Which cap should be better for AD797 compensation or 'Distortion Cancellation and Bandwidth Enhancement'?
styroflex or glimmer?
I mean the cap for 'Distortion Cancellation and Bandwidth Enhancement' (page 15 of AD797 data sheet).
http://www.analog.com/media/en/technical-documentation/data-sheets/AD797.pdf
Styroflexkondensatoren bei reichelt elektronik
styroflex or glimmer?
I mean the cap for 'Distortion Cancellation and Bandwidth Enhancement' (page 15 of AD797 data sheet).
http://www.analog.com/media/en/technical-documentation/data-sheets/AD797.pdf
Styroflexkondensatoren bei reichelt elektronik
Reason - past years ago, I build an headphone amp from a kit - the WNA MKII and testet some OPAs - IC1
LM6171 (designed for), LME49710, AD843, AD847, LT1056, LT1022, OPA602(AP), TLE2071, OPA627, Supreme Sound Opamp V5; and now AD797.
With AD797 I fear oscillation, but they work very well and with the best sound I heard with WNA MKII.
Now I will spend them the suggested 'Distortion Cancellation and Bandwidth Enhancement' caps, 47pF or 56pF (which are better?).
Unfortunately I don't have distortion measure equipment.
My measure only my ears.
The WNA MKII Thread in head-fi:
New! WNA MKll Head-amp kit. | Headphone Reviews and Discussion - Head-Fi.org
New! WNA MKll Head-amp kit. | Page 51 | Headphone Reviews and Discussion - Head-Fi.org
The schema and modifications of my WNA MKII:
Audio Project Headphone Amp WNA MKII
I found this too:
distortion cancellation for beginners
LM6171 (designed for), LME49710, AD843, AD847, LT1056, LT1022, OPA602(AP), TLE2071, OPA627, Supreme Sound Opamp V5; and now AD797.
With AD797 I fear oscillation, but they work very well and with the best sound I heard with WNA MKII.
Now I will spend them the suggested 'Distortion Cancellation and Bandwidth Enhancement' caps, 47pF or 56pF (which are better?).
Unfortunately I don't have distortion measure equipment.
My measure only my ears.
The WNA MKII Thread in head-fi:
New! WNA MKll Head-amp kit. | Headphone Reviews and Discussion - Head-Fi.org
New! WNA MKll Head-amp kit. | Page 51 | Headphone Reviews and Discussion - Head-Fi.org
The schema and modifications of my WNA MKII:
Audio Project Headphone Amp WNA MKII
I found this too:
distortion cancellation for beginners
I would use a C0G grade ceramic cap.
Now I am confuse
As far as I know, some hate ceramic caps in audio signal path - and recommend silver mica, glimmer, styroflex caps for low levels.
Are C0G/NP0 are “audiophile caps“ too?
Ceramic capacitor - Wikipedia
some hate ceramic caps in audio signal path
COG/NPO ceramic capacitors measure very well, try them and see.
COG/NPO ceramic capacitors measure very well, try them and see.
Yes a 50pF COG/NPO should be fine. I would be interested in any difference with audio, the cap was intended for precision instrument applications to achieve the best THD numbers.
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Yes a 50pF COG/NPO should be fine. I would be interested in any difference with audio, the cap was intended for precision instrument applications to achieve the best THD numbers.
Similar or better than silver mica, glimmer, styroflex caps?
COG/NPO ceramic capacitors measure very well, try them and see.
I have no equipment to measure this.
Another question, is there an measure or hearable difference with/without this cap in a AD797 design?
Here my schema:
Audio Project Headphone Amp WNA MKII
Avoid silvered mica.
Also for styroflex too?
Avoid silvered mica.
A 10-82pF air variable works, I used that to take pictures of the deepest null. BTW traderbam the null goes both ways hard to do that with ordinary feedback.
Nooo. Polystyrene are yummy.Also for styroflex too?
Don't get me started.A 10-82pF air variable works, I used that to take pictures of the deepest null. BTW traderbam the null goes both ways hard to do that with ordinary feedback.
is there an measure or hearable difference with/without this cap in a AD797 design?
The distortion reduction capacitor is really only useful for high gains >100 times.
With your low gain circuit, the distortion will be well below the noise level,
and the capacitor will not be helpful.
Hmm, controversial.The distortion reduction capacitor is really only useful for high gains >100 times.
With your low gain circuit, the distortion will be well below the noise level,
and the capacitor will not be helpful.
Anyhow, the magic mathematical "cancellation" formula relies on both the external capacitor and internal capacitor being exactly equal. They can never be equal not least because one has a silicon dielectric.
However, the external cap does provide negative feedback around the output stage in, I assume, a tight electrical loop, and should be better in than out. Relying entirely on global NFB is usually inferior in my opinion.
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Hmm, controversial.
Anyhow, the magic mathematical "cancellation" formula is a bit mythical and relies on both the external capacitor and internal capacitor being exactly equal. They can never be equal not least because one has a silicon dielectric.
No actually the junction capacitances are balanced as much as possible the MOS caps are a grown oxide that is quite good they make 24 bit switched cap circuits after all. As I said if you trim the cap through 50pf (null) to 100pF the error flips sign that is the distortion is the same magnitude but reverse phase. If you can make a normal negative feedback loop behave this way, I would be interested.
Ok Scott . BTW, why did you make Cn external rather than making an exact match internal one?
Die area, and (my secret) it brought out an internal node for playing. Why have 8-legs if you don't use them all?
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