Autoformer Tap Calculator
T2A, 3636 truncated 0-X, and 3675 comparison tool. Uses inductance ratio to estimate turns ratio, attenuation, and reflected impedance.
Working formulas
- L ratio = L tap ÷ L total
- Turns ratio = √L ratio
- Attenuation dB = 20 log₁₀(turns ratio)
- Impedance multiplier = 1 ÷ L ratio
- Reflected impedance = driver impedance × impedance multiplier
- Swamped impedance = (reflected Z × swamp resistor) ÷ (reflected Z + swamp resistor)
Tap Calculator
T2A Model 0-5, Tap 1
L ratio: 0.0500
Turns ratio: 0.2236
Attenuation: -13.01 dB (13.01 dB down)
Impedance multiplier: 20.00×
Reflected impedance @ 8Ω: 160.00Ω
Effective impedance with 10Ω swamp: 9.41Ω
Custom Calculator
L ratio: 0.1036
Turns ratio: 0.3218
Attenuation: -9.85 dB (9.85 dB down)
Impedance multiplier: 9.66×
Reflected impedance: 77.24Ω
Master Tap Table
| Autoformer | Mode | Tap | L mH | DCR Ω | L total | L ratio | Turns ratio | Atten dB | +dB | Z mult |
|---|---|---|---|---|---|---|---|---|---|---|
| T2A | Model 0-5 | 1 | 2.8000 | 56.00 | 0.0500 | 0.2236 | -13.01 | 13.01 | 20.00 | |
| T2A | Model 0-5 | 2 | 5.8000 | 56.00 | 0.1036 | 0.3218 | -9.85 | 9.85 | 9.66 | |
| T2A | Model 0-5 | 3 | 11.4000 | 56.00 | 0.2036 | 0.4512 | -6.91 | 6.91 | 4.91 | |
| T2A | Model 0-5 | 4 | 21.2000 | 56.00 | 0.3786 | 0.6153 | -4.22 | 4.22 | 2.64 | |
| T2A | Model 0-5 | 5 | 56.0000 | 56.00 | 1.0000 | 1.0000 | 0.00 | 0.00 | 1.00 | |
| 3636 | Truncated 0-X | 1 | 5.4990 | 2.1120 | 56.07 | 0.0981 | 0.3132 | -10.08 | 10.08 | 10.20 |
| 3636 | Truncated 0-X | 2 | 11.3500 | 2.8230 | 56.07 | 0.2024 | 0.4499 | -6.94 | 6.94 | 4.94 |
| 3636 | Truncated 0-X | 3 | 22.1100 | 6.2200 | 56.07 | 0.3943 | 0.6280 | -4.04 | 4.04 | 2.54 |
| 3636 | Truncated 0-X | 4 | 44.4000 | 12.7400 | 56.07 | 0.7919 | 0.8899 | -1.01 | 1.01 | 1.26 |
| 3636 | Truncated 0-X | X | 56.0700 | 15.9000 | 56.07 | 1.0000 | 1.0000 | 0.00 | 0.00 | 1.00 |
| 3675 | Full 0-15 | 1 | 0.8846 | 0.3265 | 64.00 | 0.0138 | 0.1176 | -18.59 | 18.59 | 72.35 |
| 3675 | Full 0-15 | 2 | 3.3730 | 1.5250 | 64.00 | 0.0527 | 0.2296 | -12.78 | 12.78 | 18.97 |
| 3675 | Full 0-15 | 3 | 8.1090 | 2.4580 | 64.00 | 0.1267 | 0.3560 | -8.97 | 8.97 | 7.89 |
| 3675 | Full 0-15 | 6 | 23.6400 | 8.5930 | 64.00 | 0.3694 | 0.6078 | -4.33 | 4.33 | 2.71 |
| 3675 | Full 0-15 | 9 | 36.6800 | 14.2800 | 64.00 | 0.5731 | 0.7571 | -2.42 | 2.42 | 1.74 |
| 3675 | Full 0-15 | 12 | 53.3900 | 11.4900 | 64.00 | 0.8342 | 0.9134 | -0.79 | 0.79 | 1.20 |
| 3675 | Full 0-15 | 15 | 64.0000 | 13.7500 | 64.00 | 1.0000 | 1.0000 | 0.00 | 0.00 | 1.00 |
3675 Segment Map
| Segment | L mH | DCR Ω |
|---|---|---|
| 0-1 | 0.8846 | 0.3265 |
| 1-2 | 0.7303 | 0.2709 |
| 2-3 | 0.9615 | 0.3598 |
| 3-6 | 3.9870 | 1.8730 |
| 6-9 | 1.8130 | 0.7510 |
| 9-12 | 1.1300 | 0.4307 |
| 12-15 | 0.4790 | 0.1731 |
Segment inductances are structural clues and are not additive like simple DC resistance because the winding is coupled.
Quick Translation
| Approx target | T2A | 3636 0-X | 3675 |
|---|---|---|---|
| -12 dB | Tap 1 | No exact, Tap 1 is about -10 dB | Tap 2 |
| -9 dB | Tap 2 | Tap 1 | Tap 3 |
| -6 dB | Tap 3 | Tap 2 | No exact, Tap 6 is about -4.3 dB |
| -3 dB | Tap 4 | Tap 3 is about -4 dB | Tap 9 is about -2.4 dB |