Raytheon JAN6418
Hey guys, I was looking at this:
http://secure.oatleyelectronics.com/…22{33}4
Cheap as chips and within sensible posting distance to NZ.
Any comments? Bill? Anyone else?
Apparently it’s based on the Raytheon JAN6418 mini tube which the AT3060 tube mic uses. The AT mic gets mixed reviews but I figured that this is so cheap it would make a nice little project for the evenings (NZ TV is somewhat lacking).
Sure it’s not going to be the same as those smoking, melting, glowing real tubes but AT, and apparently Geffen who also have a mic with mini tubes, can’t be completely bonkers…
Hi MarkA:
I hope you survived the Christmas Day and you’re returning to normal and all…
It must be quite the change in the routine waking up to a Summer morning instead of a northern hemisphere winter day…
Anyway, I’ve been looking at the kit you linked to…
Very interesting and fascinating…
I’ve began searching around to come up with the specs. on that 6418 tube…
I haven’t found the link/page that I’d like to see yet…
However, I’ve found a couple of interesting pages for you to check out and create your perspective on this…
I’ve discovered another kit on that site that appears more interesting to me, in my opinion…
It’s
THIS ONE…
While searching for the specs on this tube/valve I found
THIS PAGE for you to investigate…
I’ll continue searching for the page I’d like to explore…
It’s gotta be up there somewhere…
My personal comments are…
I’d get the K 270 kit…
and being the experimenter I think I am, I’d play with that kit to see if the noise floor might be low enough
to tolerate using it for our applications…
A “Smooth” Power Supply is at the top of the list conditions for what we allow, in our applications list…
It’s not so much the “Specs.” that make this preamp acceptable-or-not, It our ears that tell us what is…
This is a great little project…
Thanks for that link…
Bill…
[edit] OoHh… There’s amother link that I am unable to find that I forgot to add to my reply…
Low power, you are right, in my experience low power tubes don’t sound like high power ones, at all.
On the other hand, it doesn’t get any cheaper than that.
Unless you want to put it in a nice box, which adds money.
Boxes can be pricey.
Anyway, I’m no expert by a long shot.
Here’s the other link I was refering to…
This link
will give you the operating voltages for the tube…
I’d try to set the conditions to it’s maximum or even higher… To attempt to get the best amplitude output from it…
However, an oscilloscope would show the audio output waveform at the best voltage conditions… The load impedance of the tube is really quite high…
A good regulated power supply for this tube is a must, in my opinion…
Any ripple in the supply is a downer…
This tube was first developed in the early '70’s…
I don’t know what they used it for…
Could have been a switch for an early computer design…
Who knows 
?
Could have been designed-and-made for NASA
going into space… ??
Bill…
Quote: (TomS @ Dec. 27 2010, 3:10 AM)
Low power, you are right, in my experience low power tubes don't sound like high power ones, at all.
On the other hand, it doesn't get any cheaper than that.
Unless you want to put it in a nice box, which adds money.
Boxes can be pricey.
Anyway, I'm no expert by a long shot.
Tom - I got 207 large cardboard boxes from my recent move across the world :-)
Thanks for the links Bill. Interesting reading. There is certainly a lot of audio snobery around such things. And it kinda amuses me that 50+ year old technology is so sought after still.
Personally I think a guitarist's fingers are bigger contributing factor to the guitar's tone than the technology in the amp. I grew up with valve amps being the norm and we all embraced tranny amps when they arrived on the scene.... smaller, lighter, less hassle, more resilient. Now I've got 15 year old kids in the guitar studio asking for a tube amp to play their solo through because clearly they have magical pixie dust in them which immediately makes you sound like .
Anyway, off my soapbox now. The only reasons I'd get one of these are to add another sonic possibility to my studio for little money. I grew up building amps and effects and radios and things with my dad so I enjoy diving in and being "creative" with a soldering iron. And it is really cheap. So yeah, I'll get one and report back....
Mark
Quote: (woxnerw @ Dec. 27 2010, 7:32 AM)
Here's the other link I was refering to..
This link
will give you the operating voltages for the tube..
I'd try to set the conditions to it's maximum or even higher.. To attempt to get the best amplitude output from it..
However, an oscilloscope would show the audio output waveform at the best voltage conditions.. The load impedance of the tube is really quite high..
A good regulated power supply for this tube is a must, in my opinion..
Any ripple in the supply is a downer..
This tube was first developed in the early '70's..
I don't know what they used it for..
Could have been a switch for an early computer design..
Who knows
? Could have been designed-and-made for NASA
going into space..
??Bill..
Yeah, I don't have access to an oscilloscope nowadays. Used to take it for granted when I worked in that sphere. Maybe I can find a cheap one....
NASA.... now there's a thought. Bet they don't use tubes now.
Hey, Mark! 7.5 on the rickety stairs (Richter Scale).
I think the only REAL savings that I have ever made have been when building kits - many years ago I simply couldn’t afford the
£70 for a midi merge/splitter box. I picked up a kit for under
£10 and boxed it in some random case that I found lying around the house.
But destroying an original Stylophone and Bontempi reed organ (stupid youth) to build a “synth” was not one of my better ideas;-)
Quote: (TonyR @ Dec. 27 2010, 10:53 AM)
Hey, Mark! 7.5 on the rickety stairs (Richter Scale).
I think the only REAL savings that I have ever made have been when building kits - many years ago I simply couldn't afford the
£70 for a midi merge/splitter box. I picked up a kit for under
£10 and boxed it in some random case that I found lying around the house.
But destroying an original Stylophone and Bontempi reed organ (stupid youth) to build a "synth" was not one of my better ideas;-)
We've all done that in our yooof!
One of my regrets is giving away my Sound City valve amp head that I had in the late 70s.
It had sat in the garage as a useless, worthless piece of junk for years once I'd got my tranny combo.
A buddy needed some cash so I gave it him in around '87 and he pawned it for the price of a MacDonald's breakfast.
I now see the same amp going on eBay for almost enough to buy a whole Mac D's restaurant.
A few years later he pawned his beautiful Aria Pro II bass (the really top end one) for peanuts.
Yoof.
Nostalgia - ain't what it used to be.
Quote: (Mark A @ Dec. 26 2010, 4:15 PM)
Quote: (TonyR @ Dec. 27 2010, 10:53 AM)
Hey, Mark! 7.5 on the rickety stairs (Richter Scale).
I think the only REAL savings that I have ever made have been when building kits - many years ago I simply couldn't afford the
£70 for a midi merge/splitter box. I picked up a kit for under
£10 and boxed it in some random case that I found lying around the house.
But destroying an original Stylophone and Bontempi reed organ (stupid youth) to build a "synth" was not one of my better ideas;-)
We've all done that in our yooof!
One of my regrets is giving away my Sound City valve amp head that I had in the late 70s.
It had sat in the garage as a useless, worthless piece of junk for years once I'd got my tranny combo.
A buddy needed some cash so I gave it him in around '87 and he pawned it for the price of a MacDonald's breakfast.
I now see the same amp going on eBay for almost enough to buy a whole Mac D's restaurant.
A few years later he pawned his beautiful Aria Pro II bass (the really top end one) for peanuts.
Yoof.
Nostalgia - ain't what it used to be.
OooooOmpH!!!
Once I came home to find my Orange 100w top and 4X12 - gone!
Every thing else had "gone" too, but that was a great amp. The usual EL34's.
Hi MarkA and Gents:
This tube and design is quite “Real” as opposed to a “Pseudo” Tube Audio Circuit.
This Link
The specs on this tube are correct within limits in the “KIT Design” schematic…
The only downfall/negative feature the tube has is, when used as an audio devise is, it’s Load Impedance and Power Output of 0.0022 watts…
The K270 Kit is the one in my opinion the kit to consider selecting for using in an audio application for how we would use this preamp…
However, we need the FET junction that the K270 Kit has included that lowers the output impedance and Drive capabilities of the circuit…
What I’d do if I took the project the project on, is…,
Doing away with/re-designing the IC Circuit as the power supply conditioning circuit and power the preamp solely with a Battery Supply…
Keeping in mind that the overall current drain of the circuit is in the order of some 20 ma.
I’d consider a NiMH Battery Pack to supply some 25-30 Volts for the preamp…
A Pack made up of AA cells that are able to be setup for charging, would be the ideal source of Power…
In my opinion…
BUT…
only after the project’s merritt.
Back to this idea…
This tube and design is quite “Real” as opposed to a “Pseudo” Tube Audio Circuit.…
A 12AX7 tube is a higher Voltage devise…
with working voltages in the order of 300 volts DC…
…
where this devise operates at maximum voltages in the order of some 30 volts DC…
It’s a Class A device…
where the filament emits electrons that travel toward the plate that is controlled by grids that impede the flow of electrons…
AND…
at maximum operating devise potentials…
Talk about re-inventing the Wheel…
? 
Bill…