Bruno Putzeys paper on Negative Feedback

Status
Not open for further replies.
Jump to Latest
#221
Multitones?, maybe for loudspeakers but not low THD electronics

please show a "bad multitone" of audio electronics

we have Scott's, PMA's soundcard multitones showing the indifferent stock op amps on those boards give no noise floor rise
 
#223
Jan,
With your wide network you probably know what it takes to make great audiophile gear better than most.
Opamps are from a different industry with quite different objectives and constraints (many more constraints) and know-how. So should we expect the same outcome?
That's why I think it depends on what we expect and what the mfr intends by "designed for audio".
 
#224
traderbam said:
Jan,
With your wide network you probably know what it takes to make great audiophile gear better than most.
Opamps are from a different industry with quite different objectives and constraints (many more constraints) and know-how. So should we expect the same outcome?
That's why I think it depends on what we expect and what the mfr intends by "designed for audio".
Click to expand...

You put too much trust in me😱

If a data sheet says designed for audio, it can mean two things:

1) it's a great opamp for a lot of purposes and audio is one; mentioning it may get some sales from audio people. This is generally the case with the big manu's. Maybe Scott can comment but I doiubt very much that ADI has opamps designed specifically for audio, although they have a lot that fit nicely in audio apps and say so in the dartasheet. After all, audio is just a low-key low BW subset of all possible apps 😉

2) the opamp is really designed for audio. This is for instance the case with THAT parts - specifically for audio apps and having some attributes to make it a better fit; like VCAs, absolute value circuits, etc..

The funny thing is that the parts in cat 1) often perform at least as good or better than those specifically designed for audio. Since manu lot sizes determine to a large extend the price, they often are also cheaper than the specific audio parts. Then again, the specific audio parts sell because it appeals to people's gut feelings.

Capitalism is quite interesting, don't you think? 😎

Jan
 
#226
jan.didden said:
The funny thing is that the parts in cat 1) often perform at least as good or better than those specifically designed for audio. Since manu lot sizes determine to a large extend the price, they often are also cheaper than the specific audio parts. Then again, the specific audio parts sell because it appeals to people's gut feelings.
Click to expand...

And have the infrastructure and expertise afforded by being a bigger company (and, in most cases, owning their analog fab) to simply out-design and out-fab "made for audio" parts, even in audio bandwidth. Not to say I don't admire THAT's efforts, much of which is pro-sound dedicated (for obvious reasons). IC's for fru-fru audio? You'd never make back the physical cost of the mask set (unless done with 5 µm design rules...).

In no way, shape, or form are we hurting for stupidly good analog IC's that work in our needed bandwidth (and then continue to have loop gain for a_long_while_past 😀).
 
#227
DPH said:
And have the infrastructure and expertise afforded by being a bigger company (and, in most cases, owning their analog fab) to simply out-design and out-fab "made for audio" parts, even in audio bandwidth. Not to say I don't admire THAT's efforts, much of which is pro-sound dedicated (for obvious reasons). IC's for fru-fru audio? You'd never make back the physical cost of the mask set (unless done with 5 µm design rules...).

In no way, shape, or form are we hurting for stupidly good analog IC's that work in our needed bandwidth (and then continue to have loop gain for a_long_while_past 😀).
Click to expand...

Exactly! If you are only looking at stuff that has the words 'designed for audio' in the datasheet, you are shortchanging yourself big time.

Jan
 
#228
I have had a look at Hypex' website and some N-Core datasheets. A really great product in terms of size and power dissipation. They appear to use a load of discrete parts so I suppose I should conclude that they do not have custom ICs but use a combination of standard op-amps and various components. I wonder what op-amps it uses in its signal paths?

It is one thing to use gobs of NFB over the audio range but you only get the theoretical benefit if the circuitry providing that gain is extremely good. This brings us back to just how good for audio these op-amps are and the other components in the signal path (or affecting the signal path)?

It also interests me that some of these modules use on-board SMPS. I have never used these for audio. I like their size and efficiency, no big transformers or caps. I immediately imagine HF noise both radiated and on the rails...has anyone got experience of SMPS for audio?
 
#231
traderbam said:
It is one thing to use gobs of NFB over the audio range but you only get the theoretical benefit if the circuitry providing that gain is extremely good.
Click to expand...
No. You get the benefits of NFB unless the circuitry providing the gain is extremely bad. That is why people use NFB: to improve something which is already not too bad. For some strange baffling reason, NFB works in practice in the way which theory says it does. This is even true in audio circuits, despite their requirements being allegedly far more onerous than defence, aerospace, healthcare, scientific research and instrumentation.
 
#235

Attachments

  • 17155245_1379745695417061_6506819204631033167_n.jpg
    17155245_1379745695417061_6506819204631033167_n.jpg
    84 KB · Views: 190
Status
Not open for further replies.
Top Bottom