Simulating Troels’ DTQWT using.... ?

[Bigun]

This is an interesting speaker, with two different speaker drivers coupled onto one ‘horn’. I’d like to know if this can be simulated fully using Hornresp. And, in general, whether Hornresp allows the simulation of multiple drivers with different T/S in the same horn as well as with sound radiating from the front side of the cone. It’s not a simple TH simulation because there are drivers with different T/S and it’s not a Synergy simulation because there is output from the front of the radiator and neither is it a BLH be because there are two different drivers.

If not, I assume Akabak can do it? I’m unfamiliar with both tools and haven’t found the answer after searching the ‘net.

I’ve no immediate plans to build this speaker from Troels, it is more an example to help me ask about the capabilities of the simulation tools.

 

[AllenB]

Hopefully David will chime in. You could give a heads up in the Hornresp thread - Hornresp

 

[xrk971]

Akabak can do this easily and can have multiple arbitrarily placed drivers facing arbitrary angles and a radiator emanating from a gap on the floor. This particular sim is about 15 to 18 nodes. Placing two horn stubs radiating out of a common mouth is interesting. The radiation from one end will also go to the other closed end. That may or may not cause interference dips.

 

[David McBean]

I’d like to know if this can be simulated fully using Hornresp.

No.

And, in general, whether Hornresp allows the simulation of multiple drivers with different T/S

No again.

As xrk971 says, its really a job for AkAbak...

 

[Bigun]

thanks guys!

 

[Juhazi]

This is a good example of extravagant desings that make me curious.

Most often the "designer" shows only some favourable measurements and exstatic comments about sound quality. Details of measurement conditions and diffrent type of measurements can easily reveal eg. resonance issues and bandpass behaviour which are often happening in this kind of dual systems.

I can't find independent measurements and Troels is seems to believe in s sims with bass...

This is background story about bass tuning DTQWT-mkII

DTQWT-mkIII
DTQWT-Peter-DK/
http://www.troelsgravesen.dk/JA8008.pdf

 

[Juhazi]

Troels says: (link in previous post)
"Presenting proper images of bass capability from this construction is difficult due to front and rear mounted drivers. Normally we would take nearfield readings of both drivers and "port" (horn mouth) and splice the readings at e.g. 100 Hz and at 350 Hz (JA8008). The port output is usually presented separately. This approach doesn't work because a significant part of the lower bass comes from the horn and in order to measure lower bass we need a measuring window so wide ( > 100 milli-seconds) that we measure everything; that is 1) what comes from the drivers and port - and 2) what is reflected from room boundaries."

Impedance curve has two peaks wide apart

And room response with long gating is what he asks to look at (and it looks too lean for me!)

 

[Juhazi]

I must clarify the previous post:

In impedance curve of TWQT (with just single JA woofer) we see three hight peaks representing woofers tuning and w/t crossover.
Resonance peak/dips happen at 45Hz, 200Hz, 400Hz and 900Hz

Sadly pages of later DTQWT models miss bass response but show impedance curves with pretty similar peaks/dips.

Smoothed impedance response of DTQWT with 12" Eminence "supporting" the 8" Jantzen

 

[xrk971]

From TG website on Mk2 as background:

They are placed opposite to one another and the rear drivers are fed through a huge coil, thus only adding weight to the lower octaves. All drivers load a center horn and you may ask whether the large bass drivers won't have an impact on the front driver from sharing the same center horn and the answer is yes - and this is intentional. Air goes where pressure is low, thus when the rear bass drivers move inwards, they will push air into the large center horn and by doing so they will suck air from the front horn and pull in the membrane of the front driver. Obviously the front driver will do the same thing for the bass drivers.

To me, this seems like you might be getting some intermoduation between the woofer and the midrange.

DTQWT-mkII