Scan Speak 22W/8857T00 + 15W/8530-K00 + Vifa XT25TG30-04
(- or ScanSpeak R2904/832000)
Copyright 2009 © Troels Gravesen
Sven Felsby: "This speaker was designed for maximal bass extension on a minimal footprint. As a result we end up with an expected sensitivity of 85dB/2.8V".
So far, so good. Same midbass and tweeter as Ellam-XT, only here supplemented by an 8" dedicated bass driver taking us all the way down to 30 Hz. The price to pay is modest sensitivity, but impedance stays above 6.5 ohms and phase angles are modest, so no problem for a good minimum 100 wpc solid state amp.
To tune the port to 25Hz, the port has to
be placed vertically. Use a flanged port to minimize
Inner dimension with 4 mm bitumen pads on
all internal panels are:
Midcap outer dimensions:
What cannot be seen is what kind of bass performance we get in a given room. Bass performance is highly dependent on in-room placement of your speaker and the same speaker can be boomy in one place and lean in another. Actual SPL level at 1 meter distance and 2.8V input is useful for en estimate of system sensitivity and combined with the impedance profile may give an idea of how powerful an amplifier is needed to drive the speaker to adequate levels.
What measurements do not tell is the very sound of the speaker unless displaying serious linear distortion. The level of transparency, the ability to resolve micro-details, the "speed" of the bass, etc., cannot be derived from these data. Distortion measurements rarely tell anything unless seriously bad and most modern drivers display low distortion within their specified operating range.
Many people put way too much into these graphs and my comments here are only meant as warning against over-interpretation. There are way more to good sound than what can be extracted from a few graphs. I think I speak for all of us doing speaker measurements when I say that we learn new things every time we do one. Every graph needs interpretation in terms of what it means sonically and how it impacts our choice of mating drivers, cabinet and crossover design.