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. Those guys know there ****!

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.



THREAD 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...

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?