After all, your power supply is tasked with making AC into DC to begin with. Get a 24 volt cell arrangement with enough ah (amp hours). This circuit pulls practically nothing. The one that you have shown here is more than enough.
If properly made, that beats switching brick any time of the day 😉 You'll "see" benefits easily.
Well, it happened to me. Dead left channel in the Nutube. I was swapping components in and out and touched some patch cords together and got a horrible bit of feedback through my speakers and started unplugging stuff. Maybe I bashed the preamp? I dunno. I bought this thing in 2020 and finally got around to assembling it in 2023! Anyway, I haven't left it on all the time although it's been left on for days at a time. Sucks because it's worked flawlessly since the first time I powered it up. Minor ringing when I flip the source switch or rap on the case but that's it.
Anyway, about to order a new nutube but wanted to sanity check my voltages before I solder it in. From what I'm reading this checks out with blown channel readings as the voltage across T4 and then T6 should drop if the other channel was working.
T4 - 9.5
T5 - 9.53 🙁
T6 - .72
T7 - 20.6 🙁
T8 - 10
Considering rolling the 1000uF caps for some higher quality ones based on people's experiences but honestly it's sounded pretty good out of the box. Since I killed it and have to desolder some stuff I figured now would be the time.
Thanks in advance for any advice!
Anyway, about to order a new nutube but wanted to sanity check my voltages before I solder it in. From what I'm reading this checks out with blown channel readings as the voltage across T4 and then T6 should drop if the other channel was working.
T4 - 9.5
T5 - 9.53 🙁
T6 - .72
T7 - 20.6 🙁
T8 - 10
Considering rolling the 1000uF caps for some higher quality ones based on people's experiences but honestly it's sounded pretty good out of the box. Since I killed it and have to desolder some stuff I figured now would be the time.
Thanks in advance for any advice!
I have a few spares, graciously sent to me by Korg via Mr. Miura, critic for Stereo Sound of Japan.
Email me with your address.
😉
Email me with your address.
😉
Papa is a generous soul!
If you're swapping in a new Nutube, might I suggest the Pete Millet ( @pmillett ) isolation modification. I used them and I think it helps reduce microphonics. Pretty affordable for the mod.
http://www.pmillett.com/
May also be worth using Zen Mod's "soft heat" circuit to dial in voltage just right. Not necessary in any way, but seems like a good mod as well.
If you're swapping in a new Nutube, might I suggest the Pete Millet ( @pmillett ) isolation modification. I used them and I think it helps reduce microphonics. Pretty affordable for the mod.
http://www.pmillett.com/
May also be worth using Zen Mod's "soft heat" circuit to dial in voltage just right. Not necessary in any way, but seems like a good mod as well.
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When I put it together initially I was all "Hey, the voltages line up and it works!" and never thought about it twice. Now I'll be watching T4/5/7 like a hawk to make sure they're within spec! 🤣
I like the idea of the "soft heat" mod so that might be on the list.
This is why DIY audio rules!
I like the idea of the "soft heat" mod so that might be on the list.
This is why DIY audio rules!
I concur with the use of the Pete Millett isolation mod. It immensely improves the issues with microphonics. I've done it with both my builds and I can literally tap on the top on the chassis with no resulting sound effect. I'll be putting on the Zen Mod circuit on both the units as well. I've had to change out the Nutube once already due to one channel going dead when I turned the preamp on.
If you guys like, i can post flex pcb gerber here for that mod. You only need to source sponges. Perhaps a GB if enough people are interested, to have the cost down since reinforced flex pcb is costly.
<If you guys like, i can post flex pcb gerber here for that mod. You only need to source sponges. Perhaps a GB if enough people are interested, to have the cost down since reinforced flex pcb is costly.>
Sure, I always love having people copy my stuff without permission.
Sure, I always love having people copy my stuff without permission.
I currently use separate pcb with thin wires to decouple, does the same job, but it takes more time to implement. It has one trace less (merged gnd), does it count a copy then? Not trying to be rude, but not seeing this as an issue.
I see Pete's name all over this thread and right there on my volume control board so let's not forget why a bunch of us have this thing on our shelves. Lots of people doing lots of great work and sharing it with the community. I've been to Pete's site and seen all kinds of cool stuff I wish I could build but alas, I'm one of the people hoping there's a kit someday. But for the record, right there at the top of Pete's site is a notice saying please don't copy my stuff without attribution. Thanks Pete for sharing your work!
Not trying to contribute it to my name, and it was a talk about petes decoupling, being heavy implied. I can post my own decoupling solution, it's cheaper, does the same thing, but harder to implement. Still having difficulty understanding, since using sponges to vibration absorb is nothing new, using flexible pcb for extension is nothing new.
Hey, more solutions sounds good to me. Just throwing in my 2 cents and a thank you. Looking forward to a kit from someone. 🙂
I do have a limited quantity of the Korg NuTubes, the gift from Korg I mentioned at the beginning of this thread.
If there is enough interest perhaps we could have an offering handled through the store...
If there is enough interest perhaps we could have an offering handled through the store...
