DAC 2496 (AK4393) DAC KIT With CS8416+AK4393+5532 - Page 163 - diyAudio
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Old 15th April 2012, 05:17 PM   #1621
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A high PSSR just rejects noise.

But I think the OPA827, or most modern chips, might improve from a very low impedance supply, like Sulzer's or Jung's.

I'm not sure about the more recent Salas shunt supply versions, that have sense terminals as the Jung supply.
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Old 15th April 2012, 06:53 PM   #1622
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Default Testing to find best output opamp

Quote:
Originally Posted by skouliki View Post
I tried LME49720 biased in class a, AD8066 and LT1364. LME49720, although it had great timbre when biased in class a, was outperformed by the other two opamps. Ad8066 and lt1364 where both really good in terms of resolution and seperation. Ad8066 has a huge soundstage, but LT1364 is musically more engaging and is currently my favorite. I intend also to try LT1028 and OPA627
When I complete my DAC, Iíll post a comparison of Darioís BOM opamp (OPA827 aka OPA827AID) to one my brother recommended that I try, ADA4075-2. I donít know if itís a familiar one to anyone else posting on this forum. Does require an adaptor. (My brother designs and builds audio mixers for a living). Should be interesting.

I plan to apply Dario's shunt design, assuming it tests out well as the discussion moves forward over the coming weeks. I've aready set out to build the PSU on a separate board, so incorporating some inexpensive upgrades to the default DAC design looks very doable. (Thanks Dario and all for working on this option)!
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Old 15th April 2012, 07:23 PM   #1623
FOXYE is offline FOXYE  Israel
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Has anyone tried biasing Op-Amps into Class A?

Matrix M-Stage Class A Biasing | Headfonia

This improves the sound quite a few, especially at high.
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Old 16th April 2012, 04:04 PM   #1624
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Quote:
Originally Posted by FOXYE View Post
Has anyone tried biasing Op-Amps into Class A?

Matrix M-Stage Class A Biasing | Headfonia

This improves the sound quite a few, especially at high.
resistor biasing is not a very reliable solution

go with transistor biasing!
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Old 16th April 2012, 04:21 PM   #1625
qusp is offline qusp  Australia
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its also a bit pointless with modern opamps, which mostly have output stages that already operate in Class A, so just doing a blind mod without a scope to see if you are actually doing harm not good is not such a great idea IMO, I say just stick a good chip in there and leave it.
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Old 17th April 2012, 09:51 AM   #1626
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Quote:
Originally Posted by ClaveFremen View Post
As others reported the most rewarding swap is for opamp rails and analog 5V (U8, U9 and U10)

But you still need U9 and U6 for the analog 3.3V (CS8416)
hi Dario,
could I have you advice once more. Do i really ned U9 if I have 3 separate salas regs attached to green points (att)?
So I built 80mA 5v version for analogue part to completely remove U8.
Another salas +-12v 200mA is built for two opamps - DAC's output and preamp (LM49720HA) that I'll put in the same box. I guess opams need no more than 50mA, salas requires some 30mA, so I still have about 50mA left to pass to U6 for A+3.3...
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Old 17th April 2012, 10:20 AM   #1627
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Quote:
Originally Posted by dtses View Post
could I have you advice once more. Do i really ned U9 if I have 3 separate salas regs attached to green points (att)?
...
I guess opams need no more than 50mA, salas requires some 30mA, so I still have about 50mA left to pass to U6 for A+3.3...
According CS8416 datasheet (Va3.3 is for it) it wouldn't need more than 10mA so it should be fine.

But, in a state of the art mod, I wouldn't mix digital PS with Analog.
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Old 17th April 2012, 11:35 AM   #1628
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thanks a lot!
then probably I would use your reg - LM317+BD139 + U6 for A+3.3 part.
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Old 17th April 2012, 11:48 AM   #1629
billo44 is offline billo44  United Kingdom
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Default DAC lives!

Quote:
Originally Posted by jnewbold View Post
On my DAC kit the PCB traces were shorted between pins as follows:
(this is correct according to the kit's schematics and my DAC certainly works Ė very well)

On the AK4393/6:
12 shorted to 13
15 shorted to 16
17 shorted to 18

27 and 28 are shown as shorted to GND on the schematic.

On the CS8416,
10 shorted to 11 (and GND)
20 shorted to 21

You should be able to see, between the pins, where the PCB traces have joined/shorted them.
Well when I finally got around to checking this advice in detail, checking the pin numbers against data sheets etc, I found that pins 4 and 5 on my AK 4396 had a solder bridge. I cut that and everything sings!
Burning in out on the bench....

I'm very happy I didn't fry anything.

Cheers,
Bill.
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Old 17th April 2012, 11:51 AM   #1630
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Good news Bill!
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