If you need high strength parts, I had some parts made by Xometry of SLS nylon. The parts are stronger than conventional prints of PLA, or PETG.
What printer do you use? Recommend? If you don't want to hijack the thread, you can PM me or create another DIY thread somewhere... I believe there's quite a bit of interest in those things.
Hey guys, me again . . . so I'm scratching my head here. Was listening last night to some vinyl and after a few songs my left channel went out. Had my phono stage going into the B1 into ACA. I poked around and one weird thing I noticed is when I shut the B1 off the left channel would suddenly come to life as it powered down for a second or so. Swapped my tube set up in and everything was fine. The ACA is working fine so it's the B1. Voltages are below and all within spec. I've read about some people having issue with the NuTube but it seems odd to work fine for a week or so then just die. Haven't done anything to this since the original build. Just sitting here it's giving me an intermittent popping and static out of L channel. Sounds like a noisy tube sound. Thoughts?
T1 24.04
T3 22.40
T4 8.88
T5/6= 0.95/0.95
T7/8= 9.98/9.97
T1 24.04
T3 22.40
T4 8.88
T5/6= 0.95/0.95
T7/8= 9.98/9.97
I'll give it a go reflowing everything just to be sure. What's the deal with these nutubes? Do they have a warranty or something? I know $50 isn't anything like a 1000+ WE 300B but it's still $50 and I would expect more than a week or 2 out of the thing. The filament wire looks OK and was never glowing or showing signs of failure.
Are there any tests I can do to see if it is the tube? I have a fluke 117, LCR 45 impedance meter and a Velleman DCA55 on my bench
Why would the L channel all of a sudden come back to life for a second or two when the power is shut off on the B1? That's what has me really baffled.
Are there any tests I can do to see if it is the tube? I have a fluke 117, LCR 45 impedance meter and a Velleman DCA55 on my bench
Why would the L channel all of a sudden come back to life for a second or two when the power is shut off on the B1? That's what has me really baffled.
besides checking predetermined test points and filament check (eye, ohmmeter), nothing else
I pulled the board and reflowed everything. Didn't see anything suspicious. At first all was well and then L channel started getting static and cutting in/out. When it was cutting in/out I was measuring T7 and the DC voltage was dropping off as that channel cut out. Is this more likely a power supply issue? maybe a bad cap?
Tube resistance measurements are: F1/F1 = 11.5R, A1 330k, F2 0.4R, A2 338k, F3/F3 11.5R
Tube resistance measurements are: F1/F1 = 11.5R, A1 330k, F2 0.4R, A2 338k, F3/F3 11.5R
Alright, I can't think of anything other than the nutube died. Pulled the 1000uf elna ROA caps from the left side and replaced with some nichicon PW 1000uf 35v I had lying around. All the Elena's measured good but figured what the heck. Same as before. Now T7 is able to be adjusted to 10v but after a min or so of warming up it starts static in L channel, tube glows very weak on L side and DC voltage drops to 2 or 3v and doesn't respond to the potentiometer anymore.
Looking at the schematic, T7/8 are after the triode so it makes sense. Can't be power supply caps since they're shared R/L.
Any other ideas or should I just order a new nutube?
Any word about possible warranty with these things?
Looking at the schematic, T7/8 are after the triode so it makes sense. Can't be power supply caps since they're shared R/L.
Any other ideas or should I just order a new nutube?
Any word about possible warranty with these things?
well, choice:
- order new "tube"
- reuse hardware for something else, and build proper tube preamp
@Zen Mod - I was hoping for somewhat more technical advice but point taken. This is my first B1 build and you obviously have much more experience with these than I do- is there anything else I should look at with this specific problem I'm having or is it clearly the nutube at fault?
Regarding a "proper tube" preamp- have people repurposed this circuit with a 9 pin tube adapter and some power supply/circuit tweaks? Or were you stating that I should build something else from the parts?
Regarding a "proper tube" preamp- have people repurposed this circuit with a 9 pin tube adapter and some power supply/circuit tweaks? Or were you stating that I should build something else from the parts?
go back and see sort of soft heat circuit I drew, that's technical advice for preserving Korg tube life
my advice is, again - buy new tube and repair it, or repurpose hardware for something else; I believe it's easy to tweak existing pcb to have sort of B1 , first edition
now, proper tube preamp - means proper tube, proper (high) voltage, and everything proper
Pa gave us so many things in decades, but we must be aware of quality of every project; KB1 is often on verge to be a gimmick, and not by Papa's mistake ...... as it enfolds, too many cases of Dodo tube ... means not so good product
my advice is, again - buy new tube and repair it, or repurpose hardware for something else; I believe it's easy to tweak existing pcb to have sort of B1 , first edition
now, proper tube preamp - means proper tube, proper (high) voltage, and everything proper
Pa gave us so many things in decades, but we must be aware of quality of every project; KB1 is often on verge to be a gimmick, and not by Papa's mistake ...... as it enfolds, too many cases of Dodo tube ... means not so good product
Thanks Zen, do you know if anyone made a batch of those soft heat PCBs? That looks like the way to go once I install a new nutube.
This has actually been my first DIY experience with solid state and PCBs- the B1 and an ACA - all my builds before these have been point to point tube projects. Both have been fun and this community is really creative and knowledgeable.
If you were to build a solid state preamp which would you recommend? Sadly your iron pre is unavailable at the moment - any idea when that will be around again?
This has actually been my first DIY experience with solid state and PCBs- the B1 and an ACA - all my builds before these have been point to point tube projects. Both have been fun and this community is really creative and knowledgeable.
If you were to build a solid state preamp which would you recommend? Sadly your iron pre is unavailable at the moment - any idea when that will be around again?
@birdbox - Do you still have a few?
Matching the itsy bitsy 2SKs takes me a while, and other things in life have snatched a lot of bench time away from me. I'm hoping to have a batch available by the end of April.
My smd version of b1k didn't have an issue, but it has several possible mitigation measures. Firstly it uses tps7a4701 linear regulator which has soft start function, and it sounds significantly better than smps. Other is as many used here, nutube decoupling, there were many solutions mentioned, but the decoupling is definitely a must. Also i decouple board from the case with rubber trough hole isolators. No broken tube yet.
Hello brijac,
hello B1 NUTUBE-builders,
I have mounted my NUTUBE to an aluminum-plate. The aluminum-plate is isolated from the mounting screws / frontplate by rubber-grommets (see my post #1905 in this thread). I never had a problem with vibrations or microphonic effects.
My B1 NUTUBE is running now for 6 years without any issues. If I read here what other members/ builders are struggling with?
Hmmm...
Cheers
Dirk
hello B1 NUTUBE-builders,
I have mounted my NUTUBE to an aluminum-plate. The aluminum-plate is isolated from the mounting screws / frontplate by rubber-grommets (see my post #1905 in this thread). I never had a problem with vibrations or microphonic effects.
My B1 NUTUBE is running now for 6 years without any issues. If I read here what other members/ builders are struggling with?
Hmmm...
Cheers
Dirk
Could use a little help here - Not sure what to make of it. I got my new nu tube installed, also the soft heat board (thanks birdbox and ZenMod!). Everything working as it should and adjusted to spec. The KorgB1 sounds great as before but I've noticed 2 times now the left channel started blipping in and out. When I look at the tube you can see the glow on the left side going out as well. I'm just worried something weird could be going on and don't want to toast another nu tube. Just not sure where to go - the power supply is good. All voltage measurements are perfect. When it's working fine it sounds excellent. What the heck else could it be that would cause the left side to blip out ? All solder joints are good. I measured all resistors and caps before install. Any other component worth looking at or replacing? Could it possibly be the nu tubes are weak on the left side? I've read a few others having similar issues with left channel specifically.
Side note - the soft heat board went on nicely using a fiber standoff and nut over the existing corner standoff. Had 2 wires that have to criss cross but otherwise no big deal and easy install.
Side note - the soft heat board went on nicely using a fiber standoff and nut over the existing corner standoff. Had 2 wires that have to criss cross but otherwise no big deal and easy install.
