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stilz
Joined: Jun 22, 2010
Posts: 13
Location: Germany Eschwege
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 Posted: Mon Jun 28, 2010 10:14 am Post subject:
Forgotten Questions in last Thread |
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Hi all, I just want to post the questions i have regarding the vca module from yusynth. As long as i would like to build up the ac version(for audio?!) here are some questions... If there are allready answered somewhere in the web please excuse me, because of my internet connection speed is very very low. And googling something isn't much fun. Please excuse my poor english.
Question 1: For audio i need to built the ac-version ? As long as audio is always an ac-signal?
Question 2: The best doc i ever seen (thank you yves!!!) isn't good enough for me to complete understand. So there are parts marked as needed for the
ac-version or the dc-version. Should i just leave the parts marked with "**" and use straps to complete the signal path?
Anyone create an pcb only for the ac-version(if I am right with question 1)?
Question 3: I would like to build up two more vco's to get a big sound. Would you build each vco with it's own ADSR+VCA module? Or just the 3 vcos with one vca and one adsr?
Very nice from you to answer!
bye stilz |
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yusynth
Joined: Nov 24, 2005
Posts: 1314
Location: France
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| Posted: Mon Jun 28, 2010 1:36 pm Post subject:
Re: Forgotten Questions in last Thread |
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| stilz wrote: |
Question 1: For audio i need to built the ac-version ? As long as audio is always an ac-signal? |
As long as this VCA will only be used for audio signals then go for the AC-version. However if you want to use this VCA for audio but also for handling voltage controls then go for the DC. As a matter of fact a lot of people (and myself) use only DC VCA because they can be used for any type of applications.
| stilz wrote: | Question 2: The best doc i ever seen (thank you yves!!!) isn't good enough for me to complete understand. So there are parts marked as needed for the
ac-version or the dc-version. Should i just leave the parts marked with "**" and use straps to complete the signal path?
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OK here is what is written on my VCA page
| Quote: | Two versions of this circuit can be built :
an AC version, in such a case C3 & C4 are required, P1, P2 and P3 must be log pots;
a DC version, C3 & C4 must be omitted (use straps), P1, P2 and P3 must be lin pots |
This means if you build the AC version all the components are required and must be soldered to the PCB. If you go for the DC version, the components labelled ** are not to be soldered to the PCB and only C3 and C4 must replaced by straps.
| stilz wrote: | Question 3: I would like to build up two more vco's to get a big sound. Would you build each vco with it's own ADSR+VCA module? Or just the 3 vcos with one vca and one adsr?
Very nice from you to answer!
bye stilz |
Don't you want to have a VCF too ? The classical case would be 3 VCOs, a mixer, a VCF, two ADSR and a VCA. But you may consider any kind of combination, that's a modular is all about !
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Yves |
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stilz
Joined: Jun 22, 2010
Posts: 13
Location: Germany Eschwege
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yusynth
Joined: Nov 24, 2005
Posts: 1314
Location: France
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| Posted: Tue Jun 29, 2010 1:17 am Post subject:
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In general the VCA comes after the the VCF, this way it acts also like a noise GATE in particular for high resonance of the VCF...
For the TEMPCO a SMD is alright , what is important is to make yourself sure that the model is in the range 3300ppm to 3500ppm.
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Yves |
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stilz
Joined: Jun 22, 2010
Posts: 13
Location: Germany Eschwege
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| Posted: Tue Jun 29, 2010 1:39 am Post subject:
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Oh...I bought this one:
"RESISTOR, TEMP SENSING 1K Typ:LT73 3000 1K0J TG"
with 3000 ppm as you mentioned in your description:
"1K tempco resistor (PTC 3000ppm)
TYCO ELEC. model LT300014T261K0J or LT300016T261K0J or equivalent at www.farnell.com"
Question 1: Does the value change from 3300(3500) ppm to 3000 because of the smaller dimension of the smd resistor? How can i measure that i get the right value? Shouldn't it provide me a wide range of thermal consitatns frequencies? In other words: The same cv should give me the same freuquencie intependent from how "hot" the circuit is?
Many thanks!
stilz |
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yusynth
Joined: Nov 24, 2005
Posts: 1314
Location: France
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| Posted: Tue Jun 29, 2010 2:10 am Post subject:
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No it's OK with a 3300ppm the correction is better than with 3000ppm but 3000ppm is working OK (that's what I am using).
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Yves |
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