As I understand it there are three states that i use to compare DL (full frequency version*)
1. DL switched off, so you are hearing your system with all natural timing inaccuracies and all room induced frequency spectrum peaks and hollows added to the sound quality that your system is able to provide.
2. DL switched on and curtains drawn together, so you are getting timing correction across the full frequency spectrum but no attempts to compensate for peaks and hollows as mentioned above. This is a very interesting state that allows us to see how important impulse timing issues are with our current systems.***
3. DL switched on and.... well at this point we, the end users of DL, will have tried our best to create/use a good target curve (**see below) , so hopefully we will be getting the best timing and frequency response from our hifi/room system.
* the bass only DL lite system will not let us have control of the high frequency curtain, which means that with DL on we will always have high (>500Hz) frequencies bound/altered by the target curve in use at the time.
** having bought my m33 some time ago, i have recently home demoed several new speakers. Each of them produce very different DL shaped FR curves (even positioned in the exact same points in the room) and therefore needed very different target curve tweaking to produce the best final result to my taste.
*** only one speaker demoed out of 4 speakers showed that it already had good impulse timing naturally (Russell K 150se). All the others showed a comparatively large change when state 2. above was engaged. ( B&W805; Audiovector R3; Kudos Titan 606)
Other points of note were:
- the Russell K150se, in room FR curve, most closely correlated with the standard DL target curve. The other 3 speakers each had varying degrees of naturally raised levels at tweeter frequencies (making them sound dull with using an untweaked standard curve, as would have to happen with DL Lite).
- i redid DL measurements several times for each speaker and found that my final results improved with practice at using the software and microphone placements. Astonishing
- at no time did i notice a volume change with DL on compared to off. There may have been some difference but i didn’t notice any.
- ‘my taste’ with DL target curve tweaking is to get as natural frequency response as I can from my M33 through into my ears at my listening position. I am trying to wean myself completely from room boom and hot tweeters, both of which I have been accustomed to for 40 years or more. It is getting easier by keeping DL on at all times, and its sounding great!
- I have ended up with the Audiovector R3s because they sound good in my room AND they have the greatest sensitivity, which with my M33 solved the problem of maxing out of volume headroom with some of my input sources.