TH-Micro - a 6,5" tapped horn

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Hello

I want to share a small DIY project with you, small being the big thing about it :)

THe_little_one.JPG


th6512drawing_section_aa.JPG



More info and pictures can be found here :

Martinsson`s Blog

Best regards // Anders Martinsson
 
Looks great. Did you account for the shading effect of the driver's structure when mounted in the horn's mouth like that? Some quick experiments with my POC suggest that the frequency response can be significantly impacted for a small-mouth design if this isn't taken into consideration.

Also, if a removable panel is included on the left side, this would make it a bit easier to mount the driver.
 
Thanks for all the comments, I'm still learning about how they work, how they should be processed and what their strengths and weaknesses are.

This far I have not detected any major drawbacks of this design, but is is small and as such it's performance is limited accordingly.

The small cone area does bring along a bigger difference both in time and spl between the path loaded and direct radiating part of the sound generated, this characteristic manifests itself more at greater listening distances.

I goes deep enough for most types of music, and it does a good job as a movie sub where it adds nice distinct impacts and atmospehre.

In music it does roughly the same thing, it makes small speakers sound bigger, and if you give it enough power it can even give the listner a physical sensation, not bad of a single 6,5" driver.

The soundquality is very nice, they have a distinct, thick and organic sound that I think is the signature of TH designs.

The usefull response i would say is roughly 35-120Hz, wich i think is ok when looking at this little box on the floor, there might be (should be) dips and peaks in the frequency response that my RTA messurement can not detect.

I right now I was asked the question "can you live with this on a daily basis?" then the answer would be - yes!

Did you account for the shading effect of the driver's structure when mounted in the horn's mouth like that?
Sort of, you can see on the drawing that the last step of the folding takes a bigger leap areawise, this step is rougly equal to that of the projected area of the magnet structure.

But there still is a local compression at the driver, and maybe your sugestion would improve the design.

Would you comment on the Xmax of the simulations and the driver Xmax specifications?
Having oserved the cone excursion during program playback this does not seem to pose a problem, i regard the spl capacity as suficient for most occasions, but thats just my happy amateur opinion.

I do recomend a high pass filter at ~28Hz 24dB/Oct when listening at higher levels.

If someone decides to build one of these, please let me know.
 
What would be the effect of having the driver turned the other way? Less susceptible to little fingers that way.
If you look at the drawings you can see that the depth required for this type of mounting is not enough, unless you put some distance rings in there, but even so i fail to see how this would make the driver more protected, maybe i misunderstood you.

My suggestion would be to put an acoustically transparent protective grille in the opening instead, i intend to do so sometime in the future.

Due to it's small size this sub finds it self equally at home in in the car, at the computer or even in the kitchen, needless to say the WAF is rather high.
 
Very nice ! :)

I might duplicate that, but was wondering if the peerless sls 6,5 would work in your horn or if it fits?

Europe Audio

Also, the insane frequency response above 100hz is inherent to horn designs as I have understood it (or the pattern at least). Could you dampen it with wool or similar for a more smooth response up to maybe 150-200 hz?
 
The response is much smoother in reality (see below), I cross mine over at 200Hz (24dB/oct) with good enough results, it adds a little more punch to the sound while keeping the low end authority intact, when people ask where i cross them over they often get suprised at the answer.

A lower cross over point, say 120Hz, does not hurt, but there is more to these little boxes then the simulations leve you to belive, my own opinion, as the father of this creation leaves me biased, but this is my findings, and they apply in the case of the intended driver only.

The initial thought was to make this a sub suitable for a compact sub/sat setup, car or computer sound system, as such it is good that it can be crossed a bit higher to take the heat of the small satelites it is intended to be used with, wich usually do not preform well below 100Hz or so.

THe_frequency.JPG


Even if the RTA used abowe (PAA2) is not a high reslution device it would still show any significant deviations, such as the ones found in the simulations, and this is a near mouth messurement, when messuring in room it is even smoother, it is 10dB between the lines by the way.

Give other drivers a try in hornresp first to avoid dissapointments, please bare in mind that the design specs and statements are based on my impressions when it is loaded with the audes driver, the one specified on the drawing.

See the homepage specified in the first post for more driver choises, based on these i think you can draw conclusions about what might work driver-wise.

Please let me know of your findings, and if possible pictures of the build, that all i ask.

Br/ martinsson
 
I have only tried this TH in my livingroom and garden sofar, and it works fine in both instances, I was especially happy that it managed to preform as well as it did outdoors.

It should work fine in a car, soundpressure wise it will be sufficient for most occasions, and as you wrote size will not be an issue, and i really like the way it sounds so that should not disapoint either.

I do not know how the sound will be impacted by cabin gain, the frequency responce is "known" so prehaps someone with more knowledge in these matters could offer up an educated guess.
 
frozen wing :

I have not checked the sugested driver, but plese investigate if it works, all the necesary information is allready available (input window fields and driver T&S parameters).

I do not use plate amps, my design does not allow for one, it is to compact, but i think it may be modified to fit one if an extra compartment is added, if someone would like to present a proposal on this I'd be very grateful.

voltcontrol:

Bare in mind the size difference when you compare it to the excellent but significantly larger volvotreter design, there are no shortcuts, with deapth comes size.
 
Here is a 1PI simulation comparison between the two designs.

My 6,5" micro TH :
th6512graf1pi.jpg


Volvotreters excellent equivalent :
Tangband%20W6-1139G,%2038Hz%20TH_SPL.jpg


They are fairly simillar this far, mine is approx. 3dB less efficient but also somewhat smaller (204x440x470 vs. 613x413x215 mm).

The frequency responses are also very comparable, even if the Vovlotreter design seems to fall slightly faster (-10dB @ 34Hz instead of 30Hz) and the response appears abit more choppy upwards of 100Hz, the trends of the two are very simillar.

I agree with Volvotreter that the response is much smoother in real life, not only preception wise but also if messured.
 
Good info thamk you. The Audes (40W68) isn't available widely (I could only find it for sale at Noortehnik), and the TB next to widely available also very cheap ( Philips used it in certain home cinema sets, which can be found for +-25 Euro's 2nd hand).

So.. If anyone knows another source for the Audes...
 
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