Those PSUs I meantioned are also available in 7.5V. As far as I can see it, 7.5V should work with all other voltage regulators on the board as well and would reduce the powerloss even further.
I guess a PSU in a grounded metal enclosure is then the better choice (compared to an open frame model) as it better shields the EMI from the PSU. Maybe a metal wall inside the case between the dsp board and the PSU might also be an idea...
I also saw a small filter board in the diyaudiostore which might be worth a thought as well.
Ludwig
Member
Joined 2018
Hello Ludwing-San,
7.5V PSU will be nice for this board from the point of view of the dissipation loss. The total capacity for the consumption current will depend on the type of RPI. I'm using Raspberry-pi 3 Model B+. The latest Raspberry-pi 4 will not be a good choice from the point of view of its CPU cooling.
Measured Supply Voltage vs Consumption Current
On the current schematic design, OCTAVIA does not start if the supply voltage is under 12V. Keep running measurement result was not sure but the data is...
Downwarding working voltage must need some modification(s). I need to investigate and figure out the design, It will take some time. Let me excuse myself for that work.
CyberPit
7.5V PSU will be nice for this board from the point of view of the dissipation loss. The total capacity for the consumption current will depend on the type of RPI. I'm using Raspberry-pi 3 Model B+. The latest Raspberry-pi 4 will not be a good choice from the point of view of its CPU cooling.
Measured Supply Voltage vs Consumption Current
Condition | Supply Voltage [V] | Current [A] | VA [W] |
| DSP Only (3way C/D App.) | 12.0 | 0.31 | 3.7 |
| RPI File Playback | 12.0 | 0.53 | 6.4 |
| RPI File Search | 12.0 | 0.71 | 8.5 |
On the current schematic design, OCTAVIA does not start if the supply voltage is under 12V. Keep running measurement result was not sure but the data is...
Condition | Supply Voltage [V] | Current [A] | VA [W] |
| DSP Only (3way C/D App.) | 10.0 | 0.34 | 3.4 |
| RPI File Playback | 10.0 | 0.62 | 6.2 |
| RPI File Search | 10.0 | 0.82 | 8.2 |
Downwarding working voltage must need some modification(s). I need to investigate and figure out the design, It will take some time. Let me excuse myself for that work.
CyberPit
Member
Joined 2018
Now Installed ...
The source position indicator LED is not implemented yet.
The source position indicator LED is not implemented yet.
Hello CyberPit-San
Thank you very much for your input and the measurements!
So, for lower input voltages I think this voltage divider needs to be adapted and the timer circuit might be a bit off as well.
I saw you already changed most of the workarounds in the manufactoring files. So I am porbably good to go. For C13 I can do the same workaound ore move it a bit before ordering.
Ludwig
PS: little reminder for the missing symbols and footprints 😉
Thank you very much for your input and the measurements!
I suspect the voltage on the enable pin on the 3.3V SMPS is too low. The datasheet of the IC mentions a maximal start threashold voltage of 1.3V. So the 1.09V given by the voltage divider (R7 and R34) and an input voltage of 12V might already be very much on the edge. So lowering the input voltage will probably resulting in the SMPS not turning on. And therefore the rest wont turn on either.
So, for lower input voltages I think this voltage divider needs to be adapted and the timer circuit might be a bit off as well.
I would actually be eager to help you out there. I think I am going to order a board soon and then I can investigate what is necessary to get everythink working with lower input voltage.
I saw you already changed most of the workarounds in the manufactoring files. So I am porbably good to go. For C13 I can do the same workaound ore move it a bit before ordering.
Ludwig
PS: little reminder for the missing symbols and footprints 😉
@Maurizio @rrobot @vineethkumar01
If I see it coreectly you were interested in a group buy, am I right?
What version would you be interested in (unbalanced, balanced, differential)? And I guess there is the option between the ADAU1542 and the ADAU 1466.
Ludwig
If I see it coreectly you were interested in a group buy, am I right?
What version would you be interested in (unbalanced, balanced, differential)? And I guess there is the option between the ADAU1542 and the ADAU 1466.
Ludwig
Yes, definitely keen 😃 Although I believe you're mostly in Europe? I'm in Australia. Not a deal breaker by any means but the postage on finished boards is often painful.
I'm probably interested in balanced outputs but again that may make it expensive to ship. Exciting to see these projects coming to life! 👏
Yes. I am interested in a group buy. I am from India, though.
I am looking for an 8-channel DSP along with which a raspberry pi can be used.
I think the ADAU 1466 would fit my requirements (I don't know much about the difference between 1452 and 1466).
I am interested in the unbalanced version.
Thanks
Vineeth
All across the globe...
I just had a look, shipping to australia from germany starts around 40€, to India it is a similiar. From previous posts from CyberPit I gathered that ordering 5 boards instead of 2 boards reduces the per board price by about 20USD. However, you cannot order just a single assambled board (only 2 or 5). So it still might be worth doing a group order if you don't know someone around you who might be interested in a board as well.
With Maurizio we would actually end up with 5 boards (I take two, my brother wants one as well). For the unbalaced board, some components are not needed but I would imagine it is cheaper to order 5 balanced ones and remove some reistors rather than ordering them seperatly.
Ludwig
I just had a look, shipping to australia from germany starts around 40€, to India it is a similiar. From previous posts from CyberPit I gathered that ordering 5 boards instead of 2 boards reduces the per board price by about 20USD. However, you cannot order just a single assambled board (only 2 or 5). So it still might be worth doing a group order if you don't know someone around you who might be interested in a board as well.
With Maurizio we would actually end up with 5 boards (I take two, my brother wants one as well). For the unbalaced board, some components are not needed but I would imagine it is cheaper to order 5 balanced ones and remove some reistors rather than ordering them seperatly.
Ludwig
Hi, I could be interested by a balanced board. I only need the smaller DSP, but could be Ok to pay for the bigger one. Shipping would be to France.
This would be conditioned by the the final price.
Would you consider the roup buy only for the boards, or also the misc through hole components, connectors (also expensive to order individually)?
I can solder simple SMD parts as sometimes it helps keep the assembly costs down.
Jmf
This would be conditioned by the the final price.
Would you consider the roup buy only for the boards, or also the misc through hole components, connectors (also expensive to order individually)?
I can solder simple SMD parts as sometimes it helps keep the assembly costs down.
Jmf
Oups, one point not clear to me: what is the difference between differential and balanced? Intention is to drive class D amp boards like TI TPA or Infineon Merus chips.
Jmf
Jmf
Hi JMF11,
This might help a bit, although there is not much explaination.
Also , it is not too hard to switch between the two.
Yes, I would do a group buy here as well. This saves at least some shipping cost. I am already working on finding suppliers in the EU for the THT components or finding alternative replacement parts.
The naming might be a bit misleading. There is the option of having a differential signal over an RCA cable (this would then be single ended or unbalanced) and you can have the differential signal over XLR ( or TRS), which would be a balanced connection. Balanced means that both signals have the same impedance to GND.
This might help a bit, although there is not much explaination.
I think amp boards usaually have the balanced input (pos, neg and GND connection). But please correct me if I am wrong.
Also , it is not too hard to switch between the two.
I am looking for alternatives for the THT Caps since I cant seem to get most of them over here.
@CyberPit can you give me some advice/insight here?
C8, C22, C12: I guess they don't have special requirements since they are used for timing in the mute and shutdown delay circuits.
C13, C27 and C28: I guess these ones have more specific requirements, since the used nichicon fine gold seem to be popular audio capacitors. What is the important property here? ESR?
Also I checked the pricing, with adau1466 the price will increase by 2.87USD. When I sorted out the caps I can give an overall pricing estimate with all components.
Ludwig
@CyberPit can you give me some advice/insight here?
C8, C22, C12: I guess they don't have special requirements since they are used for timing in the mute and shutdown delay circuits.
C13, C27 and C28: I guess these ones have more specific requirements, since the used nichicon fine gold seem to be popular audio capacitors. What is the important property here? ESR?
Also I checked the pricing, with adau1466 the price will increase by 2.87USD. When I sorted out the caps I can give an overall pricing estimate with all components.
Ludwig
Member
Joined 2018
Ludwing-San,
Thanks for your suggestions. I could check the issue points very quickly. Two resistors should be changed. R33 and R7 are required to change to 3.3k ohms. After changing those resistors, I checked the timing for the delay circuit operating with 6.25V. But it is not necessary to change timing C or R.
It works as well as 12V and the heat of the series regulator is not a matter at all.👍
My variable voltage power supply could not draw the current over 1A. So I measured with 6.25V fixed voltage regulated power supply.
Measured Supply Voltage vs Consumption Current
Thanks for your suggestions. I could check the issue points very quickly. Two resistors should be changed. R33 and R7 are required to change to 3.3k ohms. After changing those resistors, I checked the timing for the delay circuit operating with 6.25V. But it is not necessary to change timing C or R.
It works as well as 12V and the heat of the series regulator is not a matter at all.👍
My variable voltage power supply could not draw the current over 1A. So I measured with 6.25V fixed voltage regulated power supply.
Measured Supply Voltage vs Consumption Current
Condition | Supply Voltage [v] | Current [A] | VA[w] |
| DSP Only (3way C/D App.) | 6.25V | 0.43A | 2.7W |
| RPI File Playback | 6.25V | 0.88A | 5.5W |
| RPI File Search | 6.25V | 1.25A | 7.8W |
Member
Joined 2018
And About the Caps...
C8, C22, C12:Your are right. An ordinary Electric Cap is enough.
C13 for analog 5V power rail decoupling. Solid type (ex. OS-CON, etc... ) might be a better fit for Low ESR and higher frequency decoupling. But I guess this Elecap type is not so critical item, but the capacitances.
C27 and C28 are definitely the Audio-grade capacitors recommended. The capacitance is 2.2uF through 10uF available. The alternative choice is WIMA Film Cap 2.2uF/50V. I like its characterized sound. (Not natural)
CyberPit
C8, C22, C12:Your are right. An ordinary Electric Cap is enough.
C13 for analog 5V power rail decoupling. Solid type (ex. OS-CON, etc... ) might be a better fit for Low ESR and higher frequency decoupling. But I guess this Elecap type is not so critical item, but the capacitances.
C27 and C28 are definitely the Audio-grade capacitors recommended. The capacitance is 2.2uF through 10uF available. The alternative choice is WIMA Film Cap 2.2uF/50V. I like its characterized sound. (Not natural)
CyberPit
Hi CyperPit,
nice to see the dsp working now with lower input voltages and thanks again for the measurements.
Regarding the caps:
Thanks for your writeup. For C27 and C28 I found today the nichicon caps, so all good there. For C8, C22 and C12 i will find some ordinary ones.
I am only a bit confused about C13. In the BOM it says 220µF 6.3V, but if i look in the datasheet for nichicon fine gold caps, such option does not exist. The link in the BOM goes to a 220µF 25V cap, but this one has a different size (not 5mm diameter and 2mm pitch as stated in the BOM). So which cap are you using, or is the (physical) size not so important because it should be layed down anyway?
Ludwig
nice to see the dsp working now with lower input voltages and thanks again for the measurements.
Regarding the caps:
Thanks for your writeup. For C27 and C28 I found today the nichicon caps, so all good there. For C8, C22 and C12 i will find some ordinary ones.
I am only a bit confused about C13. In the BOM it says 220µF 6.3V, but if i look in the datasheet for nichicon fine gold caps, such option does not exist. The link in the BOM goes to a 220µF 25V cap, but this one has a different size (not 5mm diameter and 2mm pitch as stated in the BOM). So which cap are you using, or is the (physical) size not so important because it should be layed down anyway?
Ludwig
Member
Joined 2018
Well, To prevent the heat physically, I needed a long leaded capacitor. That was the only one I have at that time.
No other meaning of choice. The board should have a bigger footprint and be away from the heat source.
Good Morning Ludwig.
I'm interested about the Balanced version of the Octavia. I will use it with Powersoft class D modules which works better with balanced inputs.
Most probably i will buy two. A friedn of mine is interested as well.
Have a great day.!!
Maurizio
Ludwig if i'm not wrong the last version of the board include unbalanced and balanced outputs already. Balanced is provide by contacts on it.
Pit is it like this?
Ciao.
Good Morning Maurizio,
Ludwig
The output circuit can do both, but you have to decide which one you want by changing and adding/removing some components. If you look at the last page of the schematic you will have a list for what you have to change for the different versions.
Ludwig