Electronics: OPAMP tests into a 270 ohm load
A friend was modifying a cheap headphone amp, and was wondering which OPAMP would work the best.So I created a similar circuit and measured several different OPAMPS loaded with 270 ohms as a 'typical' headphone load.
Note: Don't only look at the headline THD figure - also note the harmonic distortion even for some that measured well.
Measurement parameters:
PSU: 15 - 0 - 15
Gain: 2.2
Output: 2.7V RMS
Load: 270 ohms
| Opamp | THD | Notes |
|---|---|---|
| LM4562NA | 0.00027% | no data |
| NE5532N | 0.00160% | Philips |
| NE5532N | 0.00141% | Signetics |
| NE5532N | 0.00090% | Texas |
| NJM2043DD | 0.00101% | JRC / NJM |
| NJM2068DD | 0.00090% | JRC/NJM |
| NJM4558DD | 0.00604% | JRC / NJM |
| NJM4565DD | 0.00502% | JRC / NJM |
| NJM4580DD | 0.00082% | NJM / JRC |
| OPA2134P | 0.02294% | BB |
| OPA2604AU | 0.00132% | Sample #1 - brand unknown |
| OPA2604AU | 0.00139% | Sample #2 - brand unknown |
