On mine the RCA's are isolated and so are the transformers.
The '-' outputs of the DAC chip are not the same as a ground reference as It's a differential DAC chip, at least this is how I think it is (I may be wrong?)
The only reference to ground in my DAC is the one from the mains socket to the 0v connection to the anolog section of the PCB.
Someone can please correct me if I'm mistaken 🙂
The '-' outputs of the DAC chip are not the same as a ground reference as It's a differential DAC chip, at least this is how I think it is (I may be wrong?)
The only reference to ground in my DAC is the one from the mains socket to the 0v connection to the anolog section of the PCB.
Someone can please correct me if I'm mistaken 🙂
This is unsafe practices!
Connect the mains sockets safety ground with a thick yellow/green litz wire DIRECTLY to a big screw (why not M6, I remember a lecture by Morgan Jones) with star washers to the enclosure.
The connection should not be soldered but crimped and the yellow/green wire should be longer as the mains wires (when you pull out accidentally the mains socket, the ground should be disconnected as the last wire).
You can left the DAC's ground and circuit floating.
Should you have some hum problems, you can connect the DAC's ground to the same M6 screw.
Franz
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Or disconnect it 😛
In my symasyms i cant connect the safety ground to the ground of the amp, else i have strange noise on the speakers. but i dont recommend to do so, since its not 100% safe.
Yes you are correct the tamura trans connection has a ground connection but I dont think its required for the UTC-A20 I read about a 200 threads ago I think, If someone has a UTC-a20 can they please confirm this.
Thanks
I'm not too sure how connecting the mains earth to my MDF case is going to be much good 😛
No hum issues here, or any other issues.
That's OK Franz, how were you to know 🙂
So are you also saying that the PCB doesn't require a connection to ground?
So are you also saying that the PCB doesn't require a connection to ground?
Yes, it is not needed.
However: when you connect it to ground, you will shot the fuse as soon as some circuit failure should appear.
So if you have no hum problems: don't touch a running system 😀
Franz
However: when you connect it to ground, you will shot the fuse as soon as some circuit failure should appear.
So if you have no hum problems: don't touch a running system 😀
Franz
Hi Ryssen 🙂
Do you have a connection to the '0' connection at the anolog input of the PCB?
Ground loop maybe? I'm not the best one to answer though.
How have you got the board connected?
How have you got the board connected?
Try grounding the A-20 cans to ground, and I don't mean the RCA ground. I had a slight amount of hum with the open frame Tams but my canned trafos are dead silent being grounded through the chassis mounting. If you are using wood or mdf you will just have to try different arrangements. Just try to keep the active circuitry isolated if you can.
Getting back to those 10k/600ohm trafos, those are 4/1 ratio, and almost any trafo can be used in either direction. I would not even try them with this dac unless you need 8v of output for some reason. If you used them the other way you would have lots of output current but very little voltage. 5k/5k trafos would probably be close to perfect if you could find some, 10k/10k should be ok if the trafos are really well made, like the Jensen Isomax units
I'm using a chassis from an old digital set-top box, so how do I ground the traffo's if not on the RCA ??.
If you mean the analog output ground to the 0 at the trafo input,yes theres a connection(on PCB).
I use Lundahls trafo,and I have no hum from them or the opampoutput.
As mentioned above try grounding the cans.
RCAs dont actually have grounds, they are signal returns. Everyone calls them grounds but they are not. Look inside any piece of high end equipment and you will see they are totally isolated from the chassis ground, which is the ground I always refer to. In your unit, the case should be tied to the ground wire of your power cord, and the trafos will be grounded if they are bolted to the case. If you still have hum then you will have to figure out where it's coming from. It's tough to give any more help but there are a bunch of things to try.
Huh?
It's not me that has hum, I was just curious how you had yours hooked up 😉
@ Bill, thanks for those comments on the 10k/600ohm ones 🙂
