Ported TH

[Zero D]

Be interested in hearing your comments about my design for a PTH.

I realise that the output from the port will be in phase over the tuning frequency, which is counter to a "normal" TH. But if the fb of the port/back box was tuned lower/higher than the path length of the TH, could this provide Any benefits, & if so what ? Also what would the negatives be ?

If somone could model this in for eg: Horn Response or Akabak, i'ld be obliged.

TIA

 

[TundraLTD]

If it were easy to just throw a purposed meaningful script together I'm sure someone would do it. The question is why do you want to? Just because isn't enough reason for me to spend my time working on your design honestly

 

[tb46]

Hi Zero D,

There are a number of ways to model your basic idea, from the sketch it looks as if you have a throat chamber, and a chamber at the forward tap too.

There was quite a bit of discussion about those general ideas in the collaborative thread. I'll attach a text file I made from Cordraconis' "AkAbak TH's for Dummies" Post #1187. You'd find it well worth your time to go through that general area in the collaborative thread.

Regards,

 

[paulspencer]

I wouldn't call that a tapped horn. It's a bit of a hybrid that defies definition. It is a FLH in that it has a compression chamber, but the port is located where you would put the driver in a tapped horn, except it exits around the mouth only. It's an interesting idea, I'm not sure what to expect, or what advantage you expect compared to either a FLH or TH.

Some FLHs have a porte compression chamber, but the port is located on the outside of the mouth. It means less driver protection below fc, but a little extra output as a direct radiator, possibly an extended bass shelf with much lower sensitivity.

I wonder if it would be worth porting at both ends of the line. Then you have a front loaded horn combined with a tapped port. Potentially the port could gain higher sensitivity, however I suspect inferior transient response and higher group delay would be the likely result. You could design it in hornresp as a conventional FLH (that isn't hard), then experiment with the port using a prototype, trying with no ports, front port, front and rear ports.

You may squeeze a little more juice out of the driver at best. At worst, a throw away box performing poorly.

 

[bjorno]

Hi,

This is not exactly a TH but will IMO come quite close if compared as very little would be feed back into the quarter-wave line if built.

The TH IR Pre-Pulse = the output from the port has a too high Q and would not straighten out the FR.

It could,if the boxed volume and the port are completely filled with damping material but then there is almost no port output at all.

Only large TH:s like 'Kraken' (Or FLH:s) that has a very good Main-pulse and Main-pulse FR would survive a SQ test with the 'thumbs up'.

b🙂

 

[tb46]

Hi,

It's really not quite obvious where Zero D is going with this, as the drawing is incomplete, but it looks to me like Fig.2 from the patent would apply.

Regards,

 

[bjorno]

Hi,

It's really not quite obvious where Zero D is going with this, as the drawing is incomplete, but it looks to me like Fig.2 from the patent would apply.

Regards,

Hi Oliver,

Your picture depict a BP port in use. A BP port adds at least one more TF pole than a simple port has, i.e. will work if properly balanced.

b🙂

 

[weltersys]

If somone could model this in for eg: Horn Response or Akabak, i'ld be obliged.

Modeling requires driver parameters.

As has been pointed out, the chamber around the speaker can be modeled in Hornresp, but the overall cabinet as you depicted would not be very useful, though with changes might be used to allow a speaker that shouldn't be used in a TH to "kinda work".

With the Hornresp Speaker Wizard, once you load a driver's parameters in, you can see a visual representation of the cabinet, (though it does not show folds) and you can stretch or squeeze dimensions and toggle the frequency response (and displacement and impedance) to see what the results are.

Give it a whirl, David McBean has made changes to the current version of Hornresp which make it easier to use than ever.

 

[Zero D]

The screenie just shows part of the the TH, the throat. The missing parts would be as per other TH's.

@ TundraLTD

Why ? Because i feel it "might" bring some benefits.

@ tb46

I have a a throat chamber, and a tuned rear chamber.

Thanks for the Cordraconis.Txt 🙂 I'll study it.

Re patent. It does have similarities, but the patent shows an expanding horn.

@ paulspencer

Yes it's a hybrid 😉

It's an interesting idea

🙂 At this stage i'm not sure of the benefits, if any, but feel it's worth exploring, hopefully by others more skilled in the art.

I wonder if it would be worth porting at both ends of the line.

I'm not certain where you mean the other port's would be placed ?

@ bjorno

This is not exactly a TH

No not exactly 😉 I'm hoping it "might" prove worthwhile though. Thanks for doing that sim 🙂 Could you upload the HR file please, so i could experiment more with it. TIA

 

[tb46]

Hi Zero D,

This is what I "saw" when I looked at your sketch:

Regards,

 

[Zero D]

@ weltersys

You posted whilst i was composing 😉

though with changes might be used to allow a speaker that shouldn't be used in a TH to "kinda work".

Well that's a plus ! It's still early days though, so i remain optimistic 🙂

(though it does not show folds)

Yeah i know 🙁 If it did, what a difference it would make 🙂

@ tb46

Hi, yes that's more or less it 😉 Just to get this off the ground, & for simplicity, i showed the drivers tuned box @ 90 degrees to the mouth & throat. This need not be the case, & could be angled.

 

[bjorno]

Zero D:
Could you upload the HR file please, so i could experiment more with it. TIA

Here you are:

b🙂

 

[Zero D]

@ bjorno

Thanks a LOT 🙂

 

[Zero D]

@ bjorno

Hi & thanks again for the input & file, it's Really helped 🙂 I've had a play with it & come up with this. I know it's far from perfect, but some of the graphs appear quite good, too me anyway. The hump @ 80Hz would be filtered out by a LPF @ the same f. I'ld appreciate comments from you & others.

 

[tb46]

Hi Zero D,

Good to see your making progress. I'd like to point out that bjorno's Hornresp model is not tapped, and as such does not conform to your initial sketch.

You may remember the "Crazy box design - Input please!" thread and Don Hills AkAbak model, that (plus the code by Cordraconis and Mavo, see Post #3 in this thread) may give you something to start from in AkAbak, Posts #36-40 : http://www.diyaudio.com/forums/subwoofers/189223-crazy-box-design-input-please-4.html.

Regards,

 

[Zero D]

Originally Posted by tb46

Good to see your making progress.

Well trying anyway 😉

I'd like to point out that bjorno's Hornresp model is not tapped, and as such does not conform to your initial sketch.

Yes thanks, i now realise it's a reflexed FLH 😱 Naughty bjorno 😛

You may remember the "Crazy box design - Input please!"

Indeed i do ! But that's different to what i'm attempting to achieve, as for one thing, there isn't much TH going on.

As i'm still trying to get my head around HR, even though i've played with Akabak, i feel it's one more headache i don't need right now 😀

I would truly appreciate it someone could start me off with a HR file with my design, then i would find it easier to experiment more 🙂 I would then post with further Sims using high power etc drivers for All to see.

TIA

 

[tb46]

Hi Zero D,

I don't think this can be done in Hornresp, that's why I'm trying to provide you with links to Akabak code. I know that the code from "Crazy box" is not the same that you need, but there are lines in there you could use.

Regards,

 

[Zero D]

Originally Posted by tb46

I don't think this can be done in Hornresp,

That's a pity 🙁

that's why I'm trying to provide you with links to Akabak code.

I appreciate your help 🙂 I'll see if i can try to do something with it.

I know that the code from "Crazy box" is not the same that you need, but there are lines in there you could use.

Yes i do see that, & i am still looking at it.

Thanks for being there 🙂 & to Any others who could assist 🙂