We take it for granted electrostatic speakers alone will not normally reproduce lows below 100hz and should come with a sub that can at least do 25 to 125 hz to cover the deep bass especially for 6k
Wrong! Quad ESL's do not integrate with any sub as they are dipoles and most subs are ineffective at integrating correctly without smearing the ESL's transparent delivery. Now another lesser known fact is that unless an ESL is secured into a high-mass structure that keeps the entire frame from any movement at all, the smaller distance of 'back-and-forth' diaphragm modulations are shorn of the leading edge transient response power in the bass, plus the perception of extended low-frequency response. The true power of dynamics in the bass on a correctly anchored ESL is quite something to not only hear, but to feel, right in the gut, such as bass drum really struck hard in a concert hall. On the original ESL (often called the ESL-57), I designed a quartz composite stand that proved (with all the rear wadding material removed and speakers placed one-third of the way down a rectangular room) that they can go louder and with a more impactful and extended range sound without recourse to adding subs or super tweeters. These speakers also really benefit from being used in really quiet rooms with a low ambient noise-floor. This heightens perceived dynamic range. So much rubbish has been written in ignorance down the years by journalists who have not spent the time experimenting with these speakers, whose acoustic behavior requires a completely different discipline of thinking and approach. If an ideal sub were designed, I'd say that the larger, single diaphragm ESL-63, allied to a similarly high-mass elevated stand, with a low-pass crossover, placed one-third of the way into a rectangular room, would be the ideal when trying to integrate with a pair of stats; using the same dipole approach. The 63 often gets unfairly criticised as being less good sounding than it's 57 forebear, but this is due to the fact that a) The 63 has no rear wadding to limit loading the room with bass, and b) The 63 has a larger surface area dedicated to bass; conversely making the 63 a speaker best suited to larger rooms if wanting to limit the room-nodes of the upper bass frequencies that many say the 57 doesn't create. Again, all electrostatics really benefit from solid, secure anchorage and elevation from the norm, plus plenty of rear wall clearance. They also sound better if tilted with the sound directed above the listener's head, which undoes the hot-spot issue and creates a sense of greater reality to the sound. See www.eslinspiration.com for more info.
Place sound absorbers bass traps and diffusers where required in the room to care for reverberated sounds, standing waves and...(phase issues) if subwoofer is going to be integrated. I use two LD Systems 18" professional audio subwoofers left and right, next to the subs live my Quad ESL-2805 (ranging down to 33Hz) and there is no way I can feel any delay in bass response. The subwoofer cones hardly vibrate while pressurising the listening area with sweet low frequencies effortlessly. No problems with cross-overing, phase cancellations or transient response as though. A smaller subwoofer cone say 12" for example will have more throw inwards/outwards when playing at comparable dB level than a big 18". I prefer subwoofers to be a part of my system.
It's too bad these 2812/2912 Quads have had such a bad quality control problems. Poor distribution in most countries means if they develop problems (and there's a good chance they will) you'll probably have to ship them overseas to get them fixed. Buyers beware, before you buy Quad ESLs make sure you can find local and accessible parts and servicing for them.
Er, no, they go down to around 35hz. Read my earlier reply to another response above here for more info. Electrostatics amaze all who hear them in a correctly set-up demo, (and not in an overcrowded hotel room, set-up by sales people who seldom have a clue), and make normal speakers sound crude on acoustic material. If you're into drum n' bass or techno, then wardrobe speakers of big subs will be the order of the day, but for real life sound, this is the technology that has stood the test of 60-years!
I've lived with these for a couple of years and I can confirm the bass is really excellent! As Britishcomposers said they go down to 35hz or there abouts (measured). As he says, well recorded acoustic instruments are rendered with amazing accuracy and depth of soundstage. They really need raising off the ground (as the 63s I had before did) so that the bottom of the bottom bass panel is 12 inches off the floor. I have built solid 4x2''' frames which screw into the holes for the spikes and the spikes screw into t-nuts on the bottom of the frames, results with, say, huge orchestral bass drum (try BIS CD 294 Sibelius Lemminkäinen Suite) astonishing depth of bass, but no overhang or cabinet resonances just the pure sound of a very large bass drum in a perfect acoustic. A decent amplifier helps: I use the massive Quad QMP monoblocks (320w into 4 ohms). Position well away from walls behind them, but almost up against the side walls....and you'll be rewarded by one of the wonders of HiFi!
