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shake this
02-03-2012, 06:56 PM
Sorry guys, I'm sure you get tired of answering the same "will this box sound good" question but I've done about as much research as I can do. I've played around with the different box programs that are free (can't download on the company computer) and seem to be getting slightly different scenario.

The first box I built sounded good but I'm always willing to tweak things just to see. I also felt the original box was a little on the small side. Do any of you mind looking over my numbers and telling me what you think.

Both boxes are set up for a single Alpine 12" type R (not my choice, the owners)

First box dimensions were:

22x14.75x16.75
total internal volume of 1.9ft3 after speaker and port displacement.
slot port was 2x13.14x28.5
tuned at approximately 32hz

Second box I'm thinking about building will be the same basic dimensions but a little larger

25x14.75x16.75
total internal volume of 2.5 after speaker and port displacement
slot port 2.5x13.25x28
tuned at approximately 33hz

Will the two boxes in up sounding very similar or will the 2nd one be a little smoother?

btw...Alpine shows putting this speaker in a 1.5ft3 ported box. That just seems crazy small to me.

Moble Enclosurs
02-03-2012, 07:03 PM
Unless someone else can beat me to the punch, I will look over them and give you some basic info about them soon if I can. Gotta play catch up, but I would love to help. Ill re-post soon if I get the chance, ok?

shake this
02-03-2012, 07:50 PM
I really appreciate it. If you need the specs for the driver let me know and I can provide them to save you from searching for them yourself.

This box will be going into the greyhound bus so the owner isn’t looking for sound nirvana but I like to try and better myself from what I’ve done previously. I just felt the first box was lacking that “something”. It just seemed at certain frequencies it would get a little “snare-y” for lack of a better word. Best way to describe it is a change (for a split second) from a base drum/guitar to a snare drum. Maybe the driver was being over extended? I was able to remove most by adjusting the amp gains/x-over but like I said before, controlling it with box design would be better.

VisceralSound
02-03-2012, 07:54 PM
I have a box at 2.5cft and I feel even thats just a little too small but I do enjoy it, being someone who currently (soon to change to a 15"VVX) owns a Type R I'd go with the bigger box to be honest.

Buck
02-03-2012, 09:59 PM
2-2.5 at 31-33 hz, depending on vehicle. I'd do about 14 in^2 per cube. I did one in a colorado at work that was 2 @ 31 hz, side firing port and up firing sub. Sounded great. What vehicle is this going in?

shake this
02-03-2012, 10:30 PM
Oh just your typicle greyhound bus :)

http://i10.photobucket.com/albums/a125/BrandonBlount/c595f54a.jpg

VisceralSound
02-03-2012, 10:31 PM
Is this that party bus build?

Buck
02-03-2012, 10:35 PM
Is this setup for music?

shake this
02-03-2012, 11:00 PM
Yes, this is the 2nd one or as we refer to it "the big brother". We are doing 4 12's and 8 6x9's with about 3.5k watts

Buck
02-04-2012, 01:05 AM
So is the type r going in the smaller bus?

shake this
02-04-2012, 01:18 AM
We did two type r's in the small bus and putting 4 in the above bus

shake this
02-05-2012, 12:53 PM
Winisd is showing 3.5ft3 at 23hz but the Fs of the speaker is 31hz

Moble Enclosurs
02-05-2012, 06:07 PM
Im calculating [email protected] Keep in mind that Fs is not directly related to cutoff or tuning frequencies. The reason being, when loaded, this Fs changes based on the acoustical restrictions and abilities of the box at that point. You can make a speaker with an Fs of 60Hz, play a 30Hz tune in the right box with authority.
But, now the question is, what tuning do YOU want to use? Most on here will say, "41Hz is too high" because that is what they are used to, and depending on their preferences, that is correct. but this is what the sub likes the best is what I am showing you. This is the dual 4 ohm driver with the Fs of 31Hz.

But say you want to tune it to the low 30s, then I come up with 3.37ft3@33Hz, as an average of 30-35Hz for sake of argument. Port characteristics change with each change in tuning as well, but most do not account for that so I will leave that part alone for now.
:D

Moble Enclosurs
02-05-2012, 06:11 PM
Now, to keep the efficiency the same as the recommended box characteristics, tuning as 23hz can make it quite large. But I just wanted to note that even this can be ok for this particular driver. The response of this sub actually goes pretty low based on what I figured for. I am calculating that it can go all the way down to 28.69Hz in a full response LF range. So, tuning to 23Hz is not that far off from what it can really do in a box with efficiency. But again, my recommendations are shown above. Take em or leave em.

shake this
02-05-2012, 11:53 PM
I'm glad to know that I wasn't that far off on the size of box but wouldn't have thought about tuning in the low 40's. It difently should give me the SPL needed to fill the bus. Thank you for taking the time to crunch the numbers.

One question, how low below the tuned frequincie do you think we can go before audible distortion will be a factor? Most music will be dance/ hip hop with some rap thrown in I'm sure. Just don't want to tune to high and have the speaker drop out in the lower range.

Buck
02-06-2012, 12:15 AM
Im calculating [email protected] Keep in mind that Fs is not directly related to cutoff or tuning frequencies. The reason being, when loaded, this Fs changes based on the acoustical restrictions and abilities of the box at that point. You can make a speaker with an Fs of 60Hz, play a 30Hz tune in the right box with authority.
But, now the question is, what tuning do YOU want to use? Most on here will say, "41Hz is too high" because that is what they are used to, and depending on their preferences, that is correct. but this is what the sub likes the best is what I am showing you. This is the dual 4 ohm driver with the Fs of 31Hz.

But say you want to tune it to the low 30s, then I come up with 3.37ft3@33Hz, as an average of 30-35Hz for sake of argument. Port characteristics change with each change in tuning as well, but most do not account for that so I will leave that part alone for now.
:D

Calculated based on what response? (Out of curiosity)

Moble Enclosurs
02-06-2012, 01:23 AM
I'm glad to know that I wasn't that far off on the size of box but wouldn't have thought about tuning in the low 40's. It difently should give me the SPL needed to fill the bus. Thank you for taking the time to crunch the numbers.

One question, how low below the tuned frequincie do you think we can go before audible distortion will be a factor? Most music will be dance/ hip hop with some rap thrown in I'm sure. Just don't want to tune to high and have the speaker drop out in the lower range.

well, distortion can be from power or mechanical. So, as long as you do not overpower it, it will be fine. But in the sense of mechanical, this is also in a sense, partially power controlled, but what you mean is "before mechanical limitations are met" I believe. That would have to be calculated on how many volts of power you can run through the subs before limitations are figured. It could hold all through the spectrum, it could drop right below 40hz.....depends on the design.
So, I cannot answer that without doing a design. But in a conventional be, for instance, it could start to reach xmax around the mid 30s or low 30s. Again...depends. Tuning should not be used to control group delay, phase, or xmax nor distortion. Tuning should be used only for proper response range operation. The other factors should be controlled by physical means and some electrical means...not by tuning frequencies.

Moble Enclosurs
02-06-2012, 01:34 AM
Calculated based on what response? (Out of curiosity)

well wouldn't you like to know...lol j/k. No seriously though, the specs ARE the response in this case. Because they were calculated on physical and acoustical limitations to control the subwoofer at it best operating capabilities. It has nothing to do with personal preference in the specs you pointed out. It is a way to configure proper response from the sub and box only, and is only based on a bass reflex idea as of now.
Each design will have its own specs and that is even true for compression, though a lot of people believe that is solely based on VAS figures. Though this is one factor that is parallel in calculations, it is not the only determining one.
Map the specs out on a program and see what it shows. Idk what it would come up with yet because not everything has been calculated for as of this time. So, even those recommendations that I mention can be changes for personal preference.

The The thing about my recommendations that people need to understand is that these are for response calculations only as of now. Tweaks can be made to fit your lifestyle of musical choice any way you choose. Nothing says you cannot tune these to say, 26Hz and not be fine with that. But for what I figure, it is the best starting point of optimum operation of the subs of choice in whatever box I calculate for. Too many variables exist that make these recommendations solid for everyone. But I can guarantee that efficiency is going to be increased, and musicality will be amount its best in any of my figures, regardless of how low you personally want to go.
When I design, I use these calculation I have come up with as either a definite, depending on how it matches your taste and limits, or I change it a bit to better the transience of the response for a more natural output. There are likely always going to be minor changes in any design to customize it to your liking because, as we all know very well at this point, everyone's will be slightly different as a majority.

shake this
02-06-2012, 12:57 PM
That diffently clears up a few things for me. Once I get them built, I'll post back up and let everyone know what I thought of the overall performance.

Buck
02-06-2012, 01:11 PM
well wouldn't you like to know...lol j/k. No seriously though, the specs ARE the response in this case. Because they were calculated on physical and acoustical limitations to control the subwoofer at it best operating capabilities. It has nothing to do with personal preference in the specs you pointed out. It is a way to configure proper response from the sub and box only, and is only based on a bass reflex idea as of now.
Each design will have its own specs and that is even true for compression, though a lot of people believe that is solely based on VAS figures. Though this is one factor that is parallel in calculations, it is not the only determining one.
Map the specs out on a program and see what it shows. Idk what it would come up with yet because not everything has been calculated for as of this time. So, even those recommendations that I mention can be changes for personal preference.

The The thing about my recommendations that people need to understand is that these are for response calculations only as of now. Tweaks can be made to fit your lifestyle of musical choice any way you choose. Nothing says you cannot tune these to say, 26Hz and not be fine with that. But for what I figure, it is the best starting point of optimum operation of the subs of choice in whatever box I calculate for. Too many variables exist that make these recommendations solid for everyone. But I can guarantee that efficiency is going to be increased, and musicality will be amount its best in any of my figures, regardless of how low you personally want to go.
When I design, I use these calculation I have come up with as either a definite, depending on how it matches your taste and limits, or I change it a bit to better the transience of the response for a more natural output. There are likely always going to be minor changes in any design to customize it to your liking because, as we all know very well at this point, everyone's will be slightly different as a majority.

I also take most ts parameters with a grain of salt. They seem to vary greatly from what companies post.

CAT MAN
02-06-2012, 01:18 PM
I also take most ts parameters with a grain of salt. They seem to vary greatly from what companies post.

thats because of the use of the sub. factory fresh subs are within a few decimals. once they get broken in its another story. You yourself should know to get the latest test for them if you are able to test. if not most companies would be glad to assist in post break in ts specs.

duanebro
02-06-2012, 02:33 PM
I have not modeled this, I just wanted to say that the small box alpine recommended is intended for a smaller vehicle. So the op is right, a bigger box is better in this case, do to less cabin gain in a bus. I know that larger boxes have been suggested, I thought someone might wonder why the designs suggested are so different than what alpine recommends.

Buck
02-06-2012, 04:51 PM
Alpines recommendations are far from optimal for most boxes that I've done. I don't do theirs from specs.

Argent Audio
02-06-2012, 04:55 PM
Most important thing to keep in mind is that once you put any box into a listening enviornment about 75% of your calculations go out the window :)

From what I recal the new Type R's do just fine in a smaller box due to the fact that Alpine beafed up the BL product on them recently.

Andrew

pro-rabbit
02-06-2012, 04:57 PM
Are we really going back in this debate of T/S and how accurate/inaccurate they are?



On topic, depending on what the user wants, the Type R is a very "forgiving" driver. All though the enclosure makes a large difference in the over all sound/response, that sub seems to work decently well in a wide range of enclosures. Well.... It works well enough to suffice for most.

Argent Audio
02-06-2012, 05:01 PM
thats because of the use of the sub. factory fresh subs are within a few decimals. once they get broken in its another story. You yourself should know to get the latest test for them if you are able to test. if not most companies would be glad to assist in post break in ts specs.

Some companies state how much play time their woofers have had before the measurements were taken, some do not. I know most major companies give theirs around 2 hours of play time at about 80% xmax values before taking their measurements. How long a sub is fully broken in depends on spiders etc. The most noticable thing you will see after break in time if you took a second set of measurements is a drop in the Fs value.

Andrew

pro-rabbit
02-06-2012, 05:04 PM
Some companies state how much play time their woofers have had before the measurements were taken, some do not. I know most major companies give theirs around 2 hours of play time at about 80% xmax values before taking their measurements. How long a sub is fully broken in depends on spiders etc. The most noticable thing you will see after break in time if you took a second set of measurements is a drop in the Fs value.

Andrew

I can tell you that most companies do not even test their own drivers. They allow the build house to do various testing then they just regurgitate their findings. In reality a vast majority of companies alter their drivers over the course of time and the specs listed are rarely adjusted to the new product.

This is still basing a conversation on how valid T/S really are.