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post #1 of 56 Old 05-26-2018, 08:43 PM - Thread Starter
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Noob needing verification

I'm in a rabbit hole right now chasing single digit frequencies without any prior experience. Hence the noob term is very fitting. I have planned out most of my components and want to make sure that I'm not overlooking anything and that I'm not going to blow anything up. I'm planning an infinite baffle setup with dual IB3v2 18" drivers and have tried to setup WinISD to test before I purchase my amp. I'm planning to take the RCA outputs of my Marantz 6011 and connect to a miniDSP with filters to prevent over excursion of the drivers. Then I'll connect RCA outs from miniDSP to speakerpower sp2-4800 amp. I have attached images from WinISD. I just want to make sure I set WinISD up right.

Is 2 drivers correct for a dual driver manifold?
Using the sp2-4800 would 2400 be correct for the system input power using 1 channel per manifold? Seems like my max power in winISD is going to be considerably less than the 2400 provided by the single channel of the sp2-4800. Should I consider a different amp?
The IB3v2 drivers have an xmax of 34mm so if all is correct seems I should be okay, or should I target a different xmax with my filters?

Any and all pointers/corrections are appreciated, total noob here.
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post #2 of 56 Old 05-26-2018, 09:04 PM
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Quote:
Originally Posted by Tyborg View Post
I'm in a rabbit hole right now chasing single digit frequencies without any prior experience. Hence the noob term is very fitting. I have planned out most of my components and want to make sure that I'm not overlooking anything and that I'm not going to blow anything up. I'm planning an infinite baffle setup with dual IB3v2 18" drivers and have tried to setup WinISD to test before I purchase my amp. I'm planning to take the RCA outputs of my Marantz 6011 and connect to a miniDSP with filters to prevent over excursion of the drivers. Then I'll connect RCA outs from miniDSP to speakerpower sp2-4800 amp. I have attached images from WinISD. I just want to make sure I set WinISD up right.

Is 2 drivers correct for a dual driver manifold?
Using the sp2-4800 would 2400 be correct for the system input power using 1 channel per manifold? Seems like my max power in winISD is going to be considerably less than the 2400 provided by the single channel of the sp2-4800. Should I consider a different amp?
The IB3v2 drivers have an xmax of 34mm so if all is correct seems I should be okay, or should I target a different xmax with my filters?

Any and all pointers/corrections are appreciated, total noob here.
(2) 18" drivers total?!?

Ask your doctor if DIY is right for you. Side effects of DIY may include anxiety, elevated blood pressure, lightheadedness, rapid heartbeat, skeletal muscle flaccidity, euphoria, psychological dependence, insomnia, confusion, blurred vision, implusivity, uncontrolled or repeated movements.
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post #3 of 56 Old 05-26-2018, 11:04 PM - Thread Starter
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Originally Posted by michael hurd View Post
(2) 18" drivers total?!?
Will be four 18’s total, but this is for 1 manifold that will have two 18” drivers in it. Am thinking to split the 4800 to two channels one for each manifold. Not sure if you are puzzled that two drivers is inadequate or over the top. Like I said noob here looking for constructive responses
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post #4 of 56 Old 05-26-2018, 11:14 PM - Thread Starter
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I had considered the sp4-2800 and running one 700w channel to each manifold, but 350w per driver seemed like I was leaving some output on the table. I could combine two channels on the sp4-2800 and send 1400w to each manifold, but the price difference between the sp2-4800 and the sp4-2800 is minimal so I figured I would just go with the sp2-4800 and extra headroom for nearly the same price.
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post #5 of 56 Old 05-26-2018, 11:25 PM
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According to (I can't post links) the driver can handle 600 W RMS.

I haven't used the multiple driver feature in WIN ISD but your maximum power graph doesn't look like it refers to 4 drivers. So if it refers to one or two drivers the maximum excursion might not be reached but the power would definetly be too much.
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post #6 of 56 Old 05-26-2018, 11:31 PM
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Quote:
Originally Posted by Tyborg View Post
I had considered the sp4-2800 and running one 700w channel to each manifold, but 350w per driver seemed like I was leaving some output on the table.
What I would do: Simulate just one driver in your situation and look how much power ist required to get to its Xmax value.
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post #7 of 56 Old 05-26-2018, 11:50 PM
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And is it truely and IB design (no air spring)?
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post #8 of 56 Old 05-26-2018, 11:56 PM - Thread Starter
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Quote:
Originally Posted by Soldy View Post
According to (I can't post links) the driver can handle 600 W RMS.

I haven't used the multiple driver feature in WIN ISD but your maximum power graph doesn't look like it refers to 4 drivers. So if it refers to one or two drivers the maximum excursion might not be reached but the power would definetly be too much.
Hmm, I put in filters to limit the excursion. Is there a way to limit the power with DSP to protect it or is it simply a matter of not turning up the knob?
I was testing 2 drivers because I was planning to wire two 2ohm drivers in series to get a 4 ohm load to the amp. I’ll see what a single driver looks like, but I wouldn’t consider running that real world because the amp isn’t rated to run a 2ohm load. I guess it gives me an idea of how much power it can handle though. Wonder if the filters will screw up my excursion response too. I’ll give it a whirl
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post #9 of 56 Old 05-27-2018, 12:04 AM
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Hmm, I put in filters to limit the excursion. Is there a way to limit the power with DSP to protect it or is it simply a matter of not turning up the knob?
The latter

I would also just simmulate one drive and see what the result is. If you wire two in series nothing will change, because they are equal drivers and both will recieve half of the power.
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post #10 of 56 Old 05-27-2018, 12:06 AM - Thread Starter
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Quote:
Originally Posted by Soldy View Post
And is it truely and IB design (no air spring)?
Yes it is an IB design. So when I drop to a single driver and half the signal system input power in winISD to 1200w I get the same excursions, which are limited by the filters I implemented. However the maximum power that I see is flat lined at 800W down to about 20Hz so I'm guessing this would be too much power if at max volume for the driver. Can I limit this power output with the miniDSP to protect the drivers from me cranking the gain up?
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post #11 of 56 Old 05-27-2018, 12:08 AM
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Just a side note: Xmax is not a standardized term. Technically speaking there is Xlin and Xmech. Xmech is always greater than Xlin and tells you the maximum excursion before the driver gets damaged. Xmax can refer to either, but it is more common that it refers to Xlin.

Once the excursion is greater than Xlin the disortion will increase rapidly but your speaker won't be damaged.
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post #12 of 56 Old 05-27-2018, 12:13 AM
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Yes it is an IB design
So there is an "infinite" air volume on either side of the drivers? I am just asking, because a large baffle doesn't necessarly mean it is an IB (considering you want to mount 4 drivers even a large air volume could act as a spring).

Quote:
Can I limit this power output with the miniDSP to protect the drivers from me cranking the gain up?
Not to my knowledge. If the input signal is high enough there is nothing the MiniDsp can do to prevent the amplifier from pumping to much power in your speakers.

The only "safe" way would be using an amp that can't put out more than 2400 Watts in total.
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post #13 of 56 Old 05-27-2018, 12:21 AM - Thread Starter
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Quote:
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So there is an "infinite" air volume on either side of the drivers? I am just asking, because a large baffle doesn't necessarly mean it is an IB (considering you want to mount 4 drivers even a large air volume could act as a spring).
Yes it should be infinite. I am going to have outie manifolds inside the room. One with dual drivers will open up into the garage and the other will open up into the attic, so 2 drivers for the 2 car garage and 2 drivers for the attic.

I worry about the kids turning up the volume and blowing the speakers when I'm not around...maybe I need to consider a different amp...I was leaning towards the speakerpower amps, because I have heard they are reliable into the single digit frequencies. I guess I could get the sp4-2800 and split 1400W to each manifold...
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post #14 of 56 Old 05-27-2018, 12:47 AM
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Alternatively you could just use 8 drivers instead of 4
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post #15 of 56 Old 05-27-2018, 01:14 AM - Thread Starter
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Alternatively you could just use 8 drivers instead of 4
always tempting...
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post #16 of 56 Old 05-27-2018, 12:43 PM
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I'm not intimate with the minidsp, but most limiters are similar.
Very few, if any, are a brickwall, but it becomes exceedingly difficult to exceed their clamped output voltage.

When it comes to driver safety and single digit SPL, more cones and less power is better than more power and less cones.

I've never heard an IB in-person but I've heard that they sound very sterile, as the FR is very flat and free from box coloration.

I love single digits, I find myself dissatisfied with any system that doesn't have any (i.e. most systems having ONLY ported and horned subs etc).
I wouldn't be happy with a ported-only system unless it was ported to no-higher than 10hz, otherwise the rolloff will set in too early.
Gotta have me my <10hz BassILoveU, EOT, and Irene helicopter blades, can't live without it... hehe!
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post #17 of 56 Old 05-27-2018, 03:25 PM - Thread Starter
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Originally Posted by BassThatHz View Post
I'm not intimate with the minidsp, but most limiters are similar.
Very few, if any, are a brickwall, but it becomes exceedingly difficult to exceed their clamped output voltage.

When it comes to driver safety and single digit SPL, more cones and less power is better than more power and less cones.

I've never heard an IB in-person but I've heard that they sound very sterile, as the FR is very flat and free from box coloration.

I love single digits, I find myself dissatisfied with any system that doesn't have any (i.e. most systems having ONLY ported and horned subs etc).
I wouldn't be happy with a ported-only system unless it was ported to no-higher than 10hz, otherwise the rolloff will set in too early.
Gotta have me my <10hz BassILoveU, EOT, and Irene helicopter blades, can't live without it... hehe!
I want those helicopter blades and to only do this once. One and done, get it right and overkilled the first time. I'm worried about that "sterility" that I have heard about as well. I'm starting with a single manifold to see what it sounds like and will then decide if I want to add another one or switch to boxes to add in some colorations.

Regarding limiters, does anybody have some links that I could read up on regarding limiters or how to implement them?
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post #18 of 56 Old 05-27-2018, 03:35 PM - Thread Starter
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https://www.minidsp.com/products/plu.../2x4hd1-detail

Looks like the plugin for the minidsp 2x4HD has a compressor limiter built in. Anybody have experience with this function of the plugin?
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post #19 of 56 Old 05-28-2018, 09:07 AM
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Quote:
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I had considered the sp4-2800 and running one 700w channel to each manifold, but 350w per driver seemed like I was leaving some output on the table. I could combine two channels on the sp4-2800 and send 1400w to each manifold, but the price difference between the sp2-4800 and the sp4-2800 is minimal so I figured I would just go with the sp2-4800 and extra headroom for nearly the same price.
I'm not familiar with SpeakerPower amps but from what I can see the SP4-2800 is a four channel amp so you'd be sending 700W RMS to each driver, 1400W to each manifold. The SP2-4800 does seem to add some DSP functionality which could be useful though. My guess is that the SP2-4800 is the same as the SP4-2800 but with the four channels bridged to make it a two channel amplifier. Do the other pro amp offerings not go down into the single digits?

I would seriously consider putting both manifolds in the attic if that's an option. When someone is using the system it won't be pleasant to be in the garage if you use it as part the backside of the IB. The insulation of the attic works as a bass trap to absorb the energy.

I just setup a IB for music in my living room. It doesn't sound quite like a normal box but I wouldn't call it 'sterile' I would call it clean. It goes low and loud and seems to do so effortlessly (until the HVAC ducting gets buzzing at certain frequencies).
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post #20 of 56 Old 05-28-2018, 09:24 AM
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http://www.hifi-forum.de/viewthread-104-26656.html


Have you considered something like this?


SBA/DBA?
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post #21 of 56 Old 05-28-2018, 09:33 AM
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Quote:
Originally Posted by Tyborg View Post
Will be four 18’s total, but this is for 1 manifold that will have two 18” drivers in it. Am thinking to split the 4800 to two channels one for each manifold. Not sure if you are puzzled that two drivers is inadequate or over the top. Like I said noob here looking for constructive responses
How large is your room? 4 18's may be adequate, though excursion quadruples for the same sound pressure level as you lower an octave. 2.5 hz to 5 hz and 5 hz to 10 hz requires a lot of displacement for meaningful levels.

Are you looking to generate reference level sound pressure level in the bass at single digits? Do you have any measurement capabilities like RoomEQ wizard, a mic and sound card for testing?

Ask your doctor if DIY is right for you. Side effects of DIY may include anxiety, elevated blood pressure, lightheadedness, rapid heartbeat, skeletal muscle flaccidity, euphoria, psychological dependence, insomnia, confusion, blurred vision, implusivity, uncontrolled or repeated movements.
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post #22 of 56 Old 05-28-2018, 10:19 AM - Thread Starter
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Quote:
Originally Posted by timmyotule View Post
I'm not familiar with SpeakerPower amps but from what I can see the SP4-2800 is a four channel amp so you'd be sending 700W RMS to each driver, 1400W to each manifold. The SP2-4800 does seem to add some DSP functionality which could be useful though. My guess is that the SP2-4800 is the same as the SP4-2800 but with the four channels bridged to make it a two channel amplifier. Do the other pro amp offerings not go down into the single digits?

I would seriously consider putting both manifolds in the attic if that's an option. When someone is using the system it won't be pleasant to be in the garage if you use it as part the backside of the IB. The insulation of the attic works as a bass trap to absorb the energy.

I just setup a IB for music in my living room. It doesn't sound quite like a normal box but I wouldn't call it 'sterile' I would call it clean. It goes low and loud and seems to do so effortlessly (until the HVAC ducting gets buzzing at certain frequencies).
I am looking at the speakerpower amps for some admittedly completely impractical reasons, they are made in the USA. Practical reason being most important they are known for output down to 5Hz. The Fi drivers are made here in my hometown of Las Vegas and I decided to try to incorporate US made equipment where I could. My LCR will be powersound 210s, not going DIY there. Have a HSU sub and speakers in the family room now. So trying to keep homegrown as much as possible.

Back on topic, I'm pretty sure the sp4-2800 is four 700W ICE powered amps combined. SpeakerPower does have a different 2400W plate amp that they shove two together into their sp2-4800 so the sp4-2800 and the sp2-4800 are completely different components. I've been looking at how to limit my voltage to protect drivers and am starting to think the sp4-2800 would make it a lot easier and I wouldn't really even need to worry about a limiter. I would just plan on sending 700W to each driver. Even though Fi says [email protected] limit with the filters in place to limit drive excursion it doens't look like I would go above 600W according to the apparent amplifier load power reported by winISD in the attached image. I wouldn't hit the 600W limit of the drivers until 99Hz and if I use an 80Hz crossover then I don't think that I will run into that limit. Am I doing this right?

Also I'm planning a manifold for the attic, but the one in the garage will actually be more like an array. It will be 2 drivers facing the back of the main listening position and then venting into the garage to give a more nearfield response. I am planning to build the nearfield one first and then see how it sounds. I will adjust the attic manifold based on how I like the nearfield drivers. I may go four drivers in the attic manifold if I feel like I'll need it. I'll post an image in the next post. I tested the garage out by placing my HSU VTF15-MK2 inside and cranking EOT intro to get an idea if my garage door was going to vibrate and drive me nuts, wasn't too bad although I know it won't compare to a couple 18's.
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post #23 of 56 Old 05-28-2018, 10:27 AM - Thread Starter
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Quote:
Originally Posted by Soldy View Post
http://www.hifi-forum.de/viewthread-104-26656.html


Have you considered something like this?


SBA/DBA?
I dream about stuff like that...too bad my room isn't close to large enough for something like that.
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post #24 of 56 Old 05-28-2018, 10:41 AM - Thread Starter
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How large is your room? 4 18's may be adequate, though excursion quadruples for the same sound pressure level as you lower an octave. 2.5 hz to 5 hz and 5 hz to 10 hz requires a lot of displacement for meaningful levels.

Are you looking to generate reference level sound pressure level in the bass at single digits? Do you have any measurement capabilities like RoomEQ wizard, a mic and sound card for testing?
My room is 14 feet across the front where the door is and then drops to 11 feet wide in the back where I will sit. It is 16 feet deep and 11 feet tall. I have considered adding two additional drivers to the manifold in the attic if after building the the first IB with two drivers on the floor I feel like I will need more. In the image the red boxes on the riser will be vented and stuffed with insulation as broadband absorbers. The white box will be opened up at the back through the wall to the garage with a hinged cover to open and close it. I will build a shallow riser to get the main seats of the concrete.

I don't have a mic yet, but have been waiting for months to get a calibrated mic from cross spectrum labs...they have been out of stock. I was fortunate enough to grab one from the limited batch they just made available and it should ship out tomorrow. I have zero experience with REW, but am planning to dive in once I get the mic and first set of drivers setup. Just need to decide which amp I am going to purchase...
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post #25 of 56 Old 05-28-2018, 11:46 AM
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Quote:
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My room is 14 feet across the front where the door is and then drops to 11 feet wide in the back where I will sit. It is 16 feet deep and 11 feet tall. I have considered adding two additional drivers to the manifold in the attic if after building the the first IB with two drivers on the floor I feel like I will need more. In the image the red boxes on the riser will be vented and stuffed with insulation as broadband absorbers. The white box will be opened up at the back through the wall to the garage with a hinged cover to open and close it. I will build a shallow riser to get the main seats of the concrete.

I don't have a mic yet, but have been waiting for months to get a calibrated mic from cross spectrum labs...they have been out of stock. I was fortunate enough to grab one from the limited batch they just made available and it should ship out tomorrow. I have zero experience with REW, but am planning to dive in once I get the mic and first set of drivers setup. Just need to decide which amp I am going to purchase...
4 18's may be adequate in a smaller room like that, though before making permanent holes for the manifolds, I would do some investigation with a small sealed subwoofer that is easy to move, and Room EQ wizard.

Room EQ wizard also features a drag and drop speaker / room simulator. You can add multiple subwoofers, change the vertical height of the source, etc. This feature is accessible without taking a single measurement with a mic / sound card.

As you move the source in three axes, the program will calculate your frequency response.

Once you have investigated the optimum places for a subwoofer, then you can place your manifolds there, as long as there are no structural issues or other placement issues.

Here's a piston excursion calculator that may be handy.

http://www.baudline.com/erik/bass/xmaxer.html

Ask your doctor if DIY is right for you. Side effects of DIY may include anxiety, elevated blood pressure, lightheadedness, rapid heartbeat, skeletal muscle flaccidity, euphoria, psychological dependence, insomnia, confusion, blurred vision, implusivity, uncontrolled or repeated movements.
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post #26 of 56 Old 05-28-2018, 11:51 AM
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For optimum integration you will also need delay for your nearfield subwoofer manifold.

Ask your doctor if DIY is right for you. Side effects of DIY may include anxiety, elevated blood pressure, lightheadedness, rapid heartbeat, skeletal muscle flaccidity, euphoria, psychological dependence, insomnia, confusion, blurred vision, implusivity, uncontrolled or repeated movements.
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post #27 of 56 Old 05-28-2018, 12:23 PM - Thread Starter
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Quote:
Originally Posted by michael hurd View Post
4 18's may be adequate in a smaller room like that, though before making permanent holes for the manifolds, I would do some investigation with a small sealed subwoofer that is easy to move, and Room EQ wizard.

Room EQ wizard also features a drag and drop speaker / room simulator. You can add multiple subwoofers, change the vertical height of the source, etc. This feature is accessible without taking a single measurement with a mic / sound card.

As you move the source in three axes, the program will calculate your frequency response.

Once you have investigated the optimum places for a subwoofer, then you can place your manifolds there, as long as there are no structural issues or other placement issues.

Here's a piston excursion calculator that may be handy.

http://www.baudline.com/erik/bass/xmaxer.html
I like that piston calculator and it is lining up very closely with what winISD is simulating so that is reassuring that the two validate each other. Says I should get about 99dB at 5Hz with my 4 18' drivers. Now I have measured the longest diagonal of the room from that pop out for the double doors to the top corner of the ceiling to be 24.25 feet. Using 565/24.25 I get about 23Hz for where room gain should start for pressure vessel gain. Can i interpret that to theoretically mean that I will get +12dB at 11.6Hz and another +12dB at 5.8Hz. I'm sure it won't add exactly like that, but that should be enough to get me close to 115dB at 5Hz correct?

Because the room isn't exactly rectangular with that pop out for the doors I wasn't sure if I could use REW to estimate frequency response. If I can use it should I use the larger room width with the pop out of the doors at 168" or the shorter width in the back at 133"?

Thanks again for your responses!

Quote:
Originally Posted by michael hurd View Post
For optimum integration you will also need delay for your nearfield subwoofer manifold.
Thanks this is the stuff I need pointed out for me since I have never done this before. The 2x4HD miniDSP I am planning to use has up to 80ms delay for time alignment.
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post #28 of 56 Old 05-28-2018, 12:49 PM
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What box size did you set in winisd? It should be set to 100cuft or so to simulate no spring. Should not take much wattage at all to get to Xmax. That's what IB is all about. Low wattage = low heat on the coils = Less distortion. If you look at your spl curve. Wherever it is at 5hz is going to be where you'll be without room gain. You'll have to decide if that DB level is enough. Chasing single digits is about high spl at those digits or it won't be audible or felt very much. To get there you'll need a gaggle of drivers to move enough air. I think the ported IB like @MKtheater has would be a cool comprise to get more output down low.
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post #29 of 56 Old 05-28-2018, 01:20 PM - Thread Starter
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Quote:
Originally Posted by corradizo View Post
What box size did you set in winisd? It should be set to 100cuft or so to simulate no spring. Should not take much wattage at all to get to Xmax. That's what IB is all about. Low wattage = low heat on the coils = Less distortion. If you look at your spl curve. Wherever it is at 5hz is going to be where you'll be without room gain. You'll have to decide if that DB level is enough. Chasing single digits is about high spl at those digits or it won't be audible or felt very much. To get there you'll need a gaggle of drivers to move enough air. I think the ported IB like @MKtheater has would be a cool comprise to get more output down low.
At first I set the box size to 99999 but that killed my SPL estimate so I just kept taking off 9s until I got to 99 and that seemed to represent it well. Both winISD and that piston calculator @michael hurd posted show 99dB at 5Hz. If I add 2 more drivers to the ceiling manifold making 4 total in the ceiling it would make it 103dB. It really drops off a cliff after that and I would have to get up to 24 drivers to hit 115dB. That is ignoring room gain though right? I would assume that with room gain it will make a huge difference. I will have to search for this ported IB and read up.
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post #30 of 56 Old 05-28-2018, 01:40 PM - Thread Starter
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@MKtheater has an amazing setup, but I would have to skip the IB, from what I read he has a massive multidriver ported box rather than true IB. I like the idea of using the Fi speakers made here in town too. I also don't think I have the real estate in my room to go that route which is why I am focusing on the IB setup. I bet the tactile sensation in that room is unreal though...
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