Decware DNA Horn

Founder of XSA-Labs
Joined 2012
Paid Member
Is it even appropriate to compare the DNA to the FH? The DNA appears to be a hybrid bass reflex with a horn expansion. That huge chamber and small hole connecting the chamber to the horn expansion is not present on FH's. It has a big effect on the alignment. I think DNA digs pretty deep but I suspect sounds less refined. More like an acoustically amplified bass reflex.
 
Thanks for voicing that opinion, X - that was certainly my personal observation, but I'd have been concerned of being considered biased on the subject in expressing it thus.

As for sensitivity, while the audio lexicon has long been muddled by "words mean what I/ we want them to mean to buttress my/our agenda" , I've always considered the textbook definition of the term fairly clear. Of course a single number absent test conditions / parameters is close to meaningless.
Loudspeaker Sensitivity & Impedance Explained | Audioholics
 
Ok... presuming everything you measured there is correct it means that Sd=88.5 cm2 (as an aprox. average between 88.2 and 88.7)... so the people at Dibirama got it right. The TangBand people it seems where not aware that their own driver had a phase plug... Anyway... still 3 different looking sets of TS parameters... just go bigger with the enclosure... you know: just to be safe (bigger is better principle).
I think you have overlooked one thing. My measures are in one plane. The cone is a cone so you have to account for that. The depth of the paper cone to the phase plug is 26.2 mm, the height of the surround is 5 mm. It gives a total cone area of ~ 149.17 cm2 (calculated halfway to the top of the surrounds). We then have to subtract the equivalent phase plug area (converted to a 3d cone) of ~ 9.88 cm2. The area of the cone is then ~ 139.29 cm2.

How hard can it be... ;)
 
I think you have overlooked one thing. My measures are in one plane. The cone is a cone so you have to account for that. The depth of the paper cone to the phase plug is 26.2 mm, the height of the surround is 5 mm. It gives a total cone area of ~ 149.17 cm2 (calculated halfway to the top of the surrounds). We then have to subtract the equivalent phase plug area (converted to a 3d cone) of ~ 9.88 cm2. The area of the cone is then ~ 139.29 cm2.

How hard can it be... ;)

I'm sensing this Sd talk is a bit out of place and too long...
Sd (from what I know from memory) is practically used in relation to Vas as a function of the moving cone taken as a pistonic motion - key word is piston! Therefore the shape of the surface of the piston does not mater because you have pistonic motion that is not 3d it just moves back <> forth. This also answers the question - "what about the wizzer?". You have to think in terms of "column of air" if something doesn't sound right in what I said.
My Sd remark was there to point out that 3 people could not measure the same diameter of about 10 cm... which begs the question how accurate are the other measurements which we know are wacky sizes that are not constant and we know they vary from one unit to another (while Sd does not and you only need a ruler). The differences between the 3 spec sheets is too much to put a (just one) label on the driver... so you pretty much need to measure your own drivers to have a good result.
 
HP 16C Programmer Calculator

To continue the thread on calculators hehe. I bought this calculator in 1983 to develop 64 bit multiplication and division in 68000 assembly langage. I previously used TI but those things lost charge every time I turned around and could not handle 64 bit. Really junk whereas the HP has lasted all this time with many drops to concrete floor. Just put in a fresh battery every 5 years or so and keep going. I still use it. RPN is great once you get used to it.
 
Hi, I've just found an old mini boominator I made a few years back with the Aurasound drivers and throught I'd make 4 DNA horns.

These drivers have a porous dust cap meaning air is free to pass from the front of the cone to the rear chamber. Should I leave them as they are or plug the hole up?
 
For those wanting help the horn

I'm late to the party here. Here's a pic of a "simplified" DNA horn with cutting dimensions. You should buy the plans from Steve for all the dimensions. I've rounded the angles and lengths up to 1/16" (generally) and whole degrees. The horn expansion is very close in all the important places and is probably as close as anybody is going to get with standard shop tools and measuring equipment.


horn assy.jpg
 
  • Like
Reactions: 1 user
Founder of XSA-Labs
Joined 2012
Paid Member
Not sure what is meant by a “throaty” sound - but that is not what I would call something that sounds good? :)

I have not built it personally. The simulations show that it should sound fairly smooth and full bodied with good bass. The response of the simulation was quite flat from what I recall.

Maybe throaty is what you your get when the bass extension is so deep, it goes infrasonic?
 
I built a pair!

Hi everyone. First post.

I built a cheapo Chinese Valve amp, EL34 based one, just for a lockdown project. It turns out that it was a great fun electronics learning project, and it sounds great, very happy with the overall sound. The only problem was that my speakers aren't sensitive enough, just couldn't drive them loud enough (TDL Studio 2 which I love, fantastic big old lumps!). So after a fair bit of looking about I decided to build these DNA's with the Alpair A10.

I bought the drawings from Decware, (poorly dimensioned, with mistakes, but worked them out in the end..)

I've now have spent the last week building, fiddly, but a fun project.

I read that the drivers need a fair bit of running in, so whilst down the shed I connected them up and stuck them in a cardboard box and left them running for a week, they actually sounded surprisingly good!

So, I just completed them and having listened for an evening, the sound stage, clarity of the midrange is exceptional, along with the extended bass, very impressive for such a small driver. But the lower mid / upper bass seems a bit woolly and maybe boxy. Does anybody think this may be an issue with damping/ wadding? I have felt and a couple of bits of foam in the main compression chamber, as I've seen in previous projects. But there is little info as to what should be there.. there is nothing in the main horn chamber.

Any thoughts would be appreciated.

Merry Christmas to you all!
Tim
Here are a few shots of the build, including the cardboard box cabinet!
DNA Build - Google Drive
 
You might try experimenting with adding some dacron in the horn body. It's easy, cheap, and reversible. Too much will kill the base though so start out light. If the compression chamber behind the driver is not properly sized for the particular driver you may be getting some midrange leakage out of the horn mouth which can muck things up. You may be able to clean things up with stuffing.
 
Founder of XSA-Labs
Joined 2012
Paid Member
But the lower mid / upper bass seems a bit woolly and maybe boxy.

When I have "boxy" sound from a speaker, I try to eliminate as much as possible, the back cone reflections. Try lining the rear driver chamber (reach in through the cutout) and install melamine foam pads on the walls. Hot melt glue works well. Don't block the vent hole though. Add a puff of loosely teased polyfil in the rear driver chamber.