Good designs of Expo Converters? Was: [sdiy] Multiplexed Expo Converter?

[cheater cheater]

Wow, that's a lot of stuff! Thanks loads, Jerry. It'll keep me
occupied for a longer while.

Do you guys think that this could be beneficial for bigger modulars?
Just one EC driving multiple things...

Does the EC need to be close to the oscillator it's driving?

The other important question is: where do you get good oversampling
filters that would do a good job of reconstructing the S&H'd signal?

Cheers
D.

On Sat, Aug 1, 2009 at 8:53 PM, Jerry Gray-Eskue<jerryge at cableone.net> wrote:
>
> Here are some write ups on expo converters:
>
> http://www.mik-music.org/ExponentialConverter&bl=y#A_common_exponential_conv
> erter
>
> http://home.comcast.net/~ijfritz/sy_cir7.htm
>
> http://home.comcast.net/~ijfritz/sy_cir9.htm
>
> PAiA has a little different take on temperature compensation:
>
> http://paia.com/ProdArticles/9700faq.htm
>
> A good place to see various implementations are VCO schematics.
>
> - Jerry
>
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of cheater cheater
> Sent: Saturday, August 01, 2009 11:38 AM
> To: synth-diy
> Subject: Good designs of Expo Converters? Was: [sdiy] Multiplexed Expo
> Converter?
>
>
> Scott,
> thanks for your answer. I didn't know expo FM was inharmonic, I'll
> need to check that stuff out, it sounds really neat actually -
> inharmonicity is one thing you can use to make sounds much more
> interesting. On another note, PM is sort of like FM but not - it's
> very fun - check it out if you ever get a chance. Patch something
> across an accumulator cap or something (it would be more involved than
> that to get real Phase Modulation but might give you some form of
> foretaste)
>
> Guys, what are some good designs of Expo Converters?
>
> Cheers
> Damian
>
> On Fri, Jul 31, 2009 at 8:08 PM, Scott Nordlund<gsn10 at hotmail.com> wrote:
>>
>>> 1. FM
>>> I thought 'linear' audio rate FM was supposed to be much better. What
>>> can you guys tell me about expo vs linear fm? I have seen some VCOs
>>> with 'linear fm in', I guess that just bypasses the EC?
>>>
>>> Or is 'linear' audio rate FM better for the specific reason that
>>> removing the EC makes the system simpler and hence easier to make very
>>> good?
>>
>> Exponential FM is inharmonic, so it's generally less musically useful.
>>
>>> 2. PM
>>> Correct me if I'm wrong, but I think PM again doesn't need an EC, does
>>> it? Even if it's DC modulation...
>>
>> Analog phase modulation is used sometimes for radio signals, but I don't
> if or how it could be implemented for musical purposes (I can't think of any
> examples, phase shifters aside).
>>
>>> 3. AM/RM
>>> I don't think AM needs EC.. at all... correct me if I'm wrong, please.
>>
>> You could run the two input signals through exponential converters, sum
> them, then run that through a logarithm...
>>
>>
>>
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