Decware DNA Horn

In the Foam Core thread, I posted the Decware DNA BLH to see if there was any interest in doing a DIY version of it in easy foam core. See post here: Foam Core Board Speaker Enclosures? - Page 175 - diyAudio

Here is Bcmbob's build in XPS foam:
347516d1368051659-decware-dna-horn-20130508_181632-jpg


There is some interest in proceeding with it as I can see that as of now, there have been 32 views of the approximate dimensions that I posted as a pdf plan here: diyAudio

The DNA was designed for use with the now discontinued TB W5-1880 driver. In the interest of trying this design out in FC on a budget, I spec'd the following cheap 5 in aluminum cone driver from MCM: MCM Audio Select 5'' Aluminum Cone Woofer | 55-1870 (551870) | MCM Audio Select

I simulated the DNA in AkAbak with the following horn expansion profile that I derived using dial calipers from the drawing (13 segments total with the first one being the throat leading to the main horn passage. The throat width is equivalent for a 2.5 in dia hole.)

Code:
| Define Horn Segments (need to multiply by Width for area, dims in inches * 0.0254 in/m): S_Throat, S_Mouth, Length

	S1T=0.70*0.0254;	S1M=0.701*0.0254;	L1=0.18*0.0254;
 	S2T=0.64*0.0254;	S2M=0.76*0.0254;	L2=5.09*0.0254;
	S3T=0.76*0.0254;	S3M=1.30*0.0254;	L3=5.09*0.0254;
	S4T=1.30*0.0254;	S4M=2.01*0.0254;	L4=16.08*0.0254;
	S5T=2.01*0.0254;	S5M=2.88*0.0254;	L5=6.03*0.0254;
	S6T=2.88*0.0254;	S6M=2.89*0.0254;	L6=1.47*0.0254;
	S7T=2.88*0.0254;	S7M=4.02*0.0254;	L7=3.35*0.0254;
	S8T=4.02*0.0254;	S8M=4.29*0.0254;	L8=1.30*0.0254;
	S9T=4.29*0.0254;	S9M=4.30*0.0254;	L9=2.68*0.0254;
	S10T=3.83*0.0254;	S10M=4.52*0.0254;	L10=1.45*0.0254;
	S11T=4.52*0.0254;	S11M=6.16*0.0254;	L11=7.64*0.0254;
	S12T=6.16*0.0254;	S12M=7.41*0.0254;	L12=3.40*0.0254;
	S13T=7.41*0.0254;	S13M=15.68*0.0254;	L13=5.23*0.0254;

The main driver chamber was estimated to have a volume of 16.1 liters, and the throat hole leading from the chamber to the start of the horn passage is assumed to be 2.5 in dia.

The result of the simulation for the DNA with the W5-1880 driver appears to go down to about 30 Hz in bass extension - not bad. This is for the speaker placed with baffle 18 in from rear wall and 4 watts of power with listening position at 3 meters away from front baffle.

For the cheap $13 MCM drivers, I had to reduce the driver chamber volume by 6 liters to 10.1 L and this provided a much better response due to the much stiffer suspension (smaller Vas). With this driver, the bass shelf is a little tilted but nonetheless smooth and goes down to 40 Hz. The last plot shows the driver cone displacement for the MCM 55-1870 driver at 4 watts. With appropriate stuffing in the main driver chamber the resonances and peaks should be reduced significantly - so ignore the sharp peaks when viewing the plots. I still have not figured out how to implement damping/stuffing in AkAbak.

The design appears to a good one and I think worth pursuing even with the budget driver - 40 Hz extension and it appears that there may be enough bass gain to avoid using a BSC.

Some recent plans from DimeStore Dynaco:
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You are kidding right? The W5-1880 was a $160 high Vas, high Bl, low Qts, super premium driver - one of the best offered by TB. This Aura is a budget driver and I don't believe is in the same league. I can try running a sim to see what comes out.

Forums - DRIVERS for the DNA Horn

To quote Steve :

I have considered several different drivers for the DNA horn which can be found in the design notes for the DNA horn.

The DECWARE DNA Horn

You may use this as a guide when you consider drivers for the DNA horn.

I did try a less expensive Tang Band driver, the W5-1611SAF 5" Full Range Speaker with the world's worst results. Please don't waste your time with this one.

I also tried my small Lowther DX55 drivers and they sounded good, but are a primarily a midrange driver so there isn't any real bass weight. I will say, that the DNA horn made that driver, as well as the 4 inch foster drivers used in other horns, have more bass than they did in any other cabinet, but considering what this cabinet is capable of it would be a waste of a good design.

To that effect, I have found a driver that I like 95% as good as the TangBand IF you're going with lower powered amplifiers. In fact the bass was actually better, more correct, less colored. The highs are rolled off, but I still enjoyed it for an evening by itself without adding a tweeter, which it will obviously need. But I think that is fine. A tweeter floating on top of the cabinet would be very nice.

The driver is an AuraSound buy out at Madisound, so who knows how many they have or how long. The price is right a 3.60 ea.

 
You are kidding right? The W5-1880 was a $160 high Vas, high Bl, low Qts, super premium driver - one of the best offered by TB. This Aura is a budget driver and I don't believe is in the same league. I can try running a sim to see what comes out.

Spec wise, its mass corner works out close enough, ditto its Fp even though the filter chamber seems too small at a glance and no doubt why its bass performance is superior in some ways.

GM
 
I have the plans for this speaker and there aren't any suggestions of lining/stuffing the horn path. I suspect like other horns, the chamber behind the driver can get some stuffing and the inside of the folds can be lined with felt. I would like to hear from someone who built this so I think I'll check out Steve's site and look at the support forum.
 
Exactly $6/ea with shipping - still pretty good for this driver. I think it will take about 4 sheets of foam core per speaker. This will be a real value at $10 for the whole speaker that can reach 30 Hz. I look forward to seeing your build Bob.

I don't think there is any damping along the actual horn path, just in the driver chamber. The internal horn paths can sometimes be made out of acoustic ceiling tile to provide self-damping. Steve makes his speaker prototypes out of drywall.
 
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I have the plans for this speaker and there aren't any suggestions of lining/stuffing the horn path. I suspect like other horns, the chamber behind the driver can get some stuffing and the inside of the folds can be lined with felt. I would like to hear from someone who built this so I think I'll check out Steve's site and look at the support forum.

Can you tell us what the plans say for the dia of the throat hole is? 2 inches?
Thanks
 
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Dual Driver DNA?

Due to the low cost of the Aurasound NS525 drivers, and the extra free real estate on the front baffle, I asked myself what happens if you put two of these drivers on the DNA? Well, it turns out that to optimize the response, more driver chamber volume is required. One way to do this is to build an internal false wall separating the usual 7 in wide standard chamber to an external chamber occupying the entire 27 in x 12.5 in side x 0.75 in deep on each side. Add a BSC of 1.8 mH and 4 ohms with the drivers now wired in parallel. Also, the throat area has to be doubled. This design provides some additional bass extension down to 27 Hz and a more full bass response as shown in the response curve calculated below. Not sure if this is worth it considering the added complexity of the driver volume extension now required.
 

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Bob,
I think a simple 2 uF cap in series with the tweeter should do the trick to high pass at 10 kHz. Wire the tweeter parallel with the NS525, essentially presenting a 4 ohm load to the amp. The tweeter is still an 8 ohm load with respect to the high-pass filter. Here is a table for selection of cap values: Car Audio - Speaker Crossover Chart and Capacitance vs. Frequency Calculator(High-pass)
Unfortunately, a 2 uF polypropylene film cap costs more than the $0.89 tweeter!
It should help balance this driver out though. Good luck. :)

Let's see how the BOM is looking for this build:
1. NS525 $3.60 ea
2. Bargain tweeter $1
3. 2 uF cap $1.50 http://www.parts-express.com/pe/showdetl.cfm?partnumber=027-414
4. 4 sheets of FC $4

About $10 and change not including shipping. :D
 
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