Questions about Sonosub (1 Viewer)

[SteveCallas]

The only information that is on the Vents tab is number of vents, shape, diameter, length, and Vent Match. I am using WinISD 0.44. Am I missing something?

 

[Mike Keith]

Download WinISD Pro (.50a6), look on the Driver properties box and there should be 5 tabs:

"Driver"
"Box"
"Plot"
"Signal"
"Project"

The signal tab has a space for power input, you need this to tell cone excursion and port velocity. Changing the values from metric to English requires you to double click the value next to the input box. Right click on the graph for changing options to read out in the unit you want, like M for meters per second. Clicking on any part of the graph will put a cursor there and give you the exact value for that point.

 

[SteveCallas]

Ok got that working, thanks. One more question, which configuration would a sonosub most likely represent? The quasi butterworth, boom box, or chebyshev? I tried all 3 and got a different fr chart from each as well as different suggested port lengths.

 

[Mike Keith]

Sonosub alignment is no different then any box, it depends on what you want, it's a personal choice. I don’t bother with the alignments, just look at the graph and see what it tells you. In addition, I find that there is no substitute for prototypes. I started with the biggest volume design and listened to it, didn't like it very much, wanted more slam so I made another Sonosub about 50L shorter and compared them side by side, like the shorter one better so I cut the other one down to the same size and made a pair. Overall I made about 5 different versions and 4 different port types to get to what I want. If you don’t want to go to that much trouble then just take a stab at it like most do, if you post the graphs then I and others can tell you what kind of sound to expect from which FR plot.

 

[SteveCallas]

No problem.



533 liters, Avalanche 18" driver, 1000 watts, 3 6" ports 42 inches in length, tuned to 16hz.

 

[Mike Keith]

That look real good to me, a larger box will probably give you a hump just before the roll-off, some desire this for movies, but the exaggerated bass like that can make music a bit tubby in the bottom. Also remember that the larger the enclosure the more efficient the sub is, however, this IMO makes the bass a bit muffled and looses the slam. Also, make sure your Group Delay is reasonable, nothing worse then sloppy bass lagging behind the signal.

Everything is a compermise.

 

[Seth_L]

Pushing the tuning point down reduces the group delay at higher frequencies.

Where did the 20m/sec port air speed limit come from? It would seem that a heavily flared port like a Precision Port would be able to tolerate a higher air flow speed.

 

[SteveCallas]

I don't think I can physically go much larger than 533 liters for a single sub. As far as group delay, it reaches a peak of 40.2ms at 14.5hz. Port velocity reaches a peak of 19.4m/s at 14hz. Cone excursion goes over 27mm (the drivers one way limit) at everything below 13.5hz and between 21-25hz.

I'm not too knowledgable in these areas and don't know if those stats are bad. Also, does the cone excursion going over its limit below 13.5hz mean I shouldn't feed it anything below 14hz? If I did, would it damage the driver? By the way, I really appreciate all the help I'm getting.

 

[Seth_L]

You don't want to exceed the driver's xmax until you get below the tuning frequency. So, you will want to adjust your max input power to prevent that from happening.

 

[SteveCallas]

Ok thanks. Tuned it to 15hz, and lowered the power to 800 watts, and everything seems to be good now. No overexcursion until below 12hz - does this mean that anytime it tries to do 12hz and under it will cause damage, or only if played near max volume?

If I were to use a Crown amp, would I be better off using the 15hz cutoff or just letting it go full range seeing as the series I'm looking at has a 6-10db dropoff at 10hz?

 

[Seth_L]

what it means is if it tries to play 12Hz with 800W behind it you risk damaging the driver because it does not have the excusion to back up how far the magnetics will try to push the cone. A lower volume level at 12Hz will be fine.

My preference is to let subs like this run full range without a rumble filter. You are unlikely to encounter any source material which will put 800W into your sub at 12Hz. Two of this sub in your room will likely leave you with a lot of SPL headroom (meaning they can push well past reference volume) so the subs should be quite safe. Unless you have a monster sized room, even in the most demanding bass passages your subs should be just loafing along.

 

[SteveCallas]

Ok great, thanks for all your help.