Korg is cutting into our turf

[bartimaeus]

Sounds like it was inspired teenage engineering's diy eurorack synths, which are basically just screwing modules into panels. I don't really mind it so long as it keeps costs down and people have fun (as seems to be true of the teenage engineering). Even if it might mislead people into thinking that diy is fun and easy haha...

But for $300 this is a bit insane... for 2/3 of the costs you can get those vox nutube amps which korg also makes So they're basically paying you $100 to get a poweramp instead of a footswitch

At least they do include the full schematic in the manual

[Kipper4]

I concur this is not DIY.
I can see how some folks would spend $300 on a toy for the weekend.They'd spend more on a t shirt.
I hasten to add I am not so fortunate to have met many but they exist.
Preferring to buy componants and associated tooling and stuff and turn them into a useable end product from raw materials. This satisfy me. The korg stuff would soon bore me.
            Ho hum.......Not my turf

[Ice-9]

It is more of a paint by number Airfix type of model kit really.

[Rob Strand]

Here's a couple of videos about the NuTube:

Korg are putting their money where their mouth is on this product.  I saw some alternatives to tube technologies some 15 years ago or so;  not DSP emulation but new devices that capture the physics of how a tube works.   Interesting to see how it pans out sound-wise.

I was thinking thick-foam double sided tape might help reduce the microphonics but looking through the data they already suggest some sort of sponge.

I noticed the 12V circuit has a positive grid bias, where as a 80V it's negative like a tube.

Anyone know if grid looks open or like a diode when it's biased positively?   The example circuits don't seem to limit the grid current.

[Ice-9]

The biggest problem with the Korg Nu-Tube for me is that I can buy a decent 12AX7 for £6 but a Nu-Tube is £50 plus vat. The footprint size is almost the same as well. Korg recommend rubber grommet mounting for vibration, double sided sticky backed foam ape is just a little too much Blue Peter for me.

[Rob Strand]

The biggest problem with the Korg Nu-Tube for me is that I can buy a decent 12AX7 for £6 but a Nu-Tube is £50 plus vat.

Yes not cheap.    I suppose they are marketing to the HiFi people who seemingly have more money to burn.

The way it's made looks expensive. It is probably a lot bigger than it needs to be but at least it's flat.   As to why it's that expensive I'm not too sure.  On one hand it's new technology so the starting production volumes are low and it's technology that needs some tooling up,  Both of these push-up the cost.  On the other hand VFD tubes aren't *that* expensive.   So perhaps at this early stage they are trying to recoup their investment with low production volumes and that means niche markets like HiFi.   Maybe they have along term plan that tubes will get more expensive over time and there will be a point where the Nu-Tubes will be cheaper to produce and will fill the gap with a smaller price difference.

This future stuff is never easy to predict.  Electric vehicles were quite developed in the 90s and they have edged their way in only recently.   The only difference is now the technology is established and governments can force the issue by phasing out petrol vehicles.

IMHO, I have a feeling DSP emulation could win since it is cheap to produce.

[Mark Hammer]

When I see pics of some of the pedalboards that basement warriors and 2nd-tier bar band players flaunt (and that's not a criticism or dissing of them, merely a recognition that they are not multi-platinum world-touring performers with a villa on the coast and a place in the Hamptons), the idea of a $300 overdrive is surprisingly pedestrian, and not beyond the whims of many.  It's certainly more than *I* would spend, but throwing another $300 at a pedalboard already worth $3000, is something more than enough players wouldn't bat an eyelash at.  Strymon, Meris, Chase Bliss and others making pricier pedals are not going out of business anytime soon, despite how many $40 1590A minipedals we see around.

[amptramp]

You could do a real DIY version of this if you use a VFD from a scrapped radio/clock/VCR or other items that used a VFD.  These items are not that common as new items but are commonly scrapped and available either free or cheap.  I have a number of Heathkits that I have built with complete documentation and step-by-step instructions and they are a level of DIY but on the sliding scale of box of parts -> Heathkit -> modules to fit together, this is the latter and it is not that far from the finished equipment.

[Rob Strand]

You could do a real DIY version of this if you use a VFD from a scrapped radio/clock/VCR or other items that used a VFD.

I believe someone already did that!

It's a long time since I've played with VFD displays but  I remember the heaters needed to be AC so the brightness was even.   The calculator displays have one or two common wires running across all the digits.     I remember one of the larger brands (Noritake?)  had excellent documentation on these things.  You don't want heater AC getting into the audio so maybe each digits will end-up working slightly different with a DC heater.

[Edit:  Here's one example but there's more out there,
https://www.instructables.com/id/VFD-Amplifier-a-Tube-Amp-From-VCR-Screens/
]

[bartimaeus]

I almost wonder if they're charging so much for the nutube to avoid other brands using it in bad-sounding designs? To make sure we all have a good first impression of nutube haha... I mean korg's vox mv50 use nutube, and those things are only ~$250, so clearly they aren't actually that expensive for Korg to make

[PRR]

> I noticed the 12V circuit has a positive grid bias, where as a 80V it's negative like a tube. Anyone know if grid looks open or like a diode when it's biased positively?

It's such a terrible tube it hardly matters. The grid conducts dozens of uA, not a mA.

> The way it's made looks expensive.

It's real cheap. It is an obsolete product. Remember VCRs and microwaves and car radios with light-up displays which were not LEDs (or LCDs)? They were Vacuum Fluorescent. The old magic-eye tuning tube, but with hundreds of segments (laid-out to your spec, multiple colors). That's all gone out of style. Noritake was scrapping the factory. KORG apparently saved one production line from the landfill and printed a basic no-glow triode on it. IMHO it is a piece of junk at any price; worse at 2X-5X the price of a real dual triode.

The hi-fi guys do have a DIY project around it but clearly the main commercial market is guitar effects.

EDIT Actually Noritake still makes other displays, but the consumer appliance market collapsed. They have displays for gizmos. Recognize this glassware?


https://www.noritake-elec.com/technology/general-technical-information/vfd-operation

[Rob Strand]

The grid conducts dozens of uA, not a mA.

I found some more detailed datasheets.  There seems to many PDFs floating around each with different snippets of info in them.

Remember VCRs and microwaves and car radios with light-up displays which were not LEDs (or LCDs)? They were Vacuum Fluorescent.

I was quite familiar them in the 90's.   At that time they were nice a bright and had nice colors.  Good chance the documents I used in the past were Noritake.

IMHO it is a piece of junk at any price; worse at 2X-5X the price of a real dual triode.

Some compromises need to be made since these things run a lower power.  Heater current is quite low.
The gain is pretty limited at 12V but things get a bit better at 80V.   Shame they didn't try to squash the size down more.

The video mentions a microphonic "ping"  I wonder's if that the mounting, the glass,  or the suspended heater wire?

[amptramp]

You could do a real DIY version of this if you use a VFD from a scrapped radio/clock/VCR or other items that used a VFD.

I believe someone already did that!

It's a long time since I've played with VFD displays but  I remember the heaters needed to be AC so the brightness was even.   The calculator displays have one or two common wires running across all the digits.     I remember one of the larger brands (Noritake?)  had excellent documentation on these things.  You don't want heater AC getting into the audio so maybe each digits will end-up working slightly different with a DC heater.

[Edit:  Here's one example but there's more out there,
https://www.instructables.com/id/VFD-Amplifier-a-Tube-Amp-From-VCR-Screens/
]

One point they make in the instructables is that new VFD's were coming out long after the production of 12AX7 tubes had stopped.  There are some new manufacturers of new 12AX7's now (along with a lot of output tubes), so the new tube business hasn't totally dried up.  Besides, there are plenty of tubes still around.  If you join an antique radio club or a ham radio club, you will find there is no shortage of tubes.

I have one radio at home which is a portable battery tube FM/AM radio (each descriptor there cuts out a lot of riff-raff!) that uses a 1M3/DM70 tuning eye tube as an audio inverter for a push-pull DL96 output stage.

The low light emission of the cathode of a VFD means the design is temperature-limited rather than space-charge limited so this has a noise penalty.  With a temperature limited cathode, the operation of the tube depends on cathode temperature.  With a space-charge limited cathode, you always have more emission than you need, so the noise level is lower.

[Mark Hammer]

A second demo of the Nutube-based OD-S.

[vigilante397]

I've heard a fair number of tube drive pedals, and I have to say that's probably the most bland sounding one I've heard

[FUZZZZzzzz]

I've heard a fair number of tube drive pedals, and I have to say that's probably the most bland sounding one I've heard

So marketing wise its probably a good thing, since most guitarist play bland music

[tonyharker]

Why can't some people pronounce soldering properly?

[Rob Strand]

I've heard a fair number of tube drive pedals, and I have to say that's probably the most bland sounding one I've heard

It says a the end of the video it's recorded directly not through an amp.  They don't mention an amp/speaker emulation.  That's going to make the guitar sound samples pretty much useless to judge the pedal.

[Mark Hammer]

I've heard a fair number of tube drive pedals, and I have to say that's probably the most bland sounding one I've heard

Then you'll need to hear the Yamaha OD-100 Overdrive I have.  Not tube-based, but without a doubt, one of the most characterless ODs I have ever heard.  If it was a person, you'd be thinking "Oh dear lord, PLEASE don't sit next to me for this train/bus/plane ride!".

[vigilante397]

It says a the end of the video it's recorded directly not through an amp.  They don't mention an amp/speaker emulation.  That's going to make the guitar sound samples pretty much useless to judge the pedal.

I do that with my tube pedals too. It doesn't sound as good as it would with a cabsim, but it doesn't sound awful.