THAM18 details 
Tuesday, December 11, 2012, 20:09
Posted by Anders
All material : 18mm plywood
Outer dimensions : 600x800x650 (WxHxD)
Example driver : B&C18TBX100

(for larger images, open image location in separate window/tab)

Drawing details :

Hornresp simulation data :

3 segment hornresp input and spl sim for compare only, please note that this is not a correct way of simulating this folding, regard it as en educational example, the top 4 segment simulation and subsequent graph results is far more accurate.

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THAM18 - new and traditional THAM folding compared 
Wednesday, November 28, 2012, 19:47
Posted by Anders
When looking at designing an 18" (and and above) tapped horn you might notice challenges not previously encountered, this is how the new version of the THAM folding came to be.

In order to sort out if this new folding really is an improvement upon the traditional THAM folding in an 18" TH case a simple comparison was needed, and I have to stress that this is an exercise in theory, and not practical findings, at least not yet.

First we start of by designing a compact and efficient traditional THAM folded 18" tapped horn, and we spend some time trying to optimize it until a satisfactory result is achieved (see drawing below).

Then we take the same enclosure restrictions (above) but swap the folding to the new version, first seen in the THAM18 proposal, and optimize that until a satisfactory result is achieved (see drawing below).

Next we take a decent but not over the top standard 18" like the B&C 18TBX100 and simulate the two foldings in the same way (4 segment), and compare the results.

The drawing :

Traditional THAM folding inputs :

New THAM folding version :

The simulation results :

The simulations with descriptions :

The results show both a higher sensitivity (approx 2-4 dB) and a wider range for the new folding version, but remember, this is theory, but the differences seen in the simulations makes me think there is something to this.

If the theoretical performance gain is the same for smaller drivers are not yet clear, nor is it for larger ones even if this seems more likely.

The THAM18 using the new folding version seen in the drawing above is a size optimized version of the THAM18 proposal published earlier, although not yet finetuned it still shows the potential of the new folding version (or NFV for typing convenience).

The theoretical results also points to that this might be the way to go for a future 21" version, below you can see two examples of THAM18 simulated with the 18TBW100 and THAM21 simulated with 21SW115.

Regarding simulation method, below is the difference between 3 and 4 segment simualtions :

And a Akabak response curve of the THAM21 NFV from hornresp export script for comparison:

But I'm also working on getting the THAM18 simmed up in AkAbak, this is the dimensions required (just for testing, not for final result) :

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Friday, July 20, 2012, 17:17
Posted by Anders

After much iterating and many hours swapping data between hornresp and cad screens a THAM18 proposal is here, as per previous designs the THAM18 uses the now rather familiar THAM folding but in a another form, hence the name.

The design of the THAM18 posed challenges not previously encountered, preferring small yet capable designs I would have liked to see a more compact THAM18, but the laws of physics dictated differently, also taking into account that the relative cone stiffness is somewhat decreased when using lager drivers.

The goals set for the THAM18 was that it should provide something the previous THAM designs could not offer, but as always there are no free lunches, the price in this case is size.

Any revisions or alterations that may come along for this documentation (drawings) will most likely not change very much from what is presented here as far as the new concept folding goes, there might also be some detail drawings turning up within short, brace positions in side view and driver baffle are some examples of this.

Since the THAM18 is a new creation in progress there are still some areas of uncertainty, the front coupling between driver and horn, and the rather long rear horn segment along the height of the enclosure,
only a build will answer if these areas pose any real issues, my current thinking that they don't, but i feel it only fair to let you know.

The default driver of chosen for the THAM18 proposal is the FaitalPro 18HP1060, as usual questions regarding other drivers will not be answered, no offence intended but I would be doing little else if that was the case, instead i refer you to the hornresp software, all the data you need is already provided.

This is the THAM18 development proposals it stands right now (not the final release) :

Simulation input :

Simulation result :

Being a work in progress what you see here might not reflect the final result, but it should be pretty close.
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Simulation comparisons of the THAM family models. 
Saturday, March 31, 2012, 12:48
Posted by Anders
Thought I'd better sum the sims up, below you'll find comparisons between simulations of the all the current THAM models including external volumes.

The THAM15 (187 l) and THAM12 (96.25 l) :

The THAM10 (60.75 l) and THAM12 (96.25 l) :

And just for fun, why not compare David and Goliath :)
The THAM6 (42.18 l) and THAM15 (187 l) :

If I could figure out how to overlay the THAM10, 12 and 15 graphs you would see that these is a method to the madness, each models differs by approx 10Hz in response depth.

And finaly a comparison in size to a fairly standard 218 subwoofer, choosen for it's comparable sensitivity and familliar size :

Here are the different THAM series direct links

Professional application designs :





Home application designs



Simply choose, print, build and be amazed :)

oh, and yes, there is something else in the works, as always, the TPAM10HTL, meant as an as a alternative to the TPAM10HT where the "L" stands for "light" as it uses a 30Hz tuning for home cinema use instead of the 20Hz used in the TPAM10HT.
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Thursday, March 15, 2012, 21:02
Posted by Anders
It's roughly half the size of the THAM15 (35x50x55cm) but is still granting useful 50Hz response with a 100dB/W/m sensitivity flat on open ground, the driver chosen as default example is the Beyma12LX60V2.

Once again Johannes Rodin is to blame for yet another new THAM design seeing the light of day, his first words where "- it's tuned to low and the enclosure is to big" but eventually he came around to seeing it my way :)

If you csn not find your driver below and have questions like "will this driver work?" then please try yourself using the data provided above and simulate it using hornresp, if it works, please let me know, all the info you need to find out if your driver will work is already provided here.

The drawings will be updated, and the original Beyma 12LX60 will be added to the simulations, I have seen it and it looks just fine.

The designproocess :

Frontview :

Internal dimensions :

Braces and their postions :

Driver Baffle (note that the cutout is driver dependent) :

Assembly control dimensions :

Hornresp dimensions :

Default driver example Beyma 12LX60V2 :

hornresp simulation input data :

Flat on open ground 1W 1m Beyma 12LX60V2 :

Along a wall 1W 1m Beyma 12LX60V2 :

In a corner 1W 1m Beyma 12LX60V2 :

Max SPL Beyma 12LX60V2 :

Groupdelay Beyma 12LX60V2 :

System volume :

Phase :

Impedance :

Cone excusrion :

Please note that I do not judge the following simulations, this should be left to the potential DIY'er, but it goes without saying that some simulations shows better results then others.

Some designer notes - This design prefers high BL (about 20 or higher) and low QTS, but i guess thats a given to anyone visiting this page, right!* :)

*/ I try to make it a point that not only hell bent speaker nerds should be able to DIY a decent tapped horn.

Other driver examples all simulated in 1PI environment :

B&C 12PS100 :

B&C 12NDL76 :

B&C 12NW76 :

B&C 12BG100 :

Beyma 12P80Nd :

Faitalpro 12FH500 :

Faitalpro 12FH510 :

Fatialpro PR300 :

Faitalpro 12HP1020 :

RCF MB12N407 :

RCF LF12G301 :

RCF LF12N301 :

RCF LF12N401 :

18sound 12NLW9300

18sound 12W500 :

18sound 12W700 :

Beyma 12LX60 :

BMS 12N804 :

BMS 12N630 :

Eminence Kappalite 3012LF :

Eminence Definimax 40012HO :

JBL 2204H :

JBL 2206H :

JBL GTi1200 :

JBL 2020H :

Precision Devices PD 121 :

Precision Devices PD 122 :

Precision Devices PD12SB30 :

Precision Devices PDN12MH25 :

And finaly some build pictures that i got sent to me :

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