SPL Elector/Performer s1200 Pre/Power Amplifier Lab Report

Lab Report Preamp

With its analogue line stage based on the Director Mk2 (minus the DAC here), the Elector is essentially a buffered, unity gain volume control. At maximum volume the (balanced) output shows a mere –0.18dB loss while, courtesy of those VOLTAiR op-amps, the output peaks at a high 32.5V. This is also the Elector's maximum input level, a figure achieved by very few DAC/line sources aside from one or two similarly 'high voltage' and typically tube-based components, including the 92V-capable REF Phono 3SE from Audio Research [HFN Apr '22].

The output impedance [red trace, Graph 1 below] is a uniform 36ohm from 100Hz-20kHz, increasing very slightly to 38.5ohm at lower bass frequencies. This slight variation is not reflected in any significant low bass or high treble roll-off [black trace, Graph] – in fact the Elector has wide ±0.5dB response limits of 2Hz-50kHz, rolling away to just –1.8dB/100kHz (SPL quotes a –3dB/300kHz bandwidth). SPL also offers a very precise THD+N specification of '0.000992%' for the Elector although it references neither the test frequency or output level.

Leaving aside the fact that 'real world' production variations would make such a target impossible to guarantee, in practice the Elector preamp does rather better, incurring a mere 0.0001-0.0008% THD from 20Hz-20kHz at a standard 0dBV output [see Graph 2, below]. Better, perhaps, for SPL to specify its Elector preamplifier at <0.001% distortion (20Hz-20kHz, re. 0dBV). Finally, the A-wtd S/N is a respectable 93.8dB (re. 0dBV), residual noise a low –100dBV while the motorised 'Big Blue' Alps RK27 potentiometer offers a channel balance that's good to ±0.04dB at 0dB and ±1dB at –60dB. PM


Balanced line frequency response (black) and output impedance (red) at 0dBV


Distortion versus extended frequency at 0dBV (Balanced in/out; left, black; right channel, red)

Maximum output (<1% THD, 47kohm) 32.5Vrms (Balanced)
Maximum input level (<1% THD) 32.5Vrms (Balanced)
Output impedance (20Hz–20kHz) 35.8-38.5ohm (Balanced)
Freq. response (20Hz–20kHz/100kHz) +0.0dB to –0.08dB / –1.8dB
Input sensitivity (re. 0dBV) 1021mV (Balanced)
A-wtd S/N ratio (re. 0dBV) 93.8dB
Distortion (20Hz-20kHz re. 0dBV) 0.0001–0.0008%
Power consumption 18W (2W standby)
Dimensions (WHD) / Weight (total) 278x100x300mm / 4.3kg

Lab Report Power Amp

While SPL's quest for low distortion performance is firmly anchored with its line/preamp products, including the Phonitor xe [HFN Jul '21], the partnering s1200 stereo power amp is simply listed at <0.04% THD (re. 1kHz/8ohm). In practice, the s1200 meets this specification with distortion falling from 0.02%/1W to 0.01%/10W and a minimum of 0.003%/100W beyond which it increases again to 0.0055%/200W and 0.01% at the rated 300W/8ohm. At higher frequencies, particularly above 10kHz, distortion increases more markedly, although as its ~0.3-1% THD/20kHz increases only marginally with output level [see Graph 2, below] this suggests it's as much a function of the input buffer/voltage gain stage as the final power amp. Which, it must be said, is a very powerful 'engine' for the modest proportions of the SPL s1200's fan-cooled enclosure.

Rated at 2x300W/8ohm and 2x520W/4ohm it actually achieves 2x345W/8ohm and 2x630W/4ohm, increasing still further to 405W, 765W, 1.30kW and 1.59kW under dynamic conditions into 8, 4, 2 and 1ohm loads, respectively [see Graph 1, below]. Note also from this Graph that distortion under dynamic conditions is higher than with the same power under continuous conditions (0.028% versus 0.01% re. 10W/8ohm). The output impedance also follows this same 'flat' trend seen with the THD profile through bass and midrange (0.024-0.045ohm from 20Hz-6kHz) but then kicks up to 0.12ohm/20kHz and 1.30ohm/100kHz. Similarly with the frequency response: flat to within ±0.05dB from 2Hz-6kHz but then –0.55dB/20kHz and –6.9dB/100kHz. Finally, gain is +26.4dB (balanced in) and the A-wtd S/N ratio a little above 'average' at 86.7dB (re. 0dBW). PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 39.9A


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

Power output (<1% THD, 8/4ohm) 345W / 630W
Dynamic power (<1% THD, 8/4/2/1ohm) 405W/765W/1.30kW/1.59kW
Output imp. (20Hz–20kHz/100kHz) 0.024–0.12ohm / 1.30ohm
Freq. resp. (20Hz–20kHz/100kHz) +0.0dB to –0.55dB/–6.9dB
Input sensitivity (for 0dBW/300W) 135mV / 2380mV
A-wtd S/N ratio (re. 0dBW/300W) 86.7dB / 111.5dB
Distortion (20Hz-20kHz, 10W/8ohm) 0.006–0.28%
Power consumption (Idle/Rated o/p) 16W / 888W (1W standby)
Dimensions (WHD) / Weight 278x205x375mm / 25.1kg
Prices £2399/£6499 (pre/power amp)

SPL electronics GmbH
Niederkruechten, Germany
Supplied by: SCV Electronics Ltd, Herts
03301 222500