Tapped Horn For Car

[GM]

Never had any fancy measuring equipment beyond an early dbx 1/3 octave RTA/EQ with peak hold, then calc'd the peak power required, so any meter that can do this accurately seems the way to go.

GM

[GM]

Originally Posted by mwmkravchenko

Things in loudspeaker horns are not always what they appear to be.

I haven't been keeping up with these car audio threads, but IME, any acoustically small alignment and especially horns requires a low pass filter (where by 'horn' I mean any duct expanding to a terminus), so unless the room's gain curve can provide it at both ends of the alignment (highly doubtful except possibly in the smallest practical size cars), then one needs to be added to it.

GM

[mwmkravchenko]

Nobody else look at this forum has any other ideas on measuring peak voltage?

Has anybody got any experience with the peak hold circuit by Bob Cordell?

Mark

[mwmkravchenko]

Ok no great big revelations in the test and measurement department. So tomorrow I'm off for rain day and I will actually get back into the shop to make some more saw dust. We shall see what transpires.

Mark

[mwmkravchenko]

Stupid as stupid duzz. Time to fess up to the problem in the woofer. Take a look at the first picture. Note to self nail in both blocks next time!

The block was half way onto the inner woofer surround. It's amazing that it did not rip right through the surround. There is no perceptible damage to the woofers by the way. The inner driver does have a bit of voice coil rub if you help it out a bit. But that was kind of figured out from the impedance plots.





Here is the last rendition of this box. As close to the plans as I have ever laid out. I started from the mouth and worked back. Almost no wasted space. Size is 24" x 20" has the drivers in the optimal location this time as checked out in AkaBak. ( Thanks Don Hills for the gentle nudge in the right direction. And thanks to David McBean for making his program capable of creating an AkaBak script that will allow the type of horn that I'm working with.) Obviously I can't test this at the moment. I just came in from my shop. Tomorrow night I'm working so sometime this week I will put it to the test.





Mark

[winslow]

Looks great. Are those the 7s or 8s?

[Brian Steele]

Originally Posted by mwmkravchenko

Stupid as stupid duzz. Time to fess up to the problem in the woofer. Take a look at the first picture. Note to self nail in both blocks next time!

Ouch! Luckily no serious damage was done.

Are you going to seal up the box again, or leave one side removable?

[mwmkravchenko]

Hi Winslow and Brian

The drivers are 8 inch TRIO8's. This is exactly the same design as the last one. The difference being an optimal layout and position of the drvers. Almost no wasted space.

I think I will leave one side openable like the first design. At least the drivers are easily visible.

Mark

[Don Hills]

Nice layout. I like the way you solved the unequal L23/L34 dimensions. Measured performance may be a little different than the Hornresp calculation due to the "port" geometry being different than modelled. As you can see in Hornresp, small changes in the S3 area make a big difference in the response.

[mwmkravchenko]

Thanks Don

My guess is that the port between the two resonators is close. That is why I did the little diagonal in the corner as I felt that I was so close I may as well try to really replicate the simulation. Well if the non optimal one worked decently I'm expecting better from this one.

It truly is an art to fold these little beasts. I had to lay this one out twice today before it came to me that I could trim away all the excess space that I wasted the first time. I think I blew a fuse or something!

Now the volume is 24" x 20" x 9" no what about 71 litres or 2.5 cubic feet. Quite a bit smaller than my last layout. The last one was 25 3/4" x 30 5/8" x 9" or 116 litres (4.1 cubic feet)
Amazing what happens when I start from the back. Must be the Ukrainian side in me. The German side usually wins out in the end.

Mark