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-   -   Please validate TH subwoofer design (http://www.diyaudio.com/forums/subwoofers/225366-please-validate-th-subwoofer-design.html)

wxn 10th December 2012 08:31 AM

Please validate TH subwoofer design
 
3 Attachment(s)
Hi everyone, I have a nice woofer laying around (salvaged from a fried Tannoy TS8 sub) that I would love to put to use. The TS parameters are measured using added mass method (pic). WinISD believes that this driver will hit 30hz in a 40l reflex box but then after fiddling with HornResp I managed to get a response I like (pic), which intrigued me as horns have a nice reputation.

Can someone more qualified inspect this horn and point out any possible flaws and/or its fesibility compared to BR? Perhaps it could be optimized in terms of size and/or performance? My goals are <~50l volume and working band 30-80hz or so

Thanks in advance,
K.

Code:

ID=29.00
Ang=2.0 x Pi
Eg=2.83
Rg=0.00
Fta=-0.22
S1=128.00
S2=152.00
Con=20.90
F12=0.00
S2=152.00
S3=192.00
Con=278.20
F23=0.00
S3=192.00
S4=188.00
Con=20.90
F34=0.00
S4=0.00
S5=0.00
L45=0.00
F45=0.00
Sd=176.00
Bl=7.50
Cms=3.86e-04
Rms=2.44
Mmd=39.00
Le=0.90
Re=3.20
TH=1
Vrc=0.00
Lrc=0.00
Ap1=0.00
Lpt=0.00
Vtc=0.00
Atc=0.00
Pmax=100
Xmax=5.0
Comment=TS8 BH


bjorno 10th December 2012 11:35 AM

Tannoy and Audes 75W104-8 subs
 
2 Attachment(s)
Quote:

Originally Posted by wxn (Post 3278432)
Hi everyone, I have a nice woofer laying around (salvaged from a fried Tannoy TS8 sub) that I would love to put to use. The TS parameters are measured using added mass method (pic). WinISD believes that this driver will hit 30hz in a 40l reflex box but then after fiddling with HornResp I managed to get a response I like (pic), which intrigued me as horns have a nice reputation.

Can someone more qualified inspect this horn and point out any possible flaws and/or its fesibility compared to BR? Perhaps it could be optimized in terms of size and/or performance? My goals are <~50l volume and working band 30-80hz or so

Thanks in advance,
K.

Hi K,

Have a look at this:

b:)

PS: FYI,Added a Scandinavian more potent sub suggestion using IMO great drivers from another nearby Baltic Country. :D

wxn 10th December 2012 11:49 AM

My God that was quick, thanks a lot for this eye opener! This tqwt to be in a completely different league at almost half the volume... Any tips for the actual folding/implementation?

Regarding the other driver, it does seem very impressive but I guess it will have to wait for a bigger listening room and more tolerant neighbors :)

P.S. How do you put all the graphs together so quickly and tidily?

bjorno 10th December 2012 12:52 PM

Quote:

Originally Posted by wxn (Post 3278556)
My God that was quick, thanks a lot for this eye opener! This tqwt to be in a completely different league at almost half the volume... Any tips for the actual folding/implementation?

Regarding the other driver, it does seem very impressive but I guess it will have to wait for a bigger listening room and more tolerant neighbors :)

P.S. How do you put all the graphs together so quickly and tidily?

You know 'Practice makes perfect' 99% is just cut and paste..For the moment I think you should browse this forum for folding tips, there are quite a few.

I posted the other suggestion in order to put 'Baltic' driver manufacturers on the DIY-Mapp.

I understand your concerns regarding the need of a larger room and worries of what neighbor would say if this sub is cranked up above 100 dB.

b:)

wxn 10th December 2012 01:07 PM

Yes, thank you very much. Just one last question - Hornresp seems to be very fussy about few cm changes to the length of the last segment. I assume this is the distance from voice coil to the mouth opening (of S4 area) that is positioned directly above the driver, as in the other example?

bjorno 10th December 2012 01:18 PM

Quote:

Originally Posted by wxn (Post 3278613)
Yes, thank you very much. Just one last question - Hornresp seems to be very fussy about few cm changes to the length of the last segment. I assume this is the distance from voice coil to the mouth opening (of S4 area) that is positioned directly above the driver, as in the other example?

Yes That's correct for the case of using 2 Drivers(If only one Driver too) it's the distance counted from the intersection between both, thus the terminating area shown in HR is moved and in order to make the enclosure to fit the drivers,a small additional length must be added to the baffle: this will increase the total length a bit.

b:)

more10 10th December 2012 02:24 PM

Check out Forsmans design. He added a fold to the generic Tham design. What is unique with these designs are that most angles are 90 and 45 degrees, only one mitred angle is difficult to do. Exremely easy designs to build.

If you want something folded only once, check out Volvotreters designs. I did a single folded design with front chamber that I am very happy with. It lacks some bracing though, its just a prototype.

GM 10th December 2012 05:52 PM

2 Attachment(s)
Quote:

Originally Posted by wxn (Post 3278432)
My goals are <~50l volume and working band 30-80hz or so

A couple of more examples to play with in the wizard with a <50 L net Vb TH and offset driver TH [DTS] with a minor amount of peak power redistribution from the mids to the bass. 200 W peak/5 mm Xmax assumed.

Any idea what the actual/published Xmax is?

Rather than posting the design details, why not save them as a HR export txt file for others to easily import/install?

GM

wxn 11th December 2012 06:54 AM

Quote:

Originally Posted by GM (Post 3278941)
A couple of more examples to play with in the wizard with a <50 L net Vb TH and offset driver TH [DTS] with a minor amount of peak power redistribution from the mids to the bass. 200 W peak/5 mm Xmax assumed.

Any idea what the actual/published Xmax is?

Rather than posting the design details, why not save them as a HR export txt file for others to easily import/install?
GM

I have no idea about the Xmax but 5mm seems reasonable, it's not a very long throw woofer. Thanks for the tip regarding txt files!

After playing some more with different designs, it seems that while tapped horns are somewhat inferior in performance to T-TQWT, they are also a lot less sensitive to minute parameter variations. I mean, just a couple cm on any dimension in bjorno's design leads to huge resonances. Unless of course HornResp is exagerating stuff. Any input on this is welcome, especially bjorno.

Quote:

Originally Posted by more10 (Post 3278671)
If you want something folded only once, check out Volvotreters designs. I did a single folded design with front chamber that I am very happy with. It lacks some bracing though, its just a prototype.

Thanks, very nice ideas indeed!

GM 11th December 2012 08:28 AM

And yet the sub was advertised as having a long throw woofer. Shame on Tannoy.

You're welcome!

Yes, for 2-2.5 octave 'sub' apps, a TH is a better bang/buck solution IMO, especially since it's more tolerant of driver specs variation.

HR doesn't exaggerate per se, it just doesn't account for any acoustical losses due to friction, construction material's damping, etc.. Build it out of thick, highly polished steel though and I imagine the measured response would be much closer, especially WRT HF 'ringing'.

GM


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