Tube Works Blue Tube Teardown! See what's inside!

Welcome back to the bench! Today we're taking apart a 1999 Blue Tube tube overdrive pedal from Tube Works. Enjoy!
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[@DavidRavenMoon]

I have a Blue Tube I bought around 1990. The circuit is in dire need of an output buffer. The 500k pot is an indication that it has a high impedance output. It’s easily loaded down by some pedals. I used mine on bass. By the time I’d get to unity gain on the drive it would be too distorted, so I used a 12AU7 tube instead. No hot melt in my unit. The other issue is a slight hum. Could probably stand to have a DC tube heater.

[@gph2193]

The gem was their 2x90w Mosvalve power amp. That had character.

[@Loscha]

Another really great video! Thanks!

[@BlakeC27]

Someone sent me one of these to install a power jack after the transformer failed so the could use an external 15-volt AC power supply instead. I also modified for true bypass.

[@therealjamesmarchant]

The resistors look like carbon film not carbon comp to me. For those interested, current regulations require that the safety ground is connected to its own screw terminal which must be marked with a ground symbol and not shared with any other connection.

[@graybenchelec]

Correct! That was a flub on my part, definitely carbon film 1/4W

[@jesseyasaitis9036]

I have a black colored model that has transformer hum, even after I changed it.

[@maxmcmillan99]

I had a Real Tube rack unit back in the day and I recall it being somewhat noisy. I see it has half-wave rectification - for the cost of a a few more diodes, they could have improved the power supply greatly. Do you notice excessive hum? As a side note, I recall seeing on an internet forum (many years ago) an anecdotal statement that increasing the voltage to the circuit greatl improved it's performance.

[@kevinafflack]

I use the Real Tube version for a lead tone and it really sings. Unfortunately the tone controls are too interactive with each other, especially the treble. There’s only one spot where it sounds good, otherwise it rolls off all the mids and bass. Is there anyway to mod this behavior? Interesting that the Blue Tube uses a 100k vs 500k for the treble. Would changing the pot to 100k help?

[@gph2193]

Had one, nothing special to it except that the power cord was a lame pain.

[@BlakeC27]

If I recall correctly, the tone stack was of the type that if you turning the mids all the way down, the signal was lost completely.

[@kennyjohnson336]

Does the tube actually get hot? Seems like it wouldn't. 🤔

[@graybenchelec]

Sure, as hot as any other 12AX7. Whether the vents are really necessary is another question, but if you’re doing a custom enclosure why not?

[@kennyjohnson336]

@@graybenchelec Even if the tube is only getting 12V?

[@graybenchelec]

@@kennyjohnson336 I believe so, the heat in a preamp tube like a 12AX7 is 99% filament, about 1.8W.

[@BRYDN_NATHAN]

nat atbot GPT-3 [:|]... "thank you. I don't know about stompinging on a tube how about a germanium modification. more 12ax7 pls +2 [BEEP]