The Tanchjim EA FORCE is 17Ω at 120.0 dB (no reference unit printed); the Tanchjim OLA II is 30Ω at 105.8 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The OLA II needs 14.2 dB more than the EA FORCE to reach the same loudness — 0.26 mW against 0.01 mW.
| Specification | EA FORCE | OLA II |
|---|---|---|
| Impedance | 17 Ω | 30 Ω |
| Sensitivity | 120.0 dB | 105.8 dB/mW |
| Sensitivity (voltage) | 137.7 dB/V | 121.0 dB/V |
| Power for 100 dB | 0.01 mW | 0.26 mW |
| Voltage for 100 dB | 13 mV | 89 mV |
| Current for 100 dB | 0.8 mA | 3.0 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.12 Ω | 3.75 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
One caution before reading the rows. Tanchjim EA FORCE printed a decibel figure with no reference unit, so this page reads it as per milliwatt. If it is really per volt, that model needs far more than the table says. Why the two readings differ by so much.
Every source in the database that drives one of them drives the other. On power, the choice between these two changes nothing about what amplifier you need.
67 sources stay below the audible-hiss threshold with the OLA II but cross it with the EA FORCE (JadeAudio JA11, Kiwi Ears Allegro Mini, FiiO KA11, 64 more).
280 of the 280 sources here reach 100 dB on both.
The OLA II is more demanding than 27% of the 567 non-electrostatic models in this database; the EA FORCE than 0%.
| dB SPL | EA FORCE power | EA FORCE voltage | OLA II power | OLA II voltage |
|---|---|---|---|---|
| 80 | 0.1 µW | 1 mV | 2.6 µW | 9 mV |
| 85 | 0.3 µW | 2 mV | 8.3 µW | 16 mV |
| 90 | 1.0 µW | 4 mV | 0.03 mW | 28 mV |
| 95 | 3.2 µW | 7 mV | 0.08 mW | 50 mV |
| 100 | 0.01 mW | 13 mV | 0.26 mW | 89 mV |
| 105 | 0.03 mW | 23 mV | 0.83 mW | 0.16 V |
| Source | Price | Headroom, EA FORCE | Headroom, OLA II | Output impedance | Noise |
|---|---|---|---|---|---|
| FiiO BTR13 | $59 | 40.7 dB | 25.8 dB | 0.6 Ω | 1.0 µV |
| iBasso DC03 Pro | $69 | 37.2 dB | 25.4 dB | 0.12 Ω | 0.9 µV |
| Topping L30 II | $149 | 55.3 dB | 40.2 dB | 0.1 Ω | 0.3 µV |
Of the 280 sources here, 280 reach 100 dB on both. 11 of them also publish an output impedance low enough for both under the one-eighth rule and a noise figure that stays below the audible-hiss threshold with both.
The cheapest of the 11 is the FiiO BTR13, at $59. It leaves 40.7 dB of headroom on the EA FORCE and 25.8 dB on the OLA II, its output impedance is 0.6 Ω against a one-eighth limit of 2.12 Ω and 3.75 Ω, and its noise figure puts the hiss floor 2 dB and 19 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| EA FORCE | 8-48 kHZ | not printed | not printed |
| OLA II | 8-48 kHZ | not printed | not printed |
Tanchjim prints the same thing for both the EA FORCE and the OLA II: 8-48 kHZ.
For both: Tanchjim prints this row in Chinese and puts the unit only on the upper figure. Read strictly, “8-48 kHZ” starts at 8 kHz; read the way everyone reads it, at 8 Hz. The maker does not say which.
Neither range has a tolerance printed beside it, so the matching numbers say little.
Not a measurement; maker by maker.
Both have a page of their own. In full: Tanchjim EA FORCE and Tanchjim OLA II. Each figure on this page is labelled on those pages with where it came from, including the ones Tanchjim never published — what that maker publishes, counted.