Infinite baffle people, step inside.
07-17-2012, 12:38 AM
#1
Team Owner
Thread Starter
Infinite baffle people, step inside.
I thought since there are so many IB setups around here, we could use a thread to discuss IB specific tuning and tricks. I'll start off, what subsonic frequency is everyone using?
07-17-2012, 07:42 AM
#2
Racer
My subsonic is set at 20hz @12dB/octave. I had it set a little higher (~28hz) after I bottomed the single IDmax playing "Bass I Love You" I believe that song goes down to 7hz. With the dual IDmax's I think 20hz will be fine for any range of source material at reasonable listening levels.
07-17-2012, 09:43 AM
#3
Suzuka Master
I dont have a subsonic filter. ;(
07-17-2012, 02:20 PM
#6
Team Owner
Thread Starter
My subsonic is set at 20hz @12dB/octave. I had it set a little higher (~28hz) after I bottomed the single IDmax playing "Bass I Love You" I believe that song goes down to 7hz. With the dual IDmax's I think 20hz will be fine for any range of source material at reasonable listening levels.
I've got mine setup as a good compromise. With a 20hz filter I can't bottom my subs with the power I have but it definitely comes close.
That reminds me, when I had the 1,000w amp pushing them and no subsonic, I learned the hard way why you shouldn't burn your first song on a test tone CD as the 10hz one lol. I had the music cranked and it switched disks on me and the first note was 10hz. I had heard the IB15 had a "brake" to stop it from physically bottoming and it didn't actually bottom but I'm surprised I didn't rip a spider. They say these subs have 2" peak to peak excursion but it looked more like 3" that time.
I don't like subsonics but I found several songs that had 8-10hz content that would make the subs go nuts so they're pretty much mandatory for protection. Plus, if you want to get loud, just set the subsonic high enough that you can use the full thermal power rating.
07-17-2012, 02:30 PM
#7
20/24....but does it really matter for me. NOPE. Can't wait to try IB and see what the difference is. Probably go with some shallower 15's when I do that since the IDmax is pretty darn deep. I'm with you thought Matt, a few 13w7's would be pretty sick!
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07-17-2012, 04:58 PM
#8
Racer
This thread seems like a good place to revisit the topic of Qts/Qtc and what it means in the context of choosing an appropriate IB sub. I found this post by Andy Wehmeyer on DIYMA which helped me a lot in getting a grasp on the concept and why a QTC 0.707 is considered the magic number to shoot for.
Quote:
Originally Posted by 60ndown
help me understand this please,
in a larger box i see less air pressure/resistance and therefore less control over the cone, why is a bigger box 'critically damped'?
id have thought a small box would critically 'control' the cone ?
and a big box just slop about?
Andy Wehmeyer:
"Consider the following Thiele and Small parameters:
Cms = The compliance of the suspension--how easily it's moved
Vas = Cms expressed as a volume of air that has the same compliance
These two are a measure of the suspension's restoring force--how much the suspension pushes back when the motor moves the cone.
Q is a measure of the amount of overshoot allowed at resonance. High Q means that the speaker keeps moving after the signal goes away. Low Q means that the speaker stops moving more quickly when the signal goes away.
Qms is the amount of overshoot that the suspension allows
Qes is the amount that the motor allows
Qts is the total and the formula for Qts is the product of Qms and Qes over the sum of Qms and Qes--like resistors in parallel.
Now...if you look at the parameters for 99% of the speakers that are available you'll see that the Qms is always MUCH higher than the Qes. That means that the suspension allows MUCH more overshoot than the motor. Thinking a little further, you'll discover that what that really means is that the MOTOR controls the motion of the cone and the suspension contributes very little control. Both the motor and the suspension work to overcome the inertia of the moving MASS. The motor does a better job than the suspension. essentially, the suspension screws things up. The suspension is there mostly to keep the coil from leaving the gap and should be designed to apply very little force until that is about to happen.
Resonance is the point where the motor and suspension make the hand-off. Above resonance, the motor provides nearly all the control and below resonance, the suspension does more work. Above resonance we say a speaker is mass controlled and below we say it's stiffness controlled. Above resonance the motor overcomes the inertia of the moving MASS and below resonance the motor overcomes the COMPLIANCE of the suspension.
Here's an example: a super-ball is a high Q device and one of those squeezable things in the check out line of Bed Bath and Beyond is a low Q device. When you drop the super ball, it bounces back nearly to the same height as from where it was dropped. That squeezy thing falls with a thud and doesn't bounce at all.
The super ball bounces back because the rubber has a VERY HIGH restoring force--very low compliance or very low VAS. The squeezy thing has a very high compliance--very high VAS. It ABSORBES the force of the impact.
Now, back to the boxes. A woofer by itself with no box is controlled mostly by the motor but the restoring force of the suspension causes it to bounce around a bit at resonance after it should have come to a stop. When we put the woofer in a box, we ADD restoring force because the cone compresses (and rarefies) the air in the box when it moves, causing it to bounce around even more--it's a stiffer super ball. The Q is increased (and so is the frequency of resonance). If the box is bigger, there's less force applied to the cone when the air is compressed and more if the box is smaller. The box RAISES the Q. A small box raises the Q more than a large one. For a small sealed box, you need a woofer with a very low Q. A woofer with a higher Q will need a larger box. The box provides the additional overshoot necessary to achieve the desired Q.
Here's how sealed box design works. The box raises the Qms of the speaker and we choose a box volume that raises it enough to produce the desired response. Qtc is a measure of how much overshoot the whole system of box and woofer allow at resonance. A Qtc of .707 provides the best combination of flat response and low frequency extension. However, there is some overshoot involved. A Qtc of .5 is critically damped or "transient perfect". There's less overshoot.
Before you freak out and decide that you should always build a box with a Qtc of .5 for best accuracy, we have to think a little further:
Choosing .7 is like saying, "well, I know it can't be flat, so I'll choose to make it as flat as possible to the lowest frequency possible and i'll deal with the group delay (inaccuracy) below the cutoff frequency." Choosing a lower Q is like saying, "Well, it can't be flat and I don't care about low frequency extension, so I'll minimize the SLOPE of the rolloff for less group delay. I'll make it more inaccurate at some frequencies and less inaccurate at the lowest frequencies."
Why would we want overshoot? Because if the woofer contnues moving, it makes bass. We want the woofer to continue moving a little bit at resonance, to boost the bass at the bottom of the response for better low-frequency extension and flatter response. Choosing a lower Qtc is essentially managing the compromise a little differently.
The reason we care more about flat response and low frequency extension more than minimizing overshoot is because flat frequency response from the system IS transient accuracy, by the Fourier Transform. Choosing a Qtc of .7 is like saying "I want perfection down to the lowest frequency possible". Choosing .5 is like saying, "I'd prefer to have the transient accuracy be less screwed up at the very lowest frequencies and in order to get that I'll let it be a little scewed over a wider range of frequencies"
The easiest and best rule is to choose flat response and wide bandwidth if it's accuracy that you're after."
Originally Posted by 60ndown
help me understand this please,
in a larger box i see less air pressure/resistance and therefore less control over the cone, why is a bigger box 'critically damped'?
id have thought a small box would critically 'control' the cone ?
and a big box just slop about?
Andy Wehmeyer:
"Consider the following Thiele and Small parameters:
Cms = The compliance of the suspension--how easily it's moved
Vas = Cms expressed as a volume of air that has the same compliance
These two are a measure of the suspension's restoring force--how much the suspension pushes back when the motor moves the cone.
Q is a measure of the amount of overshoot allowed at resonance. High Q means that the speaker keeps moving after the signal goes away. Low Q means that the speaker stops moving more quickly when the signal goes away.
Qms is the amount of overshoot that the suspension allows
Qes is the amount that the motor allows
Qts is the total and the formula for Qts is the product of Qms and Qes over the sum of Qms and Qes--like resistors in parallel.
Now...if you look at the parameters for 99% of the speakers that are available you'll see that the Qms is always MUCH higher than the Qes. That means that the suspension allows MUCH more overshoot than the motor. Thinking a little further, you'll discover that what that really means is that the MOTOR controls the motion of the cone and the suspension contributes very little control. Both the motor and the suspension work to overcome the inertia of the moving MASS. The motor does a better job than the suspension. essentially, the suspension screws things up. The suspension is there mostly to keep the coil from leaving the gap and should be designed to apply very little force until that is about to happen.
Resonance is the point where the motor and suspension make the hand-off. Above resonance, the motor provides nearly all the control and below resonance, the suspension does more work. Above resonance we say a speaker is mass controlled and below we say it's stiffness controlled. Above resonance the motor overcomes the inertia of the moving MASS and below resonance the motor overcomes the COMPLIANCE of the suspension.
Here's an example: a super-ball is a high Q device and one of those squeezable things in the check out line of Bed Bath and Beyond is a low Q device. When you drop the super ball, it bounces back nearly to the same height as from where it was dropped. That squeezy thing falls with a thud and doesn't bounce at all.
The super ball bounces back because the rubber has a VERY HIGH restoring force--very low compliance or very low VAS. The squeezy thing has a very high compliance--very high VAS. It ABSORBES the force of the impact.
Now, back to the boxes. A woofer by itself with no box is controlled mostly by the motor but the restoring force of the suspension causes it to bounce around a bit at resonance after it should have come to a stop. When we put the woofer in a box, we ADD restoring force because the cone compresses (and rarefies) the air in the box when it moves, causing it to bounce around even more--it's a stiffer super ball. The Q is increased (and so is the frequency of resonance). If the box is bigger, there's less force applied to the cone when the air is compressed and more if the box is smaller. The box RAISES the Q. A small box raises the Q more than a large one. For a small sealed box, you need a woofer with a very low Q. A woofer with a higher Q will need a larger box. The box provides the additional overshoot necessary to achieve the desired Q.
Here's how sealed box design works. The box raises the Qms of the speaker and we choose a box volume that raises it enough to produce the desired response. Qtc is a measure of how much overshoot the whole system of box and woofer allow at resonance. A Qtc of .707 provides the best combination of flat response and low frequency extension. However, there is some overshoot involved. A Qtc of .5 is critically damped or "transient perfect". There's less overshoot.
Before you freak out and decide that you should always build a box with a Qtc of .5 for best accuracy, we have to think a little further:
Choosing .7 is like saying, "well, I know it can't be flat, so I'll choose to make it as flat as possible to the lowest frequency possible and i'll deal with the group delay (inaccuracy) below the cutoff frequency." Choosing a lower Q is like saying, "Well, it can't be flat and I don't care about low frequency extension, so I'll minimize the SLOPE of the rolloff for less group delay. I'll make it more inaccurate at some frequencies and less inaccurate at the lowest frequencies."
Why would we want overshoot? Because if the woofer contnues moving, it makes bass. We want the woofer to continue moving a little bit at resonance, to boost the bass at the bottom of the response for better low-frequency extension and flatter response. Choosing a lower Qtc is essentially managing the compromise a little differently.
The reason we care more about flat response and low frequency extension more than minimizing overshoot is because flat frequency response from the system IS transient accuracy, by the Fourier Transform. Choosing a Qtc of .7 is like saying "I want perfection down to the lowest frequency possible". Choosing .5 is like saying, "I'd prefer to have the transient accuracy be less screwed up at the very lowest frequencies and in order to get that I'll let it be a little scewed over a wider range of frequencies"
The easiest and best rule is to choose flat response and wide bandwidth if it's accuracy that you're after."
07-17-2012, 08:58 PM
#9
Team Owner
Thread Starter
This thread seems like a good place to revisit the topic of Qts/Qtc and what it means in the context of choosing an appropriate IB sub. I found this post by Andy Wehmeyer on DIYMA which helped me a lot in getting a grasp on the concept and why a QTC 0.707 is considered the magic number to shoot for.
From my understanding, having a low Fs means you can get away with a lower Qts as well and retain good low end.
Another theory of mine and something I think I've read before, low Qts does not have cone ringing or overshoot. You can use EQ to add power where it needs to be added to make up for the subtle loss in output. Can you EQ down a ringing cone on a high Qts sub?
My experiences with no theory added, the lowest Qtc system I've had was my single 12W6 with an overall Qtc of .49 integrated the easiest with my mids and disappeared. It was one of those near perfect sub stages even without eq. Anyone could make that setup sound good.
The worst was my 12W6s in too small of a box with a .86 Qtc. I would chalk it up to different systems and other variables except they were in the same car and the same amps, etc.
Right now my system has a Qtc of around .6. It seems to do everything right with very little eq but the subs don't disappear like the W6 did unless I cut the 50-63hz range a little.
My theory is that all you have to do is get close. I would rather err on the low side and use EQ if you have to. Which brings me to the next point, getting the Qts to where you prefer it will mean less eq is needed to make it sound how you want it.
Some good reading:
http://www.aespeakers.com/phpbb2/vie...php?f=2&t=2440
http://aespeakers.com/phpbb2/viewtop...&t=2789#p13009
And one of the best talking about Qts and why the IB specific drivers have the Qts lowered from the home version's .7 to .4 for automotive use.
http://www.aespeakers.com/phpbb2/vie...php?f=3&t=2693
07-19-2012, 09:00 AM
#10
After reading ALOT about IB, i did decide to breakdown and do 3 12W6's IB. Powered by JL 500/1, I think filter is set at 24 or 28 with 12db.
After nearly three months of it being installed, I still can't figure out how to tell if I'm bottoming out, so not sure as to how much more I can adjust, and what I can get out of the subs...
After nearly three months of it being installed, I still can't figure out how to tell if I'm bottoming out, so not sure as to how much more I can adjust, and what I can get out of the subs...
07-19-2012, 09:09 AM
#11
Team Owner
Thread Starter
After reading ALOT about IB, i did decide to breakdown and do 3 12W6's IB. Powered by JL 500/1, I think filter is set at 24 or 28 with 12db.
After nearly three months of it being installed, I still can't figure out how to tell if I'm bottoming out, so not sure as to how much more I can adjust, and what I can get out of the subs...
After nearly three months of it being installed, I still can't figure out how to tell if I'm bottoming out, so not sure as to how much more I can adjust, and what I can get out of the subs...
07-19-2012, 09:22 AM
#12
HE>i
iTrader: (1)
...Going to start my build, but I need help being guided in the right direction. so far, going XS65 front stage, IDMAX 12 D4 (may go with two ID's down the road).What amps would you recommend for the whole setup? already looking into the JL 500/1 for sub, and then the JL 300/4 for components?
Will be IB setup. Thanks
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oemplusmore (05-27-2013)
07-19-2012, 10:01 AM
#13
Racer
Some good reading:
http://www.aespeakers.com/phpbb2/vie...php?f=2&t=2440
http://aespeakers.com/phpbb2/viewtop...&t=2789#p13009
And one of the best talking about Qts and why the IB specific drivers have the Qts lowered from the home version's .7 to .4 for automotive use.
http://www.aespeakers.com/phpbb2/vie...php?f=3&t=2693
http://www.aespeakers.com/phpbb2/vie...php?f=2&t=2440
http://aespeakers.com/phpbb2/viewtop...&t=2789#p13009
And one of the best talking about Qts and why the IB specific drivers have the Qts lowered from the home version's .7 to .4 for automotive use.
http://www.aespeakers.com/phpbb2/vie...php?f=3&t=2693
After reading ALOT about IB, i did decide to breakdown and do 3 12W6's IB. Powered by JL 500/1, I think filter is set at 24 or 28 with 12db.
After nearly three months of it being installed, I still can't figure out how to tell if I'm bottoming out, so not sure as to how much more I can adjust, and what I can get out of the subs...
After nearly three months of it being installed, I still can't figure out how to tell if I'm bottoming out, so not sure as to how much more I can adjust, and what I can get out of the subs...
...Going to start my build, but I need help being guided in the right direction. so far, going XS65 front stage, IDMAX 12 D4 (may go with two ID's down the road).What amps would you recommend for the whole setup? already looking into the JL 500/1 for sub, and then the JL 300/4 for components?
Will be IB setup. Thanks
What's your budget? Are you planning to run the XS-65's passive or active? If you're thinking about possibly adding a second IDmax in the future you may want to consider an amp with more power.
07-19-2012, 10:44 AM
#14
HE>i
iTrader: (1)
Looks like your setup will be very similar to mine. I'm very happy with the XS-65's and the IDmax so far.
What's your budget? Are you planning to run the XS-65's passive or active? If you're thinking about possibly adding a second IDmax in the future you may want to consider an amp with more power.
Trying to keep it under $1500 if possible. Dont know anything about tuning, only if someone was to walk me through it
Might start out with basic install of everything, then go active later on.
Might have more ?'s in the future as I start this build
07-19-2012, 10:46 AM
#15
I'm jealous. That's exactly the setup I should have gone with in the first place. If they're not making any bad noises like a clacking, they're likely not bottoming out. While they have 16.5mm of xmax, they have a little over 25mm one way mechanical excursion and the motor and suspension remains quiet and they sound good all the way up unil they bottom. So basically if they look to have 2" peak to peak excursion or less, you're probably ok. It takes roughly 280w to bottom one in free air so 500w on 3 of them with a 24hz filter should not be capable of hurting them. Depending on your goals, you could take the subsonic down to 20hz/24db and probably be fine with only 500w between 3 of them. I would definitely set the filter lower than 28hz with only 500w since you can't hurt them with that kind of power.
Great reading! It inspired me to purchase a book on audio engineering.
That sounds like a sweet setup. Do you have any pictures? How do you like it so far? I agree with IHC about bottoming out. You'll definitely know if you bottom them. It will make you cringe. Not only because the sound is awful, but also because your pockets will be hurting if you damage your subs.
That sounds like a sweet setup. Do you have any pictures? How do you like it so far? I agree with IHC about bottoming out. You'll definitely know if you bottom them. It will make you cringe. Not only because the sound is awful, but also because your pockets will be hurting if you damage your subs.
I have had 1 12w6 in a sealed, than changed it to two 10s mounted on the bottom of the deck in the trunk, and now have these 3 12's. I will say that this setup is the best by far! The beauty of it is that I don't have any vibrations or rattles inside, and the only ones outside is the trunk vibrates at max, and this is when the sunroof opens up a bit too!
Though the fitment of the liners in the trunk, is horrible! Don't know what to do now that I cut it already!
07-19-2012, 12:00 PM
#16
Racer
I am a noob to most of this stuff, to the point of trying to read it and understand it, but getting confused with all this stuff
Trying to keep it under $1500 if possible. Dont know anything about tuning, only if someone was to walk me through it
Might start out with basic install of everything, then go active later on.
Might have more ?'s in the future as I start this build
Trying to keep it under $1500 if possible. Dont know anything about tuning, only if someone was to walk me through it
Might start out with basic install of everything, then go active later on.
Might have more ?'s in the future as I start this build
These are some things I would look for in a 4 channel:
1. Does at least 200 watts per channel bridged to 4ohms
2. Bandpass crossovers - Allows you to run active
3. Differential Balanced inputs
There should be plenty of amps that meet this criteria. I usually just try to find the best deal. I haven't owned any of these personally, but they seem like good options:
- Image Dynamics Q450.4 ($229 on Sonic Electronix)
- Sundown SAX 100.4 (Go for ~ $200 used on DIYMA)
- Zapco DC 1000.4 (On-board DSP)
- Kenwood KAC-X4R (On-board DSP)
- JL Audio HD600/4
- Precision Power P900.4
- Zed Draconia II
For sub amps, I would look for one that is 1ohm stable, does around 1000 watts rms, and has a subsonic filter. Should be really easy to find.
I have had 1 12w6 in a sealed, than changed it to two 10s mounted on the bottom of the deck in the trunk, and now have these 3 12's. I will say that this setup is the best by far! The beauty of it is that I don't have any vibrations or rattles inside, and the only ones outside is the trunk vibrates at max, and this is when the sunroof opens up a bit too!
Though the fitment of the liners in the trunk, is horrible! Don't know what to do now that I cut it already!
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05_NBP_TL (07-19-2012)
07-19-2012, 12:50 PM
#17
Team Owner
Thread Starter
The single 12W6 is about the best sounding sub setup I've owned. Running 3 barely changes the Qtc which IMO is good because they sound so good as is. I wish I had gone with that setup when I still owned two of them. Overall displacement is just a little less than my pair of 15s but very close so they should get loud and low.
Is there any reason they were mounted with the cones facing the trunk?
Is there any reason they were mounted with the cones facing the trunk?
07-19-2012, 01:34 PM
#19
Team Owner
Thread Starter
I've reveresed the phase on my pair of 15s opposite one another and they cancel so perfectly that you literally can't tell they're on, there's no audible sound but they still have excursion.
Some people mount a pair of subs reversed on the baffle, one with the magnet facing the trunk and one with the magnet facing the cabin and reverse the polarity so the cones are still in phase with one another. Supposedly this cuts down on vibrations but it makes absolutely no sense to me.
07-19-2012, 01:59 PM
#20
The back wave is equal to the front wave. I was more wondering because you can get a little more trunk space by facing them forward. Not a lot but a little difference. The way the face won't make much of a difference if you're running them 80hz and down. The higher up you run them, the bigger the difference in output.
I've reveresed the phase on my pair of 15s opposite one another and they cancel so perfectly that you literally can't tell they're on, there's no audible sound but they still have excursion.
Some people mount a pair of subs reversed on the baffle, one with the magnet facing the trunk and one with the magnet facing the cabin and reverse the polarity so the cones are still in phase with one another. Supposedly this cuts down on vibrations but it makes absolutely no sense to me.
I've reveresed the phase on my pair of 15s opposite one another and they cancel so perfectly that you literally can't tell they're on, there's no audible sound but they still have excursion.
Some people mount a pair of subs reversed on the baffle, one with the magnet facing the trunk and one with the magnet facing the cabin and reverse the polarity so the cones are still in phase with one another. Supposedly this cuts down on vibrations but it makes absolutely no sense to me.
07-20-2012, 09:39 AM
#21
The single 12W6 is about the best sounding sub setup I've owned. Running 3 barely changes the Qtc which IMO is good because they sound so good as is. I wish I had gone with that setup when I still owned two of them. Overall displacement is just a little less than my pair of 15s but very close so they should get loud and low.
Is there any reason they were mounted with the cones facing the trunk?
Is there any reason they were mounted with the cones facing the trunk?
The way it is installed right now is that the center cone, peaks through into the cabin through the ski pass by like an inch. The other two, are literally half an inch away from the angled support behind the backseat too.
07-26-2012, 11:19 PM
#23
Team Owner
Thread Starter
07-26-2012, 11:31 PM
#24
Team Owner
Thread Starter
So, kind of on the topic of IB....
The 10s in my doors are IB... kind of but not exactly. They require a large enclosure for a small 10" if you were going sealed. The doors to raise the Qtc a little. It's still slighly below .707 so I'm not worried about peaky response and what matters is the end result and it sounds great.
But just for the sake of discussion, anyone have any thoughts on Qts vs the bandpass it will be operating in? I highpass them at 63hz and Fs is 40hz (probably considerably lower considering how conservatively Dyn rates their speakers).
This speaker will always be operating above Fs, sometimes nearly an octive above Fs. This is where I'm a little fuzzy, it's said Qtc is not as important when the driver is operating way above Fs. I know I'm close enough that Qtc has some effect but does anyone have any thoughts of how it will react if I were to vent the door to make it effectively bigger, lowering the Qtc?
I'm not going to do any of this, just trying to get a discussion going. Oh, and I went back to IB for the midrange so now 6 of my 8 speakers are IB.
The 10s in my doors are IB... kind of but not exactly. They require a large enclosure for a small 10" if you were going sealed. The doors to raise the Qtc a little. It's still slighly below .707 so I'm not worried about peaky response and what matters is the end result and it sounds great.
But just for the sake of discussion, anyone have any thoughts on Qts vs the bandpass it will be operating in? I highpass them at 63hz and Fs is 40hz (probably considerably lower considering how conservatively Dyn rates their speakers).
This speaker will always be operating above Fs, sometimes nearly an octive above Fs. This is where I'm a little fuzzy, it's said Qtc is not as important when the driver is operating way above Fs. I know I'm close enough that Qtc has some effect but does anyone have any thoughts of how it will react if I were to vent the door to make it effectively bigger, lowering the Qtc?
I'm not going to do any of this, just trying to get a discussion going. Oh, and I went back to IB for the midrange so now 6 of my 8 speakers are IB.
07-26-2012, 11:51 PM
#25
I it were me I dont think I would want subs with that setup. I do not like lots of bass below 60hz and I bet you could get decent response with those right down to 20 hz. Perhaps I would use subs when listening to musicwith thunder in it like the thunder rolls? Anyway, if. you vented my guess is that I would still want a sub.
07-27-2012, 08:43 AM
#26
Racer
So, kind of on the topic of IB....
The 10s in my doors are IB... kind of but not exactly. They require a large enclosure for a small 10" if you were going sealed. The doors to raise the Qtc a little. It's still slighly below .707 so I'm not worried about peaky response and what matters is the end result and it sounds great.
But just for the sake of discussion, anyone have any thoughts on Qts vs the bandpass it will be operating in? I highpass them at 63hz and Fs is 40hz (probably considerably lower considering how conservatively Dyn rates their speakers).
This speaker will always be operating above Fs, sometimes nearly an octive above Fs. This is where I'm a little fuzzy, it's said Qtc is not as important when the driver is operating way above Fs. I know I'm close enough that Qtc has some effect but does anyone have any thoughts of how it will react if I were to vent the door to make it effectively bigger, lowering the Qtc?
I'm not going to do any of this, just trying to get a discussion going. Oh, and I went back to IB for the midrange so now 6 of my 8 speakers are IB.
The 10s in my doors are IB... kind of but not exactly. They require a large enclosure for a small 10" if you were going sealed. The doors to raise the Qtc a little. It's still slighly below .707 so I'm not worried about peaky response and what matters is the end result and it sounds great.
But just for the sake of discussion, anyone have any thoughts on Qts vs the bandpass it will be operating in? I highpass them at 63hz and Fs is 40hz (probably considerably lower considering how conservatively Dyn rates their speakers).
This speaker will always be operating above Fs, sometimes nearly an octive above Fs. This is where I'm a little fuzzy, it's said Qtc is not as important when the driver is operating way above Fs. I know I'm close enough that Qtc has some effect but does anyone have any thoughts of how it will react if I were to vent the door to make it effectively bigger, lowering the Qtc?
I'm not going to do any of this, just trying to get a discussion going. Oh, and I went back to IB for the midrange so now 6 of my 8 speakers are IB.
07-27-2012, 12:57 PM
#28
Team Owner
Thread Starter
I've never heard of anyone not liking bass below 60hz. There's a ton of info you're missing out on. If you truly want an "SQ" system that accurately reproduces the source material it needs to be capable of 20hz to 20khz. If you don't like material below 60hz it's probably because you haven't heard a properly set up system with a flat response. Most are heavily boosted between 45-60hz and sound like crap. But 60hz I'm really surprised about, there's a ton of material below that frequency that you're missing. Until I went IB, I had no idea just how much there was below even 35hz.
Even though my 10s might reproduce 20hz, they would not do it as effortlessly and with as little distortion and with the same impact and SPL as the 15s. Excursion would be excessive and it would lead to more distortion in the midbass frequencies. There's also the doppler effect or whatever it's called when a speaker has lots of excursion for the low frequencies and has to produce midrange on top of that.
Even though my 10s might reproduce 20hz, they would not do it as effortlessly and with as little distortion and with the same impact and SPL as the 15s. Excursion would be excessive and it would lead to more distortion in the midbass frequencies. There's also the doppler effect or whatever it's called when a speaker has lots of excursion for the low frequencies and has to produce midrange on top of that.
07-27-2012, 01:06 PM
#29
Team Owner
Thread Starter
It's possible but the problem is I'm over $1,000 into it. I don't want to take anyone's money until the subs arrive because it could always take 5 months like it did with mine and AE has a no refund policy so I would be stuck refunding money if someone changed their minds and I would have all of these extra subs. I'm sure it wouldn't be hard to get rid of them at full "normal" price but $1k is about as far as I'm willing to go as a favor to forum members. I thought about collecting money ahead of time but that would just cause headaches.
07-27-2012, 01:22 PM
#30
HE>i
iTrader: (1)
^ I must say, your willing to go out on a limb for us aziners.
even though you could sell those subs, thats a lot of $$$ to just be buying extra equipment (especially with the possible 5 months waiting period).
Have even more respect for you now.
EDIT: If there any extra subs availible, I may be willing to jump on this deal (was planning on using the IDmax 12"). Not trying to jump in front of anyone else, and if they are all spoken for, that is cool too. Whats the price on these IB subs? you can PM me the info if you want.
even though you could sell those subs, thats a lot of $$$ to just be buying extra equipment (especially with the possible 5 months waiting period).
Have even more respect for you now.
EDIT: If there any extra subs availible, I may be willing to jump on this deal (was planning on using the IDmax 12"). Not trying to jump in front of anyone else, and if they are all spoken for, that is cool too. Whats the price on these IB subs? you can PM me the info if you want.
Last edited by 05_NBP_TL; 07-27-2012 at 01:35 PM. Reason: Boom Boom!
07-27-2012, 02:47 PM
#31
I've never heard of anyone not liking bass below 60hz. There's a ton of info you're missing out on. If you truly want an "SQ" system that accurately reproduces the source material it needs to be capable of 20hz to 20khz. If you don't like material below 60hz it's probably because you haven't heard a properly set up system with a flat response. Most are heavily boosted between 45-60hz and sound like crap. But 60hz I'm really surprised about, there's a ton of material below that frequency that you're missing. Until I went IB, I had no idea just how much there was below even 35hz.
Even though my 10s might reproduce 20hz, they would not do it as effortlessly and with as little distortion and with the same impact and SPL as the 15s. Excursion would be excessive and it would lead to more distortion in the midbass frequencies. There's also the doppler effect or whatever it's called when a speaker has lots of excursion for the low frequencies and has to produce midrange on top of that.
Even though my 10s might reproduce 20hz, they would not do it as effortlessly and with as little distortion and with the same impact and SPL as the 15s. Excursion would be excessive and it would lead to more distortion in the midbass frequencies. There's also the doppler effect or whatever it's called when a speaker has lots of excursion for the low frequencies and has to produce midrange on top of that.
If by quality system you mean one that shakes your insides then I have heard them many times. Mine will do that with the single ten but that to me doesnt make a system "quality". I thought it was pretty cool when I heard my friends' civic hatchback with the first sub I ever bought but that was 17 years ago and not the way I listen to music anymore.
Last edited by stevemk07; 07-27-2012 at 02:57 PM.
07-27-2012, 04:28 PM
#34
It's possible but the problem is I'm over $1,000 into it. I don't want to take anyone's money until the subs arrive because it could always take 5 months like it did with mine and AE has a no refund policy so I would be stuck refunding money if someone changed their minds and I would have all of these extra subs. I'm sure it wouldn't be hard to get rid of them at full "normal" price but $1k is about as far as I'm willing to go as a favor to forum members. I thought about collecting money ahead of time but that would just cause headaches.
07-27-2012, 04:56 PM
#36
Team Owner
Thread Starter
I said I dont like lots of bass below 60hz. My response is pretty flat to 30 with no boosting. I would trim down the 40hz if I could but it actually sounds close to perfect to me. I like 20-60hz very much but in proportion with everything else.
If by quality system you mean one that shakes your insides then I have heard them many times. Mine will do that with the single ten but that to me doesnt make a system "quality". I thought it was pretty cool when I heard my friends' civic hatchback with the first sub I ever bought but that was 17 years ago and not the way I listen to music anymore.
If by quality system you mean one that shakes your insides then I have heard them many times. Mine will do that with the single ten but that to me doesnt make a system "quality". I thought it was pretty cool when I heard my friends' civic hatchback with the first sub I ever bought but that was 17 years ago and not the way I listen to music anymore.
An SQ system is all about "proportion" as you put it. You've made the assumption many times that I'm more into SPL which is not the case. My subs are nearly flat from 20-80hz even before eq. However, it's nice to have a system that will "shake your insides" and sound great doing so when you choose to do so.
A high tuned ported box with no eq is not exactly the epitome of flat. Why did you start this "proportion" argument anyway? You based it off of an assumption just like many people do when they see that I'm running a pair of 15s.
07-27-2012, 05:04 PM
#37
Yup. That is why our responses slope down. My 20-80 has by far the greatest response in my system. Too much sub bass brings the kick drum too close to the front of the stage so it needs to be limited for my liking. Perhaps being a musician has something to do with it.
07-27-2012, 06:05 PM
#38
Team Owner
Thread Starter
I don't see any benefit to lowering the Qtc if you are already under .707. The highpass negates the main reason you would want a lower Qts, which is more low end extension. Staying closer to .707 would give you a lower F3 point and a flatter response within the bandpass. I also don't think transient response would suffer if you're under .707 so that shouldn't be an issue either.
07-27-2012, 07:12 PM
#39
It's possible but the problem is I'm over $1,000 into it. I don't want to take anyone's money until the subs arrive because it could always take 5 months like it did with mine and AE has a no refund policy so I would be stuck refunding money if someone changed their minds and I would have all of these extra subs. I'm sure it wouldn't be hard to get rid of them at full "normal" price but $1k is about as far as I'm willing to go as a favor to forum members. I thought about collecting money ahead of time but that would just cause headaches.
Ok, I definitely want a pair though. So if you could kinda keep me in the loop I would appreciate it.
07-30-2012, 11:29 PM
#40
Team Owner
Thread Starter
Here's a great read on Qts, Qtc, and all of that stuff. It started out a little slow but the last few posts are really informative. Basically you can't go wrong with a low Qts/Qtc system but you can go wrong with a high Qtc system.
http://www.diymobileaudio.com/forum/...e-control.html
Some quotes:
My first post: This is one I see a lot, a small sealed box offers more cone control than a large sealed box or IB. My opinion is a small box means less cone control and drives down efficiency and this is why over damped subs (.4 Qts and lower) work best in small boxes.
I write this because I read nearly every day that small boxes increase cone control. I think people get confused that limiting excursion and controlling the cone is the same thing when it's not. And also that high Qts subs are usually referred to as having more damping and control when I believe the opposite to be true.
It seems like the old way of thinking that IB "needs" a high Qts sub is starting to go away.
The old way of thinking in the first reply:
Control by the air spring resulting in better transient response is not a myth.
Andy W to the rescue:
Nope. damping is control. Springiness is the opposite of control. That's what the shock absorbers in your car do. When your shocks are bad, the car bounces around when you go over a bump. Drive over a big bump with no shocks and you may find yourself struggling to keep your car on the road.
The box stiffens the spring. Its effect is similar to the difference between dropping a ripe avocado on the kitchen floor and dropping a super ball on the floor. If "control" has anything to do with finding the avocado vs. finding the super ball after the experiment (and it does), then the air in a small sealed box reduces cone control.
The misunderstanding comes from the fact that the small sealed box reduces cone movement at low frequencies (and thus reduces output at low frequencies), but it raises the resonance frequency and raises the Q which is a measurement of overshoot at resonance (the opposite of damping). When you're talking about cone control, Q is the measurement. Any suggestion that Q isn't material in this discussion is completely wrong.
This is exactly right and is expressed in the relationship between the various Q values in thiele and small parameters.
Qes is the amount of overshoot that the motor allows.
Qms is the amount of overshoot that the suspension allows.
Qts is the product of those two over the sum (same as resistors in parallel) and the fact that the result (Qts) is much closer to the Qes value than the Qms value indicates that the MOTOR provides more cone control.
So...when you put your woofer in a sealed box, Qts becomes Qtc. Qtc is the amount of overshoot that the system allows and it's higher than Qts and higher than Qms too. By the nuumbers, that means that the box increases overshoot.
Jerry's question to Andy, straight and to the point:
Andy,
Is there ever a point that a low qts (say .4 from a low qtc driver in ib) that it is detrimental to the sq of the woofer? What would suffer from such a low qts?
Andy:
No, just less bass. Think of the box as pushing the response up a bit at resonance and making the rolloff a little steeper. Usually a low Q woofer is designed so that it'll provide acceptable performance in a smaller box. A Q of .707 is the best compromise between low frequency extension and flat response above the rolloff. Lower Q begins rolloff at a higher frequency but at the very lowest frequencies it makes a little more bass.
he problem and what makes it so difficult for so many to understand is that the MOTOR controls the cone movement and the suspension OPPOSES the motor. A spring is NOT a damper. A spring is the OPPOSITE of a damper. A super ball is the opposite of an avocado.
Let's use another example. Does a spring mattress or a tempurpedic mattress offer more control?
My question to Andy:
It's so simple when you put it that way. Before this thread, I had a theory and it kind of made sense to me but now it seems so simple. A spring and damper are actually opposites. A spring stores energy and will reverberate unless you have a shock to oppose the spring, to absorb the "overshoot" of the spring. So is this overshoot why we sometimes see a peak when modeling subs in too small of a box in WinISD? Would that be considered distortion since it's not a part of the original signal?
Going a little off topic, it seems like the MS8 has an easier time "dealing" with lower Qtc subs. Would you say this is correct some of the time?
Andy:
Yes, the peak in the response of a high Q system is overshoot--also referred to as "ringing". This is what an underdamped system does and that's what a high Qtc system is.
MS-8 has A much easier time if it doesn't have to sort out a bunch of enormous peaks in the midbass. If you just have to use a high Q system with an MS-8, then enable the LPF on the sub amp to smooth out the bass a little before MS-8 tries to fix it.
From a mod, I wish I knew more about this and whether he's completely right or not but I would love to know more about the importance of Q in a speaker that will never get close to Fs. My midbass have a Fs of 40hz, likely lower knowing Dyn and the highpass is at 63hz. Not 2x Fs by any means but my midrange have a Fs around 64hz and play 320-6khz so I'm interested. Anyway, here's his post:
The further you are away from Fs with the crossover on the lowend of a passband, the less you have to worry about the Q of the driver in the enclosure. At 2x Fs it really doesn't matter. The closer to resonance, the more it matters...especially IB where Qts= system Q.
All of this deals with the anechoic shape of the lowend response.
So from what I take from this:
1)The worst thing that happens with a very low Qtc sub system is you lose a little bass in most frequencies but at some point you gain some bass at the lowest frequencies. You gain a well damped sub setup with very quick transient response.
2)The airspring of a sealed box DOES NOT control the cone better, it reduces control and efficiency.
3)The bump in output and response we see from a small box high Qtc system is actually distortion from the cone overshoot and ringing so a small sealed box absolutely can not get louder no matter how much power you send it than a large sealed or IB.
This is why say I would never run a sealed box as long as IB is an option.
http://www.diymobileaudio.com/forum/...e-control.html
Some quotes:
My first post: This is one I see a lot, a small sealed box offers more cone control than a large sealed box or IB. My opinion is a small box means less cone control and drives down efficiency and this is why over damped subs (.4 Qts and lower) work best in small boxes.
I write this because I read nearly every day that small boxes increase cone control. I think people get confused that limiting excursion and controlling the cone is the same thing when it's not. And also that high Qts subs are usually referred to as having more damping and control when I believe the opposite to be true.
It seems like the old way of thinking that IB "needs" a high Qts sub is starting to go away.
The old way of thinking in the first reply:
Control by the air spring resulting in better transient response is not a myth.
Andy W to the rescue:
Nope. damping is control. Springiness is the opposite of control. That's what the shock absorbers in your car do. When your shocks are bad, the car bounces around when you go over a bump. Drive over a big bump with no shocks and you may find yourself struggling to keep your car on the road.
The box stiffens the spring. Its effect is similar to the difference between dropping a ripe avocado on the kitchen floor and dropping a super ball on the floor. If "control" has anything to do with finding the avocado vs. finding the super ball after the experiment (and it does), then the air in a small sealed box reduces cone control.
The misunderstanding comes from the fact that the small sealed box reduces cone movement at low frequencies (and thus reduces output at low frequencies), but it raises the resonance frequency and raises the Q which is a measurement of overshoot at resonance (the opposite of damping). When you're talking about cone control, Q is the measurement. Any suggestion that Q isn't material in this discussion is completely wrong.
This is exactly right and is expressed in the relationship between the various Q values in thiele and small parameters.
Qes is the amount of overshoot that the motor allows.
Qms is the amount of overshoot that the suspension allows.
Qts is the product of those two over the sum (same as resistors in parallel) and the fact that the result (Qts) is much closer to the Qes value than the Qms value indicates that the MOTOR provides more cone control.
So...when you put your woofer in a sealed box, Qts becomes Qtc. Qtc is the amount of overshoot that the system allows and it's higher than Qts and higher than Qms too. By the nuumbers, that means that the box increases overshoot.
Jerry's question to Andy, straight and to the point:
Andy,
Is there ever a point that a low qts (say .4 from a low qtc driver in ib) that it is detrimental to the sq of the woofer? What would suffer from such a low qts?
Andy:
No, just less bass. Think of the box as pushing the response up a bit at resonance and making the rolloff a little steeper. Usually a low Q woofer is designed so that it'll provide acceptable performance in a smaller box. A Q of .707 is the best compromise between low frequency extension and flat response above the rolloff. Lower Q begins rolloff at a higher frequency but at the very lowest frequencies it makes a little more bass.
he problem and what makes it so difficult for so many to understand is that the MOTOR controls the cone movement and the suspension OPPOSES the motor. A spring is NOT a damper. A spring is the OPPOSITE of a damper. A super ball is the opposite of an avocado.
Let's use another example. Does a spring mattress or a tempurpedic mattress offer more control?
My question to Andy:
It's so simple when you put it that way. Before this thread, I had a theory and it kind of made sense to me but now it seems so simple. A spring and damper are actually opposites. A spring stores energy and will reverberate unless you have a shock to oppose the spring, to absorb the "overshoot" of the spring. So is this overshoot why we sometimes see a peak when modeling subs in too small of a box in WinISD? Would that be considered distortion since it's not a part of the original signal?
Going a little off topic, it seems like the MS8 has an easier time "dealing" with lower Qtc subs. Would you say this is correct some of the time?
Andy:
Yes, the peak in the response of a high Q system is overshoot--also referred to as "ringing". This is what an underdamped system does and that's what a high Qtc system is.
MS-8 has A much easier time if it doesn't have to sort out a bunch of enormous peaks in the midbass. If you just have to use a high Q system with an MS-8, then enable the LPF on the sub amp to smooth out the bass a little before MS-8 tries to fix it.
From a mod, I wish I knew more about this and whether he's completely right or not but I would love to know more about the importance of Q in a speaker that will never get close to Fs. My midbass have a Fs of 40hz, likely lower knowing Dyn and the highpass is at 63hz. Not 2x Fs by any means but my midrange have a Fs around 64hz and play 320-6khz so I'm interested. Anyway, here's his post:
The further you are away from Fs with the crossover on the lowend of a passband, the less you have to worry about the Q of the driver in the enclosure. At 2x Fs it really doesn't matter. The closer to resonance, the more it matters...especially IB where Qts= system Q.
All of this deals with the anechoic shape of the lowend response.
So from what I take from this:
1)The worst thing that happens with a very low Qtc sub system is you lose a little bass in most frequencies but at some point you gain some bass at the lowest frequencies. You gain a well damped sub setup with very quick transient response.
2)The airspring of a sealed box DOES NOT control the cone better, it reduces control and efficiency.
3)The bump in output and response we see from a small box high Qtc system is actually distortion from the cone overshoot and ringing so a small sealed box absolutely can not get louder no matter how much power you send it than a large sealed or IB.
This is why say I would never run a sealed box as long as IB is an option.