Creek Audio Destiny integrated amplifier Measurements

Sidebar 3: Measurements

I tried to precondition the Creek Destiny by running it at one-third its specified power into 8 ohms for one hour with both channels driven. However, it shut itself off after 20 minutes, and the area of the top panel over its internal heatsinks was very hot. Pressing the Standby button brought the amplifier back into operation.

Looking first at the Destiny's preamplifier section, in passive mode the maximum voltage gain, measured at the preamp-out jacks, was 0dB, as expected. Also as expected, the input impedance varied according to the setting of the volume control: from 16.5k ohms at low settings to a minimum of 12k ohms with the control at its maximum. These figures were taken at 1kHz; the input impedance also dropped a little at the top of the audioband, to 10.7k ohms. Source components with increasing output impedances at low frequencies, such as some tubed CD players, might sound a bit lean if used with the Destiny in passive mode. Channel matching was excellent with the volume control in its maximum position. However, a 0.67dB imbalance appeared at low settings of the control.

Switching in the active preamp appears to place the gain stage ahead of the volume control, as the input impedance was now significantly higher, at 73k ohms, and unaffected by the volume-control setting. The maximum gain in active mode depended on the setting of the three-position slide switch on the amplifier's bottom panel: 3.64dB, 6.27dB, or 9.15dB. The preamplifier output jacks offered a usefully low source impedance of 47.5 ohms and preserved absolute polarity— ie, were non-inverting—in both passive and active modes.

Turning to the amplifier as a whole, the maximum voltage gain in passive mode into 8 ohms was 33.7dB, which is significantly but commendably lower than usual for an integrated amplifier. The Destiny's output at the speaker terminals again preserved absolute polarity, and the source impedance was a low 0.085 ohm at low and middle frequencies (including 6' of speaker cable), to a still inconsequential 0.1 ohm at 20kHz. The modification of the amplifier's frequency response by the Ohm's Law interaction between this impedance and that of the loudspeaker was thus minimal (fig.1, top trace at 2kHz). Into resistive loads the Creek's bandwidth was wide, with an upper –3dB frequency of 116kHz, resulting in an excellent 10kHz squarewave shape with short risetimes (fig.2).

Fig.1 Creek Destiny, volume control at maximum, frequency response at 2.83V into (from top to bottom at 2kHz): simulated loudspeaker load, 8, 4, 2 ohms (0.5dB/vertical div., right channel dashed).

Fig.2 Creek Destiny, small-signal 10kHz squarewave into 8 ohms.

Channel separation (not shown) was somewhat disappointing but still adequate, at 66dB at 1kHz, decreasing, due to the usual capacitive coupling, to less than 50dB at 20kHz. The amplifier's signal/noise ratio was also a little disappointing, at 74.3dB, wideband, unweighted, ref. 2.83V with the volume control at its maximum. This is very much the worst-case situation; A-weighting improved the ratio to 78dB.

With both channels driven, the Destiny just exceeded its specified output power, at 103W into 8 ohms (20.1dBW) at clipping (1% THD+noise). More power was available with one channel driven. Fig.3 plots the THD+N percentage against output power into various loads; the power at clipping was 130W into 8 ohms (21.15dBW), 205W into 4 ohms (20.1dBW), and 250W into 2 ohms (18dBW). Because fig.3 indicates that the THD+N figure was dominated by noise at the 1W level, I plotted how the THD+N percentage changed with frequency at 9V RMS (equivalent to 10W into 8 ohms). The results are shown in fig.4: the distortion is respectably low into both 8 and 4 ohms at midrange and bass frequencies. However, it does rise at higher frequencies, presumably due to the amplifier circuit's decreasing amount of open-loop gain in this region.

Fig.3 Creek Destiny, distortion (%)vs 1kHz continuous output power into (from bottom to top at 100W): 8, 4, 2 ohms, one channel driven.

Note that fig.4 includes no traces showing the Destiny's performance into 2 ohms. I did try to perform a measurement into this demanding load, but the amplifier's protection circuitry muted the output after a few seconds, turned it on again a few seconds later, then muted it again. Unfortunately, this was followed by the smell of burning, and the Creek's power-amplifier section died. It's possible that fuses had blown, but I couldn't undo two of the Allen-head screws securing the amplifier's top cover to check to see if that had happened. Fortunately, by this point I had nearly completed my tests—all that's missing from this report is the input impedance of the power-amplifier section—but given Bob Reina's statement that he intends to buy the Destiny, I recommend he ask the importer for another sample!

Fig.4 Creek Destiny, THD+N (%)vs frequency at 9V into (from bottom to top): 8, 4 ohms (right channel dashed).

The Destiny's distortion content is strongly second harmonic in nature, even into low impedances (figs.5 and 6), though some third harmonic appears into higher impedances. Despite its decreasing linearity at the top of the audioband, the Destiny performed well on the punishing high-frequency intermodulation test, producing a 1kHz difference component at –80dB (0.01%) at a power level just below visible waveform clipping on the oscilloscope screen (fig.7).

Fig.5 Creek Destiny, 1kHz waveform at 19.5W into 4 ohms (top), 0.026% THD+N; distortion and noise waveform with fundamental notched out (bottom, not to scale).

Fig.6 Creek Destiny, spectrum of 50Hz sinewave, DC–1kHz, at 100W into 4 ohms (linear frequency scale).

Fig.7 Creek Destiny, HF intermodulation spectrum, DC–24kHz, 19+20kHz at 100W peak into 4 ohms (linear frequency scale).

The Creek Destiny's measured S/N ratios and channel separation are adequate rather than good, and care obviously needs to be taken that it isn't asked to drive high signal levels continuously into loudspeakers that drop to 2 ohms or below. Otherwise, it offers good measured performance.—John Atkinson

Creek Audio Ltd.
US distributor: Music Hall
108 Station Road
Great Neck, NY 11023
(516) 487-3663