Perhaps I’ll try something like that in the future for a different system and a room. Do you still use DSP with this cabinet?
Forum Replies Created
Hello Jeroen, looks very interesting for spaces with less free area behind speakers. From my experience, such spaces are not able to develop full dipole potential so it is indeed better to also try other approaches.
This resistance enclosure seem like something that Gradient speakers use in their Revolution model, also for purpose of having cardioid response.
Have you been using EQ with previous dipole configuration?dbo on November 6, 2012 at 8:17 am · in reply to: OB project with 2x LO15, B&C DE250 & Autotech SEOS 15" #10607
Crossover is digital, Behringer DCX2496 with full Selectronic mods http://www.selectronic.fr/dcx2496-modifie-par-selectronic.html#.
Slopes are 48 dB and it is all done in digital domain before D/A conversion. Drivers are in position which aligns horns and basses fronts at the baffle. In this position it seems to me that bass coils are approximately 12 mm (possibly +/- some) in front of tweeter coil. I measure positions in which I’m guessing that coils really are. During design phase, I had no intention to physically align coils, their current position is a result of overall construction.
So, until I could measure them, I digitally delayed basses for 0.03 ms, I hope I’m not too far off. It would help further if I’d know exact LO15 coil width and placement.dbo on October 19, 2012 at 9:28 am · in reply to: OB project with 2x LO15, B&C DE250 & Autotech SEOS 15" #10605
Just a bump for my question regarding time alignment in last paragraph above, perhaps someone can comment. Thanks.
I would only suggest that you don’t need a 3-way, it will make things more complicated and most likely worse.
AE 15″ in big cabinet will easily play low bass and also reach 1.2 or so kHz with reference quality, and then there are plenty of tweeters and horns which will take it from there.
I have such configuration on open baffle, but don’t see why that would not work in a cabinet too.
This is not connected to longevity issue in a proper sense, but still…
In my use, usual music, regular volume, drivers are almost not visually moving. Very loud music with lots of low bass gives them some +/- 5 mm. However, a week ago I listened Reference Recordings “Pomp and pipes”, first track, at volume I considered “realistic”. So probably not quite realistic, but anyway pretty loud and very pleasant 😉 However, the end of the finale of the first track moved cones to excursion that seemed around or a bit more than 10 mm. I admit it was a bit scary. I had not heard any thumping or otherwise ugly mechanical noise, but that made me worry some and I’ll be more careful.
Which excursion will actually destroy 15LO? Or it can reach mechanical Xmax, but that very mechanical limit will prevent that cone and coil move too far and hit or stretch something?dbo on October 5, 2012 at 10:15 am · in reply to: OB project with 2x LO15, B&C DE250 & Autotech SEOS 15" #10604
Still not measured them properly but don’t care any more. I have my own methods to adjust them. Speakers are fantastic. This is as close to perfect for speaker this size as I ever heard at any price or technology used, of course with proper EQ.
I experimented with two other configurations – only one bass driver instead of two, and 2.5-way with 15 mH coil attached in series with lower driver.
I had to readjust EQ and crossover for evaluation of both of these of course.
My impressions are that first one does not bring anything better to overall presentation, I wanted to see if it is somewhat “clearer”, but driver only have to move more for desired volume. At first, 2.5-way seemed interesting, sounded somewhat smoother, more relaxed or something like that. But over time I noticed that a part of that “electrostatic speed” is missing, relaxed was in fact a bit lazy, and bass was a tiny bit blurred, midbass lost a bit of a kick. These were all very subtle effects, I’ll be fine with it if I could not compare it to something better than this. However, I needed only a moment after I returned it into normal 2-way operation to realize that this is clearly better. Although both cones are working in 2-way and 2.5-way, 2-way gives more realistic size of everything that is going on. I know from before that I prefer larger midrange. In this case two 15″s are also better than one. As for 2.5 way, simple measurement shows that 15mH coils affects response from 100 Hz upwards. Perhaps I should also experiment with smaller coils to see what happens then.
When I’ll measure, I’ll be most interesting to see how is horn time aligned with cones. I the meantime, my thinking is that drivers are time aligned if coils of tweeter and bass are in the same plane (both xover cuts are digital 48dB Butterworth). I can easily see where is tweeter voice coil, and I guess that woofer has it between back edge of the basket and magnet. If I’m right, then bass voice coil is some 12 mm in front of the tweeter coil. So I delayed bass drivers at digital crossover for 12 mm distance.
Am I very wrong thinking like that?dbo on August 29, 2012 at 8:55 pm · in reply to: OB project with 2x LO15, B&C DE250 & Autotech SEOS 15" #10603
Thank you very much for this all in one place explanation.
Drivers are great, in my listening situation, and only “eye measured”, longest excursion is around 5 mm, that would be loud music with much low bass. In most situations, loudest I listen (meters say around 95 dBA at the seat), excursion goes to some 2 mm or so.
Still waiting to measure the speakers…dbo on August 22, 2012 at 1:09 pm · in reply to: OB project with 2x LO15, B&C DE250 & Autotech SEOS 15" #10601
Thanks for the answer John, and my respect for the drivers, they are really great. I get some fantastic music out of these.
I have Behringer microphone and can adjust time delay, crossover point and slope at digital crossover. I hope to get good help in measuring in a month or sooner. When I see exactly how it’s done I’ll invest into something of my own so I can fiddle with it and learn how to improve speakers over time.
Could you please comment on this below and help me understand it; regarding LO15 being dual coil driver.
So these coils are winded one over the other? Not one coil in in front and the other on the back?
If I for some reason connect only one coil, driver will still behave properly? Only with less power handling and warmer coil?
Regardsdbo on August 21, 2012 at 1:39 pm · in reply to: OB project with 2x LO15, B&C DE250 & Autotech SEOS 15" #10599
Thank you for your answers Simon.
For the crossover, if we were in an ideal world, you would want the same frequency with the high pass as the low pass, but depending on the design or the speakers or the room used, you can have a peak or a dip at the crossover frequency when doing that. That means you either want an overlap or you want them separated further. You can use software to model that, but the best would be to measure them. Not that easy in a home environment, but feasible if you are determined. That’s not to mention the baffle step compensation…
If it’s only about the peak or dip, then I don’t worry that much. Listening and simple measurements with handheld SPL meter are telling me this area is fine. But to know exactly if this point is the best for matching directivities of bass and horn is much more difficult task I guess. However, it should be around 1k.
I expect to measure speakers with more sophisticated equipment and educated help within a month, then I’ll get back with results.
Dual coil is only two sets of windings around the voice coil former, so you can choose between two impedances by choosing how you wire them. You can think of it as an electromagnet with two separate windings… A bit like a transformer with a center tap…
So these coils are winded one over the other? Not one coil in in front and the other on the back? So if I connect only one coil, driver will still behave properly? Only with less power handling and warmer coil?
Regardsdbo on May 20, 2012 at 8:58 pm · in reply to: Rubber ring around the edge of LO15 driver, best screws #10436
Thank you John,
yes it is an open baffle.
I guess I’ll go without that rubber then, I was afraid ring is there for reducing diffraction or something like that.
I’ll find appropriate gasket tape, I guess decoupling from baffle is more important there than airtight sealing.
Thank you Simon,
I’ll then go for smallest practical distance. Problem is once you determine positions of driver and horn cutouts on the baffle there is no longer a possibility for tweaking.
I’ll surely try 2.5 way when time comes, do you have any filter suggestions for a lower 15″ driver?
Hello Jeroen & all,
this project is the first that I see being almost the same in material as mine, only difference is I’ll use 2 LO15s per channel.
How to determine exact distance from tweeter and bass?
For a start, I plan to use bass up to 1.25kHz, and SEOS from 1KHz upwards,
both with active 48dB Butterworth.
I’ve tried to determine distance with tolvan.com xDir, but could not detect
any difference between minimum possible distance of 275mm to next practical
distance of 300 mm…
Is there an issue at all in this situation or I just need to position them as close as possible?
I would appreciate every help I can get on this.
Jeroen, do you also have any photos of the rear of the horn mounted in the baffle?