Hello,
I see there are several AK4497 topics, but not with this board and I would have specific question on this board.
I am just eperimenting with an ak4497-ph-2.1 board and found I probably want to improve the output.
Not bad as it is. I compare it to my AD1865 based, resistor I/V than transformer, than tube output dac.
This chinese AK4497 board has the details, the solid, precise base, clear highs, wide and deep sound stage, The difference is, the AD1865 is more easy to listen to. I can not describe exactly why, but especially on classicals, violin, I prefer the AD1865 based dac.
I think the AK4497 has the potential, guessing the output should be improved.
Do you guys has a circuit diagram for this?
First of all, I do not need the differential output, second, I do not need this big amplification. I will probably short the relays also.
But, it would be much easier if I have schematics.
Do you guys has any advice for this?
Thanks!
JG
I see there are several AK4497 topics, but not with this board and I would have specific question on this board.
I am just eperimenting with an ak4497-ph-2.1 board and found I probably want to improve the output.
Not bad as it is. I compare it to my AD1865 based, resistor I/V than transformer, than tube output dac.
This chinese AK4497 board has the details, the solid, precise base, clear highs, wide and deep sound stage, The difference is, the AD1865 is more easy to listen to. I can not describe exactly why, but especially on classicals, violin, I prefer the AD1865 based dac.
I think the AK4497 has the potential, guessing the output should be improved.
Do you guys has a circuit diagram for this?
First of all, I do not need the differential output, second, I do not need this big amplification. I will probably short the relays also.
But, it would be much easier if I have schematics.
Do you guys has any advice for this?
Thanks!
JG
Attachments
Looking at the datasheet of this chip, I'm lost. I do not understand for example on figure 78 and 79, why the + and - path are different? On the differential output figure 80, it is the same low pass filter. As I read this is voltage output dac.
Do you guys have a best practice recommendation for this dac output? A Lundahl interstage transformer output circuit would be nice for example.
If not an LL1527XL on the output, can you recommend a differential to single ended circuit? Would that improve at all?
As I measured with sine wave wav files, one output only provide nice looking signals also, not sure if I would gain anything with a converter, it would maybe just add complexity and color it.
?
Thanks,
JG
Do you guys have a best practice recommendation for this dac output? A Lundahl interstage transformer output circuit would be nice for example.
If not an LL1527XL on the output, can you recommend a differential to single ended circuit? Would that improve at all?
As I measured with sine wave wav files, one output only provide nice looking signals also, not sure if I would gain anything with a converter, it would maybe just add complexity and color it.
?
Thanks,
JG
The asymmetry in component values in figs. 78, 79 is similar to what Cirrus shows for an output stage for one of their dac chips. Looks to me like time constants are the symmetrically the same, but resistance values have been lowered on the non-inverting opamp input side. Only reason I can think of for doing that would be to help lower noise due to resistors. Probably the didn't go that low on the inverting opamp side because the opamp output might have some trouble driving feedback impedances too low.
EDIT: Main problem with the dac board probably has to do with: (1) dac board is two layer rather than a more proper four layer design, (2) components and or circuit and or layout on dac board (other than the dac chip itself) were likely chosen to be a cheap as possible, not for best dac performance, and (3) the whole set of boards and wires running through the air are not in an enclosed steel case with at least 18 gauge walls, or aluminum case with at least 1/2" thick walls. Boards should be carefully laid out relative to each other and low impedance ground bonds with the dac board should be carefully implemented where needed.
In short, adding a transformer will add transformer distortion and maybe help break a ground loop with downstream equipment, but it won't fix what's wrong exactly. The transformer distortion might help mask some of the other problems with a more preferred type of distortion.
EDIT: Main problem with the dac board probably has to do with: (1) dac board is two layer rather than a more proper four layer design, (2) components and or circuit and or layout on dac board (other than the dac chip itself) were likely chosen to be a cheap as possible, not for best dac performance, and (3) the whole set of boards and wires running through the air are not in an enclosed steel case with at least 18 gauge walls, or aluminum case with at least 1/2" thick walls. Boards should be carefully laid out relative to each other and low impedance ground bonds with the dac board should be carefully implemented where needed.
In short, adding a transformer will add transformer distortion and maybe help break a ground loop with downstream equipment, but it won't fix what's wrong exactly. The transformer distortion might help mask some of the other problems with a more preferred type of distortion.
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Hello Giordano,
this is the Chinese replica (in the 2nd version) of the original AK4497 Evaluation Board.
You can download the circuit documents from AKM or Mouser and they largely match.
You should not change anything on the output circuit!!! including the relay, it is already very good.
You also need the right balanced to unbalanced board. This also corresponds to the circuit of AKM.
C 2.0 Balanced auf Single-End RCA unsymmetrisch Vorverstarker Signal Converter 4 AMP | eBay
[USD 7.81] AK4497EQ DAC Decoder Official evaluation balanced line I2S DSD input brings its own soft control - Wholesale from China online shopping | Buy asian products online from the best shoping agent - ChinaHao.com
Old board V1
https://www.aliexpress.com/item/32829477641
There are a few more details that should be changed, but unfortunately I won't be able to continue with the board until the next 2-3 weeks.
That's when I got my balanced to unbalanced board.
Audio Balance Signal Balanced XLR to unbalanced RCA Single ended RCA Audio Signal Conversion Board|Amplifier| - AliExpress
Audio Balance Signal Balanced XLR to unbalanced RCA Single ended RCA Audio Signal Conversion Board|Amplifier| - AliExpress
Thank You!
I found this, but it does not look like similar to my board : https://www.akm.com/content/dam/doc...dac/ak4497eq/ak4497eq-en-evaluationmanual.pdf
This is what I find at several places, but my board has no optical/coax input, no unbalanced output. I can not really find a more relevant one : -(
Thanks,
JG
I found this, but it does not look like similar to my board : https://www.akm.com/content/dam/doc...dac/ak4497eq/ak4497eq-en-evaluationmanual.pdf
This is what I find at several places, but my board has no optical/coax input, no unbalanced output. I can not really find a more relevant one : -(
Thanks,
JG