[sdiy] help getting VCO levels down to MN32XX BBD size

cheater cheater cheater00 at gmail.com
Wed Sep 16 20:15:26 CEST 2009 

Ah, but isn't the aliasing what we're looking for? ...

D.

On Tue, Sep 15, 2009 at 11:38 PM, Tom Wiltshire <tom at electricdruid.net> wrote:
> Dan,
>
> The MN3207 datasheet gives a distortion figure of 0.4% with (presumably
> typical) input level of 250mV, and gives an input signal swing of 360mV.
> This is roughly a quarter or a third of a volt, which means that something
> is fishy somewhere. You're sticking in +/-10V, which is a 20V range, so a
> reduction of 60-80 to 1 ought to do it.
>
> Did you just stick the attenuator in front of the input amp? That's got some
> gain, and would account for the discrepancy.
>
> I'd think that cutting the level down with an active op-amp stage would be
> preferable, since you could put some capacitors in it and make it into an
> active filter to help trim the high frequencies going into the delay line
> (an anti-aliasing filter).
>
> HTH,
> T.
>
> On 13 Sep 2009, at 06:20, Dan Snazelle wrote:
>
>>
>>
>> well
>>
>> after looking at ken stones circuits and a few others and trying them
>> unsuccessfully, I decided i had only myself to blame.
>>
>> kens circuit is great and
>>
>> normally a 20 to 1 reduction would be great and works fine for interfacing
>> stompboxes.
>>
>> but i am trying to interface with specific chip.
>>
>> SO i thought about it and tried changing the ratio to something radical.
>>
>> i found that i needed a 200 to 1 reduction!!
>>
>> all is well now
>>
>> thanks so much
>>
>>
>>
>> --------------------------------------------
>> check out various dan music at:
>>
>> http://www.myspace.com/lossnyc
>>
>> (updated monthly)
>>
>> http://www.soundclick.com/lossnyc.htm
>>
>>
>>
>> http://www.indie911.com/dan-snazelle
>>
>> (or for techno) http://www.myspace.com/snazelle
>>
>> ALSO check out Dan synth/Fx projects:
>>
>> AUDIO ARK:
>>
>> www.youtube.com/watch?v=TJRpvaOcUic
>>
>> www.youtube.com/watch?v=BqIa_lXQNTA&feature=channel_page
>>
>> www.youtube.com/watch?v=V4nJPjGgOcU&feature=channel_page
>>
>> and soundtrack/design work:
>>
>> NEW: check out Dan's sound design from the 1998 award winning film SAFARI
>> by catherine chalmers
>>
>> http://www.catherinechalmers.com/videos.cfm
>>
>>
>>
>>
>>
>>
>> ----------------------------------------
>>>
>>> Date: Sat, 12 Sep 2009 21:29:49 -0700
>>> From: dixon at interchange.ubc.ca
>>> Subject: RE: [sdiy] help getting VCO levels down to MN32XX BBD size
>>> To: subjectivity at hotmail.com; guitaricon at verizon.net;
>>> synth-diy at dropmix.xs4all.nl
>>>
>>> OK, Dan, I don't profess to understand this circuit (I haven't tried
>>> using
>>> BBDs or PLLs yet), but I think I can offer some advice about your finicky
>>> bias:
>>>
>>> Don't try to set a bias by putting a trimmer between two rails. Pretend
>>> you
>>> can get the exact voltage you want with a divider (i.e., two specific
>>> resistors), build that divider, and then put a small-value trimmer in
>>> between. Then the trimmer won't be too touchy.
>>>
>>> For example, if you need 5.2V and your rails are 9V and 0V, then you need
>>> two resistors in a ratio of 3.8/5.2. 22k/30k would work nicely. Then, put
>>> a 2k trimmer in between and take your bias from the tap. The trimmer will
>>> now have a range of 5V to 5.33V. If it's a multi-turn trimmer, then you
>>> should be able to find your magic bias point easily.
>>>
>>>
>>>> for further refrence you could look at the MN3207 zombie chorus
>>>>
>>>>
>>>> http://www.synthdiy.com/files/2007/zombie_chorus_mn3207_based.jpg
>>>> --------------------------------------------
>>>> check out various dan music at:
>>>>
>>>> http://www.myspace.com/lossnyc
>>>>
>>>> (updated monthly)
>>>>
>>>> http://www.soundclick.com/lossnyc.htm
>>>>
>>>>
>>>>
>>>> http://www.indie911.com/dan-snazelle
>>>>
>>>> (or for techno) http://www.myspace.com/snazelle
>>>>
>>>> ALSO check out Dan synth/Fx projects:
>>>>
>>>> AUDIO ARK:
>>>>
>>>> www.youtube.com/watch?v=TJRpvaOcUic
>>>>
>>>> www.youtube.com/watch?v=BqIa_lXQNTA&feature=channel_page
>>>>
>>>> www.youtube.com/watch?v=V4nJPjGgOcU&feature=channel_page
>>>>
>>>> and soundtrack/design work:
>>>>
>>>> NEW: check out Dan's sound design from the 1998 award winning film
>>>> SAFARI
>>>> by catherine chalmers
>>>>
>>>> http://www.catherinechalmers.com/videos.cfm
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ----------------------------------------
>>>>>
>>>>> Date: Sat, 12 Sep 2009 18:00:22 -0700
>>>>> From: dixon at interchange.ubc.ca
>>>>> Subject: RE: [sdiy] help getting VCO levels down to MN32XX BBD size
>>>>> To: subjectivity at hotmail.com; guitaricon at verizon.net; synth-
>>>>
>>>> diy at dropmix.xs4all.nl
>>>>>
>>>>> All Ken Stone's module does to the synth level output is attenuate it
>>>>> by
>>>>
>>>> a
>>>>>
>>>>> factor of 22 across a divider and send it to the effect, and then re-
>>>>
>>>> amplify
>>>>>
>>>>> the signal from the effect by the same factor in a non-inverting opamp
>>>>
>>>> and
>>>>>
>>>>> send it back into the synth. There are some ac coupling capacitors and
>>>>> a
>>>>> few other bells and whistles, but basically its pretty simple. I don't
>>>>
>>>> know
>>>>>
>>>>> why this wouldn't work for what you want to do.
>>>>>
>>>>> Also, I don't understand what you mean by "adding the proper bias".
>>>>> What
>>>>
>>>> is
>>>>>
>>>>> this bias, and why do you need to add it? Does the flanger output have
>>>>> a
>>>>
>>>> dc
>>>>>
>>>>> component (i.e., is it not centred about 0V)? Granted, I couldn't make
>>>>> heads or tails out of your "back o' the napkin" schematic, so there's
>>>>> probably something I'm missing.
>>>>>
>>>>>
>>>>>> not sure if that will work stock as that is for using LINE with an
>>>>
>>>> effects
>>>>>>
>>>>>> chain. (i think that is why there is a 1m to ground)
>>>>>>
>>>>>> that is not my intention.
>>>>>>
>>>>>> i want to solder this up as a module for my modular
>>>>>>
>>>>>>
>>>>>> also, I am interested in how I need to modify any filtering for a line
>>>>>> level.
>>>>>>
>>>>>> the main issues i have had so far with trying to use a simple neg gain
>>>>
>>>> and
>>>>>>
>>>>>> offset opamp is that unless I add the proper Bias, it does not seem to
>>>>>> work with the rest of the circuit.
>>>>>>
>>>>>> maybe I need to just keep trying things!
>>>>>>
>>>>>> thanks
>>>>>>
>>>>>>
>>>>>>
>>>>>> ----------------------------------------
>>>>>>>
>>>>>>> From: guitaricon at verizon.net
>>>>>>> To: synth-diy at dropmix.xs4all.nl
>>>>>>> Subject: Re: [sdiy] help getting VCO levels down to MN32XX BBD size
>>>>>>> Date: Sat, 12 Sep 2009 19:41:24 -0400
>>>>>>>
>>>>>>> Ken Stone's Stomp Box Adapter?
>>>>>>>
>>>>>>> http://www.cgs.synth.net/modules/cgs60_sba.html
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> ----- Original Message -----
>>>>>>> From: "Dan Snazelle"
>>>>>>> To:
>>>>>>> Sent: Saturday, September 12, 2009 7:19 PM
>>>>>>> Subject: [sdiy] help getting VCO levels down to MN32XX BBD size
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> i got a very basic flanger working
>>>>>>>>
>>>>>>>> http://electro-music.com/forum/phpbb-
>>>>>>
>>>>>> files/snazzy_simple_test_flanger_162.jpg
>>>>>>>>
>>>>>>>> however it only works with Guitar signals
>>>>>>>>
>>>>>>>> In order to get it to work with +/- 10 volts and +/- 5volt signals,
>>>>>>
>>>>>> what
>>>>>>>>
>>>>>>>> can I add to the front end??
>>>>>>>>
>>>>>>>> in most cases I would just level shift, etc But this signal needs to
>>>>
>>>> be
>>>>>>>>
>>>>>>>> TINY (lets say .50 volts peak to peak)
>>>>>>>>
>>>>>>>> so far I cant find anyone that does this without a compander.
>>>>>>>>
>>>>>>>> any ideas, schematics or links appreciated
>>>>>>>>
>>>>>>>>
>>>>>>>> thanks so much
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --------------------------------------------
>>>>>>>> check out various dan music at:
>>>>>>>>
>>>>>>>> http://www.myspace.com/lossnyc
>>>>>>>>
>>>>>>>> (updated monthly)
>>>>>>>>
>>>>>>>> http://www.soundclick.com/lossnyc.htm
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> http://www.indie911.com/dan-snazelle
>>>>>>>>
>>>>>>>> (or for techno) http://www.myspace.com/snazelle
>>>>>>>>
>>>>>>>> ALSO check out Dan synth/Fx projects:
>>>>>>>>
>>>>>>>> AUDIO ARK:
>>>>>>>>
>>>>>>>> www.youtube.com/watch?v=TJRpvaOcUic
>>>>>>>>
>>>>>>>> www.youtube.com/watch?v=BqIa_lXQNTA&feature=channel_page
>>>>>>>>
>>>>>>>> www.youtube.com/watch?v=V4nJPjGgOcU&feature=channel_page
>>>>>>>>
>>>>>>>> and soundtrack/design work:
>>>>>>>>
>>>>>>>> NEW: check out Dan's sound design from the 1998 award winning film
>>>>>>
>>>>>> SAFARI
>>>>>>>>
>>>>>>>> by catherine chalmers
>>>>>>>>
>>>>>>>> http://www.catherinechalmers.com/videos.cfm
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> Synth-diy mailing list
>>>>>>>> Synth-diy at dropmix.xs4all.nl
>>>>>>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Synth-diy mailing list
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>>>>>>
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>>>>>> Synth-diy mailing list
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>>>>>
>>>
>>
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>
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