TrueResponse — the name given by Sennheiser to the in-house developed and manufactured 7mm IEM driver found in its Momentum True Wireless 3 and four audiophile-aimed wired IEMs: the flagship IE 900, the IE 600, the IE 300 and the IE 200. To understand why they don’t sound alike, we’d need to get Sennheiser’s Product Manager for Audiophile products, Jermo Köhnke, on the horn.
In this episode of the Darko.Audio podcast, Köhnke takes us deep into the back story of the TrueResponse driver’s development and production and how it is implemented and tuned differently within each IEM model. The first wired model out of the gate to feature the TrueResponse driver was the flagship IE 900 (US$1499) where three Helmholtz resonator chambers are milled into the underside of the aluminium housing to extend and smooth the treble response. The more affordable IE 600 (US$799) uses the same TrueResponse driver but the earshells are 3D printed with ‘ZR01 amorphous zirconium’ and feature only two resonators — and there’s no mention of them being of a Helmholtz type.
But then comes a twist in Köhnke’s tale. The IE 600 was reportedly voiced in order to satisfy those wanting to see more obvious pinna gain in frequency response measurements: an amplitude lift starting at 1kHz and topping out at around 3kHz, as popularised by the Harman Target Curve. The way Köhnke tells it, pinna gain was purposefully omitted from the IE 900 in order to optimise its sound quality. Having lived with both models for the past two months, I can say with a reasonable degree of confidence that the superior-sounding IE 900 contrasts the IE 600 as sounding a little muddy in all but vocal presence. It seems Sennheiser’s customer base hears it that way too with sales of the IE 900 apparently outstripping the IE 600 with ease.
Did Sennheiser produce an inferior-sounding headphone just to placate the online measurement mob? Without hearing the IE 600’s original voicing, we’ll never know for sure but in Jude Mansilla’s video coverage of the IE 900, the Head-fi head honcho’s frustration with those who would prioritise their eyes over their ears is palpable.
Further information: Sennheiser
👉🏻 As mentioned in this podcast…
Sennheiser Momentum True Wireless 3
Sennheiser’s TrueResponse driver
Darko.Audio may earn a small commission from items purchased via affiliate links.