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Discussion Starter #1

Could not wait to veneer the entire thing, so I just did the bottom so I could put the feet on, and thus USE IT.

The feet give it a "floating" sort of look, and allow me to slide it around on the carpet.

Used two of the $2.50 wallyworld pillows for stuffing.


With the grill on, held on with partsexpress magnets.


Ep2500, bassis, it's all good. Great actually.
 

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Discussion Starter #3
It is a ring made from some high quality 3/4" plywood. Just cut out using a router. The outboard edge and top were chamfered using a bit my Brother in law had lying around. I used a set of the magnets from partsexpress for attachment, which is what I used in my wwmt's behind it. I really think that makes for a slick finished project. Just sink them in and veneer over them.
 

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I like the feet. Is that some sort of foam sandwiched in there?

I think your build is a good example of intelligent use of EQ in a moderate sized box. There is nothing wrong with using a little EQ. I'd challenge anyone to hear the difference between moderate amounts used and running the same setup in a larger box without EQ. Where you get into trouble is with large amounts of boost.

Kevin Haskins
Exodus Audio
 

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Discussion Starter #5
I like the feet. Is that some sort of foam sandwiched in there?

I think your build is a good example of intelligent use of EQ in a moderate sized box. There is nothing wrong with using a little EQ. I'd challenge anyone to hear the difference between moderate amounts used and running the same setup in a larger box without EQ. Where you get into trouble is with large amounts of boost.

Kevin Haskins
Exodus Audio
Thanks, the spacers on the feet were not my idea originally, but once I saw them, I liked! They are plain old 1/2" ply painted black.

The boost is easy to over do, even with this beast I suppose. Who doesn't like MORE? Still playing with that control.:bigsmile:
 

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I think your build is a good example of intelligent use of EQ in a moderate sized box. There is nothing wrong with using a little EQ. I'd challenge anyone to hear the difference between moderate amounts used and running the same setup in a larger box without EQ. Where you get into trouble is with large amounts of boost.
I have heard this before and understand the concept. However, I didn't catch how much EQ is being used in this design. What is considered moderate? 6 dB? 10 dB? I am curious about this for my future builds.

Mike
 

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I have heard this before and understand the concept. However, I didn't catch how much EQ is being used in this design. What is considered moderate? 6 dB? 10 dB? I am curious about this for my future builds.

Mike
I'd say that it depends. You have to consider the SPL requirements, the driver and a lot of factors. Pushing a small 4" midbass with 12dB of gain is one thing. Pushing a big 18" driver with the same boost is another.

Kevin Haskins
Exodus Audio
 

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I'd say that it depends. You have to consider the SPL requirements, the driver and a lot of factors. Pushing a small 4" midbass with 12dB of gain is one thing. Pushing a big 18" driver with the same boost is another.

Kevin Haskins
Exodus Audio
Fair enough. So since I am talking about large subwoofer drivers like the Shiva-X (12") or Maelstrom-X (18") at reference level SPLs in an average size home theater room (I know, there are still a lot of variables) what do you think a reasonable EQ would be? Digital desire indicates he is using 10-12 dB and that is within the ballpark of what I would have guessed even if it is a little on the high-end of that ballpark. I would actually have guessed I shouldn't push much above 10 dB.

I agree on the finish. Very, very nice. Congratulations digital desire!

Mike
 

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Discussion Starter #13
Thanks!

I have already destroyed a tc2K 12" with the bassis and ep2500, although it seems it may have been predisposed to it...

I am going to go easy on this one! But you do raise a good question: Kevin, where would you set the boost? I keep the other controls Fs =30 and the q's at 7.

You also have the "gain" on the power amp, and the sub level on the avr to fuss with. I keep those fairly constant, unless I get a very bass heavy action thriller, then I turn the LFE down a smidge. Unless I'm alone. :yikes:
 

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Fair enough. So since I am talking about large subwoofer drivers like the Shiva-X (12") or Maelstrom-X (18") at reference level SPLs in an average size home theater room (I know, there are still a lot of variables) what do you think a reasonable EQ would be? Digital desire indicates he is using 10-12 dB and that is within the ballpark of what I would have guessed even if it is a little on the high-end of that ballpark. I would actually have guessed I shouldn't push much above 10 dB.

I agree on the finish. Very, very nice. Congratulations digital desire!

Mike
I'm going to squirm out of an answer. It depends.... you have to really look at the model and understand how much output you are trying to get a given frequency. It requires x4 air movement for every octave you drop so it doesn't take long to run out of stroke with a small equalized subwoofer. Even the Shiva-X will quickly run out of stroke if you try to get a lot of output @ 20Hz sealed.

The Maelstrom is MUCH more capable than a single Shiva so what is acceptable with the Maelstrom, isn't necessarily with the Shiva. Also, most people will find themselves power limited with the Maelstrom. The amplifier will clip as they push more power. Under the same circumstance with the Shiva you would pop the driver.

So... you can get away with more boost on large well-built drivers. Its funny to call the Shiva small but compared to some products we have coming down the pike, it is our little guy, and you just cannot equalize it the same in a small sealed box as you can some of the bigger drivers.

Kevin Haskins
Exodus Audio
 

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I'm going to squirm out of an answer. It depends.... you have to really look at the model and understand how much output you are trying to get a given frequency. It requires x4 air movement for every octave you drop so it doesn't take long to run out of stroke with a small equalized subwoofer. Even the Shiva-X will quickly run out of stroke if you try to get a lot of output @ 20Hz sealed.

The Maelstrom is MUCH more capable than a single Shiva so what is acceptable with the Maelstrom, isn't necessarily with the Shiva. Also, most people will find themselves power limited with the Maelstrom. The amplifier will clip as they push more power. Under the same circumstance with the Shiva you would pop the driver.

So... you can get away with more boost on large well-built drivers. Its funny to call the Shiva small but compared to some products we have coming down the pike, it is our little guy, and you just cannot equalize it the same in a small sealed box as you can some of the bigger drivers.

Kevin Haskins
Exodus Audio
Hahahahaha! OK, ok, I'll back off on trying to pin you down. :bigsmile:

So is it safe to say that excursion is the major limitation here? As long as the driver is within a safe excursion limit, there are no adverse effects of EQ boost? That was not my understanding. Any other thoughts on EQ? I notice the O Audio amp you suggest with the Shiva-X has a 5 dB boost at 20 Hz so I assume you feel that is reasonably safe for 500 watts into the Shiva-X.

The Maelstrom is a beast! Probably overkill for my needs but after seeing this completed sub, I have to say I am tempted...

Mike
 

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Yea... the Shiva can easily live with 5-6dB of gain as long as you don't expect reference levels at 20Hz. Remember, 3dB is a doubling of power.

The limit is sometimes mechanical, and at some point you crossover into a thermal problem. It isn't a well-defined point because the power handling of the driver is highly dependent upon how much air is moving over the coil/former, ambient temp and the type of signal being played. So... due to all the variables there isn't a hard and fast answer that fits all situations. If you put it into a small enough box and tried to apply enough EQ, I'm sure there is a tipping point where you get into thermal limitations, especially with higher frequency test tones.

The adverse effects from EQ are more heat in the coil and higher power compression. If you design a system to work at the limits of a driver, you have to put the R&D time into finding out exactly where that limit is. A commercial subwoofer manufacture will do that with extensive testing of a product (hopefully) before putting it out into the public. As a DIYer, your much better off estimating on the conservative side.

Kevin Haskins
Exodus Audio
 

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Yea... the Shiva can easily live with 5-6dB of gain as long as you don't expect reference levels at 20Hz. Remember, 3dB is a doubling of power.

The limit is sometimes mechanical, and at some point you crossover into a thermal problem. It isn't a well-defined point because the power handling of the driver is highly dependent upon how much air is moving over the coil/former, ambient temp and the type of signal being played. So... due to all the variables there isn't a hard and fast answer that fits all situations. If you put it into a small enough box and tried to apply enough EQ, I'm sure there is a tipping point where you get into thermal limitations, especially with higher frequency test tones.

The adverse effects from EQ are more heat in the coil and higher power compression. If you design a system to work at the limits of a driver, you have to put the R&D time into finding out exactly where that limit is. A commercial subwoofer manufacture will do that with extensive testing of a product (hopefully) before putting it out into the public. As a DIYer, your much better off estimating on the conservative side.

Kevin Haskins
Exodus Audio
Thanks. That helps a lot. Basically, for me it means try to be careful but...if the woofer blows, back off somewhere and try it again. :spend:

Mike
 

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Thanks. That helps a lot. Basically, for me it means try to be careful but...if the woofer blows, back off somewhere and try it again. :spend:

Mike
As long as you don't try something silly, you won't have a problem. People get into problems when they don't understand the design issues and limits and try silly things. Think about what you are doing when you put 6dB of gain into a product @ 20Hz. You have four times the amount of power going into the device at that frequency. Most subs can easily live with that if you are playing music. The power levels in the program material are low to begin with @ 20Hz and they are transient in nature. There are plenty of sub-killer movies that will push the limits but most likely it will be mechanical ones because a single 12" driver isn't sufficient for high levels at subsonic frequencies. Also... @ 20Hz the cone is pumping back and forth and you have a healthy amount of air movement over the coil & former.

Kevin Haskins
Exodus Audio
 

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As long as you don't try something silly, you won't have a problem. People get into problems when they don't understand the design issues and limits and try silly things. Think about what you are doing when you put 6dB of gain into a product @ 20Hz. You have four times the amount of power going into the device at that frequency. Most subs can easily live with that if you are playing music. The power levels in the program material are low to begin with @ 20Hz and they are transient in nature. There are plenty of sub-killer movies that will push the limits but most likely it will be mechanical ones because a single 12" driver isn't sufficient for high levels at subsonic frequencies. Also... @ 20Hz the cone is pumping back and forth and you have a healthy amount of air movement over the coil & former.
Me? Try something silly??? :dumbcrazy:

Uh, yeah it wouldn't surprise me if I messed up a couple of drivers "experimenting." Your comments are re-assuring though. :)

Mike
 
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