A Debate on the many different aspects of sound
02-24-2005, 07:13 PM
#191
1000 Watt CAFz'r
Join Date: Aug 2001
Posts: 1,770
Originally posted by Tim Baillie.:
Wow, this post has just become a post of who can one up another on opinions [img]smile.gif[/img]
Wow, this post has just become a post of who can one up another on opinions [img]smile.gif[/img]
so there
[ February 24, 2005, 08:14 PM: Message edited by: pinhead ]
02-25-2005, 01:02 AM
#192
500 Watt CAFz'r
Join Date: Oct 2004
Posts: 870
Since almost no manufacturer gives specs for their drivers, how do you know they're built for IB.
I would guess that most make em to sound good in the display board, cause that's where the choice is usually made to buy em or not.
Given a choice, I find that most uneducated consumers will choose the louder, brighter speaker at first listen, and it takes a bit of guidance to show them that the better speakers have had some flaws removed (take out anything, and efficiency drops), but are nicer to the ear.
Once you point out the sharp edge on a female vocal, or show em how the cheap one makes you want to turn it down, and the better one makes you wish you had a bigger amp, cause it sounds so damn good loud, then they get it.
K, another change of topic.... The baffle is the most imortant part of any enclosure.How do you get a true IB in a door, when you cover the main baffle with a piece of plastic with a small grill on a factory panel. I've found that once the door panel is in place, there is a huge change for the worse, as a huge pressure wave is trapped behind the door panel.
Picture a drop of water hitting a puddle....the pressure changes direction, and makes a wave tangential to the direction of the original drop. Very little pressure hits the bottom of the puddle.
A high pressure wave from a woofer does the same thing....the initial wave hits a wall of stationary air in front of the woofer, and creates a pressure wave sideways along the baffle. If there is a gap between the mounting baffle and the door panel, then the majority of the wave is inside the door panel, causing it to flex out of phase with the original driver.
Some flat panels are easy to fix...a spacer ring and a bit of gum gum can seal the gap between panel and woofer ...but what about the ones with lots of curves? Like an Impala or some of the Ford trucks. How do you get all the pressure through the panel and into the car?
[ February 25, 2005, 02:16 AM: Message edited by: Car Trek ]
I would guess that most make em to sound good in the display board, cause that's where the choice is usually made to buy em or not.
Given a choice, I find that most uneducated consumers will choose the louder, brighter speaker at first listen, and it takes a bit of guidance to show them that the better speakers have had some flaws removed (take out anything, and efficiency drops), but are nicer to the ear.
Once you point out the sharp edge on a female vocal, or show em how the cheap one makes you want to turn it down, and the better one makes you wish you had a bigger amp, cause it sounds so damn good loud, then they get it.
K, another change of topic.... The baffle is the most imortant part of any enclosure.How do you get a true IB in a door, when you cover the main baffle with a piece of plastic with a small grill on a factory panel. I've found that once the door panel is in place, there is a huge change for the worse, as a huge pressure wave is trapped behind the door panel.
Picture a drop of water hitting a puddle....the pressure changes direction, and makes a wave tangential to the direction of the original drop. Very little pressure hits the bottom of the puddle.
A high pressure wave from a woofer does the same thing....the initial wave hits a wall of stationary air in front of the woofer, and creates a pressure wave sideways along the baffle. If there is a gap between the mounting baffle and the door panel, then the majority of the wave is inside the door panel, causing it to flex out of phase with the original driver.
Some flat panels are easy to fix...a spacer ring and a bit of gum gum can seal the gap between panel and woofer ...but what about the ones with lots of curves? Like an Impala or some of the Ford trucks. How do you get all the pressure through the panel and into the car?
[ February 25, 2005, 02:16 AM: Message edited by: Car Trek ]
02-25-2005, 01:46 AM
#193
500 Watt CAFz'r
Join Date: Oct 2004
Posts: 870
I tried the Fusion mids in some different boxes, and the results are pretty close to what I predicted from the measurements I did.
At first I was getting very skewed results, but a bit of investigation revealed that the output of my test amp was far from flat.I'm using a disc of test tones as a source...I'll try to find the generator I used to make it....an on-line deal. Very useful disc for demoing, and testing. I put some sweeps...20-100hz, 20-500 hz, and 20-2500hz that are great for finding rattles and buzzes. If anyone wants a copy, I'm sure I can figure out how to send it.
When you follow the steps in the T/S calculator, it says don't adjust the volume after you've set it up. Re-checking the output voltage at each frequency, I found it to be off quite a bit, so by re-adjusting it as I go, to compensate , I was able to get very close to the published specs on several woofers I measured.
These Fusions have an EBP of 72, so can be used either ported or sealed. Ported definately has more punch and as long as there's a high pass filter, they have a lot less distrtion cranked up ( I was using a Phoenix XS-2500 for testing). Sealed went lower with no high pass, but not as loud.
I've decided on .9 ft at 55 hz for two woofers. 9 sq inch ports x 5" long. Gonna be a bit difficult to get exactly .9 ft, as the panels aren't wrapped yet, but I should be close. If I have to re-tune after, I'll be able to reduce the area of the port and tune lower, or I can reduce the box size a bit.These doors are gonna rock!!!
I took some pics, but they turned out fuzzy. I'll try another camera tomorrow.
At first I was getting very skewed results, but a bit of investigation revealed that the output of my test amp was far from flat.I'm using a disc of test tones as a source...I'll try to find the generator I used to make it....an on-line deal. Very useful disc for demoing, and testing. I put some sweeps...20-100hz, 20-500 hz, and 20-2500hz that are great for finding rattles and buzzes. If anyone wants a copy, I'm sure I can figure out how to send it.
When you follow the steps in the T/S calculator, it says don't adjust the volume after you've set it up. Re-checking the output voltage at each frequency, I found it to be off quite a bit, so by re-adjusting it as I go, to compensate , I was able to get very close to the published specs on several woofers I measured.
These Fusions have an EBP of 72, so can be used either ported or sealed. Ported definately has more punch and as long as there's a high pass filter, they have a lot less distrtion cranked up ( I was using a Phoenix XS-2500 for testing). Sealed went lower with no high pass, but not as loud.
I've decided on .9 ft at 55 hz for two woofers. 9 sq inch ports x 5" long. Gonna be a bit difficult to get exactly .9 ft, as the panels aren't wrapped yet, but I should be close. If I have to re-tune after, I'll be able to reduce the area of the port and tune lower, or I can reduce the box size a bit.These doors are gonna rock!!!
I took some pics, but they turned out fuzzy. I'll try another camera tomorrow.
02-25-2005, 08:11 AM
#195
Guest
Posts: n/a
what are the specific things that speaker designers do when designing a coaxial or any speaker for that matter, specifically for and ifinite baffle application
cartrek, your testing reveals some interesting results, what was the hipass filter set at, what are the parameters your calculator came up with, give some more details on your listening evaluation, that would be cool, what music do you use for evaluating
cartrek, your testing reveals some interesting results, what was the hipass filter set at, what are the parameters your calculator came up with, give some more details on your listening evaluation, that would be cool, what music do you use for evaluating
02-25-2005, 08:25 AM
#196
1000 Watt CAFz'r
Join Date: Oct 2003
Posts: 1,783
Car Trek, I'm currious how you adjusted your amp at various frequency points.
Did you remove the driver load from the amp, and then measure voltage at the terminals, matching them equally before reataching the driver?
Or did you keep the driver connected measuring the voltage across the terminals and matching it at different frequencies?
Adam
Did you remove the driver load from the amp, and then measure voltage at the terminals, matching them equally before reataching the driver?
Or did you keep the driver connected measuring the voltage across the terminals and matching it at different frequencies?
Adam
02-25-2005, 09:49 AM
#198
1000 Watt CAFz'r
Join Date: Jun 2002
Posts: 1,242
Originally posted by defro13:
are most car speakers meant for ib? i would seriously qusetion that. anyway i have used many speakers in sealed in cars, mostly k/p, but most of the time the k/'s were very samll and the performance was so so.
are most car speakers meant for ib? i would seriously qusetion that. anyway i have used many speakers in sealed in cars, mostly k/p, but most of the time the k/'s were very samll and the performance was so so.
All of MB Quart’s midrange/midbass speakers are optimized for infinite baffle/free air mounting, which is essentially mounting in the door or factory speaker locations. They will work best in this type of mounting using the door cavity as the enclosure. Sealed enclosures are not recommended since they would require larger than practical volumes for the speaker to function optimally. This holds true for all MB Quart products with the exception of our subwoofers. If a midrange/midbass driver is put into a small sealed enclosure, it will alter the speaker’s response characteristics and you will not get the full amount of bass or midbass that the speaker is capable of producing.
02-25-2005, 10:12 AM
#199
500 Watt CAFz'r
Join Date: Oct 2004
Posts: 870
I adjusted the output level of the amp with the driver and resistor attached,( ummm perhaps I should have used a pure resistor as a load),and measured voltage at the amp.
then I re-attached the meter to measure voltage at the driver, after the resistor.
A good linear amp, and a signal generator would make life a lot easier, but what are ya gonna do when you have a rock and a piece of flint?
I'm not sure of the exact HPF setting as it's a dial on the amp, but I assume somewhere around 50-60 hz.
I usually use Annie Lennox Medusa for listening. I tried a few CD's, but that one I've listened to death since it came out, and I have a good idea what it's supposed to sound like.
I didn't bother hooking up the passive crossovers or tweeters....just wanted to hear differences between the midbass in different boxes.
Parameters I came up with are:
Fs 55 hz
Qe .717
Qm 6.57
Vas .4
EBP 76 (fs/Qe) so midway between ported or sealed
then I re-attached the meter to measure voltage at the driver, after the resistor.
A good linear amp, and a signal generator would make life a lot easier, but what are ya gonna do when you have a rock and a piece of flint?
I'm not sure of the exact HPF setting as it's a dial on the amp, but I assume somewhere around 50-60 hz.
I usually use Annie Lennox Medusa for listening. I tried a few CD's, but that one I've listened to death since it came out, and I have a good idea what it's supposed to sound like.
I didn't bother hooking up the passive crossovers or tweeters....just wanted to hear differences between the midbass in different boxes.
Parameters I came up with are:
Fs 55 hz
Qe .717
Qm 6.57
Vas .4
EBP 76 (fs/Qe) so midway between ported or sealed
02-25-2005, 10:27 AM
#200
Guest
Posts: n/a
j race, so if you could get the right box volume for a mbq speaker, sealed would be optimum if i read correctly, but if you couldnt get the volume ib would likely be better, i think i said that very thing a few pages ago, the vented or sealed application only works if the right volume could be attained
