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gibbo9000

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About gibbo9000

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    David

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  1. Not sure of availability in SA, but if you can get hold of a Rythmik would be worth a look/listen The 12" take bass well down below 20Hz, sealed enclosure, and typically have PEQ built in (along with phase, volume etc. typical on others) to dovetail with Kef's. Come up in classifieds every now and then. Popular in Europe and US.
  2. These certainly sound interesting if they do what the marketing spiel says. But I didn't find any notes on best practice for using them. Is it just 1 or 2 placed anywhere in the room, or is it closer to one behind each speaker to absorb the rear waves and create more of a front focussed cardiod radiation from the speakers?
  3. As you have mentioned above there are multiple elements that can be added into the criteria for a truly active speaker - ending up with a complete room acoustic feedback mechanism. Not sure we are there yet. So best I can do is a couple of thoughts on examples. Rythmik subwoofer certainly has a form of feedback from cone to amplifier with their 'Direct Servo' technology - but as far as I can tell its main function / impact is to force the position of the cone independent of the pressure behind the cone in its sealed enclosure. So should provide a truer wave out the front - relative to a sub where the pressure is not compensated for. Has EQ and DSP on board, but need manual setting are are not distinct from many others in that respect (but they do sound good in 2.1 applications) In terms of pushing to your boundaries on the definition of truly 'active' speakers, the Kii Three appears to have some interesting breakthroughs. 6 speakers per enclosure, each with its own amp including feedback from associated speaker. 2 face forward, two sideways, and two rear facing. While the DSP is not real time reading room feedback, it is actively creating a Cardiod distribution (sound predominately forward to listening position) down to 50Hz or so by using the rear facing drivers to null the sound from rear of speaker and minimise the impact of the rear wall reflections / indirect signals on room interactions. That is well beyond my working definition of a crossover or EQ. While not actively reading the room, it is taking a lot of room interaction out of the equation - and the results are compelling putting 20Hz to 20kHz response in a 'big' bookshelf speaker. Have full EQ capabilities built in to tailor settings -- and certainly heading in the direction where you could imagine them adding a Dirac like application to automate measurements and EQ settings. I am sure the tech will take a while to trickle down to mainstream consumer speakers -- but if you are interested it is worth reading some of the technical reviews online to get a sense of where things are heading. Their marketing hype on 'Active Wave Focussing' as they call it is here: https://www.kiiaudio.com/acoustics.php Gibbo
  4. Just a heads up that an alternate approach is to use one of the wireless adapters available. A few around. This is the SVS one: https://www.svsound.com/blogs/svs/how-to-set-up-a-wireless-subwoofer
  5. Read the reviews - need to be heard to be believed! A bargain at half of current retail price. Attached example from Sound on Sound review. GLWTS (if you can part with them!)
  6. Stacks would be fun - but BXT's would be better. From the emerging reviews on them they are a lot more than a sub, and your experience supports that. Enjoy them! I will keep playing and try not to get too tempted. I am not a bass head, but I do want to try some target curves that are a bit more intensive in the lower range for classical / orchestral, and I sense the sub will add some grunt there without sacrificing SPL overall.
  7. Thanks Ray. Rythmik feels good and tight as it is meant to be, and miniDSP setup can easily handle second. It has two SPDIF out - one going to Kii's and second to DAC (currently using combined signal on one channel out to sub, so second into other channel of DAC and away it would go). It is small step up, but I sense there is a lot more to the line source concept of the BXTs and the impact they have. Well set up sub just unloads the low end of Kii's a little when pushed - perhaps 5 - 10% improvement if pushed on loud/deep base, but little on most of my listening. To emulate BXT's I might need two stacks of 3 subs! I sense part of my result is a bit obvious. Given I have used Dirac to set a specific response curve for Kii's (no Sub), and then also asked Dirac to set the same curve for Kii's plus sub, and the sub is time aligned and below 50Hz, they should really sound the same until the Kii's run out of puff - which is only when pushed very hard by my standards. I have only very rarely seem the red light, and they were accidents. Without Dirac 'normalising' the two they may sound more different, but that would be equivalent to setting a different curve. So interesting and a small step up -- but from an awesome base. I am still wondering what a 30-40% improvement could possibly sound like?!
  8. The Kii's now have a subwoofer friend. Ended up going with the Rythmik F12 based on certainty of low down frequency response and matte black colour goes with Kii stands. I am using a MinDSP SHD Studio that is only digital out, so had to add a DAC for sub. Took me a few days and a couple of detours to master REW for delay calculations and get consistent, sensible results. And they showed the sub was a good 90ms ahead of the Kii's! Can get some of that back by turning off 'Exact' mode in Kii's, but that is not recommended for stereo. Unfortunately adjustments on sub and in MiniDSP could only add around 40ms delay on sub, so I had to add an external delay - currently a Blustream analogue in/out device, but looking for a digital one. Armed with that I got the sub and main pretty tightly time aligned. At this stage I have followed the Kii advice above on keeping the sub below 50Hz and have two settings for testing - one with XOver at 30Hz and a second with XOver at 40Hz. Both use Linkwitz-Riley filters at 48db/octave. Sounds highly technical but I take the simple version - keeps output constant through XOver frequencies, and the 30Hz one has sub completely turned off by 50Hz. I then calibrated both XOver steups, along with a no sub version, to Dirac house curve from ~18Hz up. MiniDSP makes it easy to switch between the 3 different configurations in almost real time. Now I have some listening to do. Initial impressions are that the sub does very little work unless listening to tracks with lots of deep base and up loud. At my normal listening levels the audible changes are definitely quite subtle. Nothing dramatic, just a sense of slightly more power / ease. No large change in sound stage (but the starting point is pretty good!). Will do some more listening, and perhaps try moving the XOver up to 50Hz to see if letting sub do more work alters anything more dramatically - but I doubt it - it seems to fit in pretty seemlessly. Gibbo
  9. Agreed. But it appears real. Main speakers are active with DSP built in - and in their most 'accurate' mode (they call 'Exact') they note a 90ms delay. I would say there is more in addition to that. I have tamed the timing reference/measurement issue and get consistent delays around 220ms. MinDSP will take 30ms max out of that (by delaying signal to sub) and that reduces to 190ms as expected. Sub delay/ phase can take a further 20ms out. So now looking at audio delay processors as an option into sub.
  10. Thanks for the input guys. @snoopy8 was close. As well as letting REW know the timing reference speaker, you need to leave that speaker turned on!! REW will only send the timing reference 'chirp' to that speaker, not the full signal. I was turning both mains off when measuring sub as sub takes signal from both mains. So now I have a new problem - sub with its DSP is a good 200ms ahead of main speakers - more than MiniDSP of sub phase control can fix!
  11. There seem to be two concepts at play here from what I can tell, but using similar wording. First is, as you say, which speaker is the timing reference 'speaker' from which relative delays are calculated. For me that is main left. That is set in REW and left the same for all 3 sweeps in a 2.1 system (L, R and Sub each done individually with only the relevant speaker active) Then there is the timing reference 'signal' that REW includes in each sweep (the chirp near the beginning). I understand it uses that to calculate the 'system delay' for each speaker. But with a sub, that 'chirp' isn't audible and REW complains and says it can't determine a 'system delay' for that speaker. At least that is my understanding . . .
  12. I disabled all the filters into and on sub, and cranked the volume into/on sub as high as I could stand - and thought I heard something of the timing reference, but not enough for REW to recognise.
  13. I am basically following this approach: https://www.minidsp.com/applications/auto-eq-with-rew/measuring-time-delay which suggests using the timing reference in REW measurement. Works fine for mains, but sub doesn't reproduce timing reference tone given its frequency response. In my case REW on laptop with out as USB into MiniDSP SHD Studio. SHD provides two digital outputs - one to main speakers (active with digital in) and other via DAC to Sub. Umik measurement mic connected back to laptop. And I am only doing this in 2.1 config, not HT as per link.
  14. Have been using REW to attempt to get a time delay / phase correction for sub-woofer. Both mains and sub-woofer are active with inbuilt DSPs (with their own delays) so pure physical alignment of speakers isn't sufficient. The underlying challenge is that the limited frequency response of the sub-woofer stops it reproducing the timing reference signal for REW. According to other posts I have searched it should still attempt to estimate the delay, but warn that it may not be accurate. I can't get it to even provide an estimate. So: Any thoughts on how to get it to estimate? If that is not possible, is there an alternate approach to deriving it from the available data? Failing that I guess I am back to SPL measurements as a surrogate. Any thoughts? Gibbo
  15. Hi There, I am not sure anyone quite understood your question . . are you looking for eco friendly music producers or or producing processes or something like that. Perhaps have a look around and see if you can find any similar threads and post there. All sorts of wide ranging experience if you go looking. Welcome on board anyway.
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