How About An Octal Preamp Tube Upgrade?

[Jeffblue]

I have a BK Butler/Tube Works Blue Tube pedal that I modified form using a 12AX7 to an octal 6SL7 dual triode. I punched a hole in the side of the housing to accommodate the larger tube, I created an 9 pin to octal pin/socket adapter with the appropriate wiring and installed the tube. The pedal sounds hugely better and looks pretty sick with the tube partially exposed with the filament lit.

 

[Securb]

I have the rack unit. Could you take a picture of the adaptor and describe what you did? This sounds very cool.

 

[Jeffblue]

Taking the pedal apart is a PITA. What I did do was go online to find the pinout of each tube, draw out which wire goes where by matching the filaments, plates, grids and cathodes. Acquired a 9 pin male plug and an octal female socket and then matched them. Takes some effort but well worth it. If I decide to take it apart, I'll get back to you.

 

[eclecticsynergy]

Cool mod.

Can you clear something up for me?
Some have said the tone controls on these are passive and cut-only, rather than cut-and-boost.
Is it true that they're flat at their max setting rather than at twelve o'clock?
Or is that just bullsh¡t from some clueless idiot on the Web?

 

[Jeffblue]

No way, the tone controls do seem to boost and cut. Great pedal built like a tank.

 

[devastone]

Did you change the heater voltage from 12 to 6? Do those have hit B+ voltage or are they starved voltage designs?

 

[Jeffblue]

Both the 6SL7 and the 12AX7 have a filament voltage of 6.3 volts. The pedal does have a transformer in there which tells me that it is NOT a starved plate design.

 

[Mincer]

Generally, what is the sonic difference between a stock Real Tube and a Blue Tube?

 

[Jeffblue]

I believe the Real Tube is the predecessor of the Tube Driver and I believe sounds better than the Blue Tube pedal. I had a couple of Real Tube pedals and traded them off. Wish I had them. The blue tube pedal is an excellent pedal in it's own right, modifying it certainly improved it sonically. Not sure I would have done this mod to a Real Tube pedal.