- This topic has 12 replies, 2 voices, and was last updated 1 year, 1 month ago by .
-
Posts
-
Hello folks.
I might be ahead of schedule here, but I have a question regarding the signal path wiring so far in the build process. I have noticed that the instructions are to only attach the ground in the signal wire to the phono socket, and not to the driver board. According the schematic the signal ground is part of the loop, as should be, but for now my kit does not have signal ground comming in since the phono socket is isolated from the chassis, and the signal wire from the phono socket is isolated from the driver board. The prototype has this wiring, and functions, so my question is should the phono socket not be isolated from the chassis perhaps? Or should the signal wire carry ground from phono socket to the driver board?Hi Sondre. So on the GU50 the signal wire central conductor is what carries the signal and it gets attached to pin 2 on the GU50 socket. On that end of the signal wire, the ground is cut off and not connected to anything. On the other end at the driver board, there’s a “Signal Out” blue junction. The central conductor that carries the signal goes to the positive terminal, the ground shield goes to the negative terminal and it will have a path to ground from that point through the board and the black lead that then goes to the star ground.
One of the differences that you might be noticing with the prototype is that R7, which is a resistor that goes to ground, used to run directly from the GU50 pin 2 to the tag strip, and then to ground. That resistor was moved to the new driver board to make assembly easier.
I hope that clears things up. Let us know if you need more clarification.
Hi Sondre,
So the pin 7 ground on the tube is just for the internal shield.
When you say “Phono Socket Ground” I assume you’re talking about the RCA in jack? If so, it isn’t connected to the ground of the chassis intentionally so we can isolate the grounds between the pre-amp and the GU50. The ground from the pre-amp will be connected to the RCA shield conductor.
Once the amp is hooked up in circuit, it will have a ground path.
Sorry about the confusion! Technically the driver board is designed to allow a ground wire to be connected at that blue junction (The signal in junction) and it will connect with the rest of the ground path present on the signal board. We design each of the boards this way so we can choose where to take the ground off. However, if we connected the RCA ground to the board, and the board to the chassis star ground, we would then have a ground loop. Where the amplifier has two paths to ground, one through its own IEC socket. And the other through the RCA cable and the pre-amp.
The schematic shows it as being connected to ground because it will be when it’s running. But I’ll have a talk with James about this and see if it’s better to change how we display this on the schematic so it’s less confusing and more accurate to the real world.
Charles
Hi Sondre,
Small correction. So I talked with James and we reviewed the schematic and the schematic for the amp starts at the “Signal IN” junction on the driver board. So the RCA in plug with its lead is not shown, and the schematic is true to the build.
Charles
Ah, so in your case if the amplifiers don’t share a common ground through the house wiring. Then you’ll want to modify the signal lead from the RCA in so that the ground lead connects to the driver boards signal in. The same as the one that leaves the driver board towards the GU50 socket.
Are you going to have enough signal leads left to get this done?
Hi Sondre, just had a conversation with James about it. If the signal leads is already made up, he’s asking if you can finish the build as is and test to see what happens. We’re curious about the wiring setup and what impact it will have on the build. If it doesn’t work, then modify the build to include the ground connection. Let us know if that works for you.
Interesting, well let’s see what happens with it. This is why we value test builders so much, keep us up to date. I’m going to get back to the build videos!
Hi Sondre,
Sorry I’m just replying now. Thanks for testing that for us, go ahead and make the mod and let us know how it turns out!
- You must be logged in to reply to this topic.