Korg nutube - Page 1
Forum section: electronics / general

author: bd139
author_rank: Super Contributor
timestamp: December 19, 2017, 07:53:32 am
content: Interesting idea:http://korgnutube.com/en/And you can actually just buy them:https://uk.rs-online.com/mobile/p/double-triode-valves/1449016/Edit: and they have design tutorials:https://www.rs-online.com/designspark/design-of-a-korg-nutube-amplifier-part-1-tube-basicsNow to mug some guitarists. Mwuhahaha.

author: ataradov
author_rank: Super Contributor
timestamp: December 19, 2017, 08:48:06 am
content: QuoteAnd before this glorious invention we had no practical use for VFDs?QuoteWhat is so unique about vacuum tube sound that can't be reproduced by a digital post-processing?

author: bd139
author_rank: Super Contributor
timestamp: December 19, 2017, 08:58:07 am
content: You’re 100% right on both counts. However when someone starts selling a new tube I think about shrugging my morality for a bit and jumping on the bandwagon. Gotta eat.

author: kalel
author_rank: Frequent Contributor
timestamp: December 19, 2017, 09:08:54 am
content: Whatever the sound difference might be (I really don't know), the question is is it being emulated by signal processing on many consumer devices (for example an effect you can choose)? This probably needs a bit more work and might not be included in many devices.You can definitely use various VST plugins on a computer, but I'm not sure if they exist on consumer devices made specifically for music playback.

author: ataradov
author_rank: Super Contributor
timestamp: December 19, 2017, 09:11:02 am
content: Quote from: kalel on December 19, 2017, 09:08:54 amThere may be a couple of reasons to not include that. There is either no difference, or difference is negligible. Or people that go for this kind of thing are looking for physical glass, not the actual sound.

author: bd139
author_rank: Super Contributor
timestamp: December 19, 2017, 09:17:38 am
content: Tubes are a faith argument so it’s about money or no money really.Oh and supporting a dying VFD company

author: CJay
author_rank: Super Contributor
timestamp: December 19, 2017, 12:23:41 pm
content: ISTR these Korg NuTubes are low voltage and actually look very little like a 'traditional' valve/tube so they may not satisfy the afficionados for whom a glowing matched pair of KT88s or EL34s is the only real answer (where and how it needs to be inserted is a matter of hotly debated opinion of course)I was going to order a couple to play about with as they look fun but wow, expensive, for the next couple of months I'll stick with silicon and maybe next year if I can sell on some of my junk^h^h^h^h valuable collection of vintage electronics I might treat myself to some.

author: iampoor
author_rank: Frequent Contributor
timestamp: December 20, 2017, 08:41:43 am
content: Quote from: ataradov on December 19, 2017, 08:48:06 amWhat is so unique about vacuum tube sound that can't be reproduced by a digital post-processing?Sonically, you can get very similiar results, but sometimes the dynamics and "feel" of playing through digitally emulated vacuum tubes is just off. This is especially important in certain styles of music, and with certain guitar tones (Blues music comes to mind)! Of course, I am specially referring to vacuum tube guitar amps, many of which have little to no negative feedback.Of course, this is a subjective opinion, but one that I have found many musicians I know have. I wonder if it has to do with the digital approximation of the transfer curves not being completely accurate? Also might be manufacturing tolerance of tubes, from my understanding, the parameter variation is pretty wide.

author: ataradov
author_rank: Super Contributor
timestamp: December 20, 2017, 09:01:17 am
content: Quote from: blueskull on December 20, 2017, 08:59:26 amBut you've got to admit they look cool.I think they missed the price point though. This needs to cost at least $150-200. Otherwise the stereo base is too narrow.

author: Unknown
author_rank: Unknown
timestamp: December 20, 2017, 09:21:48 am
content: QuoteThe 'warm' valve sound is actually because of a lack of linearity but that whole page has obviously been written by marketing and is full of freshly laid BS.I don't really get the whole DSP quest, surely it's better to use them to improve the sound. The beauty of valve amps is they are really simple and you can knock one together in an afternoon, spending months emulating this in a DSP seems like a lot of wasted effort.

author: iampoor
author_rank: Frequent Contributor
timestamp: December 20, 2017, 09:49:34 am
content: Quote from: ataradov on December 20, 2017, 09:01:17 amConsidering how many well manufactured modern production tubes are avaliable for under 15$ a pop, I dont think so.This is targeted at the musical instrument market in low budget applications.http://www.voxamps.com/MV50

author: CJay
author_rank: Super Contributor
timestamp: December 20, 2017, 10:10:08 am
content: Depends what the amp is for but why shouldn't people use valves/tubes if it gives them a sound they like?For musicians a valve amp is as much a part of the instrument as, for instance, the neck of a guitar or even the strings and a good guitarist will 'play' the amp as well as the guitar.Now if we are talking HiFi then colouring the reproduction of the input signal is a bad thing IMHO, I want my amp to be able to produce clean bass, sharp clear highs and not add its own sounds.

author: bd139
author_rank: Super Contributor
timestamp: December 20, 2017, 10:24:47 am
content: Got to agree there. Some good points.The "high end hifi" is where the crackpottery is really.

author: GK
author_rank: Super Contributor
timestamp: December 20, 2017, 01:28:35 pm
content: Wonder how microphonic they are. Datasheet specifies a "Resonance Frequency" of 5.8 kHz, but says nothing else with respect to microphony (no sensitivity spec. for a specified operating point with respect to acceleration). How much warm glow do you get from a pair of 12mW heaters? Maybe the purported glow is vacuum fluorescent-like if you wind the anode voltage up high enough.There was also this new twin triode a few years ago by a company called Techtube IIRC. This creation might have been the last gasp of a dying CRT manufacturer as the tube looks internally like a pair of re-purposed CRT electron guns. Company went belly up as far as I can tell.

author: rdl
author_rank: Super Contributor
timestamp: December 20, 2017, 02:13:22 pm
content: Quote from: blueskull on December 20, 2017, 08:59:26 amI actually like lights on audio equipment, preferably blinky active ones. I think they missed an opportunity here. I bet it wouldn't have cost that much more to add some pulsating bargraphs or some such thing. No reason audio can't be fun.

author: CJay
author_rank: Super Contributor
timestamp: December 20, 2017, 03:32:16 pm
content: [quote author=rdl link=topic=100708.msg1379852#msg1379852 date=1513779202I actually like lights on audio equipment, preferably blinky active ones. I think they missed an opportunity here. I bet it wouldn't have cost that much more to add some pulsating bargraphs or some such thing. No reason audio can't be fun.Isn't that the whole reason for listening to music, fun?

author: kalel
author_rank: Frequent Contributor
timestamp: December 20, 2017, 03:51:18 pm
content: Music is definitely about fun. I like little audio spectral analyzers (with LEDs or whatever). I prefer those that do actually work (there are some fakes ones too, responding to audio level only and simulating the frequency data).

author: woody
author_rank: Frequent Contributor
timestamp: December 20, 2017, 04:02:36 pm
content: Turns out that SlimDevices were really ahead of their time. Lights, spectrum, AND a VFD

author: CJay
author_rank: Super Contributor
timestamp: December 20, 2017, 04:30:05 pm
content: Quote from: woody on December 20, 2017, 04:02:36 pmNow there speaks a person who probably didn't live through the 80s boombox fashion...

author: woody
author_rank: Frequent Contributor
timestamp: December 20, 2017, 05:00:08 pm
content: Quote from: CJay on December 20, 2017, 04:30:05 pmWanna bet??

author: SeanB
author_rank: Super Contributor
timestamp: December 20, 2017, 05:24:10 pm
content: Wonder just how good a regular run of the mill VFD would work there, it does after all fit the definition of a directly heated triode, having a heater, control grid and anode. Wonder if I should dig out some of the old single digit VFD devices I have and see if they actually have any gain as an amplifier. Multiplexed array will be harder to use, though you do get multiple anodes in there, or you can have a mixer using multiple grids to modulate the current.

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 20, 2017, 06:29:28 pm
content: Quote from: SeanB on December 20, 2017, 05:24:10 pmYes, it should work, the orininal audions were just lightbulbs with bent wire and a piece of sheet metal. But it won't be very good, with those teeny tiny dim filaments and an emmisive anode pissing away the electrons. Ideally, the amplication would be the same as a battery operated tube, but I doubt it. I don't know how it will effect the amount of electrons reflecting off the anode either. As a tube guy, I wouldn't use this joke of a toy for anything other than a display. Total wankery. I don't have anything against mini or flat tubes, but the fact they only have a single tiny filament for that size of anode, their anode does not maximize the electron collection (IE it's not wrapped around the filament) and that they sprinkled glowy crap on their anode for no reason, means they are just playing pretend and know nothing about amplifier tubes.

author: CJay
author_rank: Super Contributor
timestamp: December 20, 2017, 06:45:25 pm
content: Quote from: SeanB on December 20, 2017, 05:24:10 pmThere are youtube videos and blog posts dedicated to that very subject, I think one of them even suggests that a VFD is useful as an RF amplifier*edit* It's not even a new discovery, this one is from 2005 or earlier...https://www.electronicspoint.com/threads/vfd-as-an-audio-rf-amplifier.29314/

author: JPortici
author_rank: Super Contributor
timestamp: December 20, 2017, 06:50:23 pm
content: Quote from: bd139 on December 19, 2017, 07:53:32 amso they finally are available to the public.. huh. have yet to see a design with those

author: chris_leyson
author_rank: Super Contributor
timestamp: December 20, 2017, 07:07:40 pm
content: I was wondering when somebody would get around this, it's just a directly heated triode, in fact a dual triode even better. Uses easy to fabricate parts and planar construction. Of course the directly heated cathode limits the output power somewhat and the fluorescent anode, well I guess it's a direct indication of how much anode current you are drawing at least you get a visual indication if the it's biased up correctly. 30,000 hours operating life not so good. Forgot to add: at least it's putting some VFD manufacturing plant to some good use and you never know there might be some interesting spin off from it.Just got the datasheet, interesting, I want one or maybe two

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 20, 2017, 07:18:14 pm
content: Don't buy them! That link provides more evidence that they're full of audiophool crap.QuoteTranslation: Ooo, our glowy schmoo provides amplification because we said so.Now, they at least openly admit their gain is only a max of five, but they claim to use less power and be small. Now I wonder what technology could compete with that? HMMM...

author: rdl
author_rank: Super Contributor
timestamp: December 20, 2017, 07:26:58 pm
content: The VOX MV50 guitar amps that use them seem to get good reviews. Of course, the power amp is digital. The Nutube is used as preamp.

author: Yansi
author_rank: Super Contributor
timestamp: December 20, 2017, 07:35:49 pm
content: typical gain of ... only 5?Thats a shite tube. Really shite for a guitar overdrive amp.

author: chris_leyson
author_rank: Super Contributor
timestamp: December 20, 2017, 07:42:40 pm
content: Quoteand only £26.31 from RS Components Stock No. 144-9016

author: Yansi
author_rank: Super Contributor
timestamp: December 20, 2017, 07:57:43 pm
content: I've noticed that too. I think we won't be quitting designing from convetional tubes anywhere soonAnd by the way, I came up with the idea to use a VFD display as an amplifier tube, when I was like what... 13 years old?But in fact never tried, as from many experiments with VFDs I already knew the gain was very small (you need to change the grid voltage a LOT to move some anode current).

author: calexanian
author_rank: Super Contributor
timestamp: December 20, 2017, 08:05:15 pm
content: Is this any more practical than a cheap tube from china, of which there are millions out there already in general use? If this is a real market, I might have a crack at it. I can literally make a better twin triode in my garage that will at least plug into a 9 pin socket and handle proper voltages found in those circuits. Perhaps it is time for me to make audio tubes.

author: bd139
author_rank: Super Contributor
timestamp: December 20, 2017, 08:55:34 pm
content: It looks cool though. Normal tubes are a bit shit. I bought a 12AU7 for something a while ago and was disappointed that you could barely see the heater glow. RF PA tubes are the only really interesting ones.

author: rdl
author_rank: Super Contributor
timestamp: December 20, 2017, 11:21:18 pm
content: I've got one of those S5 kit amps. It's been stored away for years, but best I remember the tubes lit up okay. You could at least see them in a normal brightness room.

author: floobydust
author_rank: Super Contributor
timestamp: December 21, 2017, 04:02:04 am
content: The "basic circuit" Nutube is totally cringe worthy. Run it at the very low end, plate supply 12V at 18.2uA and 0.7V 17mA filament.It looks internally like a repurposed VFD.

author: Cyberdragon
author_rank: Super Contributor
timestamp: December 21, 2017, 06:05:27 am
content: OUCH, MY EYES!That's a nasty circuit! Nitpick time! First of all, they used another transistor as the preamp, instead of the other section of the tube, which remains unused. Their tube requires 40V minimum plate voltage, but they run it from 5V to 30V and require positive bias, which is called space charging, which can yeild gain (in fact tubes can pass significant current in space charge mode, the highest I've personally recorded is 160mA at 12V, this tube will definately not achieve that though) but I don't think it's good for linearity or distortion. Their volume control is varying the bias...Just...stop...no, that's not good for consistant operation, unless this is a crude distortion control.

author: iampoor
author_rank: Frequent Contributor
timestamp: December 24, 2017, 05:19:19 am
content: Quote from: Cyberdragon on December 21, 2017, 06:05:27 amHave you ever designed a guitar amp, or do you play guitar? I think the variable bias volume control is a rather clever way to design an amp that can be easily overdrive with pedals or playing dynamics. But thats the musician in me speaking.