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Thanks for the update Dinx, we’re glad you can finally enjoy your universal.
We’d love to see a picture of your motorized pot, we actually had the same idea and ordered in a genuine alps to replace the generic one. Does it last long on the 9v cell?
Cheers!
CharlesHi Stan,
The yellow heater wires are definitely a little trickier than everything else. I’m using the same stuff in the build video that you use in the kits so it is definitely possible to get them to take a twist. Here’s a couple of things that might help.
Make your twist tighter, as tight as you can get. We included lots of extra heater wire so if you lose a bit of distance it’s not a big deal.
Twisting “Technique” is key here. When you’re twisting two wires together you want to make sure you’re doing three things at the same time. With your off hand that’s holding the already twisted wire, you want to make sure you are grasping it firmly just back from where the next twist is happening. Essentially you’re supporting the current twist until the next twist locks it in place, then you move up with it to the next one. Next, when twisting you want to make sure that you are twisting both of the wires around each other evenly and at the same time, it can take a bit of practice to get this right (It took me a bit) but you want the two to be as even in their twist as possible. This helps the twist hold a lot better. Next, once the twist is done, you want to continue holding those wires while you move up your other hand to “Capture” that twist with the thumb and forefinger. Essentially at no point does the wire have the option of unravelling because you’re always holding onto both wires in some way.
Take your time with it, I didn’t show me twisting the wire on camera fully because it takes time to do it right. My instinct is to rush with it, and sometimes I even have to go back when I see I twisted a section unevenly or too loose. So try to be patient with it and follow the above advice and it should make a difference.
Let us know if you have more trouble with it, and thanks for posting on the forums to add to the resources for the kits.
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!
Hi Gilbert,
Sorry for the late reply here, we’ve had a busy few days. I would first try a different SMPS if possible and see if that eliminates the issue. If you could share some photos of the build as well for us to review, that could help us track down any issues.
Thanks!
CharlesHi Dinx,
Can you describe your setup for us? The way the universal preamp is designed, is so that the grounds between the input and output stay isolated from each other to prevent ground loops. This should work in the majority of the situations, but let’s see how you have things setup and go from there.
Charles
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, 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.
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,
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
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. 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.
That’s great to hear Marc!
We like the extra set of inputs as well and think it adds some nice versatility, while saving a lot of cable swapping.
Thanks for being one of our first test builders and helping us make these kits even better.
That 18mm pad was another mistake on my part, but we’re going to have that fixed for the main kits. You’ve been a great help to us already. I just finished uploading up to episode 8 on the channel so hopefully that will help you along.
Let us know if you need any more guidance in the meantime.
Hi Marc,
Yup, you’ve got the right idea. You should be able follow most of the e80cc build and apply it to the 6or12sn7 universal kit. The capacitor mounting method is the same as on the Yuri as well. Just watch the length of your leads.
The biggest differences are the DC in resistor to drop 7v to 6.3v and the PCB.
Let us know if you have any more questions and we’ll help you along.
Charles
Hi Marc!
Thanks for building one of the first kits. It sounds like you’re having fun with it.
When Jim brought the PCB issue to me it was a bit of a “duh” moment. I spent so much time trying to get the board design perfect, I hadn’t considered that the socket pins could be cutting it close to shorting on the jumpers. We’re going to provide some electrical isolation on future kits and the issue is going to be fixed on the next board revision.
So this was great feedback and exactly the reason why we want to work with test builders first. An extra set of eyes will often see something we missed.
More build videos coming soon (though at this point we might have to catch up to you!).
Have fun and stay safe,
Charles