Raidho TD2.2 Loudspeaker Lab Report

Lab Report

Raidho claims 88dB sensitivity for the TD2.2 but our results come in a little lower. While a simple mean of the FFT data gets quite close at 87.3dB, the pink noise and 'music' figures of 85.6dB and 85.4dB indicate that an 85.5dB specification might be nearer the mark, though this is around 2dB better than achieved by the D2.1. A nominal impedance of 6ohm isn't quite justified either, given that this suggests a minimum modulus of 4.8ohm whereas we measured a minimum of 4.4ohm. Impedance phase angles are moderately high, and although the EPDR falls to a minimum of 2.1ohm at 94Hz, this suggests that the TD2.2 is slightly easier to drive than typical modern speakers of its form factor.

Forward frequency responses [see Graph 1, below] were measured at 1m on the tweeter axis and show a hint of a 'BBC dip' centred on 2.5kHz, followed by a mildly shelved-up treble. Because of the latter, and a dip of unknown origin at 375Hz, response errors are on the high side at ±5.2dB and ±4.5dB, respectively. Pair matching over the same 200Hz-20kHz frequency range is fair at ±1.0dB and improves to a fine ±0.6dB below 16kHz. Diffraction-corrected nearfield bass measurement showed the LF output to decline gently below 100Hz before steepening to the expected fourth-order roll-off below 35Hz, with a creditable 37Hz extension (–6dB re. 200Hz). As we have seen before with isodynamic tweeters, THD at 10kHz was a little high at 1.1% although past experience has also shown that these can give variable distortion results when measured nearfield. The treble resonances visible in the CSD waterfall [see Graph 2, below], which would usually be ascribed to breakup modes in the bass-mid driver, are lower than seen in the D2.1. KH


375Hz dip is unexpected as is the slight upper-mid depression, but presence/treble return strongly


Cabinet modes are well controlled but cluster of resonances at 3-8kHz is linked to bass/mid driver

Sensitivity (SPL/1m/2.83V – Mean/IEC/Music) 87.3dB / 85.6dB / 85.4dB
Impedance modulus: minimum & maximum (20Hz–20kHz) 4.4ohm @ 125Hz, 30.0ohm @ 23Hz
Impedance phase: minimum & maximum (20Hz–20kHz) –51° @ 69Hz, 31° @ 20Hz
Pair matching/Resp. error (200Hz–20kHz) ±1.0dB/ ±5.2dB/±4.5dB
LF/HF extension (–6dB ref 200Hz/10kHz) 37Hz / >40kHz/38.6kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m) 0.5% / 0.1% / 1.1%
Dimensions (HWD) / Weight (each) 1055x200x520mm / 45kg
Price £38,000

Raidho Acoustics (Dantax Radio A/S)
Supplied by: Decent Audio, Stockton-on-Tees
05602 054669