when i was a newB several years back i read an amazing page that i now understand as a cars transfer function and for some reason i'm digging through CK and i can't find it!! Any help would be amazing
-Drew
Replies (16)
Victor on 06/24/2008 20:49:01
http://www.bcae1.com/spboxad1.htm
scroll down.... on this page to read about the transfer function... although it wud be better understood if you read the entire thing .....
Ash on 06/26/2008 06:41:24
I remember a while back we had a few dicussions about transfer function that went a little more in depth. Probably would be hard to find though since the topic was more likely related to some other question in general.
What is it you would like to know?
newB on 06/26/2008 07:30:24
well i understand the concept and can even teach it to those i am installing for, but that article is what opened my eyes as to why rear firing trunk setups sound better to the ear. basicly somebody on another forum wanted more depth than i felt comfortable answering and wanted to reference the article from way back when.
me:
"not because it "pounds the cab floor"
your taking your small cabin volume and adding distance between the wave source and your ear decreasing the transfer function.
-Drew"
Vman. Josh
"Can this also be taken as; it forces the wave to travel farther ( given that a wavelength can be 33 feet long ) the longer it takes to reach your ear, the more it evolves, from just a form of resonance? Does that make any sense?"
i wasn't sure how to answer him!!
-Drew
swez on 06/26/2008 11:00:40
To answer this type of question properly, one needs a strong backround in physics, acoustics and advanced math. We all have limitations and in this case, I'll plead insanity and say... "Duh... I dunno".
One thing we do know, the speed of sound in "air" is roughly 1130 ft/sec. Another thing we know, a 30 Hz tone is about 36' from node to node. That's a very large waveform envelope to work with. The time it takes a given band of frequencies to reach our ears is pretty well fixed, based on speed and distance from the sound source.
Yes, there's a lot more too this, but it's OK to say... "I don't know". If it matters that much to another person, let them dig until they find the answers. Even better, once they find the answers, try to explain it to others at a level we can comprehend?
Beyond that, it's back to physics and complex math equations. Not my forte sir... We all have limits. SMILE
Swez
Victor on 06/26/2008 16:50:14
I want to upload a word file.... how do i do it..???
if not, gimme your mail id... will mail the file to you...
newB on 06/26/2008 17:07:33
saxophonewonder2002@yahoo.com
or
www.myspace.com/saxwonder05
-Drew
Victor on 06/26/2008 21:20:43
have mailed you....cc:swez...
swez on 06/26/2008 21:59:53
Good read Victor and this makes a lot of sense. This is one good reason to experiment with woofer placements to find the sweet spot.
Thanks for the FYI,
Swez
newB on 06/27/2008 05:00:24
OH MAN good info there!! first thing i did was run out and push the box all the way into the back and found that the top/mid was either unchanged or minor improvement with a new found explosive bottom end!!
The excursion on my Eclipse 10" is intense and i'm hoping that loading it so close to the back will help it out (to a small degree) I'm pretty sure the woofer has dual spiders. The rated RMS is unknown but i'm giving it ~1kw of power in 1.5cuft @40hz 25sqin of port with solid results, especially for being a single 10
-Drew
swez on 06/27/2008 06:05:50
Did some experimentation here too in the garage. Have a pair of Sound Stream SPL-10's in sealed box on a dolly. Rotated the box to various positions and noted some change in low-end bass when facing the wall or into a corner. (Old T/F trick)
I don't push them very hard with a 300 watt JBL 2 channel amp in bridged mode, but when I dialed it up and walked outside, could hear plenty of bass at the front curb some 80 feet away and main garage door and aluminum siding rattled pretty good too.
Hum, will have to be mindful of that little experiment so I don't tick off the neighbors. It did not sound all that loud in a 24' x 24' garage, but with all doors closed, there was plenty of bass out in the yard.
My bad?
Swez
newB on 06/27/2008 06:13:30
dangit swez now i'm going to have to do a similar experiment in my garage.
-Drew
swez on 06/27/2008 06:24:35
Hey Drew, just watch the clock when you try this experiment. Don't even think about it after 8:00 PM if there are small children near your place. Waking wee toddlers after they have gone to bed will make for bad relations with the neighbors or folks who work the early AM shifts.
Swez SMILE
Ash on 06/27/2008 07:09:01
Please send me that one too please:
asplundher@yahoo.com
Transfer function & phase (subs facing rear falls under) is two different things. However, I've always had a question about phase aligment applications that I could never really find an answer to:
In a vehicle with a trunk when the sub's enclosure is mounted similarly like that of a infinite baffle, sealing the trunk off from the listening area so all waves are forced forward, do we get the same effect as facing the subs to the farthest rear?
I prefer trunk models this way and have quite a few like that. There is an example on the net by Eddie Runner that explains phase pretty good, but the example doesn't show the particular install that I prefer. I would think the effect would be the same, but with less chance for trunk rattles. Hatchbacks, sorry, I guess it won't apply....
http://www.installer.com/tech/aiming.html
swez on 06/27/2008 09:27:01
Ash,
Copy sent your way. Have a look and try a few things anew.
Swez
Ash on 06/27/2008 10:39:18
Now that's funny.... happened to be the same topic with same examples, though I think Runner's example seemed a bit more easier to understand.
I would think that really applies to hatches & with trunk subs too big to fit near the rear seat. By isolating the trunk from the listening area as far as sub firing, I believe you will get the same effect as far as phase goes.
Transfer function (cabin gain) being the lift in lower frequencies is a bit harder to utilize as far as dead on accuracy. This you will have to take some measurements of the individual car's natural lift to see what areas are affected. Then match an appropriate subwoofer that can use the extension for a desired response.
Usually only people competing in SQ or SPL worry about the latter, but it does make a big difference.
Both anomolies are not limited to subs as front stage mid bass is affected as well.
I'll stop there as it gets pretty deep on out and I don't like wearing high tops. GRIN
swez on 06/27/2008 13:11:32
Wanna borrow my extra pair of chest waders? Oh, they are size 13 boots... too small huh? SMILE
Swez
-Drew
Replies (16)
Victor on 06/24/2008 20:49:01
http://www.bcae1.com/spboxad1.htm
scroll down.... on this page to read about the transfer function... although it wud be better understood if you read the entire thing .....
Ash on 06/26/2008 06:41:24
I remember a while back we had a few dicussions about transfer function that went a little more in depth. Probably would be hard to find though since the topic was more likely related to some other question in general.
What is it you would like to know?
newB on 06/26/2008 07:30:24
well i understand the concept and can even teach it to those i am installing for, but that article is what opened my eyes as to why rear firing trunk setups sound better to the ear. basicly somebody on another forum wanted more depth than i felt comfortable answering and wanted to reference the article from way back when.
me:
"not because it "pounds the cab floor"
your taking your small cabin volume and adding distance between the wave source and your ear decreasing the transfer function.
-Drew"
Vman. Josh
"Can this also be taken as; it forces the wave to travel farther ( given that a wavelength can be 33 feet long ) the longer it takes to reach your ear, the more it evolves, from just a form of resonance? Does that make any sense?"
i wasn't sure how to answer him!!
-Drew
swez on 06/26/2008 11:00:40
To answer this type of question properly, one needs a strong backround in physics, acoustics and advanced math. We all have limitations and in this case, I'll plead insanity and say... "Duh... I dunno".
One thing we do know, the speed of sound in "air" is roughly 1130 ft/sec. Another thing we know, a 30 Hz tone is about 36' from node to node. That's a very large waveform envelope to work with. The time it takes a given band of frequencies to reach our ears is pretty well fixed, based on speed and distance from the sound source.
Yes, there's a lot more too this, but it's OK to say... "I don't know". If it matters that much to another person, let them dig until they find the answers. Even better, once they find the answers, try to explain it to others at a level we can comprehend?
Beyond that, it's back to physics and complex math equations. Not my forte sir... We all have limits. SMILE
Swez
Victor on 06/26/2008 16:50:14
I want to upload a word file.... how do i do it..???
if not, gimme your mail id... will mail the file to you...
newB on 06/26/2008 17:07:33
saxophonewonder2002@yahoo.com
or
www.myspace.com/saxwonder05
-Drew
Victor on 06/26/2008 21:20:43
have mailed you....cc:swez...
swez on 06/26/2008 21:59:53
Good read Victor and this makes a lot of sense. This is one good reason to experiment with woofer placements to find the sweet spot.
Thanks for the FYI,
Swez
newB on 06/27/2008 05:00:24
OH MAN good info there!! first thing i did was run out and push the box all the way into the back and found that the top/mid was either unchanged or minor improvement with a new found explosive bottom end!!
The excursion on my Eclipse 10" is intense and i'm hoping that loading it so close to the back will help it out (to a small degree) I'm pretty sure the woofer has dual spiders. The rated RMS is unknown but i'm giving it ~1kw of power in 1.5cuft @40hz 25sqin of port with solid results, especially for being a single 10
-Drew
swez on 06/27/2008 06:05:50
Did some experimentation here too in the garage. Have a pair of Sound Stream SPL-10's in sealed box on a dolly. Rotated the box to various positions and noted some change in low-end bass when facing the wall or into a corner. (Old T/F trick)
I don't push them very hard with a 300 watt JBL 2 channel amp in bridged mode, but when I dialed it up and walked outside, could hear plenty of bass at the front curb some 80 feet away and main garage door and aluminum siding rattled pretty good too.
Hum, will have to be mindful of that little experiment so I don't tick off the neighbors. It did not sound all that loud in a 24' x 24' garage, but with all doors closed, there was plenty of bass out in the yard.
My bad?
Swez
newB on 06/27/2008 06:13:30
dangit swez now i'm going to have to do a similar experiment in my garage.
-Drew
swez on 06/27/2008 06:24:35
Hey Drew, just watch the clock when you try this experiment. Don't even think about it after 8:00 PM if there are small children near your place. Waking wee toddlers after they have gone to bed will make for bad relations with the neighbors or folks who work the early AM shifts.
Swez SMILE
Ash on 06/27/2008 07:09:01
Please send me that one too please:
asplundher@yahoo.com
Transfer function & phase (subs facing rear falls under) is two different things. However, I've always had a question about phase aligment applications that I could never really find an answer to:
In a vehicle with a trunk when the sub's enclosure is mounted similarly like that of a infinite baffle, sealing the trunk off from the listening area so all waves are forced forward, do we get the same effect as facing the subs to the farthest rear?
I prefer trunk models this way and have quite a few like that. There is an example on the net by Eddie Runner that explains phase pretty good, but the example doesn't show the particular install that I prefer. I would think the effect would be the same, but with less chance for trunk rattles. Hatchbacks, sorry, I guess it won't apply....
http://www.installer.com/tech/aiming.html
swez on 06/27/2008 09:27:01
Ash,
Copy sent your way. Have a look and try a few things anew.
Swez
Ash on 06/27/2008 10:39:18
Now that's funny.... happened to be the same topic with same examples, though I think Runner's example seemed a bit more easier to understand.
I would think that really applies to hatches & with trunk subs too big to fit near the rear seat. By isolating the trunk from the listening area as far as sub firing, I believe you will get the same effect as far as phase goes.
Transfer function (cabin gain) being the lift in lower frequencies is a bit harder to utilize as far as dead on accuracy. This you will have to take some measurements of the individual car's natural lift to see what areas are affected. Then match an appropriate subwoofer that can use the extension for a desired response.
Usually only people competing in SQ or SPL worry about the latter, but it does make a big difference.
Both anomolies are not limited to subs as front stage mid bass is affected as well.
I'll stop there as it gets pretty deep on out and I don't like wearing high tops. GRIN
swez on 06/27/2008 13:11:32
Wanna borrow my extra pair of chest waders? Oh, they are size 13 boots... too small huh? SMILE
Swez
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