If you read the entire site it would take a while for sure 😉
The upper baffle drivers are not really that expensive if SEAS drivers are available to you. The woofers, DSP crossover and multiple amplifiers are where the price shoots up.
You could make something very nice out of the Scanspeak 3.5" fullrange, a Discovery 8" woofer and a small tweeter of choice. Scanspeak make some 10" drivers that would work well enough or Dayton Reference drivers would also be worth looking at.
I actually preferred not having the tweeter be dipole, so you could save money there.
Look at John K's Nao Note speakers designed around the same time as LX521, I don't think his site is still around but there would be information somewhere.
To do it right is expensive and a lot of effort, to not do it right is easier and cheaper but likely to be ultimately disappointing 🙂
The upper baffle drivers are not really that expensive if SEAS drivers are available to you. The woofers, DSP crossover and multiple amplifiers are where the price shoots up.
You could make something very nice out of the Scanspeak 3.5" fullrange, a Discovery 8" woofer and a small tweeter of choice. Scanspeak make some 10" drivers that would work well enough or Dayton Reference drivers would also be worth looking at.
I actually preferred not having the tweeter be dipole, so you could save money there.
Look at John K's Nao Note speakers designed around the same time as LX521, I don't think his site is still around but there would be information somewhere.
To do it right is expensive and a lot of effort, to not do it right is easier and cheaper but likely to be ultimately disappointing 🙂
Interesting. I found the opposite: running a monopole tweeter meant the mids and bass were dipole (with the room interaction that entails), while the tweeter had a completely different signature from the very different room interaction.
I couldn't find a way to enjoy it, and abandoned that project.
FWIW, I'd say the most difficult part of doing an OB well is the bass. I used a Beyma 15P1200Nd per side on some fairly small baffles, and needed +27dB of LF boost to get to 25Hz.
The bass was very good, though, although all that EQ (and power to back it up) meant it was easy to pass Xmax at demo levels.
Chris
I don't want to aim for disappointment, even if its not much work, but would for example the driver set you mention above be "not right" leading to disappointment, and is passive as opposed to active not right as well. i am sure its all a question of degree.
Just now i plugged in a pair of 2 way ported box speakers i built >25 years ago, originally with stands that escaped somewhere, and first, they worked, and secondly, really weren't bad particularly if one ignored the lack in bass...a question of degree, but they were never going to give you that moment where attention is grabbed and you smile!
That bass unit sounds massive for an ordinary domestic environment, and its excursion also, but i think your work looks like outside and public? i shall read more of these various sites when the sun goes down
The OB project was intended for home HiFi applications. I just happened to have a few high-power 15"s around to play with.
IIRC, it was getting to 30mm p/p travel when I chickened out and decided that was enough.
Chris
IIRC, it was getting to 30mm p/p travel when I chickened out and decided that was enough.
Chris
I rarely see cone movement on my bass units at all, and if anything its a few mm....i guess i dont play it loud enough!
A frame for the bass makes a huge difference and still is a good dipole, just crossover below the cavity resonance frequency
Yes, sorry, that's what I mean. A frame like Linkwitz uses for the LX521 also gives a little force cancellation and I imagine less cavity resonance.
So..........if i were to borrow the components out of my Fusion boxes for a while and mount the woofer in an H frame/box and the mid and tweeter on a flat panel above on the same plane as the woofer within its frame all perhaps in the same dimensional pattern as the Fusion uses, i might have an interesting experiment to compare open baffle sound to boxes. If i were to read a lot i might be able to programme the Hypex better for the bass on OB.
I am not sure whether the few encouraging responses justify the effort or whether people are really saying that to better the Fusion sound its got to be a pretty good OB and such a route is likely well compromised.
Lock down continues and now its raining hence the time to ponder such things!
Hard to say why you found it so different, I liked both original Orion and LX521, the bass was better with LX521 due to the upgraded woofers otherwise i would have had a hard time picking a huge difference, the dipole tweeter did create some odd happenings on some tracks which was not so apparent with the monopole tweeter. The LX521 crossed to the tweeter at about 6.4K so avoiding it would affect less of the FR than on an old Orion style at 1.6K.
Both had about 20dB of boost, the analogue ASP handled that better than the DSP for me I tried to DSP the Orion and it was a fail for that reason.
The upper drivers drove me to turn the sound down on the LX521 before the woofers gave out but they were moving with anything with very low frequency content, anything above 30Hz was no issue.
The drivers I mentioned are good, they are not expensive but are as good quality as the SEAS drivers in the LX521 excepting the woofers which are better but expensive. The upper and lower mids can be passive, the LX521 as originally designed used just one cap and coil, that helps cut down one amp channel.
Dipoles of the type of the LX521 and Nao Note do need quite a lot of EQ and they do not rely on a very wide baffle. A DSP solution like a MiniDSP or similar is a good way to get the EQ needed as well as time aligning the drivers through digital delay. Getting the same response passively would be difficult and very expensive due to the number of components and without a design to go off trial and error is better done actively if you have enough amp channels.
Not really going dipole puts a lot of strain on the woofers, Linkwitz has a calculator that shows the difference between closed box and dipole for volume displacement requirements. Below 50Hz the dipole starts to need more and by 30Hz the difference is quite significant.
As above you wouldn't normally but with sub 30 or 20Hz material dipole woofers really get moving. The EQ continues to rise as the frequency falls the lower you go the more the excursion has to compensate.
The V frame is a good option but not quite as easy to build. Still had a cavity resonance at 280Hz that needed some EQ. Two 10 or 12" woofers mounted in opposite directions works well in this application. For anything that needs below 30Hz at any reasonable volume a closed box sub is a good addition.
You certainly could give that a go and see if you like it. You would need a way to measure the drivers to get the EQ set correctly. I doubt you will get a better result than the Fusion doing that though unless you really like the spatial presentation of the dipoles and value that more.
You might be able to make a sort of Hybrid active passive with the Hypex to give you EQ ability on two channels and cut down on the components you need.
So whether you think that is worth trying is up to you 🙂
I have REW and a UMIK1 so can do the measurements i might need......so its down to guessing whether the spatial presentation appeals enough!
I think my room is a pig! - however its the only one i have, i attach a diagram prepared when i was trying to get a better set up and was asking people, i think its now quite reasonable although i have a peak at 600hz to sort still. I will build a slotted absorber on the front of my corner LM panels to try and grab that.
i have a ceiling arrangement set out over the various angles, LM in both front wall corners, broadband on other parts of the front wall, diffusion on side first reflections and the back wall.
Things do get moved around and i also listen from my desk where i am now typing which is just behind the normal listening position.
The room is a mess right now but here is a quick sweep i did.
If i were to succumb to the OB experiment they might be similarly sited
Attachments
Hi! One option could be putting the 12" woofer on a flat(ish) baffle, avoiding cavity resonances and let the woofer run a bit higher in frequency, giving the 6-inch midrange (it's the low-excursion 18M-version you have, right?) a bit of relief. Look at Kyron Audio Kronos for an example... You would sacrifice some low end extension, but if you like the results you could buy another pair of woofers... 🙂 Good luck!
The set up and distances look ok for dipole. The first reflection will be reduced due to the dipole null. Frontwall, I mean the wall behind the speakers, should have diffusion, if any treatment, don't absorb what's coming from the rear of the speaker. Absorption would be best on the backwall, although it's far enough away as that you may not need any.
That will make measurements for sure, how to take them and interpret them is the hard task 🙂
You have a few peaks and a number of dips the 60Hz one being due to placement based boundary interaction. REW has a room simulator that is good for working out placement by moving the speakers virtually until you get the best response. Worth a try if you haven't done it. 600Hz is beyond the transition point of most rooms so a defined peak like that is odd. Have you measured the speaker outside or gated inside to see if it is still there?
A good thread to read is Juhazis aino Gradient good documentation of that speaker from concept through design and measurement
I was going to try multi quote but didn't have the skill, sorry! - so one at a time.
The mid is ScanSpeak 18M/8631T00, i dont know if its low excursion.....
Kyron, amazing looking work, perhaps more opportunity in OB for DIY than first meets the eye..........but design is a different question. i cannot escape feeling an appeal to hear that more open sound.
So, is the angled baffle to equidistance the woofers from the ear as close as one can? - if so, that thinking negates all the hard work that others have done with flat baffles or perhaps angled single plane ones, i wonder where the big performance results come from.
Most of my panels remain portable as they are experimental and DIY, so i can shift things around, in fact i certainly don't regard the Fusion set up as final yet