Magnatone M10A tone stack
Tone stacks and tone controls from amps and pedals, from their schematics, with the stage that drives each one and what it feeds. Turn the knobs and watch the curve. Pin a setting to compare, change any part, and listen through a speaker. Pickups and guitar knobs are on the Guitars page.
The Bass 1 and Treble 1 controls of the Magnatone M10A, with every part as on the bench.
Swipe sideways for the whole drawing. Tap a part to change it. The source drives the end marked in, and the load hangs on the end marked out.
At this setting
0 dB is the source’s voltage with nothing hooked to it, so the curve shows what the stack cuts. A tube source changes the curve only through its output resistance, not its gain.
Pin this curve keeps what the graph shows, up to three pins in their own colors. Pins stay when you switch stacks, so you can lay a Marshall treble sweep over a Vox one. In a sweep, the lightest line is the knob at 0 and the darkest is 10.
Listen
You hear a picked string through a guitar on full, with 15 feet of cable. Play without it leaves the stack out.
Source and load
Driven by
Driving
The knobs
- Bass 1
- Bass, 1 MΩ. Its wiper feeds the output through 120 kΩ. Toward the top the 470 pF across the upper part of the track is shorted out and the .0047 µF across the lower part leaves the lows standing, so the bass comes up. Audio taper and its direction are typical, not on the drawing.
- Treble 1
- Treble, 1 MΩ, between the treble cap and the .0047 µF to ground. Its wiper is the stack’s output. Turned up, the wiper moves toward the 470 pF and the highs. Audio taper and its direction are typical, not on the drawing.
Parts
- 47 nF
- Coupling cap from the first plate into the tone stack, .047 µF.
- 330 kΩ
- The bass side’s feed, 330 kΩ from the coupling cap to the top of the bass pot.
- Bass
- 1 MΩ, Bass, 1 MΩ. Its wiper feeds the output through 120 kΩ. Toward the top the 470 pF across the upper part of the track is shorted out and the .0047 µF across the lower part leaves the lows standing, so the bass comes up. Audio taper and its direction are typical, not on the drawing.
- 47 kΩ
- From the bottom of the bass pot to ground, 47 kΩ. It sets how far the bass can be cut.
- 470 pF
- 470 pF from the top of the bass pot to its wiper. It lets the treble past the upper part of the track.
- 4.7 nF
- .0047 µF from the wiper to the bottom of the bass pot. It shorts the lower part of the track for the treble and mids.
- 120 kΩ
- 120 kΩ from the bass wiper to the treble wiper, where the two halves of the stack meet. It keeps the two controls from shorting each other.
- 470 pF
- Treble cap, 470 pF from the coupling cap to the top of the treble pot.
- Treble
- 1 MΩ, Treble, 1 MΩ, between the treble cap and the .0047 µF to ground. Its wiper is the stack’s output. Turned up, the wiper moves toward the 470 pF and the highs. Audio taper and its direction are typical, not on the drawing.
- 4.7 nF
- .0047 µF from the bottom of the treble pot to ground.
Source and load
Source: 55 kΩ, the output resistance of the stage before it on the bench at 1 kHz. Load: 1 MΩ, the input of what follows it on the bench, from its impedance at 1 and 10 kHz.
Values, wiring and drawing are taken from the Magnatone M10A on the bench, so the two always match.
Warnings. The summary above the graph turns red if the stack can’t be solved as set, usually from a part at zero or a shorted pot track.
How this tool works. We solve each stack with the circuit bench’s engine: the source stage’s operating point first, then every part at 161 frequencies from 20 Hz to 20 kHz. A stack that’s also in a bench circuit is built from that circuit file, so the two always match.
The curves are small-signal. They don’t show clipping or grid current in the next stage. For the stage before or after a stack, try the gain stage tool.
Spot an error, or want a circuit added? Email info@swellamps.com. A schematic or a clear photo of one helps. Anything you send may be used to improve these models and our desktop app.
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