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Tagged: ui
- This topic has 11 replies, 3 voices, and was last updated 2 months, 1 week ago by clambton29.
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April 18, 2022 at 9:21 am #14170marchunterParticipant
Hi folks
Marc is my name and I started a build of the 6SN7 pre.
I got started with the PCBs as that is the first thing up in Jim’s video’s.
First off I want to just state that Jim has been so helpful and encouraging along the way. The parts are beautiful, especially the boards.
I am a novice at this but learning fast. I have built one amp so far and it is running and sounding beautiful. My soldering skills are getting pretty darn good.
Ok, as Jim says enough blah, blah, blah.
The PCBs went perfectly as all I had to do was follow Jim’s vid build. I did vary a little bit and built two boards at once. I found that to be pretty easy. So PCBs went together no sweat.
I then got a little antsy and started in on then signal boards. Jim doesn’t have a video out yet so I took a look at the E80CC vid and figured it looked pretty easy also. I knew that certain parts and places would change and was prepared for that. I did mess up one thing and that might have been fortuitous. I installed the jumper in the center of the board used in the E80CC kit. It’s not used in this kit. Oops.
But it did show that using the octal socket instead of the nine pin may (if forced down onto the board by a grizzly) come dangerously close to the pads for the jumper. I knew this because in installing the jumper the reverse side pads where the wire came through and the solder volcano was causing interference with the octal socket sitting flat. After Jim corrected me that the jumper is not used, I took it out and made sure the pads were clean and laying low. I have checked and checked mine and the octal leads are well clear of the pads. So my accident/mistake gave Jim and Charles a heads up to a “maybe” problem. Don’t be a grizzly!!!
Today I started in on the chassis/plinth. I gave it a very lightly stained oil rub and it really brought out the grain.
Looks beautiful.
More to come.- This topic was modified 2 years, 9 months ago by Jim Lambton.
April 18, 2022 at 9:42 am #14171clambton29KeymasterHi 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,
CharlesApril 18, 2022 at 9:59 am #14172marchunterParticipantThanks Charles
Enjoying it vary much.April 18, 2022 at 11:45 am #14173marchunterParticipantCharles I am mocking up the chassis and doing prep work on the parts.
On the two big caps on top I am assuming the prep is the same as the vid on the Yuri caps where Jim attaches a lead to each pole to be connected later. Is that correct?April 18, 2022 at 1:12 pm #14174clambton29KeymasterHi 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
April 21, 2022 at 7:27 am #14212marchunterParticipantWork progresses along.
I am using the E80cc build vids that I figure are universal as Charles suggested above.
I am loving the fact that this kit is thought out so that it can be taken apart and repaired or to fix my attempts at making things better that turn out to be steps backwards. For instance yesterday I had the bright idea to make things neater by strapping together wires. One problem, the wires were separate channels. I had an inkling that this may be a boo boo so I emailed Jim and asked about it. I can just see him getting the email and putting palm to forehead and muttering something about knuckle draggers. 🙂 Anyway he graciously confirmed my suspicions that it was not a good idea.
I have just drilled out the 30mm C4 pad to accept both the R6 resistor and the C4 capacitor. I had installed the C4 capacitor into the 18mm pad as it fit really well. One problem, the 18mm pad goes nowhere. Another mistake brought on by trying to be neat. Gotta get over that and pay more attention.April 21, 2022 at 8:06 pm #14214clambton29KeymasterThat 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.
April 25, 2022 at 10:48 am #14228marchunterParticipantWell well well, I have finished wiring my pre amp. The last thing I finished this morning was the heaters. Jim as usual was very generous with his answering my questions.
I wired it as to what I see depicted in the schematic. Jim tells me he would wire it a bit different and I can’t wait to see it. However he told me what I did will work fine. I’m trying to follow Jim’s design closely so that he and Charles can evaluate.
I then started to test the system and gave myself another problem right off the bat. I wasn’t getting the drop in voltage I was expecting. I only was getting .23 of a volt. This is where I figured out I’m not so smart. I was using the tubes Jim supplied with the kit. 12 volt tubes. Yes I know I’m stupid. I figured it out when I put a set of 6SN7s I have and got the perfect voltage drop then swapped the supplied to back in and again got a small drop. I then looked at them closely and saw, yes you are a moron, they are 12 volt. I write this down to keep others from doing the same thing.
Upshot is the heater circuit works perfectly.
I’m just waiting for a couple caps to install then I will be entirely done.
THANK YOU JIM.May 1, 2022 at 4:17 am #14254marchunterParticipantAll finished and playing music.
Let me go back to the beginning and tell you why I bought this kit. I have a set of mono blocks that are so wonderfully transparent it’s heaven. Only problem is you can’t run more than one source. So obvi I needed a pre. I started out with only the mono’s which were fed by a digital receiver/DAC. So the signal path is very uncluttered. Once you have the need for more sources you start to cloud the signal path with “stuff”. But I needed a way to play my vinyl as well as digital. So Jim and Charles’ pre kit was my answer.
I now have the same digital path as well as my vinyl and it’s fairly astonishing to me that I don’t hear any type of signal degradation with now a pre amp and a phono stage in line. Of course I hear the vinyl noise but that is a good thing. When I switch to the digital side I hear nothing different then what I heard before. THIS PRE AMP IS DEAD QUIET. That to me is where the rubber meets the road. On the digital side it’s the source I hear. On the vinyl side it’s the record and the recording I hear ONLY. This is a wonderful tool to evaluate recordings.
Thanks guys for a wonderful pre. You got it right.May 1, 2022 at 5:39 am #14255clambton29KeymasterThat’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.
December 7, 2024 at 10:16 am #17378Mike KisselParticipantI have finished my Universal Pre-Amp build and am very, very happy! I have two questions.
1) I believe this is just a happy accident. My front piece of plinth wood did not have a hole pre-drilled for the volume control. Since I use it with an amp that has volume control it didn’t bother me, so I just ran a continuous wire omitting the volume control. My question is, does this hurt the amp or tubes since it is being ran at full power all the time?2)In picking out a DC power supply for the 6V & 12V power supplies. What is the minimum and maximum amperage that should be supplied by the power supply.
December 8, 2024 at 12:52 pm #17383clambton29KeymasterHi Mike,
Definitely an accident on the plinth. I’m surprised we let that slip through, each preamp that requires a volume control has to be cut and drilled and have the volume pot manually fitted to it and it’s one of the last steps before we ship. So my apologies that this wasn’t done on your unit. I’m glad that it wasn’t necessary in your case, but if you ever decide it is then let us know and we will get you a replacement front panel or plinth with a properly fitted pot.
Having the volume pot out of circuit shouldn’t cause any problems for the amp or the tubes, as long as you have control of the volume at a preceding stage then you should be fine.
For the DC supplies, it all depends on what you intend to run. We like to go oversized with our DC supplies and use 5A for both the 6v and 12v versions. But you don’t need to go that high. We recommend somewhere around double the required current so the supply can safely handle the startup surge. If you’re using 6SN7 tubes, that would be 2 x 600mA for 1.2A total and 2.4A doubled to be safe. For 12SN7 tubes, it would be half that at 1.2A to be safe.
Cheers and happy listening!
Charles -
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