04-08T10:13:17.908+02:002022-04-08T10:13:17.908+02:00sorry i meant "i can hear the note going done...sorry i meant "i can hear the note going done slowly"Debidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-57000981745508018292022-04-08T10:12:21.423+02:002022-04-08T10:12:21.423+02:00Well it s far better now but i doubt my wiring is ...Well it s far better now but i doubt my wiring is correct, it looks like it's working better as following : adsr output into input 1 of the vca, and vco into the "control input" of the adsr.. i was doing the opposite. I still can't shortten the note with the release pot as i would like but i guess it's because of the square wave gate, it's like with release pot at minimum i can't hear the note shutting up slowly and then bouncing before the gate signal is on again... Debidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-49551735855648939342022-04-08T09:58:23.919+02:002022-04-08T09:58:23.919+02:00Ok cool.Ok cool.Eddy Bergmanhttps://www.blogger.com/profile/13286799069112368259noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-83852486186877305232022-04-08T09:47:37.980+02:002022-04-08T09:47:37.980+02:00Ok so i think i understood.. its problem of naming...Ok so i think i understood.. its problem of naming pot legs.. in my mind i thought the leg 3 is the third leg from left to right.. when i guess you was talking about the middle one. So i have a clean square wave coming out this leg ! i fix it and see how things go. CheersDebidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-379319264111965032022-04-08T09:38:28.006+02:002022-04-08T09:38:28.006+02:00yep looking at you 8 step sequencer content, i fou...yep looking at you 8 step sequencer content, i found : "The pulses are really clean looking 8 Volt squarewave pulses with a 50% duty cycle so if you use the gate output into the ADSR, it will sound as if a key is pressed every time the sequencer switches to an other note".. so the problem is coming from here i guess. Debidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-13813882943120809572022-04-08T09:35:15.747+02:002022-04-08T09:35:15.747+02:00Hello, yes sure i forgot to mention the 1V/oct of ...Hello, yes sure i forgot to mention the 1V/oct of the vco.. Unfortunatly, it doesn't go as it should, so i checked the signal coming out the gate jack from the sequencer and its a triangle form signal with -5vdc offset, may be the shape is not "radical" enough to make it look like a note played with a keyboard. Im digging but yes im enjoying it so far, i will find out. About keyboard for sure im going to buy a something like the swing from berhinger but im not sure if its clean of bugs right now. cheersDebidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-84297500979988347822022-04-07T20:29:54.498+02:002022-04-07T20:29:54.498+02:00Okay I see. Those are good clear tutorial videos. ...Okay I see. Those are good clear tutorial videos. In your last comment you say VCO output into VCA. That is correct but don't forget the CV output of the Sequencer must go into the 1V/Octave input of the VCO (or a CV input of the VCO) otherwise you won't hear any notes, only a single tone going on and off in the rythm of the Gate pulses from the sequencer. If you're really getting into building and playing it might be wise to get a Doepfer A-190-3 MIDI to CV converter and a Arturia Keystep keyboard so you can actually play notes but that costs a few hundred of course.<br />Eddy Bergmanhttps://www.blogger.com/profile/13286799069112368259noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-23026157998396944492022-04-07T19:36:35.969+02:002022-04-07T19:36:35.969+02:00Well i think its being really clear by watching th...Well i think its being really clear by watching this video https://www.youtube.com/watch?v=tiD3yNEkXgg. So tomorrow when i get back to school, i try this : gate output from sequencer into the gate in of the adsr, output of adsr into control input of the vca.. then vco ouput going to input of vca.. and see how it goes but i guess its how it works ! can't wait to make some noise. Debidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-7087219725003139492022-04-07T19:30:25.026+02:002022-04-07T19:30:25.026+02:00by the way i need to learn a bit more about the co...by the way i need to learn a bit more about the combo adsr vca because i heard the adsr alone wouldn't let me hear the effect of the release pot if i don't send the adsr output to the vca linked to a gate signal going also to the vca. Im refering to this video i watched quickly yesterday https://www.youtube.com/watch?v=amAmSGz7LUUDebidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-79095489653793958172022-04-07T19:26:56.074+02:002022-04-07T19:26:56.074+02:00Hi Eddy, unfortunalty i don't have keyboard, i...Hi Eddy, unfortunalty i don't have keyboard, i only send cv to the vco with the 8 step sequencer. i had the vca working as i guess its supposed to : for example i sent a sine wave into the "control input" and my vco into the input, i can see on the scope the amplitude of the vco waveform going up and down cause of the sine wave (sorry i refer to the yusynth version so its still a bit confusing to me what should be related the "adsr In" regarding to the yusynth circuit. First i thought i could use the adsr without vca, to shape note played by the sequencer but the release does not affect the lenght of the note played by the sequence, same for the attack.. i might have a bad DPDT and ill replace it tomorrow.. I can also try to use a push button to feed the adsr as a keyboard key would do and see if i can shape the enveloppe of the signal but from now i think im almost there so it's cool. Debidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-74001915733498127432022-04-07T09:53:08.548+02:002022-04-07T09:53:08.548+02:00Congratulations on getting it working! As for the ...Congratulations on getting it working! As for the VCA. If you can only get very attenuated sound out of it then maybe the VCA doesn't open up enough. That could be because the signal from the ADSR is too weak. So the fact that you only get a signal at the output if you put voltage on the CV input is correct. That's how it should work. The VCA only lets sound pass if you press a key on the keyboard. I explain that in the text. Good work on etching a print for it. That's always better.Eddy Bergmanhttps://www.blogger.com/profile/13286799069112368259noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-30716166985945952582022-04-07T09:44:41.712+02:002022-04-07T09:44:41.712+02:00I also didn't mention i etched this circuit wi...I also didn't mention i etched this circuit with yusynth layout. Debidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-20149659150454911632022-04-07T09:44:02.007+02:002022-04-07T09:44:02.007+02:00Hello Eddy, i can make sounds with my modules and ...Hello Eddy, i can make sounds with my modules and im really happy now. I still have to make the adsr and VCA work. I have pain understanding what's wrong with the vca because i tried lot of things (as replacing chips, check pots,)... if i check with the scope, should i see the signal moving at the balance trimpot wiper leg if i play with it ? because following yusynth calibration tutorial i only have a solid +12V... I also only have a signal at the output if i send something into the "control input".. but at the end the signal is really attenuated wich makes no sens for a vca.. Anyway im close to the end with my first modules set up. CheersDebidoobshttps://www.blogger.com/profile/17682166552646138610noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-74569297949696602082022-01-04T08:45:33.155+01:002022-01-04T08:45:33.155+01:00Hi Gabriel. For noise and audio sources you should...Hi Gabriel. For noise and audio sources you should use the AC input. The DC input is for CV signals.Eddy Bergmanhttps://www.blogger.com/profile/13286799069112368259noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-11279361265056801972022-01-04T03:19:16.855+01:002022-01-04T03:19:16.855+01:00hi! thank you for your help that you gave us.
Que...hi! thank you for your help that you gave us.<br /><br />Question 1: i've build three DC version of this design. When i insert a noise source (white noise), i can hear feedthrough (leakeage) even with the gain pot at cero position. So i need to lower the input attenuator to reduce this... <br /><br />This is normal? Do i need to change to the AC version?Gabrielhttps://www.blogger.com/profile/03428806295637506048noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-58902704157874065082021-10-03T11:30:48.170+02:002021-10-03T11:30:48.170+02:00Yes I've been guilty of obsessing over a wavef...Yes I've been guilty of obsessing over a waveform too. I learned that it's mostly the tops and bottom sides that produce the distinctive sounds. For instance (as an unrelated example) squarewaves; the wave goes up and at the top slopes down a bit and then goes down to the negative side of the wave. That wave will sound the same as a squarewave that is perfectly straight/horizontal at the top and bottom. Anyway, glad you got it going. It might even perform a little better once it's on a stripboard because breadboard contacts have some capacitance in them. Good luck with the build and contact me if you have more questions. Eddy Bergmanhttps://www.blogger.com/profile/13286799069112368259noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-56370515477427783042021-10-03T10:25:40.335+02:002021-10-03T10:25:40.335+02:00Many thanks Eddy, I did some more adjustments to A...Many thanks Eddy, I did some more adjustments to A1 (balance) to achieve the best shape possible. Thanks for the feedback - I think this might be a case of obsessing over an oscilloscope waveform rather than considering the real world. If it's normal for the VCA to 'colour the sound' a little then that's totally fine. Just needed to confirm I wasn't missing something. Thanks again for the great blog posts, they were extremely helpful. Now to get these off the breadboard and into modules!JamesPearsonhttps://www.blogger.com/profile/06952680963778740948noreply@blogger.comtag:blogger.com,1999:blog-8559314700259794131.post-35038659108425018602021-10-02T21:22:05.843+02:002021-10-02T21:22:05.843+02:00It's a common thing with this VCA that is does...It's a common thing with this VCA that is does do that to triangle waves a tiny bit but it's really not that big of a deal. I use this VCA as my main one and the sound is just fine. If you're using the AC output maybe try the DC output? I don't know. I find that in normal use it's not an issue and in my VCA the distortion of the triangle wave is only in so far that it has somewhat curved sides but the top and bottom is still sharp and pointy and therefore I can't hear an audible difference in mine. It's not the transistors in any case.Eddy Bergmanhttps://www.blogger.com/profile/13286799069112368259noreply@blogger.com