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AK4499EQ - Best DAC ever
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Old 3rd April 2020, 03:59 AM   #331
AllenB is offline AllenB  Australia
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AK4499EQ - Best DAC ever
Some OT moved.
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Old 3rd April 2020, 04:13 AM   #332
JohnW is offline JohnW  Hong Kong
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Quote:
Originally Posted by Zoji6645 View Post
Seems to me ECPU is unacceptable for Audio. The dielectric is Acrylic, which has worse DF (~1%) than PET. PPS or polyprop should be used.
COG or NPO ceramics are fine to use. Never X7R ceramics.
Read Bateman much?
Depends what your trying to achieve.

For SURE ceramics / Acrylic should never be used DIRECTLY in the signal path - but the lossey nature of Ceramics is very useful in digital decoupling as it helps to dampen transient current induced ringing on power rails...

Low loss caps perform worst as they tend to resonate more with the load step... sometimes being lossey is a good thing...

Its a really hard subject, I'm constantly fighting the sonic signature of capacitors - I try to avoid ANY in the direct signal path, but then PSU capacitors are also very much in the signal path...
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Old 3rd April 2020, 04:25 AM   #333
JohnW is offline JohnW  Hong Kong
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Originally Posted by Markw4 View Post
John,
I've never seen Crystek clocks in those frequencies, but Accusilicon makes some...
Crystek makes CMOS output parts to 130MHz:-

Crystek

The Accusilicon parts I've measured are PLL based production programmable parts - this allows Accusilicon to cheaply manufacture small batches of custom frequency parts.

PLL based designs have much poorer close-in phase noise (where it matters for audio) then even a simple well designed XO circuit - I recommend to avoid Accusilicon unless you are certain they are not PLL based parts - even better if they provide PN plots...
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Old 3rd April 2020, 06:15 AM   #334
Terry Demol is offline Terry Demol  Australia
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Originally Posted by JohnW View Post
Sorry, I cannot help as I dont use LTspice so cannot open your files - I find the schematic entry of LTspice to be so hard to use - just plan awful...
Ltspice is well worth persevering with if you don't already use another decent simulator. Very powerful and handy tool.

TCD
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Old 3rd April 2020, 06:19 AM   #335
Terry Demol is offline Terry Demol  Australia
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Quote:
Originally Posted by JohnW View Post
Crystek makes CMOS output parts to 130MHz:-

Crystek

The Accusilicon parts I've measured are PLL based production programmable parts - this allows Accusilicon to cheaply manufacture small batches of custom frequency parts.
John, which parts have you measured?

Quote:

PLL based designs have much poorer close-in phase noise (where it matters for audio) then even a simple well designed XO circuit - I recommend to avoid Accusilicon unless you are certain they are not PLL based parts - even better if they provide PN plots...
I believe their fixed oscillators are good. It's difficult communicate with them
and get any info from them. If anyone has a reliable contact please PM me.

TCD
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Old 3rd April 2020, 06:51 AM   #336
Terry Demol is offline Terry Demol  Australia
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Quote:
Originally Posted by JohnW View Post
Depends what your trying to achieve.

For SURE ceramics / Acrylic should never be used DIRECTLY in the signal path - but the lossey nature of Ceramics is very useful in digital decoupling as it helps to dampen transient current induced ringing on power rails...

Low loss caps perform worst as they tend to resonate more with the load step... sometimes being lossey is a good thing...

Its a really hard subject, I'm constantly fighting the sonic signature of capacitors - I try to avoid ANY in the direct signal path, but then PSU capacitors are also very much in the signal path...
You might try a combination of 2 polymer smd caps. Kemet have a decent
cap modelling tool and the right combo will go out to 1GHz. The board lyt,
as you know, will dominate.

TCD
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Old 3rd April 2020, 07:57 AM   #337
JohnW is offline JohnW  Hong Kong
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Originally Posted by Terry Demol View Post
John, which parts have you measured?
I believe their fixed oscillators are good.
Terry,

Sorry confirming with my notes I've confused projects / manufacturers - I was asked to measure an Accusilicon TCXO IC (Die package) for a large 3rdf party "Crystal" manufacturer - I've not measured there larger 14pin DIL type XO's... my contacts are within Asia...

The PLL based XO part I mentioned was a 7050 SMD part from Abracon - we where working with both devices at the same time...

Working indirectly with Accusilicon I know they provide PN measurements and appreciate Close-in phase noise requirements for audio, but they have REALLY poor sales support outside of China, in fact from what I understand they really only have the engineering resources to work on a one to one basis with key accounts...

I apologise for my confusion..
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