The last few years have seen me abandon mechanical switches and relays completely for any signal duties. They are just to unreliable at the very low currents they have to pass.
Many switches use what is termed "montage grease" which holds the parts together as they are assembled.
Many switches use what is termed "montage grease" which holds the parts together as they are assembled.
While building a USB DAC into the O2, I started to wonder if it is OK to have the USB DAC's USB connector touch the O2's aluminium enclosure, which is grounded at the O2's input ? I understand that this will produce a loop, but what I'm really asking is if it is OK to connect the DAC's USB connector to the DAC's output ground...?
As far as damaging anything, then there should be no problem as long as the points that touch are of the same potential... which using the O2 input ground as the reference against which all is measured means that there should be no voltage between this point and the point on the USB connector it touches.
When it comes to possible low level interaction causing hum/interference etc (ground loops as you say) then you will just have to try it.
When it comes to possible low level interaction causing hum/interference etc (ground loops as you say) then you will just have to try it.
The thing is, the ground on the digital side of the Dac seems to be clearly seperated from the analog side, yet the multimeter says they are connected. I can't find any direct link between both ground planes. Is it connected inside a chip / through components? This is why I don't like the idea of a loop between them...
What is the DAC? For example in an ODAC the USB shield (i.e. connector body) isn't connected to anything, however the - power line from the USB supply is the ground for everything from digital power supply to the analog output.
The Dac is a pcm2706/es9023 board I bought on ebay a while ago.
I guess I'll just desolder and isolate the body of the USB connector. Then I'll need to glue the connector down with some epoxy to keep it in place...
I guess I'll just desolder and isolate the body of the USB connector. Then I'll need to glue the connector down with some epoxy to keep it in place...
Is is this one?
TI PCM2706 ESS Sabre ES9023 USB DAC 44 1K 48K 16 Bit | eBay
I have one on order too as curiosity got the better of me. Would be interesting to see a schematic for it, especially to see what the ferrite on the bottom left of the board is doing, its possible its the USB shield connection.
TI PCM2706 ESS Sabre ES9023 USB DAC 44 1K 48K 16 Bit | eBay
I have one on order too as curiosity got the better of me. Would be interesting to see a schematic for it, especially to see what the ferrite on the bottom left of the board is doing, its possible its the USB shield connection.
Yep, it's that one. The listing ended a long time ago, you still haven't received it? I'll take a look at the ferrite...
I posted it to a relatives address as they wouldn't ship to Ireland, its probably there and waiting for me.
Ok, so the +5V from the USB go through the ferrite at the bottom of the board and the other ferrite actually seems to connect both ground planes. So that's how they are connected....
When you say both ground planes, are you referring to the digital and analog side of the circuit?
How are the USB - and socket shield connected up?
How are the USB - and socket shield connected up?
Hi all,
In all manuals we can see 2 methods to connect O2 and ODAC according to usage of 3.5 input socket: 1) to keep O2 input on it, 2) to change it to ODAC output.
However, ODAC has two outputs: four pins in the middle of PCB and 3.5 mm socket. Why nobody uses them both? Pins to connect ODAC with O2 and 3.5mm socket to get direct ODAC output. Does such setup affect the output quality with some negative influence of O2 input?
In all manuals we can see 2 methods to connect O2 and ODAC according to usage of 3.5 input socket: 1) to keep O2 input on it, 2) to change it to ODAC output.
However, ODAC has two outputs: four pins in the middle of PCB and 3.5 mm socket. Why nobody uses them both? Pins to connect ODAC with O2 and 3.5mm socket to get direct ODAC output. Does such setup affect the output quality with some negative influence of O2 input?
Hi all,
I built my amp about a week ago and have no problems on battery with ac plugged in, but on ac without the batteries I can just barely hear the music.
Is this normal behavior, or is my amp defective in some way? My power cord is 15V AC 500mA testing at 18V AC so I am positive it is not the problem.
I built my amp about a week ago and have no problems on battery with ac plugged in, but on ac without the batteries I can just barely hear the music.
Is this normal behavior, or is my amp defective in some way? My power cord is 15V AC 500mA testing at 18V AC so I am positive it is not the problem.
Measure the supplies on battery and then mains and post the results back here. In particular, are you getting the -/+ 15 volts from the two regulators when running on mains.
Edit... 12 volt regs aren't they. Haven't got the circuit in front of me.
I am very new to audio so would you please explain which places I am measuring and which setting I am using to measure them?
My step-dad did all the measuring while I was building this, and I have no experience with a multimeter.
Firstly, in post #1 of the thread there is a fault finding guide that I put together. Its in the link at the bottom of the post.
OK, you put your meter on DC volts, and if you have to manually select a range then use something like 25vdc or higher. To make sure your meter is reading as expected try it across a 1.5volt battery first and make sure you get something in the ballpark displayed correctly. When you are happy that you can use the meter to measure DC voltage we move on 🙂
Now connect the black lead of the meter to the O2's ground (that's any part of the circuit marked with the ground symbol. The black lead stays connected there for now.
Now try and follow the tests (using the red lead to probe the voltage points) I describe in the first post link. As your amp works on batteries you have no need to remove the opamps. Work your way the through the tests that will confirm if the regulators and supplies are OK and report back with any unusual readings.
And be careful measuring. If you slip with the meter lead and short something out then it could damage components.
I get no reading on D5, and on ac power all the op amps only read 0.2V DC.
Could the one diode be the entire problem or is there something else?
I checked all the nearby electronic stores today and the only diodes I could find are 1N4001/4002/4004/4007, will either of these work as a replacement for the 1N5818 in D5?