Sub cancelation

[bugflipper 10+ year member]

I am having trouble with rear seats eating up the bass in a vehicle.With the seats down and the subs loaded on the back gate everything is perfect. When the seats are up, they are at such a steep angle it just cuts the bass to nothing. They are plastic backed, such as a cargo area. I have tried to load the subs on the back of the seats but the same thing happens.

Years back when I owned a shop I designed some boxes for a guy into spl competition. I tried to draw a sketch (sorry). The front would be open. The other three sides would be sealed along with the top over the sub. Lets say 5" above the woofer so it could load. Then it would be above the rear seat facing forward. The original design was with 4 boxes and 8 15" using 4 hcca 2100's. Believe it or not sq was very good. Just way to much spl.

I am open to any ideas since this has me baffled. This is the grocery getter/ t-ball vehicle so I want to stay small on power if I can. SPL with seats down in back is 140, 118 with up and 114 with no subs in the mix. Getting air turbulence even at 118 with the wind felt on the arm hairs, just no sound.

HHR SS

JL 10w7 x 2

Orion HCCA 250 running at 500 rms total (250 per sub)

Box is slot ported tuned to 26 hz.

I am into rock and don't like boomy that much. Only tight bass.

I have not really kept up with current events. Just looking for ideas on what to do. Normally I only run 1 10 in a vehicle but this was a very large area. Thought about even angling at a 45 to the rear wall to get it to bounce over the rear seat but would loose the loading. Any ideas will be very much appreciated. Please ask to clarify that lousy sketch if needed. Ramp on inside above sub was phase 2 of what we started with. Increased output and sharpened punch.

Thanks

Click to read more...

 

[braggpawn 10+ year member]

Firing the subs up with be my best bet....puzzling

 

[bugflipper 10+ year member]

Tried up as well 125 db seats up. 132 seats down. Actually this is the loudest with seats up and used it for the trip last week. Also tried down firing just now with 4" space. 118 up 138 down. This is driving me nuts. I have moved the box to every conceivable location in the back.

Thanks

 

[braggpawn 10+ year member]

might have to settle with the 138 without a different box or better equipment. I sure screwing around with it enough will bring you to that conclusion lol

 

[AudioDave]

might have to settle with the 138 without a different box or better equipment. I sure screwing around with it enough will bring you to that conclusion lol

nothing wrong with his equipment. Just novice to even say that.

Aside that comment. if your not into deep bass then anything below 30HZ on your tune is too low. Remember theres a huge difference between mid/level and sub bass frequencies esp with rock music. Your w7 were made to handle a truckload of bass regardless of the frequency.

My advice, redo the box. Subs are nondirectional, so placement if the box is correct wont matter. Also firing subs upward is very hard on spiders. It will over years reduce life of the subs. Dont let anyone tell you different. I dont know because you didnt post the specs of the box, on the size etc.

 

[bugflipper 10+ year member]

Box is 1.6 ft3 per sub. Slot ported with separate ports. Tuned to 26 hz. Cut off frequency 20 hz. 3/4" mdf. I like deep bass just not boomy. The idea was to tune low to gain the db advantage of a ported enclosure without the disadvantage of turning it into a boom boom machine. Just a sq ported box. I crossover at 80 hz. Sealed is actually the norm for sq. But I wanted a more efficient box so I could use a 250 instead of a 2100. I just didn't want to deal with the footprint of a 2100. It would have had to of been mounted in the open since the tire area was too small for it.

As for equipment

Pioneer AVIC-Z110BT ddin touch screen nav head unit

6.5 hertz millies x 4 some of the better sounding components out there

Milbert BaM-235ab Tube amp arguably the best tube amp ever made

Milbert TC-2R Tube Preamp / Crossover before the orion.

A red hcca is arguably one of the best amps ever produced. All of mine have been going for 15 years or better. This one will do 1600 rms @ 1/2 ohm bridged. THD @ 1600 is .03% with 110 s/n don't know of any others that are that clean. zapco and mcintosh can't even do that.

Very few sq subs out there better than a w7. Especially for the $250 I gave for the pair at 2 months old.

Don't know why I would need better equipment. Already working with some of the best sq gear out there. Not trying to go for spl here. Looking for transparency. Not overpowering bass.

I put a sheet of plywood from the rear seat to the back of the box. 140 db at the headrest. So now thinking of making a mdf wrapped in vinyl. When the seats lay down it would go flat. When up it will ride the back seat up and be a ramp. I will hinge it to the box. And most likely mount little wheels on the upper side to ride the seat back. Just a thought unless you guys can steer me in a better way. Or suggest a box to combat the seat.

Thanks

 

[thehardknoxlife 10+ year member]

The key to SQ is blending. Trying to get the most "db's" out of your substage is pointless and wasteful considering your front set-up. I mean can you really expect a set of components to blend with two w7's full tilt and still be on the SQ side?

The first thing I would do is ditch the ported box, then I would try to isolate the subs from the trunk by making an enclosure that fires directly into the cabin.

 

[bugflipper 10+ year member]

The key to SQ is blending. Trying to get the most "db's" out of your substage is pointless and wasteful considering your front set-up. I mean can you really expect a set of components to blend with two w7's full tilt and still be on the SQ side?
The first thing I would do is ditch the ported box, then I would try to isolate the subs from the trunk by making an enclosure that fires directly into the cabin.

You are missing the point totally. Not trying to get maximum spl. I am trying to fix a cancellation issue. If I were going for spl I would run a 2100 and 15" subs. I generally run 1 10" sub. This is a very large open space. I ran 2 and a sq ported box to increase db for the large area. Once I get the cancellation issue worked out then I can focus on dialing it in. This thread is not how do I get it louder. It was about how to stop the seat from canceling out the bass. Most of my setups are running in the mid to high 130s. I honestly can't see how 250 running to a w7 rated for 700 is anywhere near full tilt. Sorry not getting it. Not trying to be obtuse. Perhaps seeing the db readings one would assume I was trying to achieve more. Just trying to get back what was lost.

No trunk in this vehicle and I would like to see out the back window. Don't want to back over any kids.

Thanks

 

[AudioDave]

Did you read my post?

1'd change the frequency from 26 to about 35 with a cutoff of 25-30. Raising the cutoff will not also make it punchier, it also takes some coloration out of the subs. When the coloration is reduced so will the reverb, crosstalk and cancellation. There is no other way to do this unless u use below's suggestion. Ported or sealed is irrelevant to that concept. Sealed generally goes deeper but is not as accurate with rapid tones or short bursts, which is why in DB Drag they use vented 95% of the time.

The other thing is make a single reflex bandpass AKA 5th order. (see pic) This design was created for just this reason. If you design it correctly (i can send specs if needed) 1 of those subs on that amp is more than you will ever need. 2 would be unbelievable. These were created just for SUVs, Vans, Hatchbacks etc to kill that coloration. +3-6db gain with a decent preamp and a little higher cutoff will rock that van. Also by doing a bandpass, the sub has almost zero coloration (aside whats outside the port), so there is nothing for the frequencys to dip, curve or cut off like seats, roofs etc. The sensitivity of the speaker also goes up, managing it takes less amp power to do more sound.

Forget the spl for now, If you decide to go thisw route and take the time to do it right, I promise you that you will get the best of both worlds and your equipment will thank you for it by preforming at its best.

Let me know -