Burmester 077/218 Pre/Power Amplifiers Lab Report

Lab Report

Burmester 218

Weighing in at 42kg and very nearly a full half-metre in width, the 218 might be expected to have an equally 'massive' 8ohm power specification. However, while the 218 is rated at a relatively modest 165W/8ohm, and achieves 2x193W/8ohm in practice, the power supply regulation is sufficiently stiff to accommodate peaks at <1% THD of 221W, 419W, 738W and 1.13kW into 8, 4, 2 and 1ohm loads, respectively [see Graph 1, below]. With a current capacity of 34A, the '165W' 218 is thus very tolerant of low and difficult loudspeaker loads. The output impedance is a fairly consistent 0.014-0.019ohm (20Hz-20kHz), maintaining its +0.0dB to –0.06dB response (20Hz-20kHz) into most loads. At the extremes, the 218 dips to –0.5dB/1Hz and –1.15dB/100kHz. Gain is more than high enough at +34.3dB (balanced input) and noise very low, yielding a very wide 95dB (re. 0dBW) A-wtd S/N ratio – so the 218 is a very quiet amplifier.

Just as critical, from a subjective standpoint, is the uniformity of the 218's distortion profile, no doubt informed by Burmester's proprietary 'X-AMP technology'. Versus level, distortion remains <0.002% from 1W to 140W and only touches 0.0028% at the rated 165W (all re. 1kHz/8ohm). Versus frequency, distortion gently climbs from 0.0007%/100Hz to 0.0017%/1kHz and 0.008%/20kHz (re. 10W/8ohm), a pattern that holds true at lower and higher power outputs [see Graph 2, below]. Intermodulation distortion is <0.0003% (re. 10W). Finally, stereo separation is a wide 70dB+ (20Hz-20kHz), channel balance/matching is good to 0.01dB and any DC offset at the output is held to below ±2mV – impressive bearing in mind the 218 is a fully DC-coupled/capacitorless amplifier. PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 33.6A


Distortion versus frequency versus power output (1W/8ohm, black; 10W, pink; 100W, red)

Power output (<1% THD, 8/4ohm) 193W / 320W
Dynamic power (<1% THD, 8/4/2/1ohm) 221W / 419W / 738W / 1131W
Output imp. (20Hz–20kHz/100kHz) 0.014-0.019ohm / 0.053ohm
Freq. resp. (20Hz–20kHz/100kHz) +0.0dB to –0.06dB/–1.15dB
Input sensitivity (for 0dBW/165W) 55mV / 715mV
A-wtd S/N ratio (re. 0dBW/165W) 94.6dB / 116.8dB
Distortion (20Hz-20kHz, 10W/8ohm) 0.00065-0.0078%
Power consumption (Idle/Rated o/p) 46W / 540W (1W standby)
Dimensions (WHD) / Weight (total) 496x216x479mm / 42kg

Burmester 077

Burmester's 60-step volume control operates with a mix of 1dB and 2dB steps (one 2dB step for every three 1dB steps) to offer a reliable 80dB range and a channel balance error of <0.1dB down to volume setting '15'. Gain is variable within either 'Low' or 'High' master modes, with the default '00' gain setting offering +3.5dB (or +6.5dB in 'High') adjustable to +15.6dB and +19.2dB (+12dB input gain setting in 'Low' and 'High' modes) and down to –2.5dB and +13.1dB (–06dB gain setting in 'Low' and 'High'). The maximum output(s) are 3.5V in 'Low' and 21.5V in 'High' M-Out modes regardless of input level 'gain' settings. Output impedance is 112ohm in 'Low' and 64ohm in 'High', and the A-wtd S/N is 99.1dB and 92.5dB, respectively, but there is no difference in the ±0.0dB response (20Hz-20kHz) which reaches +0.5dB/1Hz and –1.45dB/100kHz. Distortion is lowest in 'Low' mode at 0.00015-0.0003% [20Hz-20kHz, 0dBV; black trace, Graph 2] with 2nd-4th harmonics dominating.

Used as a DAC/preamp with upsampling enabled, the 077 delivers a 2.63V balanced output for a 0dBFs digital input (the output clips beyond volume position '55'). Distortion is a low 0.0006-0.0016% (re. 20Hz-20kHz) at this full scale input [see red trace, Graph 2] and falls to a minimum of 0.0003%/1kHz and a lower 0.00009%/20kHz over the top 30dB of its range [Graph 1]. The A-wtd S/N is a fine 109dB, linearity good to ±0.2dB over a 100dB range and channel separation is an excellent 130dB. Wolfson's WM8741 DAC [see Burmester 069, HFN Jan '12] has built-in jitter rejection (all sample rates <10psec), while the linear phase digital filter confers 99dB stopband rejection and a 'digital' response of –0.0dB/20kHz, –2.1dB/45kHz and –14.5dB/90kHz with 48kHz, 96kHz and 192kHz media, respectively. PM


Distortion versus 24-bit digital signal level over a 120dB range at 1kHz (black) and 20kHz (blue)


Distortion versus frequency at 0dBV output [96kHz/24-bit digital in, red; analogue in, black]

Maximum output / Impedance 2.63V / 112ohm (balanced)
Input sensitivity (re. 0dBV) 666mV (balanced)
Freq. resp. (20Hz-20kHz/100kHz) +0.0 to –0.01dB/–1.45dB (pre)
Freq. resp. (20Hz-20k/45k/90kHz) +0.0 to –0.04/–2.10/–14.5dB (DAC)
Digital jitter (USB at 48kHz/96kHz) 8psec / 9psec
A-wtd S/N ratio (re. 0dBV/0dBFs) 98.8dB (Analogue) / 109.2dB (Dig)
Distortion (20Hz-20kHz; 0dBV/0dBFs) 0.00015-0.0003%/0.0006-0.0016%
Power consumption 52W (W standby)
Dimensions (WHD) / Weight (w PSU) 450x156x346mm / 25kg (51kg)
Prices (pre/power): £35,900 (inc. choice of one module)/£34,600

Burmester Audiosysteme GmbH
Berlin, Germany
Supplied by: Burmester Audiosysteme GmbH
+49 307 879680