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Origin of the 6G15/6G12 Reverb/Vibrato unit |
| Note: I have since updated the Re-Vibe below to incorporate the Tore T mod. |
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| This is a Fender schematic for the 6G15 stand alone reverb unit. The area outlined in Blue is the area we are interested in. Click on the image above to see the full sized image. This schematic can be found on page 154 of Gerald Weber's Hip tube amp book. |
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| This is a Fender schematic for the 6G12 Concert amp. The area outlined in Red is the Vibrato circuit area we are interested in. Click on the image above to see the full sized image. This schematic can be found on page 288 of Gerald Weber's Hip tube amp book. |
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| Here we see how both Fender circuits were joined together to form a reverb/Vibrato unit The Blue 6G15 Reverb unit circuit is on the left. The Red 6G12 Vibrato circuit is in the middle. Jeff Gehring's summing circuit is on the right. Click on the image above to see the full sized image |
| 6G15 Notes: The Fender 6G15 Reverb unit is actually a parallel effects loop. You will note that the input from the guitar comes in at the far left of the reverb circuit. The input then splits two ways. (1) The upper path flows through the reverb circuit and comes out at the middle wiper of the tone control and then exits through a 250p capacitor. The upper path is the wet reverb signal. (2) The input also goes down to a cathode follower stage. The cathode follower stage is the dry no effects signal. In the stock Fender reverb unit, the upper wet reverb signal and the lower dry cathode follower signal stage come back together at the mix pot and then exit the reverb unit via the output jack. This is how you get a dry no effects signal mixed with a wet reverb signal. |
| 6G12 Notes: The Fender Concert 6G12 Vibrato circuit receives input from the concert pre amp. The pre amp stage is above the vibrato circuit in the Original Fender schematic above. The vibrato circuit will pass the pre amp signal right through with no vibrato added if the vibrato is turned off. If the vibrato is turned on, the pre amp signal is subjected to the vibrato circuits vibrato effect. The signal exits the vibrato circuit at the right end where the two 470K resistors join together. |
| The 6G15/6G12 reverb/vibrato unit has a summing circuit to mix the signals from the Fender
6G15 reverb circuit and the Fender Concert 6G12 Vibrato circuit together. The summing circuit is a simple voltage divider but as mentioned above it also mixes two signal inputs and then the final mixed signal exits to the output jack. It's a simple circuit but it is doing several chores at one time. |
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| There are few minor changes over the stock Fender circuits listed below. 6G15 Reverb unit changes: 6G12 Vibrato circuit changes: |
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| Update: There was quite a bit of hum in the original Re-vibe. Tore T. has come with an excellent mod that eliminates the hum completely. See the original schematic and layout diagram on the library page and compare these to the updated Tore T mod layout and schematic to see what was changed. I updated my Re-Vibe with the Tore T mod and it is now dead quiet. |
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