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Multi-Way Conventional loudspeakers with crossovers

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Old 21st January 2013, 05:16 PM   #71
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All I can say is thank you to you, Inductor, and to Dumptruck that you are willing to help me. As I said before, my knowledge is too little to judge the content of the posts.
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Old 21st January 2013, 05:34 PM   #72
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Maybe this is a better way to put my question on the 4 pi crossover:

If the pad is 25/16, the impedance of the driver around 10Ω, then in parallel with 16Ω it's about 6Ω, then add 25Ω in series, you get ~30Ω. This is why the simulation doesn't work, but more importantly, it's not the HF impedance of the 4 pi (Pi Speakers - four Pi loudspeaker performance data), so what am I not getting here? EDIT: oh, backwards pad, I got it now.

Last edited by dumptruck; 21st January 2013 at 05:38 PM.
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Old 21st January 2013, 05:38 PM   #73
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I guess Inductor will give you a better answer then I could do
All I know is that Wayne told me that the 4pi crossover is one system (the compensation part interacting with the rest of the crossover). Maybe there are other parts of the crossover that you omitted in the simulation but that are important to make it work?
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Old 21st January 2013, 05:43 PM   #74
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I figured it out, got it to match his system measurement. It is true that Wayne's crossover can't be split up, which is why we are talking about these stand-alone CD compensation circuits in the first place. If Wayne wants to design one, that would obviously be great for your purposes, and please post it here.
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Old 22nd January 2013, 03:51 PM   #75
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Quote:
If Wayne wants to design one, that would obviously be great for your purposes, and please post it here.
I kwow, but I can't ask that from Wayne. He already gives so much important information that is the result of decades of work, the 'secret' of his perfect speakers. It would be asking too much.

But making a circuit that compensates the DE250 and that summs perfectly the drivers through the crossover region is unfortunately not for me. I have neither the advanced knowledge nor the time to do so

Because I'm a little bit tight on budget, I'll use the 'oldschool-crossover' for a while: picking a crossover frequency and slope for each driver with the active crossover (too bad I can't delay the drivers with the crossover because it's not too sofisticated). I guess this will also sound good (but not perfect).
When I have more budget, and when I know exactly how the modified 4pi speakers sound like, I will do the update to one of Waynes (perfect) passive crossovers. Then I will also hear the difference of a perfect crossover, which will satisfy me even more

All I read on the forum and on Waynes forum has been very helpfull to understand the goal of crossovers and the beauty of a perfect crossover that matches the different drivers!

When I start building the cabinets, some photos will be posted to illustrate the goal of this thread
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Old 22nd January 2013, 05:13 PM   #76
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The phase alignment/tracking is the real meat of the crossover design. I don't know where time alignment is starting out in a 4 pi without crossover, but if you get lucky you'll can get phase to line up at least a little bit at some acceptable active crossover point (1300-1600 acoustic or so).

As far as the compensation circuit I gave you, I assure you it's a trivial bit of passive EQ that you can use with confidence and even tweak by ear. It's nothing as fussy as an actual passive crossover. It would be nice if somebody would pop in to back me up on that since apparently I'm suspected of being clueless, but I guess you could post what I gave you in another thread or forum for a second opinion.
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Old 22nd February 2013, 02:56 PM   #77
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Hello, it has been a while, but I found some time and started building the 4pi speakers, in a temporary active crossover version.
Later, when I'll have put some money aside (once again) for the 4pi project, I'll upgrade them with diy passive crossovers, following the schematics of Waynes design.

I bought the B&C de250 drivers in Belgium, Wayne shipped 2 H290C horns (they sound great! even without CD compensation), and I could buy 2 second hand JBL 2226 drivers.

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horns arrived!

Bought 2 MDF panels (240cm * 122cm, 1 speaker = 1 panel) and started with the bass reflex ports:
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strengthened the opening for the JBL driver

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glued the bassport to the front baffle

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the cabinets are rising!

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Installing braces between woofer and tweeter (for isolation material)

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T-nuts for woofers

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to be continued...
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Old 11th March 2013, 10:52 AM   #78
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the speakers are almost finished! I'm waiting for the x-over components, for now, the speakers are driven with active X-over. Some pictures:

Soldered some cables and connections
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Built in the connectors
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As my amp has no delay relay, I built 3 circuits (2 circuits are used for the 4pi speakers) that delay the signal 6 seconds when the amps are turned on.
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Cut the insulation in parts and glued the insulation in the cabinets:
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Old vs new
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Nearly finished:
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to do:
- glue has to be removed
- cabinets have to be painted (dark grey)
- passive X-over has to be installed

The cabinets fit now in a shelf. Later on, I'll glue thin panels of walnut wood to the side baffles and the back. (dark grey front baffle will stay as is)
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Old 13th April 2013, 09:23 AM   #79
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Hello, I finished the 4pi speakers. Passive x-overs are installed (there IS a difference with the active x-over! :-) ), the glue is removed and the cabinets are painted.
I guess this thread is not the right place for a build thread, but it is thanks to the comments of other members in this thread that I decided to make the 4pi speakers, so I'll leave it here.

The last pictures:

- ordered the components for the cross-overs and tried to make a good looking assembly
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- Painted the cabinets
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- cabinets in place
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It might be better to add an acoustically transparent fabric behind the BR-port, because the insulation popping out isn't really good-looking.
BUT: Great sound! Detailed, rich and powerfull! I went to an audio shop and listened to a lot of speakers that even cost more, but the dynamics of those speakers didn't equal the 4pi's!

Last edited by vandevoordekoen; 13th April 2013 at 09:26 AM.
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