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THX120 sub placement question


Tom Adams

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LMAO.......man, I just love reading you guys going back-n-forth. It's like two kids getting all giddy over building a tree house. I'm not making fun of you. Seriously, I'm not. I just think it's funny to see your enthusiasm coming out via words.

Ok.....and now Tom comes in and spoils the fun. [;)]

First, I was thinking in terms of spending $1K to $1500 max for a DIY gig. And now the costs have gone above $2500 in some cases (I'm feeling here the same as when I manage a project and have to put the brakes on the designers/engineers. They get all gung-ho and I have to remind them about budgets. No fun sometimes). So..........

Might I ask we step back, take a deep breath and re-group? After all your spending MY money! LOL....[:D]

1. If I were gonna spend $2500+, I'd buy some ready made powered subs, hook them up, grab a beer, and watch a move. So I'm asking that we try to keep the project $1500 or less total. I know, I know.....justa few more bucks and I could have _____ . Listen, you're smart and talented guys. I'm confident you'll rise to the challenge and amaze even yourself. [:)]

2. The dimensions I gave you is the max envelope I have to work with. Personally, I'd like to see what we can do with something smaller....let's say by 6" less (or more depending on design) per dimension.

3. I'm confident I could figure out how to cut complex shapes, however, if I don't have to, I'd prefer that route. You wouldn't want me to go postal trying to get a shape right would ya?? Uhhh....don't answer that. [:)]

4. Did I mention the budget? Oh, yeah. Nevermind.

5. I kinda like the notion of a built-in amp, but an outboard is NOT out of the question since I can easily hide it. Well, that is if the area behind the Corns are not completely filled with a 12 cu. ft. cabinet. [;)]

6. Did I tell you what my budget is? (sorry - occupational habit).

7. I'd gladly sacrifice some low freq. extension for output. Oh, and I'd like this thing to be "musical" as well.

There ya go. The challenge has been laid out. [:)]

BTW - I sincerely appreciate you guys helping me make something like this happen. [Y]

Tom

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Thanks Tom Adams,

1. I thought DrWho was going a bit out there using tumults, I did

remember you wanted to do it on the cheap and once you add passive

radiators its not cheap anymore.

2. I thought 12 cubic feeters on both sides are way way too big.

3. nothing complex, I will show you on autocad how shapes are done. It

is surprisingly simple to do just thought has to come out. Hell if you

want I have the nationwide cellphone plan with the unlimited nights and

weekends where I can call to make sure you have good clue. Plus I am on

aim all the time, forum, we can even use skype or a video game walkie

talkie type program to talk on how to lay the plan out.

4. yes

5. To keep it on the cheap, I think the BASH amps on partsexpress that

provide 500 watts and only cost 300 dollars are cost effective plus no

highpass at 20 hertz to limit the low end. There is also another BASH

amp by "o-audio". google for more info.

6. yes And I think daytons, ascendant audio www.ascendantaudio.com, or

some aes av-12 come to mind www.stryke.com (it links you to the new

website automatically)

7. Do you want sealed then?

How good are you with them power tools Tom? Do ya think you will have

all 10 fingers at the end of the project? and two eyeballs? On a

Serious note, if you don't trust yourself you might as well buy some

subs because power tools and nervousness is not a good recipy. remember

SAFETY GLASS, SAFETY PRECAUTIONS, AND WORK IN A SAFE ENVIRONMENT

Also the reason why DrWho and I go back to back is cause he is 1 year older and I used to be an engineer [:|]

Hey Tom BTW not all youngins' are whippersnappers [:P]

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lol Tom - you mentioned you were wanting to go with the Ultra2's so I used that for the budget [:P]

You aren't going to be able to outperform them for half the price...

Btw, what do you think about the TC Sounds option? You could do two

cabinets each with a 15" driver for $1308. I know it's pushing the

limit of your "DIY Budget" because you'd still need an amplifier, but

technically it's more of a pseduo DIY project if you go that route

because it would be custom build by another company [;)]

I suppose you could always go with a single 15" titanic in a 10 cubic

foot enclosure tuned to 18Hz powered by the Dayton 500W amp....Two

units would do a clean 120dB with an F3 of 20Hz and everything would

cost you $830 before shipping.

Who let the reality drive kick in? [;)]

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lol Tom - you mentioned you were wanting to go with the Ultra2's so I used that for the budget [:P]

You aren't going to be able to outperform them for half the price...

Btw, what do you think about the TC Sounds option? You could do two cabinets each with a 15" driver for $1308. I know it's pushing the limit of your "DIY Budget" because you'd still need an amplifier, but technically it's more of a pseduo DIY project if you go that route because it would be custom build by another company [;)]

I suppose you could always go with a single 15" titanic in a 10 cubic foot enclosure tuned to 18Hz powered by the Dayton 500W amp....Two units would do a clean 120dB with an F3 of 20Hz and everything would cost you $830 before shipping.

Who let the reality drive kick in? [;)]

Uh - huh......I see how you & jay are. Someone else comes along wanting DIY sub help and I get dropped like a hot potato. [;)]

You're right DrWho - I don't have expectations of whipping Ultra2's at half their cost. But I would certainly think I could get damn close for $1500. Yes? No?

I'm gonna have to look into that TC Sounds option a bit more. However, a) it defeats my urge to DIY and B) what would I be gaining going that route versus just buying SVS or (on closeout) Klipsch Ref?

I'm sorry for the stoopid questions and I'm really not trying to string you guys along. I sincerely want to build my own subs. Maybe I just don't know what info you're looking for???

Tom

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No I was waiting for you to respond Tom. It gets quite boring posting on a forum when no one responds!

Yes to the 1500, well close

DIY please

there are no stoopid questions and I really won't be offended if you

just go buy some ultra 2 or the tcsounds.... I liked informative post

and feedback etc etc

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Well I'm sure you could turn the TC sounds into a DIY project....most of the people working at these companies love helping out with DIY projects (prob for the same reason I'm helping you out for free). [;)] I was just thinking you could find a driver from them that would suit your 10 cubic foot cabinet. You're targetting a cabinet volume that doesn't really have any optimal drivers for it on the market. Your other option is to go smaller and not have the same bang for the buck option.

The other nice thing about TC sounds is you'd get a good deal on the amplifier and a prebuilt active eq/filter which is necessary for milking the last few drops out of the design...I'm sure you could design the filter yourself if you wanted, but that gets expensive when you're not purchasing parts in bulk (and I wouldn't be able to design the circuit for you either) [;)]

Just to stress the point, you would not be getting a driver that SVS or klipsch or any of the other companies that use TC sounds to build their drivers...it's part of the agreement these companies have with TC sounds. You would however get to bank in on that research and get a driver much better suited for your application - and you wouldn't be spending that much more in the process (assuming they will sell you just one or two drivers).

Btw, the reason I haven't been making any designs is because you haven't voiced any preference for the direction you want to go [:P] And I'm still a bit confused about the dimensions you want to limit yourself to...weren't you just going to put the sub behind your cornwalls? And then couldn't the sub be the HxW of the cornwall with an 24" depth or so? (which yields about 12 cubic feet if I remember correctly). I guess I just don't see how you get 2x3x2 on the dimensions.

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Ok.let me see if I can bring this back in-line.

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

First the 2x3x2 dimensions came about by me measuring what I thought would be an acceptable envelope to work within. That is to say, I wanted to define the maximum volume I could use that would also allow the subs to be hidden behind the Corns. Im trying to maintain a balance between performance and esthetics. Ultra2s or Ref.s or ??? would be acceptable placing them on the stage because of their looks. The bottom line is that I have no issue about a large DIY as long as it isnt very obvious. Which is why I mentioned that if the enclosure were smaller than 12 cubic feet, all the better.

Another thing Im trying to consider is how far away from the back wall the Corns wind up being. In order to keep all my front speakers fairly even, I dont want to pull the Corns too far forward because that would require the Heresy center to have to be pulled forward as well. Once again, esthetics comes into play. The Heresy pulled 2 feet forward would put it nearly in the center of the stage.

And while Im on constraints, weight is a factor too. Im not gonna build these things in place and they have to be toted up a flight of stairs. So some consideration needs to be given to the weight of these things. I'm thinking 110 pounds is about the limit.

Theres this matter of low frequency extension and output that I probably owe you and its something Im struggling with for I dont know what levels I want. And my brain tells me that its a piece of the equation you need. Any suggestions as to how I might derive this?

So, I feel we have two paths to take (correct me if Im wrong). We can either a) come up with a less than 12 cubic foot design that will not stand out behind the Corns or B) we look at some type of front firing/front port thing that would go on the stage flanking the Heresy. Well I guess the third option would be to chicken out and just buy a pair of subs. But I ain't clucking yet!! [:)]

Has this message helped or hurt the discussion/direction?

Tom

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Well for starters we dont' want to sacrifice the HF/MF nature of your setup...in other words, you want your center and cornwalls to be equidistant from the listening position. So if your heresy is tucked all the way back, then your cornwalls will need to come out a bit. Think radius of a circle from the main listening position...I would first find the optimum location for your cornwalls and go from there...(first find where the music sounds the best, and then position the heresy accordingly).

The next step would be to determine the extension and SPL's that you want to achieve. What kind of music and movies do you watch? For movies I would generally recommend at least 20dB of headroom above average. The idea here isn't insane SPL capability, but rather lowering the distortion at normal levels. The other idea here is to maintain unclipped transient peaks...one of my favorite pieces of music has a 60dB transient at the beginning...so if I've got it cranked up to 80,90dB, then I would need a system capable of over 140dB of clean output in order to get the full sensation...this is of course a bit rediculous and would probably kill me, lol...but it gives you an idea of what could be needed.

The THX standard for creme of the crop subwoofage is a peak 130dB @ 30Hz...which the klipsch ultra2's are capable of. But that doesn't mean output below those frequencies isn't necessary...and a sub capable of 130dB @ 16Hz would not be "overkill" because there is a lot of source material that requires it. Again, the point isn't to listen at 130dB, but the headroom really cleans up the levels around 100dB.

I think your best bet right now is to try and demo the systems of guys in your area with nice subs and see what kind of systems satisfy your listening habits. Another thing to do would be to find guys with similar tastes in music and movies and see what minimum they would recommend. Surely you can think of other guys on the forum that you find yourself agreeing with most of the time....they would be the best people to get advice from.

Btw, for acoustic reasons I vote for front firing subwoofers flanking the heresy. There is just something about having subs firing straight at you that makes them that much more musical.

If you're looking for my opinion, I think your best option would be to target at least 120dB of output with as low of an F3 as you can afford (both in cabinet size and cost of the drivers).

So ya, hope this helps...it's funny actually that your problem is not knowing what you're wanting to achieve [;)]

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Well for starters we dont' want to sacrifice the HF/MF nature of your setup...in other words, you want your center and cornwalls to be equidistant from the listening position. So if your heresy is tucked all the way back, then your cornwalls will need to come out a bit. Think radius of a circle from the main listening position...I would first find the optimum location for your cornwalls and go from there...(first find where the music sounds the best, and then position the heresy accordingly).

The next step would be to determine the extension and SPL's that you want to achieve. What kind of music and movies do you watch? For movies I would generally recommend at least 20dB of headroom above average. The idea here isn't insane SPL capability, but rather lowering the distortion at normal levels. The other idea here is to maintain unclipped transient peaks...one of my favorite pieces of music has a 60dB transient at the beginning...so if I've got it cranked up to 80,90dB, then I would need a system capable of over 140dB of clean output in order to get the full sensation...this is of course a bit rediculous and would probably kill me, lol...but it gives you an idea of what could be needed.

The THX standard for creme of the crop subwoofage is a peak 130dB @ 30Hz...which the klipsch ultra2's are capable of. But that doesn't mean output below those frequencies isn't necessary...and a sub capable of 130dB @ 16Hz would not be "overkill" because there is a lot of source material that requires it. Again, the point isn't to listen at 130dB, but the headroom really cleans up the levels around 100dB.

I think your best bet right now is to try and demo the systems of guys in your area with nice subs and see what kind of systems satisfy your listening habits. Another thing to do would be to find guys with similar tastes in music and movies and see what minimum they would recommend. Surely you can think of other guys on the forum that you find yourself agreeing with most of the time....they would be the best people to get advice from.

Btw, for acoustic reasons I vote for front firing subwoofers flanking the heresy. There is just something about having subs firing straight at you that makes them that much more musical.

If you're looking for my opinion, I think your best option would be to target at least 120dB of output with as low of an F3 as you can afford (both in cabinet size and cost of the drivers).

So ya, hope this helps...it's funny actually that your problem is not knowing what you're wanting to achieve [;)]

Your last comment is probably the truest statement (unfortunately). And I think that points out that I need to do more research before I run out and start making sawdust. So, point well taken.

FWIW.....in my minds eye what I think I've always seen was a sub set up similiar to what rplace has in his room which is two bass cabinets flanking his center channel. Funny how that lines up with your "acoustic reason" concept. So maybe we should go down that path since it would involve the least compromises??

Tom

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Tom you thought we forgot about you!

think again these are preliminary autocadd drawings. DrWho needs to get

it together [:P] and not make it a 16 cubic footer port length and a 8

cubic footer. DrWho basically did a Nasa Mars accident......

Also this drawing does not have braces but its a good start

drwho needs to learn to give me external dimensions not internal as its

easier to build out to in instead of in to out on autocad.

post-13377-13819281459448_thumb.jpg

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I know you guys haven't forgotten about me. Actually, DrWho & I have exchanged a couple of PM's and we've settled on a concept. And that is two cabs that will flank my Heresy center channel. I still owe DrWho some dimensions for him to work to.

I'm thinking I'll probably start a new thread for this new concept.

BTW - the AutoCAD drawings look nice. Thanks!! [:)]

Tom

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