Moby said:
Coming gently... 😉
I added 2 caps at input for the one who want to play security. Others can strap them with a short wire. I also corrected an error on digital GND pins (for DEQ v2). The second board can be fixed with a screw coming from the input board HE10 connector.
Thats great Stef. Count me for 2 boards ;-) I forget to ask...Did you left the resistors arrangement (332-332-332 ) in front of the AK ? Maybe that's the reason for 1632 overheating.😕 Is that 500 ohm load must for AK chip or it can be higher?
Ok 1632 is capable for delivering a lot of ma's at output but in that case heat is normal
Ok 1632 is capable for delivering a lot of ma's at output but in that case heat is normal
Moby said:Thats great Stef. Count me for 2 boards ;-) I forget to ask...Did you left the resistors arrangement (332-332-332 ) in front of the AK ? Maybe that's the reason for 1632 overheating.😕 Is that 500 ohm load must for AK chip or it can be higher?
Ok 1632 is capable for delivering a lot of ma's at output but in that case heat is normal
Heat seems normal with OPA1632. Unconnected to the ADC, I have the same temperature. I also tried THS4131, same temp.
Look at the THS4131 datasheet. You'll find more information.
The new boards will be more expensive. On a panelized Europe board, I can put only 2 sets of board... The HE10 female connector (Farnell 1034417) is also 2€ more expensive than the previous one.
Stef...
Must be that chip is biased high...but that's ok 😎 I also think that temp. issue is not so important...but I'm still thinking about redesigning complete in/out board and placing that in separate box. Do you know is that "short" termination of AK input rule or it can be higher? BTW, I don't know about price of your previous input kit. So, what's the price for new one?
Moby said:
Currently, I don't plan to "produce kit" for the analog boards. Just to produce a set of boards for me.
I'm not sure that the balanced input and ouput lines to the AKM DAC and ADC can support long wires going to an external box.
Stef...
Why do you think that few cm of low z balanced analog signal can't be extended for few more cm's?
stef1777 said:
I would assume the opposite, especially if you use pair twinned flat cable for the differential signal . What would the difference from a normal balanced driver be (apart from consumer signal level and somewhat lower drive capacity)
The DAC can drive fairly low impendance circuits, and with the voltage available signal immunity should be fairly high. Then it is a matter where to put the low pass filter /differential reciever to remove spurious from the DAC oversampling...
That filter would also remove digital noise and PS switch noise.
And 50(60)*n Hz hum...
Interesting subject as well. As I wrote, "I'm not sure". I've tried to find literature on this subject but nothing found. Nothing on ADC input or DAC output wire length on the datasheets. Many blabla about digital wiring or clock wiring but this is another subject.
The only fact yet. Behringer put a large ferrite around the flat cable. As they love produce cheap device and as this ferrite is expensive, they should have a good reason for that.
Put both signal in an external box will be more than "few more cm's". 😉
Stef...
The only fact yet. Behringer put a large ferrite around the flat cable. As they love produce cheap device and as this ferrite is expensive, they should have a good reason for that.
Put both signal in an external box will be more than "few more cm's". 😉
Stef...
Stef, sorry , where is that ferrite. I can't see it in DCXstef1777 said:
😕
By separate box I was thinking about one more "floor" 1U box. So cables will go instead of to back , simply up. 😉 Maybe the stock cable will be able to reach. Also, digital and analog will be physically separated better.
I aint got no ferrita in my boxa... guess it is the super cheap stuff.
anyhow. I guess you come to a point where the driving capacity of the DACs internal OP is not sufficient to drive the capacitance in the cable.
reading the datasheets it specifies full drive into 600 ohm (min load) and maximum 3.3 mA output (@ DC ?) so based on this we can calculate how milli A you can deliver to a capacitive load.
I dont know the capacitive load of the cable but it should be in the range of a few hundred pF per meter.
Then we can calculate Slew rate of the output and compare this to minimum necessary slew rate for the box to reproduce the sinus we need.
As digital signals are many MHz the capacitive load/drive capacity is much more important here so the digital signals are not slowed down.
without doing any calculations I estimate that the DAC can drive any reasonable audio load (> few kOhm) without any problem with long cables. Longer than you find usable (who wants a bloody flat cable through the room 🙂
anyhow. I guess you come to a point where the driving capacity of the DACs internal OP is not sufficient to drive the capacitance in the cable.
reading the datasheets it specifies full drive into 600 ohm (min load) and maximum 3.3 mA output (@ DC ?) so based on this we can calculate how milli A you can deliver to a capacitive load.
I dont know the capacitive load of the cable but it should be in the range of a few hundred pF per meter.
Then we can calculate Slew rate of the output and compare this to minimum necessary slew rate for the box to reproduce the sinus we need.
As digital signals are many MHz the capacitive load/drive capacity is much more important here so the digital signals are not slowed down.
without doing any calculations I estimate that the DAC can drive any reasonable audio load (> few kOhm) without any problem with long cables. Longer than you find usable (who wants a bloody flat cable through the room 🙂
Hi Folks!
I finally received the new prototype boards this week and found some time yesterday to assemble one of them.
At start, all seems fine this time. The input board work. Nothing is too hot and I can close the box now. 😉
I plan to build the output board now. The board fit well as well but I need to assemble it before claiming success with this second try.
Cheers,
Stef...
I finally received the new prototype boards this week and found some time yesterday to assemble one of them.
At start, all seems fine this time. The input board work. Nothing is too hot and I can close the box now. 😉
I plan to build the output board now. The board fit well as well but I need to assemble it before claiming success with this second try.
Cheers,
Stef...
Good news stephane ... looks very fine ... 
God speed the plough!
Go on output board go on
and finally come to me .. come to me
God speed the plough!
Go on output board go on
and finally come to me .. come to me More picture. No yet connected the output board live. I've to left. Will try later.
I added 2 small (optional) heatsink on the OPA1632s for the fun. Temp is 54° without heatsink.
ps for Moby: temp is better as the new boards are not on top of the DSP board and components fit vertically.
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An externally hosted image should be here but it was not working when we last tested it.
I added 2 small (optional) heatsink on the OPA1632s for the fun. Temp is 54° without heatsink.
An externally hosted image should be here but it was not working when we last tested it.
ps for Moby: temp is better as the new boards are not on top of the DSP board and components fit vertically.
Ouf ca marche !!!
An externally hosted image should be here but it was not working when we last tested it.
Ca marche bien ? tres bien ? or only ca marche ?
... when your boards will be available to order ?
... when your boards will be available to order ?
artquake said:
Very well. On my office sound installation for 2 full days without problem. End of week, il will connect it to my main sound system, the one with the big Dynaudio.
artquake said:
I don't really know. I've to clean up the schematics and write the BOM. No many free time right now, and for the next coming month.
And it will depends how many people want the boards. It was not my project to build boards for others. At unit, they are expensive to produce due to their special size (small but very long). If qty is low (<20), the unit price is around 25€ with VAT for the set. I can do a group buy but I need a minimum of 10 people (or 10 set of 2 boards).
Stef...