Hornresp

[revintage]

This is the link I mentioned earlier.

http://home.earthlink.net/~jmarkwart...spexemplar.pdf

VOTT with 416 and 40Hz porting. Lowering Vrc to 100dm3 and tuning it to 45Hz looks OK too.

[djn]

Originally Posted by revintage

About VOTT, tune it to ca 40Hz. With 1,8cm baffle thickness it will be something like 200cm2.



djn,

where are the T/S parameters? They are not AE´s site. This is all there is:

FS: 23.2Hz
Qts: 0.28
Vas: 467L

Estimated the other values in course sim and I guess it is better to check the drivers from Great Plains. The main reason is TD15x´s high cone mass.

The T/S are kind of hiden on the site. When you go to a particular driver, there is a "down load plans" in the bottom right corner. Click that and you get a page with a link on it to there forum. Click that link and you get a list of all there drivers, click the driver you are looking for and you get a page with all the T/S. Here is the T/S for the TD15x

TD15X- 8ohm
Fs 23.2 Hz
Qms 3.82
Qes 0.31
Qts 0.28
Vas 467 Liters
Cms 0.45 mm/N
Mms 105 grams
Sd 855 cm2
Rms 4.0 Kg/S
Bl 16.7 T/m
Re 5.6 ohms
Z 8 ohms
Le 0.3 mH
Pe (max) 500 Watts
Pe (transient) 1000 Watts
"no" 1.82 %
1WSpl 94.8 dB
Linear Xmax 14 mm (peak)
Mech Xsus 20 mm (peak)

[djn]

Originally Posted by revintage

This is the link I mentioned earlier.

http://home.earthlink.net/~jmarkwart...spexemplar.pdf

VOTT with 416 and 40Hz porting. Lowering Vrc to 100dm3 and tuning it to 45Hz looks OK too.

Hi Lars, is this for the whole VOTT cab or just the top horn flare with the bottom of the cab cut off?

[revintage]

"VOTT" is for the whole cab. It is somewhat troublesome to sim as we can not combine Off-axis response with Combined(shown here). Combined is only with Constant Directivity.

Unfortunately the AE speaker is not suitable if we should believe the sims. The low mass-corner makes it perform bad in the midbasshorn/upper register. Nor will it perform well this type of basscab in the lower range.

[djn]

Thanks Lars. I was planning on just using a vented cab with the Lambdas, but these half VOTTs came my way and I thought I give them a try.

Maybe I will still use them just to get a real world measurement and see how them compare. I don't have vented cabs at the moment anyway so I'll see what happens.

[revintage]

these half VOTTs

Oooops, missed that. Can you estimate the total volume left behind and under the horn? I can then make a new sim for you. Upper response will not be better though.

[djn]

Here is a pic of the actual horn that I have. I am not sure how to estimate the volume with those curved walls. My best guess is 1.5 cu ft??? The back volume is everthing behind the horn flare so I can close off as much as I need to achieve the best results.

I will be using them standing tall unlike the picture. I will be crossing over to the midhorns from 500 to 700hz

[djn]

I just took a tape measure to the cabs and I am guessing that the back chamber is 3 to 4 cu ft, but like I said in my last post, I can reduce that for the best outcome. I have 4 very good subs so what ever the bottom end comes out at, I can fill in with the subs.

[djn]

Ok, I ran the cut down A7 horns in HR and here is what I came up with. Can someone check my math here. I am really not good at this.

The SPL responce is just a bump. Can that be flattened out or does is not take into account the higher freqs the driver will produce?

I will be crossing these over at 500hz but the SPL responce shows it is near 10db down at 500hz. Is that right or is that where the horn effect is down?

[GM]

Attached files to load into HR are the compression loaded 416-8A and AE TD15X in A7 horn sections. Back when I was doing these conversions I just kept reducing the rear chamber's Vb until I found the flattest impedance, so each one was custom tuned. This included blocking off the horn cavities and filling them with expanding Styrofoam, though for HIFI/HT, filling them with sterilized sand, kitty litter/oil dry or similar is preferred. The rest was filled in as required with scrap wood/whatever and fine tuned with R-19 fiberglass insulation wadding.

To ~ mirror the measured flatness of the impedance plots though, I had to increase MathCad's rear chamber's net Vb for HR's to match up, so I'm guessing this is where the acoustic smoothing/whatever comes into play, but again, each cab ideally needs to be custom tuned.

To get a simple pistonic horn + driver summed response, use TOOLS/Directivity/Response and 0 degrees off axis. The Altec's is 'in the ball-park', so I assume the AE's will be also, i.e. a poor driver/horn match for compression loading.

Of course, you can use the full space to lower tuning and use EQ to smooth out the leftover 'bump', but power handling is dramatically reduced.

GM