What is this 'tube' in a 65 Amp London Pro?

[ranjam]

Hello! I hope this isn't a totally ridiculous question. In a 65 Amp London Pro, not mine, there is a 'tube'. It is a white plastic 'sleeve', marked Jet City 1612. It appears to have a bulb inside that glows, but it can't be a tube. Or is it? No Google luck, so I ask here. Thanks, and I apologize if this is a ridiculous question.

[teemuk]

I take a guess:

https://www.youtube.com/watch?v=3YdrNjipRgo

[ranjam]

No guess, that's it! Thanks! How it got into this 65 Amp I don't know, the website makes no mention of this being an option. Sounds cool, though. But teemuk, thank you again. The mystery is solved.

[xtian]

Here are some detailed specs:

http://www.robertsaudiotech.com/designs ... .php#specs

Only ~53mA for the heaters, instead of 300mA for 12AX7.

[C Moore]

Here are some detailed specs:

http://www.robertsaudiotech.com/designs ... .php#specs

Only ~53mA for the heaters, instead of 300mA for 12AX7.

Would they even need "heaters".?
Maybe these things rectify the heater voltage to run the solid state device.?
Aren't these some type of a transistor.?
Thanks

[xtian]

They're patented; guess you can look that up?

[Gainzilla]

Interesting backstory: Doug Roberts is the son of Jazz legend Howard Roberts. We used to hang in the same circles back in the day, and I knew him and his brother Jay pretty well. Doug is quite literally a genius, having worked for NASA as an engineer as a teenager. He is actually the original designer behind the Soldano SLO100... I played through his prototype, through his guitar which was loaded with pickups that he made himself (vacuum sealed and injected with some inert gas). I remember harmonics lept off the fretboard, and I played out of my mind. I sounded like a legend through that rig. Of course, I was a shred-head so I always thought I sounded like a legend. hehe

Anyway, Mike Soldano was a friend of Doug's. If memory serves, they built an amp like his together, and when Mike suggested they market it, Doug basically gave his blessing to go forth and conquer. An amp probably seemed like small potatoes to him. It's nice to see Doug getting involved in the industry. He was a pretty serviceable guitarist as well.

Cheers

[romberg]

They're patented; guess you can look that up?

One of the drawings on the patent is an actual schematic of the circuit. Looks to me like an op amp driving a transistor and some LEDs to make it glow.

Mike

[ranjam]

My guess, based on size constraints, is a simple power mosfet like an IRF820 that can work off of the B+ in the amp. I've seen it done a few different ways, even added as a discreet component, inside a few amplifiers. Sounds cool, but it did throw me for a loop having it mounted inside a tube-like enclosure. And the LED is a neat touch.

[Aurora]

A possible clue ???

http://ludwigomen.blogspot.no/2012/08/blog-post_16.html

[guitarmike2107]

Nice engineering but I would like to see there market research that said this is a product that the masses want, most people I know are trying to get more valves in, not take them out, surely the only reason to have them is as a backup in the toolbox?

[guitarmike2107]

Nice engineering but I would like to see there market research that said this is a product that the masses want, most people I know are trying to get more valves in, not take them out, surely the only reason to have them is as a backup in the toolbox?

[xtian]

Well, I ordered a set (blue/amber/red). We'll see!

[guitarmike2107]

How about doing a blind test for this thread? will be interesting to know if you use them or stick with glass.

Every video I have seen puts them in V1, which modifies front end gain but doesn't overdrive them in any way, will be interesting to see if you notice an effect fitted later in the amp...

[rp]

Nice engineering but I would like to see there market research that said this is a product that the masses want, most people I know are trying to get more valves in, not take them out, surely the only reason to have them is as a backup in the toolbox?

I was thinking the exact same thing, kind of backwards marketing. Most people even kids with something ss dream of a tube amp. Never ever met anyone with a tube amp that dreamed of ss. You can get a great sound out of both, doesn't really matter much to me, but the marketing mojo is all with the tubes. Maybe some sort of survivalist business plan, getting ready for the tube-apocalypse.

What happens if you stick it into a cathode follower?

Xitan report back. I'm just curious if they are at least a fun toy like those $20 remote controlled helicopters. Like I said I like ss so it could be fun to make a tube amp just like ss.