Eva said:
I can understand the phase shift, but the cancelling each is over my head. if all the drivers and ports were pointing in the same direction, would there be any way of compensating. I'm currently running an infinite baffle type set-up, with 4 x 8" drivers. would it require more power or less ?
The phase step is introduced at different frequencies depending on the tuning of the vents. Also, cancellation or poor summing happens when you put together several systems that don't have the same phase response (you can imagine it as several horses pulling a stone block through ropes in different angles, the more dissimilar the angles the more energy wasted).
Which is the Qts of your drivers? You can probably gain some LF efficiency just by going into sealed boxes of the right volume.
Which is the Qts of your drivers? You can probably gain some LF efficiency just by going into sealed boxes of the right volume.
You did a very clever work by leading the radiation of the speakers directly to the cabin. The remaining work is just to prevent them to radiate into the hatchback, and that will make a *great* improvement.
You already have the front chambers of a 4-th order bandpass system, and you can tune it by changing the size and the shape of the openings to the cabin (note that all should be the exact same size and shape, also, you have left these openings free, haven't you???). An ideal tuning should be around 105Hz (you can use a signal generator and feel the cone with a finger to check this, minimum feeling of "vibration" is achieved at the tuning frequency, it may be hard to detect if you are not used to it, disable any lowpass or eq to do that test). The only remaning bit are sealed or reflex back chambers of suitable volume (tune them in the 35Hz range if you ever go for reflex).
Also, if you decide to rebuild the box, try to avoid parallel walls as that will produce cleaner midbass output and will allow to cross the "rear bass system" higher and get more "punch" without actually perceiving anything coming from behind. Note that such a bandpass system is already self filtering, so it may ask for a low-pass as high as 250Hz when properly tuned.
You already have the front chambers of a 4-th order bandpass system, and you can tune it by changing the size and the shape of the openings to the cabin (note that all should be the exact same size and shape, also, you have left these openings free, haven't you???). An ideal tuning should be around 105Hz (you can use a signal generator and feel the cone with a finger to check this, minimum feeling of "vibration" is achieved at the tuning frequency, it may be hard to detect if you are not used to it, disable any lowpass or eq to do that test). The only remaning bit are sealed or reflex back chambers of suitable volume (tune them in the 35Hz range if you ever go for reflex).
Also, if you decide to rebuild the box, try to avoid parallel walls as that will produce cleaner midbass output and will allow to cross the "rear bass system" higher and get more "punch" without actually perceiving anything coming from behind. Note that such a bandpass system is already self filtering, so it may ask for a low-pass as high as 250Hz when properly tuned.
ok, you lost me again, but if i'm understanding this right, i should minimize the amount of air flowing through the grill between the speaker chamber and the cabin. right now the opening is very close to the and designed to be the same as the displacement of the driver cone. so air flow is not restricted, but not helped either. You can see how the original box was a sealed wedge type, and then the top ripped off. the trunk portion is also sealed off from the cabin. and this car is a convertible with the top folding on top smothering the opening. ( i turn down the sub when the top is down). given the limited parameters what would the best type of enclosure be, to maximize sound quality ?
I think that you misunderstood me. The drivers should radiate into the cabin through that opening in the ceiling of the enclosure and in the back of the cabin that some of your pictures show, nothing should restrict air flow between the drivers and the cabin (you should seal the borders of that opening to prevent any sound from escaping to the hatchback, though).
It's in the hatchback space where additional either sealed or reflex-to-the-cabin enclosures should be added.
It's in the hatchback space where additional either sealed or reflex-to-the-cabin enclosures should be added.
is your car a hatchback or does it have a normal trunk?
If it's a trunk, the best way to do sub bass in a car is free air period...you may loose a Db or two, but the low end ext. you get along with the seamless ability to be able to blend it with your front stage is why if aplicable, will always be the best way to go... also..there will never be any reason why you should ever cross a sub any higher than 100Hz...in fact..if your doing a 2way look to have an xover point in the 60-50Hz range and even lower if doing a 3way..the whole point of car audio is to have as close to a live performance as possible......which means having as much of the freq range infront of you...which n turns means having the sub play as small as a freq range as possible..
If it's a trunk, the best way to do sub bass in a car is free air period...you may loose a Db or two, but the low end ext. you get along with the seamless ability to be able to blend it with your front stage is why if aplicable, will always be the best way to go... also..there will never be any reason why you should ever cross a sub any higher than 100Hz...in fact..if your doing a 2way look to have an xover point in the 60-50Hz range and even lower if doing a 3way..the whole point of car audio is to have as close to a live performance as possible......which means having as much of the freq range infront of you...which n turns means having the sub play as small as a freq range as possible..
trusound said:
Thats where i'm at right now, IB, and just enough low-end to punch it up a bit. I'm also adding some mid-bass drivers to the doors soon, just to help out with bottom end in the front when the top is down and help with the transition to my mid's.
i was just wondering if its worth rebuilding another box. a multiport would of be unique, but alot of work.
you'll get the punch you're looking for in your midbass drivers..with a properly dampn'd door mounted to a thick and sturdy baffle..there should be no reason why a 6.5/7/8 inch driver couldn't give you the output you're looking for...having any sub play high unless it's infront of you almost always tends to draw your stage back...
so my advice...stick with IB....look to getting a set of Dyns, SEAS, Scans, Focal or Morel that have great midbass output and sound fantastic and put them in your door....your needing better midbass...not better subbass
so my advice...stick with IB....look to getting a set of Dyns, SEAS, Scans, Focal or Morel that have great midbass output and sound fantastic and put them in your door....your needing better midbass...not better subbass
trusound said:
I'll be adding some of these
EU700's
they will going in a fibreglass enclosure that replaces the bottom half of my door panel. fortunately i have enough room in the doors that they won't stick out very far. I'm considering throwing in another set of components in the door pod, but i'm cautious, been trying to keep it simple, and yet i keep being drawn to more is better. they either go in the door or rear fill. thought's?
my advice...keep it simple...no rear fill and ix-nay on the multipe comp sets..you'll have big issues with phasing and side biasing...
you should have no issues playing it down to 60-40hz, which will help you not only blend your subbass with your front stage, but you'll have a huge freq range playing infront of you which is always best.....you may also should try flipping the subs out of phase to see if that helps with bringing the bass upfront...
hope this helps
you should have no issues playing it down to 60-40hz, which will help you not only blend your subbass with your front stage, but you'll have a huge freq range playing infront of you which is always best.....you may also should try flipping the subs out of phase to see if that helps with bringing the bass upfront...
hope this helps
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