Here's the first revision of the mini-build guide for installing Zen Mod's Soft Heat circuit for the Korg NuTube B1 preamp. Feel free to post pictures of the modified board here to help others understand how to go about doing it.
Here's Mouser cart link for folks who want to buy the parts themselves.
Note that NO Trace Cutting is required with this approach. Removing the 270 ohm resistor is the "cut" and allows one to revert back to the original design w/o the soft heat circuit easily if one so desired.
Here's Mouser cart link for folks who want to buy the parts themselves.
Note that NO Trace Cutting is required with this approach. Removing the 270 ohm resistor is the "cut" and allows one to revert back to the original design w/o the soft heat circuit easily if one so desired.
Last edited:
Birdbox, have you actually built one of these "heaters?" I posted a question to Zed Mod concerning the interface of the back of the LM317 chip with the board & whether an insulator has to be used.
Thanks, Pete
Thanks, Pete
I do not believe an insulator is needed. A quick check of datasheet would confirm. If there's concern is heat dissapation, I don't think the Korg draws much current.
I populated a few PCBs and I didn't use an insulator, but have not yet got them installed in my Korg B1's yet.
I populated a few PCBs and I didn't use an insulator, but have not yet got them installed in my Korg B1's yet.
Last edited:
So here are my two implementations of the Zen Mod soft-start/heater boards on two different B1Ks. The vertically positioned one was allowable because of greater clearance in the case in which it resides. I used solid core wire which held the boards in place. R2 was changed to 137R (140R would have been fine too). This allowed me to adjust T5&T6 to over 700mV if so desired although I could not get T5&6 to get closer to 20mV to each other no matter what 0.1% 475R resistors I used on the B1K board.
Attachments
Oh, that's fantastic! Nice work. I'm probably going to copy your approach. What gauge solid core wire did you use to add the rigidity to the "floating" board?
Replacement NuTube from @Nelson Pass installed and working! Voltages set to 9.5V and I'm gonna hook it up later today. I did have one issue with the SoftHeat board. I wired it using jumper wires which are pretty stiff so right now it's just "floating". I initially had screwed a PC motherboard spacer onto the existing spacer and hogged out the opening of the board & voltage regulatora tad to accommodate the slightly larger PC screw. When I grounded the board the power LED would just flicker and not power up. The only thing I could think of is that I must have hit an internal trace inside the SoftHeat board by enlarging it?!? It was only a very small much, I used a drill bit and hand threaded it through. Anyway, gave up and just left it free floating.
Has anyone tried to squeeze the AmyAlice power board inside this case with the existing board? The only thing I can really think of is moving the existing NuTube board way over to the left and putting the AmyAlice board on the right side. Thoughts?
Has anyone tried to squeeze the AmyAlice power board inside this case with the existing board? The only thing I can really think of is moving the existing NuTube board way over to the left and putting the AmyAlice board on the right side. Thoughts?
Ok, here's what I came up with. If I was one of you guys designing these things I'd probably have spent more time but honestly I just wanted to get it put back together! I didn't have any of those tiny nuts but I did have a plethora of PC standoffs so that's what I used. 😀 I was a little off on one of the new holes I drilled so it's a bit off. In hindsight I should have replaced the existing power wires with something longer.
I can tell you it sounds fantastic! Maybe it's a little placebo effect but I swear it sounds a bit more airy. I set the voltages of T7/T8 to about 9.6 or so.
I can tell you it sounds fantastic! Maybe it's a little placebo effect but I swear it sounds a bit more airy. I set the voltages of T7/T8 to about 9.6 or so.
Attachments
@bjsilverballs
I think you did a great job of implementing both the AmyAlice and Soft Heat PCB's into your Korg B1 NuTube.
I plan to make a 3D printed "beam" that slides into one of the slots on the side of the standard chassis and allows the PCB to mount to that beam. I simply have not had time to design and test that out yet. Once I get a functional and tested prototype design in place, I'll post it for anyone to use.
Your solution is not hard to implement and looks to require only drilling some extra holes into the chassis bottom plate. Easy and simple solution.
I think you did a great job of implementing both the AmyAlice and Soft Heat PCB's into your Korg B1 NuTube.
I plan to make a 3D printed "beam" that slides into one of the slots on the side of the standard chassis and allows the PCB to mount to that beam. I simply have not had time to design and test that out yet. Once I get a functional and tested prototype design in place, I'll post it for anyone to use.
Your solution is not hard to implement and looks to require only drilling some extra holes into the chassis bottom plate. Easy and simple solution.
One could always use this version of the AmyAlice if space is limited in one's build (https://www.diyaudio.com/community/threads/amyalice-slim-smps-filter.409775/#post-7922919). I've built both the original & this slim version.
Cheers
Cheers
This was my first time soldering SMD components so I was thrilled that it worked first time. I watched a YT tutorial that made sense to me. The only thing that was more challenging was the flow through caps because I was using a chisel tip.
Next project is to assemble two more AA units and shoehorn them into my ACAs. Thanks again @birdbox !
Next project is to assemble two more AA units and shoehorn them into my ACAs. Thanks again @birdbox !
Soft heat installed and dialed in perfectly! Thanks birdbox and Zen Mod! Thanks Ixnay for parting with one of your NuTube B1 builds! Mark Johnson for the AmuAlice incoming power filter! Need to get it officially chassis’ed up but couldn’t wait to give it a listen!
