Hearing Is BelievingDriving the Output Stage
The first four clips demonstrate swapping V1 (the first preamp tube) in a Fender ’62 Princeton Chris Stapleton Edition (a reissue of the brownface Princeton 6G2 circuit) from the original 12AX7 (Clip 1) to progressively lower-gain tubes: a 5751 (Clip 2), 12AT7 (Clip 3), and 12AY7 (Clip 4). You can hear how the gain content decreases with each swap, and if the alteration from one to the next might seem subtle, jump from the original 12AX7 to the 12AY7 to hear how dramatic the overall spread can be. Both the amp’s volume and tone controls are set to 7 out of 10.
The guitar is a Gustavsson Fullerblaster—a high-quality T-style with a Wolfetone single-coil bridge pickup in a traditional Tele bridge, and a ThroBak PAF-style humbucker in the neck position. You’ll hear the bridge pickup in the first segment of each soundclip; the second segment features the neck humbucker.
This time the same tubes—12AX7 (Clip 5), 5751 (Clip 6), 12AT7 (Clip 7), and 12AY7 (Clip 8)—are swapped in and out of the lead channel of a Marshall modded-plexi-style Friedman Small Box 50-watt head driving a 4x12 cab with Celestion Greenbacks. These soundclips demonstrate how the gain characteristics change in an amp where the overdrive is generated more in the preamp. The Friedman’s gain knob is at 6 out of 10, with the master set to 4 out of 10.
The guitar is a 2016 Gibson Custom Shop Les Paul 1958 Reissue with Monty’s PAF pickups. I’m using the bridge pickup on these soundclips.
Swapping the Phase Inverter
In these four soundclips, the Friedman Small Box’s phase inverter is swapped from a 12AX7 (Clip 9) to a 5751 (Clip 10), 12AT7 (Clip 11), and 12AY7 (Clip 12). To help us hear how the progressive decrease in PI-tube gain eases up on the output stage, I’m using the amp’s rhythm channel (gain at 4, master at 5).
The guitar is the Gustavsson Fullerblaster again, on its Tele-style bridge pickup.
Mix ’n’ Match
For Clip 13, I return to the Friedman’s lead channel and Les Paul’s bridge pickup. To hear the change in drive characteristics with preamp-generated gain into the lower-gain phase-inverter tube, I’ve used a 12AX7 in the V1 position and a 12AY7 for the PI.