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Multi-Way Conventional loudspeakers with crossovers

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Old 7th September 2019, 04:03 PM   #2701
Matty is offline Matty  Germany
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Originally Posted by Mattes View Post
Hi,

after some work, investigations and experiments, my OB speaker is now nearly finished. Thought Iīll show you some photos therefore. This installation is a free-swinging OB with fieldcoil widerange driver (Fertinacoustics 21M8EX), bass driver (AE Dipole 18 with double magnet) and ambient supertweeter (Peerless OT 19). Iīve had lots of input from this nice forum, many will recognize techniques for example developped by Michael (the free-swinging approach) or by Erling (the minimum baffle, hope I remember that right), and of course Iīll have to thank Rudolf for his work, and many others too.

This is a form-follows-function design and no gimmick. It has the one and only purpose to make me happy when Iīm listening to music, and for me itīs the most satisfying outcome Iīm able to produce.

Over the month and years of work, they got the name "les fleurs noires", due to form and the french origin of the main driver.

All the best

Mattes
Hi Mattes,

your speakers really look terrific! Congrats!
And I'm very impressed about the level of detail on which you optimized them to your ideas.

However, I have some questions.

As you state, that it is a form-follows-function design with no gimmicks, I would really be interested in how exactly the very special shape of the baffles works. I think, I have a rough idea, but it would be great, if you could give as more insights in how you developed it to exactly what it is, which sources (of knowledge) you used and of cause, measurements would be great

2nd question: I've seen you already used the Acoustic Elegance Dipole 18 Woofer in your prototype speakers, so you seem to be happy with them.
What do you think about them? Did you compare them with alternative solutions? And have you always been satisfied with them in terms of max SPL at the lowest frequencies?

I'm short before buying them as well for my open baffle project, but I'm unsure if one per side is sufficient or if I need two of them.

Thanks and best regards
Matthias
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Old 7th September 2019, 09:36 PM   #2702
Mattes is offline Mattes  Germany
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Originally Posted by carlthess40 View Post
What’s a good program for doing crossovers for a OB speaker using a single 12” or 15” driver?
Hi Carl,

Perceval has answered the program question already, but this is only a first step. Youīll clearly need measurements and therefore several handfuls of coils, caps and resistors...
and thatīs how I do it. With a little experience itīs not that much guesswork, but I first need a good handful of crossover elements and a mic and REW. The finetuning of a crossover is a personal, subjective and questionable process incorporating, taste, room, synergy, mood, quality of red wine sipped... and I do it by ear. Just for me alone, without the need to sell or prove anything to anyone... now thatīs a big relief after having it done for money as well in former years.

All the best

Mattes
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Old 7th September 2019, 09:40 PM   #2703
Mattes is offline Mattes  Germany
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Hi Adason,

Iīve tried several active approaches in history, and also with these speakers, using high-class DSPs and DACs. It was fine for 48 hours, then I returned to the passive filter. Donīt ask me why... active measures easily better, but somehow...
The filter used now looks more complicated than it is, due to the fact that itīs balanced.

All the best

Mattes
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Old 7th September 2019, 09:55 PM   #2704
Mattes is offline Mattes  Germany
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Hi Matthias,

your questions will easily open up a longer discussion (not that Iīm afraid of it...), and I think itīs better to split off same from here.

Anybody else interested?

The AE 18 is, in short, not perfect, but I havenīt found any alternatives giving 25 Hz in a reasonably sized baffle with a reasonable efficiency (around 85-87 dB in this case) with a passive filter and no DSP. If you sacrifice one octave in the bass, you gain 6 dB efficiency...

The AE 18 needs a lot of power. I found that the AD 1830 is a pretty good alternative, does (depending on baffle of course) around 90 dB and goes down to around 40 Hz. If thatīs OK for you, you can save a lot of money (I even might have a pair to sell from experiments). If you want to go lower, you pay a lot more, or go active.
However, the AE 18 is a quite good driver. I pimped it with a second magnet to get the Qts to 0,66 instead of 0,81, prefer it that way.
To find out if itīs loud enough is difficult - room, amp, and how loud? I DO LOVE to listen to Jonas Hellborgīs Silent life. My SPL metre shows something between 100 dB and 107 dB peaks at listening position, amps full force, maybe 700 watts in 3 Ohms per side... itīs bloody loud!

All the best

Mattes
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Old 8th September 2019, 02:39 AM   #2705
ScottG is offline ScottG  United States
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The dipole 18 has dual-coils. Optimally one coil should be part of your analog system (perhaps even w/ a minimalist high-pass ie. series cap), and the other "active" DSP-eq.ed. at a lower freq. to correct for loss - ideally with a very high "current" amplifier (to lower non-linear distortion and get some benefit from that rising Impedance at resonance).
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Old 8th September 2019, 07:10 AM   #2706
Juhazi is online now Juhazi  Finland
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Mattes, what xo type did you use with dsp? I prefer LR2 acoustic over steeper ones. 48 or 96/Oct may look good on-axis, but drivers don't integrate sonically, off-axis suffers too.
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Old 8th September 2019, 09:30 PM   #2707
Mattes is offline Mattes  Germany
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Hi Juhazi,


with this design, I first tried to approximate the well-running passive filter, which is even a bit flatter than LR2, more something like B2, with an ADI-2 pro DAC "misused" as active CO. As above, after 48 hrs. I switched back for passive... but donīt ask me why. Measurements where very close of each other (sadly lost in a HD crash), but somehow I preferred the passive approach, well knowing that this is against "common wisdom", and of course not intending to start a new active/passive debate...
But Iīm completely with you with regard to steep filters; I always preferred to work with material which donīt need to be filtered very steep. In fact, I donīt remember having ever built something steeper than 2nd order... but of course, as in the CO pictures above, shallow filters do not necessarily mean low count of elements.



Regards to Finland


Mattes
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Old 8th September 2019, 10:21 PM   #2708
Mattes is offline Mattes  Germany
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Hi Scott,


never thought of this concept, have you ever tried it? I have at least trouble imaginating a decent HP cap for this, please forgive me... but I also feel no urge to change the current application for the AE 18.
Looking forward to learn about practical results though!


All the best


Mattes
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Old 9th September 2019, 03:31 AM   #2709
ScottG is offline ScottG  United States
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For the AE 18 I haven't (other DVC's yes), but I did recommend it to John/AE originally.. I even participated in a thread here a long time ago about an "optimal" dipole woofer.

The high-pass isn't necessary.. BUT it can help with power-use for the "full-range" amplifier, plus it can sometimes improve/shunt back EMF that might "load" the output of that amplifier. Just a big cap with a high-voltage bypass cap typically around 100 Hz, perhaps a Mundorf Evo Oil 220 uf with a Cornell Dubilier 940C 1 uf/2kv in parallel.

As to the current amplifier - I've never seen that done, it would be a monstrous amplifier though. (..as an example: First Watt F1 is a current amplifier - with an output impedance around 30 ohms if I remember correctly. It's not a particularly powerful amplifier though - which is something required here.)

See what even this modest amplifier does with Impedance near resonance:

http://www.firstwatt.com/pdf/art_cs_amps.pdf


The more normal approach is using a high-output large current reservoir/ps amplifier like the Behringer KM1700. It's really of little importance what the quality of the amplifier is (provided it's a decent design) because it's basically in-use at low freq.s. HOWEVER, in this case I do like an LCR to flatten Impedance at resonance.


btw:
it would be preamp > amp > high-pass VC 1
and
preamp > miniDSP > bass amp > VC 2
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Old 9th September 2019, 12:44 PM   #2710
Matty is offline Matty  Germany
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Originally Posted by Matty
As you state, that it is a form-follows-function design with no gimmicks, I would really be interested in how exactly the very special shape of the baffles works. I think, I have a rough idea, but it would be great, if you could give as more insights in how you developed it to exactly what it is, which sources (of knowledge) you used and of cause, measurements would be great
Quote:
Originally Posted by Mattes View Post
Hi Matthias,

your questions will easily open up a longer discussion (not that Iīm afraid of it...), and I think itīs better to split off same from here.

Anybody else interested?
hey guys - I need your votes

Last edited by Matty; 9th September 2019 at 12:53 PM. Reason: Added another quote which helps to understand my comment
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