Having a very hard time getting help. PROS ONLY!

[ciaonzo 5,000+ posts]

//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif I wouldn't put that much faith in me. There are people here like ciaonzo and JimJ who know more about audio than I could hope to.

You're too kind, but thanks. I'm not that smart. Besides, you're the one who'll be an EE soon. I'm just drawing from years of experience which means I did it the hard way. //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[Redlineaudio 10+ year member]

Lots of good input in this thread, particularly in posts #17 and #19, so I won't reiterate anything there. One concern of mine is that you're using two low pass filters. This can work but it takes some planning. If you cascade two filters you can get good results and you can get very bad results, all depends on the application and the execution. If you use two steep filters right on top of each other you will get a peak right around the filter pole in the pass band. Couple that with a high inductance figure for your driver and you can get quite a nasty peak. I can't say for sure if that's what you've got going on but it's a possibility. Try using one low pass at 24dB instead of two at whatever they are now. That's not accounting for anything that anyone else has already pointed out.

Go back to this post and start there. I did not see in the posts where you had changed this. Filters have a peak before they roll off, two peaks could be causing the problem.

Next I would change the sub location. from the end to the side. cut a new hole and just put a board over the end. See if that helps.

Also I am not a pro but I did stay at a holiday inn express last night.

 

[ciaonzo 5,000+ posts]

Go back to this post and start there. I did not see in the posts where you had changed this. Filters have a peak before they roll off, two peaks could be causing the problem.


Next I would change the sub location. from the end to the side. cut a new hole and just put a board over the end. See if that helps.

Also I am not a pro but I did stay at a holiday inn express last night.

Haha, caught me off guard with that one. I was bustin' a gut. //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[mbrooky 10+ year member]

ever thought of trying to cap the the hole and mounting the sub on the side or top so it has something to load off of instead of just straight into the port...might help some...or just build another...

edit: just noticed that redline suggested it as well..//content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[mendon mafia 10+ year member]

Go back to this post and start there. I did not see in the posts where you had changed this. Filters have a peak before they roll off, two peaks could be causing the problem.


Next I would change the sub location. from the end to the side. cut a new hole and just put a board over the end. See if that helps.

Also I am not a pro but I did stay at a holiday inn express last night.

hahahaha good one.

i already have tried using one or the other or neither and either way same problem.

i will try sub location i guess ill try that after trying a 45 since its easier.

 

[mbrooky 10+ year member]

i wouldn't waste my time on 45s...don't see how that would change anything...change sub location...

another guy had the same problem...this did not work:

but this did:

and what's funny is he could've just capped the first enclosure and relocated the sub above the port...but instead spent more money on basically the same enclosure with the sub in the right location //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[mendon mafia 10+ year member]

in my case i needed to design the way i did because there was 2 of those same enclosures side by side firing into the cabin of my sedan through the trunk ports in the middle.

 

[mbrooky 10+ year member]

ah i see....well scrap it then and do a new build //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

this should work for ya:

3cuft@34Hz 43.75 sqin port 32x20x14

 

[PV Audio 5,000+ posts]

i wouldn't waste my time on 45s...don't see how that would change anything...change sub location...
another guy had the same problem...this did not work:

but this did:

and what's funny is he could've just capped the first enclosure and relocated the sub above the port...but instead spent more money on basically the same enclosure with the sub in the right location //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

And probably paid 60 bucks for the PWK design too, eh?

 

[ciaonzo 5,000+ posts]

I modeled for both "flat" and output-oriented but mbrooky beat me to the punch for the output numbers. His results matched mine nearly perfectly so I just modeled what he posted instead and created an overlay plot so you can compare the two. The bluish color is the "flat" model and will cater to a better balance for music purposes. The magenta color is the output model will provide more impact and will suit hip-hop nicely. It will have a higher group delay but nothing grotesque. I come from the school of anything higher than 10milliseconds above 40Hz is undesirable so this one just sneaks in there. Both are good models and it will come down to personal taste. Somewhat flat in-car response is achieved with 2cu.ft. @30Hz, 31.5sq.in. of vent area (I modeled with 14 x 2.25) with 43.25" of length. A minimal amount of lining on the walls but do not inhibit airflow for the vent. I did not bother with a drawing because I assume you know how to figure for volume and displacements. I rarely bother with a drawing, truthfully.

The six graphs illustrate the following;

Upper left - normalized frequency response (generic in-car transfer function applied)

Upper right - group delay

Middle left - vent velocity with 2000 watts of power input (both are great)

Middle right - acoustic power, this helps you visualize the thermal and mechanical limits.

Lower left - excursion with 2000 watts of power input

Lower right - impedance curve

http://i704.photobucket.com/albums/ww43/ciaonzo/Temp/mendon.jpg

 

[PV Audio 5,000+ posts]

Whoa, post up the phase plot for that. Your group delay plot is beautifully smooth //content.invisioncic.com/y282845/emoticons/drool.gif.b5e863e893038027711d4402f340dad0.gif

 

[ciaonzo 5,000+ posts]

Whoa, post up the phase plot for that. Your group delay plot is beautifully smooth //content.invisioncic.com/y282845/emoticons/drool.gif.b5e863e893038027711d4402f340dad0.gif

Actually, that's about as ugly as mine get. Not my kind of driver truthfully, no offense OP. You should see the group delay plots on my esoteric approaches.

Gimme a minute to model that one again so I can get you the phase plot. I'll model it with and without the inductance so you can see the impact it has on phase magnitude.

 

[ciaonzo 5,000+ posts]

This is my "flat" model from above (bluish plot)with another plot which excludes the inductance spec (magenta). Note how it peaks in the pass band and how it affects the minimum phase (middle left graph).

http://i704.photobucket.com/albums/ww43/ciaonzo/Temp/PVphase.jpg

 

[SicAudio 5,000+ posts]

great job Ciaonzo i did the same thingwith his orignal box and that sub plots horible in the box he had. how did you copy the screen shot in bpp? i use it as well and never figured it out lolz.

 

[ciaonzo 5,000+ posts]

great job Ciaonzo i did the same thingwith his orignal box and that sub plots horible in the box he had. how did you copy the screen shot in bpp? i use it as well and never figured it out lolz.

Thanks. Indeed, the original does plot quite horribly, lol. Again, no offense mendon. //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

Once you have everything in order, just hit "Print Screen". Next, open up Paint and paste it. Then "save as" whatever. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif