[averell]

Hello,

well I am thinking about making my first DIY project. I always wanted to but I thought I would never achieve a professional finish so I never went ahead.

Recently, I moved from Paris France to la Reunion Island and got my gallos stolen, so I was in the market for a new pair of speakers. I thought I would just buy a new pair of gallos and then I saw these Emerald Physics CS2. Astonished was I. What a nice design! So I mailed the brand owner and asked him how much it would cost to send these to my place. $1600! It simply blowed out my budget.



Then I realised that these speakers could easily be cloned without having too much hassle with the finishing process. No paint. So I went ahead and started sourcing all components needed. The subs will remain the original Eminence Alpha-15a as they have a high QTS and are fairly priced while the horns will change and become a pair of 56cm musique-concrete horns together with a 1 inch B&C DE250 driver.



I studied what it would look like before starting cutting everything and had several solutions. Here they are. The gray circle is a 15 inch subwoofer, for comparison.



I like the last design but I have two questions about the overall design.

Is it recommended to use such a d 'appolito configuration with an open bafle design? I have absolutely no idea and no skill at all.

What about the depht of the bafle, I'd be tempted to make it extremely large to avoid the need of a foot. It would just stand on the baffle. Is that a good solution?

Thank you

Frederic

[-Richard-]

Hi Frederic ~

It would be wonderful if I had the kind of DIY experience in OB implementation to advice you definitively on which of your designs would work best for you. I don't. So why am I writing you?

To inspire you to experiment with your very interesting design ideas.

Why not set up an experiment with your DIY project... keep everything "rough" so that you can try out various combinations of driver heights and so on and then report back to the AC OB thread with your findings?

We would all very much like to know how your progress is unfolding.

Using side "wings" to create a stable OB that does not need stands seems entirely workable to me... if I understood you correctly.

Warmest Regards ~ Richard

[mcgsxr]

I agree with Richard here, it is best to play around with configurations in cheap wood, I have been using mdf for over 2 years.  I found the sound, but lost the initiative to upgrade to better wood!

As for the ability to have a folded baffle (ie one with wings) stand alone, that is how mine work.

In time I expect to rebuild my baffles, with a U baffle for the bass, so that too will be able to self support.

The major difference I will seek to include in the next iteration, will be magnet mounting the woofer, so as to isolate it from the main baffle - I was warned by my fellow builders, but had to try it the easy way first - the bass vibrations alter the overall sound, and work to avoid this would be well invested.

Good luck!

[iON]

Hi Frederic,

Let me start by saying it sound like a fun project! Here are some thoughts:

First of all, the sensitivity of the horn and the bass section differs a _lot_. Therefore I think that the best way is to use biamping with active filters, especially since this is your first DIY project.

Regarding d'Appolito I wouldn't recommend it with in this case. I probobly would place both woofers like it is done in CS2 or the R909 to get as much help in the bass region as possible. Also, I think there's a good reason to why you dont see a lot of 2 way speakers with 15 inchers in MTM configuration.  I dont want to discurage you from experimenting though, experimenting is a great way to learn! (For example of a well designed OB with d'Appolito Check out the NaO II)

Regarding the baffle question I definitly think that a thick baffle would work, (or a winged solution for that matter).

Best of luck!

~ ion

[averell]

Hi Frederic ~

Why not set up an experiment with your DIY project... keep everything "rough" so that you can try out various combinations of driver heights and so on and then report back to the AC OB thread with your findings?

Hello Richard,

that is a good idea. I was thinking about using a glass panel these days, but trying with various combination could be a first step before making something serious. I have actually ordered a piece of black acoustic "tissus" to see how it will look like before I order the wole setup.

I'll keep you informed as I do not have news to give. (I live in la Reunion island and it takes one week when I order something before it comes to me)

[averell]

Hi Frederic,

Let me start by saying it sound like a fun project! Here are some thoughts:

First of all, the sensitivity of the horn and the bass section differs a _lot_. Therefore I think that the best way is to use biamping with active filters, especially since this is your first DIY project.

~ ion

yes it will be bi-amped with a behringer DCX2496 active filter

I have done some more works about the design of the speaker and it will finally not be a MTM configuration but like the CS2 too.

Bye

[averell]

hello here,

I did not forget here. I have just ordered my horns. The project has changed since I realised my initial project would be too dangerous as it could easily fall on the floor, and it was big.

I have changed my design and it should look like that when I've finished, much shorter and stable. 2 more drivers per unit too.

Sorry for the poor quality.

I keep you informed.

Bye

[averell]

I wonder how I can link the 4 subs to not kill my amp.. this is my concern at this time. Can someone help?

[Russell Dawkins]

Not clear which is the front on your design.

As to connecting 4 speakers, each 8 ohms - connect the - of #1 to the + of #2, then connect the - of #3 to the + of #4. You now have 2 pairs of woofers wired in series, with an impedance of 16 ohms a pair. You need to connect these two pairs in parallel, then your amp will see an 8 ohms impedance.

This is where the need to know more about your configuration come in:
If you want all the cones to move out at the same time, you connect the + of #1 and #3 together and that goes to the amp's + output. The negative (-) of #2 and #4 are also connected together and go to the negative output terminal of the amp.

If the fronts of one pair of woofers and the backsides of the other are facing the listening area, then all bets are of, as you would need to feed the one pair with one amp and the other pair with another amp, because there would need to be a delay on the closer pair.

At this point, no offense intended, but I would think you might be better off buying the Emerald Physics if your knowledge is such that you have to ask how to wire series-parallel. Either that or choose a less complex design, like the CS2 configuration with only two woofers wired in parallel for 4 ohms.

[averell]

Hello Russel,

I finally sticked to 2 subwoofers.



Bye.

[jimluu]

You are using a compression driver and some sort of front horn?  How low do you plan to use the horn?  Seems like much of your midrange will be firing sideways.  And your open baffle woofers will also fire sideways.  The radiation pattern of the OB drivers is a figure 8 I think, so the front of your speakers will be in the dead spot.  You'd have to position it carefully against a wall or something. 

[Rudolf]

averell,
this design http://www.diyaudio.com/forums/showthread.php?postid=978388#post978388 is reminiscent of yours and does make sense positioned in room corners. Otherwise jimluu and Russell are right in warning against designs which seem much too "adventurous". 

[averell]

hello,

well, I have been hesitating a lot these days about to adopt or not the quadrupole design that was shown a bit sooner.

In the end I think that I have more chances to get a better result with a standard dipole or I would have been obliged to add a medium with the quadrupole.

[averell]

You are using a compression driver and some sort of front horn?  How low do you plan to use the horn?  Seems like much of your midrange will be firing sideways.  And your open baffle woofers will also fire sideways.  The radiation pattern of the OB drivers is a figure 8 I think, so the front of your speakers will be in the dead spot.  You'd have to position it carefully against a wall or something. 

not exactly a figure 8 radiation pattern.

check here: http://www.kettering.edu/~drussell/Demos/rad2/mdq.html