Tube GUITAR

[Colas LeGrippa]

Hola amigos , hace mucho tiempo !!!!


I have developed a tube guitar with my friend Jean Luc, a guitar maker, here in Montreal. I did the electronics and he fitted the tubes in a self made guitar. Jaw dropping idea, great sound, hum free. Approx 25db of gain. One tube per pick up. Leds inserted in the P90's, and yellow orange leds inserted under the tubes to simulate the heaters colour. Six months of work part time to develop the power supply and to eliminate switching pops and hum. I hope he'll succeed with his idea !


Colas

[shooter]

brings a new meaning to hot pickin

nice design

[Toxophilite]

Wow!


Out of curiousity are the tubes only for show?


It reminds of an apex stereo tube preamp I have
The 'tube' was the selling point and they have it mounted behind a little grill dead center of the front panel.
When you turned the preamp on you could see it slowly light up. I always thought it was pretty bright for a 12AX7.


I opened it up once to swap in another tube for fun (no difference as usual) and was hilariously surprised to note that they had put 2 LEDS behind the tube (as your friend did) as the normal tube heater glow wasn't very impressive looking through the front grill. They even designed it to war, up at the same speed as the tube. It's a good preamp but I thought it was like tube foley to have LEDS

[kagliostro]

Cool Job, really nice


Franco

[scrimpus]

 

[92Volts]

I am curious about the power supply! I've seen a high-voltage switching PSU which could make high voltage with a 12v input or similar. Conveniently the heaters need 12v as well. . Something like that should be plenty for low-power preamp tubes, but keeping noise low is another question!

Getting power into the guitar is another issue. I guess a stereo TRS cable could carry +12v in on the "extra" line and the other two are ground and signal as normal? Or you could stuff tons of lithium-ion batteries in there! 

[Colas LeGrippa]

Exactly, stereo cable from the psu to the guitar carrying 12V on the ring, tip being the signal, sleeve the shared gnd- Heaters, leds and plates run on same  12VDC . TPDP switches are used for true bypass, while pots are used in conjunction with rc filters to yield pleasant and natural frequencies.


Colas

[Colas LeGrippa]

sorry, TPDT switches, not TPDP

[Colas LeGrippa]

Switching power supplies are not suitable for audio. I had to build a magnetic one, the most important part being the regulator for humfree operation.


Colas

[92Volts]

Exactly, stereo cable from the psu to the guitar carrying 12V on the ring, tip being the signal, sleeve the shared gnd- Heaters, leds and plates run on same  12VDC . TPDP switches are used for true bypass, while pots are used in conjunction with rc filters to yield pleasant and natural frequencies.


Colas

Interesting, which tubes did you use? I'm impressed that you're getting a significant amount of gain with only 12v on the plates. It's not impossible, but is definitely tricky to do that.

Switching power supplies have been used in audio with varying degrees of success, it would be key to keep them some distance away from the signal. Having one inside a guitar would be very challenging. It makes sense you kept the entire PSU external from the guitar. You're also free to use a traditional magnetic PSU that way. A switching PSU would be needed if anything was going on inside the instrument mostly due to size, as well as other concerns, which could be a big issue in terms of noise.

[Colas LeGrippa]

Hi buddy !


I used 12au7's  which give the best tone of the 12AX series. Each tube is wired in cascode for max gain but it is possible to use only the first half for less gain, with the second half like a cathode follower to act as a buffer for minimum noise in case of long cable run. There are so many ways to do it and my friend and client  Jean Luc already ordered form me a preamp with paralled halves  for less gain and a preamp with a cathode follower. It is possible to wire the 4  stages in cascode for metal gain. The RC possibilities are almost infinite...Definitely 12Volts give a lot of gain !


Colas