[sdiy] Discrete Op Amps

[David Moylan]

I agree with the BS comment.  I doubt the gain "per stage" is lower. 
With current source loading etc. gains per stage can be very high.  I 
think most off the shelf opamps would beat these discrete opamps in 
measured specs for what opamps are supposed to be.  The most obvious 
characteristic is massive open loop gain (which usually gets assumed to 
be infinite in the equations).

Where typical IC opamps may _potentially_ be inferior for audio is most 
likely in the type of distortion and the transition from clean to 
overdrive.  The discretes will probably have more baseline distortion. 
That alone might make listeners like them (dependent on the level).  I 
would expect they would have lower open loop gain, softer transition to 
overdrive, require less feedback for equivalent gain, etc.

The whole thing is very similar to the tube/transistor debate.  I think 
results would be very dependent on the circuit around the opamps and I 
don't think the claims should be taken at face value.  I'm a firm 
believer that the only valid tests are double blind listening tests.  Do 
you think you could tell the difference in the same circuit?

To me, if you don't like the massive gain plus feedback topology that 
opamps require why not just design discrete stages to provide gain/drive 
you need?


On 04/30/2017 01:06 PM, cheater00 cheater00 wrote:
> Every load of bullshit starts as truth that gets twisted and facsimiled.
> So let's pick out what might be true.
>
> He says that the single transistors in a monolithic IC op amp can
> dissipate much less, so their gain is lower, and therefore there must be
> many more stages. Can this be true?
>
> My guess is also that control (feedback) topology ends up being much
> more complicated, resulting in less pleasant edge cases (ie what happens
> when the op amp reaches an unusual or extreme state). Is feedback
> topology a large issue in op amps like it is in amplifier circuits? Does
> using more stages make this problem bigger?
>
>
> On Thu, 20 Apr 2017 20:47 Mike HEQX, <mike at heqx.com
> <mailto:mike at heqx.com>> wrote:
>
>     https://www.youtube.com/watch?v=nZqmbo9CGO0
>
>     And this is the other character that Orange has teamed up with to
>     market their products.
>
>
>     On 4/20/2017 11:32 AM, Justin Herrmann wrote:
>>     "Top notch, you know..."
>>
>>     That's all the convincing I need!
>>
>>     Seems legit.
>>     On 04/20/2017, 10:16 AM Quincas Moreira <quincas at gmail.com>
>>     <mailto:quincas at gmail.com> wrote:
>>
>>         oops, wrong link! i meant
>>         this https://www.youtube.com/watch?v=tKanR1aM16I
>>
>>         Sent from my iPad
>>
>>         On Apr 20, 2017, at 9:21 AM, Elain Klopke
>>         <functionofform at gmail.com <mailto:functionofform at gmail.com>>
>>         wrote:
>>
>>             So... Quincas... you're selling the Tsunami module for $43
>>             a pop? ;P
>>
>>             On Thu, Apr 20, 2017 at 9:07 AM, Quincas Moreira
>>             <quincas at gmail.com <mailto:quincas at gmail.com>> wrote:
>>
>>                 this showed up on youtube today... Orange amps guy
>>                 selling snakeoil for 43 bucks a pop...
>>                 https://youtu.be/wulg6GZj6oE
>>
>>                 Sent from my iPad
>>
>>                 On Apr 13, 2017, at 8:56 AM, Phillip Harbison
>>                 <alvitar at xavax.com <mailto:alvitar at xavax.com>> wrote:
>>
>>                     Quincas Moreira wrote:
>>
>>                         I like them, I cannot lie
>>
>>                         > There's a big BUT however:
>>
>>
>>                     I can't deny. ;)
>>
>>                     --
>>                     Phil Harbison
>>
>>
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