The DSC1 DAC as a way to understand how a simple DSD DAC actually works

[HallmanLabs]

I have a quick question about the DSC1 DAC (2016 model). I have two Rubycon Black Gate Non-polar caps I was hoping to use. I was told I can't use them in place of the two 100uF electrolytic caps towards the XMOS/Amanero pins, since that position needs polarized caps.

 

Then I realized that there are two other 100uF caps, the WIMA caps (coupling caps I believe). Is this a good use of capacitors as expensive as these? If not, any recommendations for where/how to use these non-polar Black Gates? Coupling is the most common way I see most non-polar caps being used.

 

I have upgraded 10k:10k transformers on the way, but I think there is room where the WIMA is soldered, comparing with my current 600:600 transformers.

 

Thanks for any info!

[jabbr]

38 minutes ago, HallmanLabs said:

I have a quick question about the DSC1 DAC (2016 model). I have two Rubycon Black Gate Non-polar caps I was hoping to use. I was told I can't use them in place of the two 100uF electrolytic caps towards the XMOS/Amanero pins, since that position needs polarized caps.

 

Then I realized that there are two other 100uF caps, the WIMA caps (coupling caps I believe). Is this a good use of capacitors as expensive as these? If not, any recommendations for where/how to use these non-polar Black Gates? Coupling is the most common way I see most non-polar caps being used.

 

I have upgraded 10k:10k transformers on the way, but I think there is room where the WIMA is soldered, comparing with my current 600:600 transformers.

 

Thanks for any info!

 

To be clear, can you post the schematic you are using because the dsc1 schematic does not have transformers.

[4est]

45 minutes ago, HallmanLabs said:

I have a quick question about the DSC1 DAC (2016 model). I have two Rubycon Black Gate Non-polar caps I was hoping to use. I was told I can't use them in place of the two 100uF electrolytic caps towards the XMOS/Amanero pins, since that position needs polarized caps.

 

Then I realized that there are two other 100uF caps, the WIMA caps (coupling caps I believe). Is this a good use of capacitors as expensive as these? If not, any recommendations for where/how to use these non-polar Black Gates? Coupling is the most common way I see most non-polar caps being used.

 

I have upgraded 10k:10k transformers on the way, but I think there is room where the WIMA is soldered, comparing with my current 600:600 transformers.

 

Thanks for any info!

By the sounds of it you have the Asian DSC1.Difference. There is no place(need) for nice audio grade electrolytic caps on this board- there are no coupling capacitors or low frequency needs. The 100uF electrolytic caps are for digital power and the WIMAs are actually 100pF used as part of the final filter. Lastly, if you are looking to replace the transformers, you need to remove the older ones or you will be putting both new and older one's primaries in parallel. If you are looking for a bump in performance, replacing the transformer is likely a good place to start. You could also add tantalum power decoupling/bypass caps at the power in of each shift register. You could aslo upgrade your Amanero if you are using the original or similar. LKS makes a pin compatible board with nicer clocks. Of course power supply upgrades for the Amanero too!

[4est]

On 3/23/2018 at 7:35 PM, HallmanLabs said:

I figured being non-polarized would come back to bite me on this design after looking at it closer. Any suggestions on what to use these for?

Although Miska is correct of course, he is talking about the REAL DSC1, not the eBay ones. There is nothing biting you, they just aren't required. You could use them in your DSC1.Diff, but a solid polymer cap seems more appropriate. One of mine came with them, but the other came with regular looking electrolytic caps.

[HallmanLabs]

14 minutes ago, 4est said:

By the sounds of it you have the Asian DSC1.Difference. There is no place(need) for nice audio grade electrolytic caps on this board- there are no coupling capacitors or low frequency needs. The 100uF electrolytic caps are for digital power and the WIMAs are actually 100pF used as part of the final filter. Lastly, if you are looking to replace the transformers, you need to remove the older ones or you will be putting both new and older one's primaries in parallel. If you are looking for a bump in performance, replacing the transformer is likely a good place to start. You could also add tantalum power decoupling/bypass caps at the power in of each shift register. You could aslo upgrade your Amanero if you are using the original or similar. LKS makes a pin compatible board with nicer clocks. Of course power supply upgrades for the Amanero too!

 

I figured those WIMA were way too small for uF scale compared to my huge 0.1uF\100V WIMA caps, commonly used at a Coax input. Thanks for waking me up this morning with that!

I do realize I have to remove the current transformers before adding the new ones

I attached the DSC1 board I am using, don't have the schematic currently.

 

Edit:
 

Quote

Although Miska is correct of course, he is talking about the REAL DSC1, not the eBay ones. There is nothing biting you, they just aren't required. You could use them in your DSC1.Diff, but a solid polymer cap seems more appropriate. One of mine came with them, but the other came with regular looking electrolytic caps.

I knew it! I thought I had asked a similiar question on this forum before, but when I checked my activity it wasn't showing up for my posts. So I made another one thinking I had asked over on DIYAudio instead of here.

I believe the transformer I picked was recommended in this thread.



 

[jabbr]

1 hour ago, HallmanLabs said:

I attached the DSC1 board I am using, don't have the schematic currently.

 

Whatever this DAC is, I object to calling it a DSC1 ... primarily because @Miska released the DSC1 as "Open Hardware" and this thing doesn't release a schematic is is required under the open hardware license.

 

The point of this thread is to use the open hardware design as a way for people to understand what the DAC is doing -- almost all DACs are closed design and folks can then argue about e.g. PCM vs DSD but who really knows. Without a schematic discussion of this DAC does not help us to understand the benefits of modifications such as transformers, various types of capacitors etc.

[jabbr]

Is this what we are talking about @ppy http://www.audiodesignguide.com/DSC1/index.html ?

 

If so, great, and I see the schematic 

[HallmanLabs]

With these TPS7A4700 Power Supply Regulators. Does the EN pin need to be used or is that optional just to light an LED?

If it does require a signal, does it need the positive (high) or the ground (low). My module has the P marked instead of the N, I believe that is inverting the output vs non-inverting, but figured I'd mention it just in case.

Thanks as always for any guidance you can provide. My DSC1 is coming along nicely. Besides this EN connection on both of the TPS7A4700s, I have the upgraded 10k:10k perma-alloy transformers installed and I added Neutrik XLR jacks. Pics to come soon!

 

On 4/10/2018 at 10:08 PM, jabbr said:

Is this what we are talking about @ppy http://www.audiodesignguide.com/DSC1/index.html ?

 

If so, great, and I see the schematic 

That is a schematic for an upgraded DSC1 that many have been trying to get ahold of, called v2.5 (printed on the PCB). I stated and showed pics of mine, you should see a clear difference between that and the original DSC1 that only has balanced outputs.

That design has a portable transformer board so they can easily test multiple transformers, and it has both balanced and unbalanced jacks. What the forum was saying is that anyone selling a DSC1 has to release a schematic of their own under the Open Hardware rules.

The official name of the one I have is the generic DSC1.Difference with a date printed of 2016.07.30

[HallmanLabs]

In case someone else has a similiar question about the TPS7A4700, the answer lies in the datasheet:

 

 

Quote

 

"Enable pin. The device is enabled when the voltage on this pin exceeds the maximum enable voltage, VEN(HI). If enable is not required, tie EN to IN

Enable (EN) And Under-Voltage Lockout (UVLO)

The TPS7A470x only turns on when both EN and UVLO are above the respective voltage thresholds. The UVLO circuit monitors input voltage (Vi) to prevent device turn-on before Vi rises above the lockout voltage. The UVLO circuit also causes a shutdown when Vi falls below lockout. The EN signal allows independent logic-level turn-on and shutdown of the LDO when the input voltage is present. EN can be connected directly to Vi if independent turn-on is not needed."

 

The last sentence confirms what I assumed. If you don't care about having an enable button/independent turn-on option and are fine with the input voltage being applied as your switch, it works fine.

 

http://www.ti.com/lit/ds/symlink/tps7a47.pdf