[sdiy] Using both OTAs in 13700 as one OTA

[Mattias Rickardsson]

Aha!
It *was* a beautiful trick. :-)

http://electronotes.netfirms.com/AN399.pdf

/mr


On 8 February 2016 at 19:09, Ian Fritz <ijfritz at comcast.net> wrote:
> The reference to the original Jung article is JAES, 23, 1975. This method
> was widely used in EN projects. I looked at using this method with the
> LM13700 to aid people who want to build off of these projects, but who can't
> obtain the CA3080. It's also an easy way to improve S/N by 3dB, as pointed
> out by Serge T. in his EN article from when the chip was new.
>
> I couldn't wade through Aaron's article either.  It sounded like negating
> then subtracting?  Isn't that the same as adding?
>
> Ian
>
>
>
> On 2/8/2016 2:41 AM, Mattias Rickardsson wrote:
>>
>> On 4 February 2016 at 05:52,  <ijfritz at comcast.net> wrote:
>>>
>>> Good grief!  Just connect them directly in parallel.  An example,
>>> complete
>>> with the W. Jung trick:
>>>
>>> http://electro-music.com/forum/viewtopic.php?highlight=jung+ota&t=50884
>>
>>
>> What does it do? What is the "trick"?
>> I feel like one of the answers in that thread:
>> "I hadn't heard of this trick before, is there an article somewhere
>> that explains the benefit of drawing bias current from V-? I feel like
>> there's something obvious that I'm missing."
>>
>> I spontaneously found Aaron's idea potentially better than nothing,
>> but I haven't plunged into it.
>>
>> /mr
>>
>