SiloSub Design Help

[Doug Montgomery]

Hello fellow Polkster's. Just wanted to say I am a born Polkster thanks to my good friend (who BTW steered me here). I have a set of Polk SDA 1B's for my fronts, CSI30's for my rear surrounds and a CSI400 center channel. All powered by a new $600 Denon AVR 3803..oh and a Veledyne 80 watt powered Sub.

O.k....got a few questions..looking for advice.

I bought a ADCOM GFA555 Amp to use for a sub project. It produces 850 watts bridged mono into 4 ohms or 325 into two channels @ 4 ohms.

I have BassBox 6 Pro, and have been looking into some differnet configurations for "Sonotube" type subs. I would like to use compound isobaric in push-pull..only because I have read it is a much better bass response. I'm looking for the best (not cheapest) configuration for my use (music and home theater). I see using a port type design with two drivers in standard push-pull gives me much lower and louder bas...but I have wattage to spare. I could even buy a secound ADCOM and have TWO seperate subs at 850 watts per!!

I am worried about group delay and effiecency (Is group delay important at low freq?)

So..what say ye?

And what speakers to use?..I need two 10 inch per sub with a 4 ohm It (Impedence total).

Attached are some examples I have done

Thanks

FugtheBose

[Dr. Spec]

Group delay is only important in the mid bass region. It is inaudible at the lowest octaves. If GD stays below 20 ms until you get down around 25 Hz, you are all set.

Modeling a sub strictly from software is a mistake, IMO. Go to the Adire and Stryke and Acoustic Vision websites and look at the actual designs they have built and recommend for different drivers.

One of the best values in DIY IMO is the Adire Tempest or Stryke AV15 based subs. The Stryke AV15 is a recent generation II improved driver and is on sale or $165 and is a screaming deal for that price. Two AV15's in a vented enclosure or an IB application is ALL you will ever need in the bass department if you are looking to go DIY.

[Doug Montgomery]

Dr Spec,

Thanks for the reply..but from all the reading I was doing..I thought staying around the 12" size was better?

I was under the impression that the bigger drivers don't react as fast as the smaller ones. Would putting them in a IB design compensate for that?.

So two subs with two Stryke AV15's in it would be fine eh?

Thanks

[jdhdiggs]

Bigger drivers can react as fast or faster than smaller drivers. It all has to do with Forec=Mass X Acceleration. See, your concern is based on that if mass (size) goes up, the speakers will slow. In some of the better 15" woofers, their force increase (Huge motors) far outweighs the increase in mass from their smaller brethren and can go just as fast if supplied with the required power from the amp.

Having said that, the old adage that there is "no replacement for displacement" is very prevelant for higher SPL subwoofers. The AV-15 that Doc recommended is probably, one of, if not the best DIY bang-for-the-buck speakers out there for subwoofers in this regard and the 15 inch diameter means over 50% greater displacement per unit of speaker travel.

[Doug Montgomery]

Thanks....you understand I have been reading alot of books and websites adn I am just trying to narrow it down before I start this project

Would you recommend Isobaric then or push pull?

Thanks Again

[jdhdiggs]

Once again, with my understanding of subs, the answer would be "depends". For me, I would do a larger box and not do the push pull design. Just simpler from my perspective. Hopefully someone else will give you better/more info.

[Doug Montgomery]

Thanks..I hope so too.

Here's one of the links I used:

http://www.danmarx.org/audioinnovation/theories.html

[tryrrthg]

I plan on building a sub soon too.

Post your questions HERE (http://www.hometheaterforum.com/htforum/forumdisplay.php?s=&forumid=22). Those guys know there SHIT!

Good luck, have fun!

[Doug Montgomery]

O.k..have been plying with a few different designs. I looked at the Stryker AV15 MKII.

Seems I can get a better response curve with the Adire Brahma 15. However..I wanted to put two drivers per enclosure and still keep the impedence at 4 ohms. Both the Stryker and Adire have 2 ohm DVC, so I will only be able to put one driver per enclosure.

In your opinion, will one Adire Brahma 15 per enclosure with 850 watts applied X 2 subs and amps be a good sounding sub in a 20x15 room?

How does my attached plot look?..Any other suggestions?

Thanks Guys

[gatemplin]

Hey Fug,

I just built a diy Adire Tempest (15") sub in a 15 X 25 room and couldn't imagine wanting more. However, your amp would be overkill for the Tempest so I would suggest the Tumult. The SPL s will be so loud that you dont need an isobaric design unless you want a very small box. If I were you I would to a sealed Tumult using that amp. If you have lots of money you could build this http://www.acoustic-visions.com/~acoustic/products/subwoofers/pre_finished/pinnacle_everest.shtml

[Doug Montgomery]

$2500 !!! ..WOW

That is SOME sub though!! (400 lbs!)

Sealed Tumult?...How about ported to lower the F3?

Appreciate everyone's opinion

[gatemplin]

You can also lower F3 by building a box with a Q of 0.7 this will give you the flattest response. I suggested a sealed box because I think that the Tumult was designed for smaller sealed enclosures and about 1kW of power. Check Adire's website for specs and you can model them in Winisd. Maybe Adire has a version of Lspcad for the Tumult but I dont think they do yet.
You could build a ported sub but they are more tricky for a first time DIYer.

[Doug Montgomery]

Can anyone helpme figure out why the Brahma has a higher SPL than the Tumult with the same enclosure?

The Tumult has a higher VAS

[gatemplin]

I dont know why, they are both excellent drivers. Personally I would tune to 17 -18 Hz. Also where are you going to get flared 8" ports. Are you going to make them. An 8" sonotube should suffice. That is a huge box, maybe also try the Maelstrom. I notice that you wired the coils in series.

[Ceruleance]

RE: The pinnacle everest,

seems like you could build that for a lot less, albeit with slightly less capable drivers

2x Stryke AV15 = $350
4x PR = $300?

if you do the cabinet work yourself seems like you could come in at under a grand for the whole project. You can bet yourself that if I owned some decent power tools this is what I would be doing right this minute

[goingganzo]

i would say dual av15 trust me this is alot of bass i can hit 110+ lotr ring drop but i tuned alittle low but i have 110+ down to 15hz and can go past 120 at 40 hz

[Doug Montgomery]

Gate,

I wired the coils in series cause each one is 2 ohms. My ADCOM is only stable to 4 ohms.

On the Pinnacle with Strykes..if I could get the plans with all the dimensions..I might.

I was gonna use sonotube..only cause it was gonna be a downfiring and I read that circular cabinets don't have the wave reflection that a box does.

Plus, don't you have to "tune" PR's with weights or something..or can you just put them in?

Thanks again guys

[Dr. Spec]

Yes, you have to buy different weight PRs for the desired tune. That is why you can get a low tune from a PR in a smaller box.

Stryke is probably the best known user of PRs. They can perform extremely well. They have a somewhat higher GD over vents, but again if occurs at a low frequency, it's not an issue at all.

If you are just starting out DIY, I recommend a sono-tube style cylinder sub using a Tempest or AV15 and a triple 3" flared vent kit. Easy to build and a very strong and versatile performer.

[Doug Montgomery]

A triple 3" flared vent kit. Would that mean I would use three 3" vents (plot that in my software?)

Thanks

[Dr. Spec]

Correct, like the SVS Plus series. I can help you tune the port length after you decide on tube size.

[Doug Montgomery]

What do you think about the Tumult?

[tryrrthg]

I like the way this guys subs look on paper. 200 to 250 liters, AV15, 8 inch port. I'd look into something like this.

http://members.cox.net/frankcarter/Pictures/Miscellaneous/ttt.jpg

THREAD (http://www.hometheaterforum.com/htforum/showthread.php?s=&threadid=161927&highlight=AV15) where he talks about them.

[Dr. Spec]

Yeah, Frank Carter is a cool guy and a certified bass nut. Subs like that are not hard to build. He went with a single port and a fixed tune.

With dual AV15's he hardly has to worry about headroom, but Gonzo bottoms his on the ring drop at around 25 Hz at 110 dB because his sub is tuned too low (about 16 Hz if I recall).

You can go with a higher tune point with multiple ports and then tune lower if needed by port plugging.

If you tune fixed, I recommend around 22 Hz and with room gain you will see extension well into the subsonic region.

Frank's subs are extremely large and are probably very efficient.

[tryrrthg]

How big of a room are we talking here, to bottom out two AV15's?

[Doug Montgomery]

Not to sound too much like a NEWBIE idiot...could you explain this statement "but Gonzo bottoms his on the ring drop at around 25 Hz at 110 dB because his sub is tuned too low (about 16 Hz if I recall)"

Thanks

[Ceruleance]

The ring drop is a scene in Lord of the rings fellowship of the ring where the ring hits the ground and the sound is a high volume low tone, about 22 hz if i recall. So this scene is used by people to test their subwoofers. Dr. Spec is saying gonzo's is tuned too low, which is limiting his output in the 20 hz range. If you search this forum for 'ring drop' you will find a couple threads on it


What's the best free tool for modeling a complex enclosure? (dual drivers, multiple PR's..) win ISD pro sucks

I want to build the everest with stryke drivers, but i need the plans

[Doug Montgomery]

Thanks :)

Are the plans for the Everest available?

[Doug Montgomery]

Two questions please

1. Is there a significant advantage to having TWO subwoofer enclosures in two sides of a room vs ONE enclosure? Some have said sub-bass sounds are omni-directional and cannot be determined in there position. I know this to be untrue to an extent.

2. I am looking for a website that may have the specs and price/ordering info for the below driver (Seismic 8196 HK):

This was posted by John from Stryke about the Wilson XS :

"Well, i never said the XS was a bang for the buck sub or anything. The woofers are anything but weak though. They use the Seismic 8196 woofers with the Aurasound NRT motor. They have a BL^2/Re of 129. Very few woofers anywhere have a motor that strong. For comparison, the Tumult which is a favorite of many people here, has a BL^2/Re of only 53.48. The seismic has almost 4.5L of displacement, and the NRT motor is one of the most linear designs ever done. The 98dB 1w efficiency of the the woofer doesn't hurt either.

A pair of 7" vents may seem underported, but when tuned to 16hz, the only place you would have issues with vent noise is below that point. A rough model shows it to do 125dB at 20hz with vent velocity of only 20ms."


The link I have is this:

http://seismicsubs.com/

Theres no info on there though....could use the complete specs for plotting in BassBox

Thanks,

[Doug Montgomery]

Well I just called Barry Bozeman of Seismic and he stated he has no drivers available for sale..only end products. He may not be selling individual drivers anymore, but won't know for at least 4 months.

So in the imortal words of Gilda Radner...."Nevermind" :)

[jdhdiggs]

That, and I doubt that those siesmic woofers are even close to a reasonable range... Two woofers in a bax and charging $30K for it? Each woofer would be at LEAST $5K (Yes, I know I'm going off of the full retail, but anyway you cut it, way too expensive)

I agree with someone else when they were saying to go with a sonotube. The AV-15 with a decent tube and vents should be less than $600 with amp and finishing and outperform darn near anything close to it's price.

Also, if that driver doesn't cut it for you, you could pull it and replace it with the tempest. If that doesn't cut it, you have some other issues... :D

[Doug Montgomery]

Issues?..Me...Why..whatever do you mean ? :)

Well.....well see how it goes.

I will be starting this in a few weeks.

I was actually trying to keep the sono tube size down and still be at 15-20 HZ at the F3.

Might look into PR also. Can you use a PR AND a Vent?

[Dr. Spec]

That post by John was later refuted. Check the entire thread.

No, you cannot use both vents and PRs (I supposed you could try, but I think it would be a disaster).

A small enclosure will lack the volumetric efficiency of a larger enclosure and will roll-off quicker, lacking output at Fb. It would likely require EQ to achieve a flat response down to the resonance frequency of the enclosure.

[Doug Montgomery]

Thanks Dr. Spec...hope I'm not too much of a PIA :)

[Doug Montgomery]

Using Bassbox Pro..would this Krell MRS type system be considered Standard or Standard Push-Pull in the mechanical configuration section??

[Ceruleance]

im pretty sure push-pull. Good luck building that monster, seems like the only way they get decent response out of it is by driving the hell out of it, 2.6 kW....

[Doug Montgomery]

Oh No thank you...not looking to build that..was just curious as to its configuration. I'm assuming they are out of phase..so when one pushes out, the other is pushing in..to canel out harmonics or non-linearity. But was wondering how that effects SPL, effiency and power needed.

2.6 kW..Damn....reminds me of 'Back to the Future'

:)

[Dr. Spec]

That Krell is a joke. For what - $20+ grand? GAFB. I could spend $2500 and beat it senseless.

[Doug Montgomery]

O.k.."Hi"..its your local PIA..LOL :)

I'm trying to get things ready for my project and need some more advice. i understand that someone stated you should not decide solely on plots from a program..but they should be used for a "estimate" I believe. For instance I use CircuitMaker to design circuits before I breadboard..just to make sure it will work..not to mention I can add things like temperature and see how it "should" react.

O.k...After reading the "Black Hole" thread..I am thinking of making a Wholoper. Was thinking of a prism with 6 sides and 4 drivers with their VC and the drivers wired so as to have a 4 ohm load and 3 to 4 3" double flared vents. Based off ALL of your great input and my reading..these seem like the best choices for drivers.

Brahma 15 ($439 ea)
Tulmult 15 ($
Dayton Titanic MK II 12 ($128 ea)
Stryke AV12 or AV 15 ($140/$165 ea)
Tempest 15 ($150 each)

Money is no object (to a point..don't forget WAF). I would like to keep it below $1000 or so. Based off the cost up there....would it be better to use four 12" or 15"?

Also, would 4 12" MKII have a higher SPL and faster response than 2 15" drivers?

I saw this statementr on another site...could someone put this in a plainer english?:

"The amount of low bass a system can deliver is directly proportional to the amount of air it can move, i.e. it's proportional to the driver's Vd spec. Although the obvious solution to low bass is to simply use a larger driver, this approach has some drawbacks:

The large box is constrained due to the dimensions of the driver, i.e. there has to be at least one face of the box large enough to fit the driver.

As a driver's diameter increases, its useful off-axis response decreases. For example, the average 12" driver has a conservatively rated upper limit of ~550 Hz while the average 5" driver has a conservatively rated upper limit of ~1300 Hz. Note that this limitation is imposed by the physics, and is always there regardless of the driver's on-axis frequency response.

The next obvious solution is to use multiple smaller drivers. Typically, these are use in vertical arrays. Doing so provides the same wide horizontal dispersion as a single small driver (albeit at the expense of vertical dispersion (which is often a good thing since it eliminated floor and ceiling bounce). On the other hand, arrays of subwoofers typically are put on adjacent sides of a box rather than aligned vertically on a tall box. Array systems may be sealed or ported.
The only caveat for designing arrays is that too many people base their estimates of how much bass they can achieve by simply multiplying the number of drivers by the individual drivers' area (Sd). This is deceptive since bass is dependent on Vd, not Sd. An array of drivers works as if it is a single driver with an Sd value equal to the sum of all the drivers in the array, but a Vd value calculated from the Xmax value of a single driver."

Thanks

[Ceruleance]

can you link me to that thread please?

[Doug Montgomery]

By your command! :)

http://ldsg.snippets.org/boxes.php3#SEALED

[Ceruleance]

thanks! that was much more informative and all inclusive than some of the other sites! ELF design and tapered design were particularly interesting (ala sunfire and B&W)

[goingganzo]

actuley i never dertermanded of it was the amp or the driver. i have the amp in a different room. and that is 110 with the rs meter

at normal vewing levels i dont even come close to my limits. i can also push past 120 with playing brass monkey.

[Doug Montgomery]

huh? :)

[Dr. Spec]

The upper frequency limit of a woofer is indeed size related. But you will be crossing over at say 80 Hz, and even an 18" Maelstrom can play that no problem.

Sd is the effective surface area of the driver. xMax is the maximum linear excursion the driver is capable of. Vd is the volume it displaces with one full piston stroke.

And speaking of stroking - avoid pie-in-the-sky complex designs and stick to reality when building your first DIY sub. If you want to talk sub design theory and various configurations ad nauseum, the DIY sub forum is the place to do it.

http://www.diysubwoofers.org/talkshop/

My last recommendation and post to this thread will be an AV-15 II based sono-tube subwoofer with a downward firing woofer, baseplate, and at least three 3" flared vents, tuned to 22-23 Hz and powered by around 500 watts continuous into 4 ohms. Not hard to build and will perform extremely well even in large rooms.

[Doug Montgomery]

Dr Spec,

After reading your post, I am getting the impression that you are upset with me?

I appologize if this was the wrong place to talk about this. I was under the impression I could. I was in no way not heading everyone's word in here, although this is my first DIY sub, I also wanted something that looked well inthe livingroom and performed well also.

I was just trying to understand all the terminology and find out wht some things plotted differently than I expected them too. Bouncing ideas off of fellow forum members is what I have done in other forums and found it a nice way to get ideas.

I will refrain myself from posting such things in here again


Again..I appologize to anyone I have upset

[jdhdiggs]

I do not see doc as upset, he seems to not want you to overreach. Unless you have mad carpentry and wiring skills with all the proper tools, I would definately go with one woofer sonotube.

How big is your room BTW? A four woofer configuration in a non-IB setup sounds like either overkill or an underenclosed or huge subwoofer.

Also, for under $1K, you''ll have a hard time buying all the wood, bracing, wiring, screws, glue, speakers, PR or vents, amp, and eq in a 4 speaker setup.

In the end it's your decision but unless you have an enourmous room, a single 15" sonotube with the right driver should give you almost all the performance you could want. If not, build a second and co-locate. Two of the AV-15 and the sonotubes with good amp and vents for about $600-700 fully constructed.

[Doug Montgomery]

The room is approx 17X13, however the back has no corners..it opens to my kitchen and living room.

I like the SonoTube, but think the wife would NOT like it. Was looking at something like the SVS B4 Plus. Smaller cube with a low (18-20 Fb) and a pretty flat to 16 HZ response.

As I hope all can tell..I have beeen doing ALOT of reading and "testing" in BassBox Pro.

Thanks Again,

Doug

[goingganzo]

actuley around 1k for dual av15
165 per sub 175 with delevery
350 for amp samson s1000 500 per side
200 for svs bass box
ports 20 bucks
materals 100-150


this is my take if you want to buld a ported box you will need to spend 50-100 on clamps. pen state has good clamps prety cheap.lowes and hd will cut the pannels for you. they do a good job but can need to be trimed. also go dual 4 in flaired vs 3 3 in flaired and buy the flaired ends and buld them your self 5 bucks vs 23 for complete. also if you buld a big box buld horsonal and vertal brases it saves you money and weight.

[Doug Montgomery]

The $200 fot SVS Box...what is that? If I am building the box, do i need to order this from SVS?

Also, I already have a ADCOM GFA555 that outputs 850 bridged into 4 ohms

Thanks Again,

Doug

[goingganzo]

it has a ss filter gain and phase 0-180 or so the ss filter is so you dont over drive your sub below tune and the gane is for pro amps but you dont need that and the phase is for ajust phase. plate amps come with all this at least most and that is y you pay more for a plateamp.

[Doug Montgomery]

Thanks bud

Would you happen to have the particulars on the SVS B4 Plus?

I.E. its dimensions and if the four drivers are really a pair of isobarics in a push pull setup?

looking at the picture I jusdged its size, but could not get the specs they tought.

Doug

[Ceruleance]

doug, do a search for the B4 on hometheaterforum, or on this forum, you will find pictures that explain exactly how it is set up. Its basically a box within a box, there are the 2 outward firing drivers on either side, but then right behind each of them is another driver that is firing into the box, and the chamber that has the backs of those two drivers is open to the room and covered with grill cloth.