Topping B100 review (RCA input)

This test review is a follow-up to my previous B100 review. Topping support dept. has informed us that the amp should not be supplied by a signal from the RCA==>XLR adapter cable. It is a direct BTL output design and with the adapter only one half of the amplifier is working.

The Topping B100 is a small, affordable, 1-channel Class B amplifier. It claims excellent distortion parameters and output power of 100W/4ohm/THD+N<1%.

1. Test conditions

The amplifier was tested with a power supply sent by Shenzenaudio with the amplifier. 4ohm (and 8ohm) resistive load was used. As per the manufacturer, the rated output power should be 100W/4ohm/THD+N<1%.

I needed to use the USB isolator to get the lowest background noise with the RCA input.

2. Pre-conditioning

1 hour pre-conditioning at 1/8 rated output power (as per FTC) was not used as the amplifier runs hot with the longterm sine wave signal. Short pre-conditioning at 7W/8ohm was used instead.

3. Frequency response

Frequency response was measured at 9W output power into 4ohm load and it is flat, no need to show.

4. Power frequency response

Was impossible to measure, as the amplifier shuts down itself below reaching the rated power into 4ohm.

5. Distortion

5.1. Distortion at 7.1W/8ohm (near 1/8 of maximum power at 1kHz/8ohm)

Both distortion and noise are very low at this power level.

5.2. THD vs. output voltage into 8ohm and 4ohm load at 1kHz with measurement bandwidth 45kHz. The stepped sine test uses 0.8s long sine bursts with 0.5s interval between them.

8ohm

Maximum sine power before hard clipping was 54W/1kHz into 8ohm. The amp failed to reach the company rated power 70W/8ohm/THD+N<1%.

4ohm

The amplifier shut down itself at 94W with the 1kHz stepped sine and failed to reach the company rated power.

5.3. THD vs. frequency at 9W/4ohm (at 1/10 of maximum power into 4ohm)

5.5. THD vs. frequency at rated power

Not tested for the reason explained here above.

6. Company specifications

7. Conclusion

Topping B100 has had extremely low noise and distortion and very flat frequency response. However, it was not able to reach the company specs in the rated power, measured neither with continuos sine waves, nor with the stepped sine method. It failed to meet the power specifications.

Pavel Macura 11/27/2024