[sdiy] Happenin' new opamp

[Michael E Caloroso]

For CV I've been using the LF351/LF353, better offsets than the '07x.

I wouldn't use a quad package for CV though.

MC

On 4/23/18, Rutger Vlek <rutgervlek at gmail.com> wrote:
> Interesting to hear what everyone's favourites are. I also selected the
> OPA1679 recently for new designs (audio), but still wondering which opamp
> to use (or keep using) with respect to CV/DC stuff. I'd like to improve
> upon the offset and drift I've seen with the TL074, and rail-to-rail would
> be awesome as I've seen situations where Eurorack audio-rate-CVs at high
> frequencies really suffer. Any other suggestions for a good
> price-quality-ratio part for CV paths?
>
> Rutger
>
> 2018-04-19 19:28 GMT+02:00 Oren Leavitt <obl64 at ix.netcom.com>:
>
>> Thanks for the info on OPA1678/9! I do still find myself using the LT1013
>> a lot for CV/DC stuff (where the slow slew rate isn't an issue).
>>
>>
>>
>> On 4/19/18 11:16 AM, Tim Ressel wrote:
>>
>>> I pretty much use just 2 amps now; the 1678/9 any time I need
>>> performance, and the TL082/4 for generic stuff. My new filter module is
>>> a
>>> good example: 1678 for the audio processing and a TL082 for CV
>>> processing.
>>>
>>> In a way it feels funny to reduce the huge universe of op amps down to 2
>>> parts. I know there are many applications where other amps are better.
>>> High
>>> power, high voltage, high accuracy, high frequency, etc. But for what I
>>> tend to do these two pretty much cover it. Many thanks for the dudes who
>>> came up with it!
>>>
>>> --Tim (parts nerd) Ressel
>>>
>>>
>>> On 4/19/2018 8:15 AM, Steve Lenham wrote:
>>>
>>>> I too designed the 1678 into a new product after Tim's original post
>>>> drew it to my attention, and they work very nicely.
>>>>
>>>> The power of networking, eh - wonder if it will catch on?
>>>>
>>>> Cheers,
>>>>
>>>> Steve L.
>>>> Benden Sound Technology
>>>>
>>>>
>>>> On 19/04/2018 15:40, Matthias Herrmann wrote:
>>>>
>>>>> Nice.
>>>>> I use the OPA1678 as my new working horse for quite a while now.
>>>>>
>>>>>     *From: *Synth-diy <synth-diy-bounces at synth-diy.org
>>>>>     <mailto:synth-diy-bounces at synth-diy.org>> on behalf of Mattias
>>>>>     Rickardsson <mr at analogue.org <mailto:mr at analogue.org>>
>>>>>     *Date: *Thursday, 19 April 2018 at 14:16
>>>>>     *To: *Tim Ressel <timr at circuitabbey.com <mailto:
>>>>> timr at circuitabbey.com>>
>>>>>     *Cc: *Synth DIY <synth-diy at synth-diy.org
>>>>>     <mailto:synth-diy at synth-diy.org>>
>>>>>     *Subject: *Re: [sdiy] Happenin' new opamp
>>>>>
>>>>>     I'm throwing in some news (for me at least) about the fairly new
>>>>>     OPA1678/79 low-noise rail-to-railFET-input op-amps that I was
>>>>> trying
>>>>>     as substitutes for the OPA1652/54, which has a price more than
>>>>> twice
>>>>>     as high. The specifications are remarkably similar, and by
>>>>> accident
>>>>>     I got in contact with TI's John Caldwell. He writes:
>>>>>
>>>>>     "I’ll let you in a on a little secret, the silicon is identical
>>>>>     between the two devices. OPA1652 was released by another engineer
>>>>>     before me, and when I took over the portfolio of audio op amps I
>>>>>     personally felt that OPA1652 was too expensive to address the bulk
>>>>>     of audio opportunities. For that reason, we made some changes to
>>>>> the
>>>>>     production testing (used new test hardware that let us test more
>>>>>     units faster) to reduce the manufacturing cost and re-released the
>>>>>     device at a lower price point.
>>>>>     Fun fact: the OPA1652 / OPA1678 has the lowest broadband voltage
>>>>>     noise of any FET-type input amplifier in TI’s portfolio. It even
>>>>> has
>>>>>     lower broadband voltage noise than the much more expensive
>>>>> OPA827."
>>>>>
>>>>>     I don't know if this was known before, but anyway great to have
>>>>> the
>>>>>     same brilliant chip for a fraction of the price... and isn't it a
>>>>>     great attitude about quality product sales? :-)
>>>>>
>>>>>     Regarding the inputs, which they don't mention being FET in the
>>>>>     OPA1678 datasheet:
>>>>>
>>>>>     "We received your feedback on the OPA1678 datasheet. With regards
>>>>> to
>>>>>     mentioning the input device type, the OPA1678 is fabricated on a
>>>>>     CMOS process, so yes the device type is indeed a FET (MOSFET).
>>>>> This
>>>>>     is also shown in the simplified diagram of the internal
>>>>> architecture
>>>>>     on the first page.
>>>>>     Calling it a “FET” input sometimes raises confusion between
>>>>> whether
>>>>>     or not the devices is JFET or CMOS and I wanted to avoid that when
>>>>> I
>>>>>     wrote the OPA1678 datasheet."
>>>>>
>>>>>     /mr
>>>>>
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