Tapped Horn corrections needed ?!

Bongo wrote: Did anyone do a simulation of the WAE tham12? -Do you have the hornresp input data?
I'm eager to build one, I'd like to go lower than the tham12, I've been checking out 2 other versions, the fth12, but it has too much of a dip, then this version: forum.speakerplans.com/tham-12-a-compact...opic64833_page2.html
That sims very nice, but I can't find the plan!
The case with WAE is the opposite, no input data, I'd have to spend some time getting it right.

High Bongo,

This is a TEST version, please remember that. The version numbers are NOT used, it was merely a question to the "world" what is the effect of "throat correction", so forget the version numbering at this stage. It juist used the latest drawing I had and added some details of correction.

kind regards,

Frans

Bongo wrote: Thanks, that's easy to find, I'm glad about that, I was after WAE input, I did a simulation of the big version with numbers from the drawing, no big hit in spl.

High Bongo,

This one was designed with a Faital Pro 12FH510, of which I was OK with up to some 400 watts (loud enough for me when using 2 TH's put side by side). I did NOT use the corrections.
Please keep in mind that most designs are depending heavily on speaker characteristics. Just like with bass reflex, the Tapped Horn (which is a COMPLETELY different animal!) depends on this data. One speaker can perform great while another just sucks in a TH design.

ALSO, the more you fiddle with details like the throat corrections and stuff, the bigger change you get for screwing it up completely. This is REAL complex stuff.

If you want to play it safe and use a good design, go for Martins versions. I understand that you would like to play it deeper, which means longer L23, which means bigger box. Why not go for the THAM15, thats low AND loud, while size is kind of in between small and big TH.

Martinsons versons can handle a number of speakers in the same design , which has a big plus. Look at his web-site, it is all explained in detail. Just ask for him if it is OK to build it. Most people post to share knowledge and learn, NOT copying for COMMERCIAL use.

If you want to use my design, use it as a starting point. Go to Hornresp and start working with your speaker and my design and work on it to your own liking .

Some Hornresp quick tricks;

- Smaller L12 gives more "high freq"
- Smaller S2 gives higher SPL (MORE demanding on the speaker)
- Longer L23 gives lower "low knee"
- Longer L34 could smoothen out the mid-high freq. part
- Bigger S4 reduces the "dip" (but so does adding a conductor, so change the L)

kind regards,

FRans

Bongo wrote: I see that you built 2 versions, preferring the bigger?
It's strange this .jpg is called version 2, even though the drawing says version 1
If you look here there's a slightly newer version, but it's still called version 1!

I tried to sim the bigger version with the numbers from the drawing
Ovindas version actually plays a bit lower, according to the sim, but the mouth is a bit strange, the box is smaller, I won't go as deep, but nearly.

Bongo,

I build the standard THAM 12 and later the V1 as shown in the drawing. Yes, I did like my version, because it does go deeper. That is what could be expected, it's bigger and has a longer path. This does NOT mean, the THAM is not working, it is designed with a different goal (small, simple, forgiving for any speaker). Its all about compromise, how big (or rather how SMALL) do you want it to be. My target was to be able to carry a complete PA in a normal road car, NOT using a van or truck. That;s why I tried the THAM12, which is exactly that. SMALL (for a tapped horn), LOUD and forgiving for a speaker. ALSO, "easy" to build, thus NOT expensive. I did some tests with a 5 string bassguitar and found I needed to go deeper, that;s why I started a slightly bigger version.

What I found out later, is that bracing is key in this type of enclosures.

RULE OF THUMB (at least MY version of it): Brace all panels that have one side facing "to the outside world" with the internal panel facing it. So bottom panel to LSP panel, Back panel to internal, Top panel to Internal. Panels that have both sides IN the horn do not need bracing.

I did NOT brace the bottom in this version, later tests showed you NEED to do this (do NOT forget to calculate for cone displacement XMAX, so the cone dos NOT hit the brace when you want to go to volume level 11). This in case you have an amp that goes to 11, most stop at 10 :silly:

ALSO, i made it out of MDF, Birch Multiplex improves sound quality in a BIG way. Go for 18mm, even for these "mid" size TH's.

kind regards,

Frans

Thank you for your help! 18mm sounds massive, but I have it in stock!-)
I tried playing arounf with the loudspeaker wizard a bit, the driver is not the best for a tapped horn, it likes to go low & it likes compression, but going down to 30hz changes the design and of course response drops

What do you mean by " - Bigger S4 reduces the "dip" (but so does adding a conductor, so change the L)" adding what conductor & changing what L?

My driver has quite a dip between 50 & 100 hz.
I tried the biggest of your versions, thought it must be the newest. My sims with your design goes a tiny bit lower but it's not as loud as tham12.
fth12 is a nice design too, but it gives my driver a bigger dip.

Bongo,

18 mm does sound massive, but i've seen some people building these cabinets with "wrong" wood resulting in vibration resulting in distortion. 13 ply 18 mm birch seems to be the best for this type of cabinets. If the Pro's use it, it should be OK

In hornresp, you have to entre the speaker values, including Le ( "L" was a typo in previous message). For SOME speakers, adding a conductor in parallel to your driver reduces the dip between 50 & 100 Hz, which is always there. You can simulate this by increasing the Le value in your simm in Hornresp, which is Le of driver + Le of conductor.

You should be able to go as loud as the THAM12 (or even get louder). Louder starts with a SMALLER S2 (higher compression). Keep on working on the simm, or just use the THAM, since this seems to support your driver better.

The bigger dip you find in tfh12 is most likely due to a non optimal combination of driver and cabinet.

Thank you!
Never got satisfying results out of simming the wae, it's playing deeper but not loud. guess that might just be the trade off, but the tham+ 5cm does better, I've been drawing that up now.

What do you mean by conductor? I'm not sure?

I could post the sims for fth12, WAE (big) & the plan of tham12+5cm as I did all this now, here's my input for the WAE:

ID=34.20
Ang=1.0 x Pi
Eg=2.83
Rg=0.00
Fta=9.22
S1=52.00
S2=189.20
Con=22.00
F12=0.00
S2=189.20
S3=653.66
Con=222.00
F23=0.00
S3=653.66
S4=1073.00
Con=25.00
F34=0.00
S4=0.00
S5=0.00
L45=0.00
F45=0.00
Sd=530.00
Bl=26.00
Cms=1.25E-04
Rms=2.91
Mmd=78.00
Le=1.70
Re=5.50
TH=1

Hi Bongo

You should sim your bass cabinets in 2pi i.e. sub middle of the floor. Now you'll get too optimistic results with 1pi (sub on the floor/wall junction)

So Ang=2.0 x Pi gives more truthful results.....

I know:-)
Hornresp just does 1pi standard, not much of a matter to me, as long as they're the same when compared.
Tapped horns won't go any deeper anyhow, like horns, so it only affects the overall spl output.

Hi Bongo,

What is the driver type you are using.

By conductor I mean a coil like that is used in an audio filter. Maybe it's not the right word, I'm just Dutch so...... :blush:

The driver is rcf lf12n401, the dip is very outspoken and it has a boost at 50hz, can use quite some compression i guess, good horn driver, big bl, low qts