Help with Tapped Horn Sim - DLS Nobelium

[Jamii]

Hi Guys,

Can I please get some help with this tapped horn that I'm trying to design, it's for a DLS nobelium 12" for my car.

Design requirements are;
Fairly flat from 30-80hz
low group delay in the pass band
high efficiency (95dB+) in the passband

so far this is what I have.









Any pointers would be much appreciated

Regards
James

 

[Jamii]

Attached hornresp export if anyone wants to play with the design on my behalf.

 

[NEO Dan]

Are there two versions of this driver, single and dual VC?

 

[Brian Steele]

How do plan to implement a TH that's 460 cm (15') long and varies from about 2" to 6" high along its cross-section?

 

[GM]

Any pointers would be much appreciated

Greets!

For 'starters', the Cms, Mmd specs should be 1.43e-04, 148.41.

I'm curious, how did you arrive at Mmd = 155? When I tried to let HR calculate it, it returned an error message.

Anyway, for 30-80 Hz with low GD at a realistic compression ratio [CR]:

GM

 

[Jamii]

Hi GM,

Thanks for the reply, I had a feeling something was "off" , I followed the tapped horn tutorial to get my initial figures, but the response was not very good so I had a trial and error with throat size, horn mouth size etc.

I had some calculated values from another program "BassBox 6 Pro" that fills the missing parameters when you enter all the parameters yo do know; this is where i got MMS & RMS figures from. I'm not highly confident that it's accurate but it was a starting point for me.



I'll take a look at your design now so I can figure out where I went wrong.

Thanks!

 

[GM]

Greets!

You're welcome!

Well, as you can see, you loaded Cms wrong and the way around all this is to double click on the Cms box to pop up a window to load Vas and let HR calculate it, then do the same for Mmd to input Fs.

If you prefer to input a published Cms, then if done wrong, when you try to input Fs it will either return an error message or an obviously incorrect Mmd, though you can always double check both at this point by double clicking on Sd to pop up what Vas, Fs it actually has calculated.

Ditto for either entering BL or Qes and Rms or Qms, then double clicking again on Sd to see what all HR calculated.

GM

 

[Jamii]

Thanks GM I appreciate your help, still green at hornresp. I might crosscheck all the TS values with HR as a sanity check, it would be possible I think to attempt to measure the TS values using REW (room eq wizard) I believe as well.

Next step is to try and fold the box in Sketch up, have to measure up available space in the car first.

 

[Jamii]

OK! A follow through. Big thank you to GM for pointing me in the right direction with Hornresp programming.

1) I have finalized a design that will fit within size constraints & design parameters.




2) Folded the design in sketchup, tried to follow S23 length close as I could.


3) Construction Begins!

used a new Jasper jig to flush mount the driver in the baffle, T-Nuts & Bolts to hold it in.




Used Loctite construction glue and over 100 screws to put it together. 45' bracing to try and keep the area the same through the corners.

 

[Brian Steele]

3) Construction Begins!

There doesn't seem to be an "access panel" in your build. What happens if you need to swap out the driver after you've built the TH?

 

[Jamii]

There doesn't seem to be an "access panel" in your build. What happens if you need to swap out the driver after you've built the TH?

It goes in the bin 🙂 (semi-serious)

The lid is not glued on, I used self adhesive high density foam tape and a tonne of screws. so I can get to it that way.

 

[NEO Dan]

Way to commit

 

[Jamii]

In for a penny in for a pound as they say

Seriously need to retune my DSP though; but it's not easy to get to. Currently has a linkwitz-transform for the 10" sealed sub that I had in there, so as you can imagine it's a bit BOOMY!

Also needs more power. Currently feeding it 300-400W and it's loud... but only using 1/3 xmax .

more is always better!

 

[GM]

The lid is not glued on, I used self adhesive high density foam tape and a tonne of screws. so I can get to it that way.

Due to the relatively narrow screw 'flanges', this isn't a good plan if you have to remove it > once or twice unless you replace the foam each time with the possible exception your 'high density' foam tape is NEMA 3R rated [or local equivalent] neoprene as even a leak so tiny you can't see it will negate much of a TH's output, ergo its ability to keep the driver from violently bottoming out in the BW above its tuning.

GM

 

[Jamii]

Not quite sure why everyone is so hung up on driver access; now it's in - it's in, if I remove the driver it will be to throw the box out so,..

It's sounding quite nice now I spent a bit of time yesterday playing with the DSP, removed the linkwitz-transform EQ, changed the crossover & level matched by ear. No EQ yet.

I have a REW setup so once I do some real measurements & an EQ adjustment I'll post the results vs. sim

Cheers
James

 

[GM]

Well, if the box is a throwaway...... seems a shame though, since TL, TH alignments are pretty tolerant of specs, so don't need an exact replacement if it blows; not to mention that with digital EQ being pretty cheap nowadays it allows them considerably more flexibility.

GM

 

[Jamii]

Well sorry maybe my point was unclear; the box is not a throw away, I'm very happy with the sound so I have no intention of swapping drivers at this stage!