DIY newbie looking at subwoofer options

**ThomasW** · 12 July 2005, 17:23 Tuesday

If you simply take one or more of the preassembled boxes from PE and reinforce them you'll need minimal tools and know-how.

The use of the term 'powerful' problematic. Output in any loudspeaker is limited by the available amplifier power and the amount of air being moved. The greater the amount of air moved, the louder the sound.

There are these things called T/S parameters. They tell us about any given raw loudspeaker. It's not important to know want all of them are. It's handy to know a few. Xmax is the distance forward and back that the cone can move and still be controlled by the motor. Sd is the surface area of the cone. Vd is Sd times Xmax and it tells us how much air is displaced when the cone cycles in and out a full stroke.

To compare the raw performance of any two drivers start by comparing Vd. The 15" Tumult, displace 5.1L of air (I think that's a conservative figure). In comparison the old Tempest displaced ~2.5L. So in theory 2 Tempests move about the same amount of air as one Tumult.

It's impossible to know about the SVS drivers since they don't publish that data. Obviously 12" drivers aren't going to move as much air as 15"s or 18"s. Multiple 12"s will of course move a ton of air.

**ajpoe** · 12 July 2005, 19:40 Tuesday

Ok thanks! These are the kinds of things I never understood and why I never spent too much time reading in the DIY section. So, let me throw out some things... the 15" Titanic MKIII subwoofer kit is only $688 and includes everything. 1000 watt plate amp, driver, box, etc. I was thinking I would use the 1000 watt plate amp from PE regardless of the driver. The Titanic claims it can sweep over 3 liters of air which beats the Tempest, but not the Tumult. The Tumult driver alone is more than the whole kit though. Is the Titanic kit going to be inline with the SVS Ultra and also sound good with music? I could build 2 of them for less than $1400 and the holes are already cut with the kit.

If I went with the 15" Ascendant Avalance, it is $229, the box is $150 and the amp is $400. I'm probably looking around the $800-$850 mark. 2 of those would be around the same price as a single Seismic 12 and I'd have to cut the holes myself. The Tumult would be running upwards of $1300 for a single box.

As far as price vs. performance for these 3 drivers and using the sealed PE box (assuming its big enough and I brace it better, please advise here), what route would you go? Also, are there any other drives I should be looking at? Will that sealed PE box design let me get sub 20 Hz extension and still be clean for music but shake the foundation with movies?

**ThomasW** · 12 July 2005, 23:28 Tuesday

Let's continue to stick with the basics.

The two most popular kind of subs are sealed and 'vented'. Vented includes ports and passive radiators, they work the same way.

A sealed sub will have the least amount of low fequency output because it gets no free boost from the box.

PR's or ports boost the output of the sub at a specific frequency (that frequency is referred to as the tuning frequency). SVS lists the tuning frequency in the model designation of their tube subs. For example the 16-46CS is tuned to 16Hz, the 20-39Cs is tuned to 20Hz and so on.

If you blow across the top of a beer bottle, the sound made is the tuning frequency of the bottle. Adding liquid to the bottle decreases the space inside and the tuning frequency goes up. The same is true of a sub. The larger the box the lower the tuning frequency. This is true of any sub sealed or vented.

To get a sub to play low there are a couple of options, use a large box, or use EQ. One does get some free boost to the lowest frequencies from the room (room gain). This is something that the user can't control since it's a function of the placement of the sub and the geometry of the room.

So what does this all mean?

You chose the compromises your willing to live with. Larger boxes = lower bass and higher efficiency.

Sealed boxes are the easiest to create.

With enough EQ and amplifier power, a relatively small box can play loud and low, but there are limits to this.

Now to some specifics. I think you want to use something other than the PE amp. Don't be fixated on 1000watts. You may want to create 2 subs using smaller amps.

Now for a few specifics. I don't think you want the full PE kit. There are better products available.

For example......

SVS uses B.A.S.H. amps. You can buy 500 watt units from O-Audio

There's a company called Rythmic Audio they offer a amp/driver combo with a servo circuit that would work well in the smaller 2 cu ft PE box. Obviously 2 or more of these would be necessary

**ajpoe** · 13 July 2005, 11:02 Wednesday

I'd like to do something that will be at the very least flat to 20 hz. In reality, I'd like to get something that will play a bit lower. I was thinking about getting 2 PC Ultras which are tuned to 20 Hz, but if I had the headroom, try tuning them to 16 Hz. Whatever I get, I will be getting a BFD to EQ.

I know a guy that does wood working for a living and thought I'd call him about pricing on a custom cabinet(s). If that Tumult is really 3x more powerul than an SVS Ultra driver in the right box, I can have him make it, get the driver and that SVS 1000 watt amp and have one hell of a sub that would probably still cost less than a single Seismic 12. Designing a box is another issue though as I'd have no idea where to start. May be that is something you guys have a program that can tell me what I'd need?

And, I'm still very interested in doing 2 12" designs with the smaller BASH amps you described instead of just a single box. I'm open to anything DIY as long as I can get better performance for the price. If this guy isn't too expensive to do a cabinet, I can get a lot more creative (when I say I, I mean you :T )

Size/style isn't as important to me and I have no WAF. I don't mind having bigger boxes as long as they look nice, but I don't want to be rediculous either. Right now I have 4 subs, 2 stacked on the left and 2 stacked on the right. They only have a footprint of 14" x 16" but are over 40" high with one on top of the other. A box that is 18"-20" wide isn't a big deal. I probably wouldnt want to go much more than that if I had 2 b/c of room width issues, but higher is ok.

**Andrew Pratt** · 13 July 2005, 11:42 Wednesday

I'd like to do something that will be at the very least flat to 20 hz. In reality, I'd like to get something that will play a bit lower. I was thinking about getting 2 PC Ultras which are tuned to 20 Hz, but if I had the headroom, try tuning them to 16 Hz.

Might I ask why you want to go that deep?

Also what sort of room is your theater in and is there an atic, crawlspace, storeage room or basement adjacent to it?

As for the box's if you go sealed there's really nothing to worry about as long as the internal volume is close to the recomended volume for the driver you choose. Ported box's are a little more critical as the calculations for the volume and port have to be more precise but again its not that difficult at all. Unlike speakers that play higher freq's the physical shape of the box isn't critical so it opens up a host of design oppertunites that aren't available for tower mains etc.

**ajpoe** · 13 July 2005, 16:00 Wednesday

I really want to feel the bass. I would be very happy with a frequency response like you have though Andrew as it gets plenty of usable bass under 20 Hz. But I also want to produce enough SPL to really feel it hit you. My buddy's Plus/2 is like that but in a smaller area. You can really feel your pant legs move and it hit you in the chest in scenes like the Monster Inc. sock explosion. I wouldn't mind getting a little cleaner than his too.

Here is a rough sketch of my room. The green is couch and chairs, yellow tables, grey is TV, audio rack and a DVD rack near the couch. The black boxes are my mains and the red are my subs. If you count the dining room, its about 25' wide, 13.5' of the width is my living room. It's a bilevel so the room is about 15' back until you reach that dotted line behind the couch. Add another 6.5' behind the couch where the stairwell and front entrance are. I have cathedral ceilings so no attic to work with and the basement is finished so nothing there either. Using an average of around 10', I have about 4000 cubic feet to work with in that area, not counting the kitchen (bottom right).

I think something on par with dual SVS PC Ultras would be good. If I can do it cheaper on my own then great... I'd like to try. If not, then I'll just have to save up for something like that. I just want to make sure it will sound great for music and still move things for movies.

**ThomasW** · 13 July 2005, 17:45 Wednesday

It's no big deal to recreate the performance of the PC-Ultras for quite a bit less money.

I'll need to get creative to find you 12"s or 15"s that are of the build quality of the driver used in the Ultra. The Tumult is certainly their equal. In the not too distant future the new AscendantAudio drivers should be available. They should be quite a bit less money than the Tumult

Do you want the look of a tube sub? If so your builder certainly should be able to make them. You can show him THIS and THIS link as an examples, (note that these are 20" diameter tube for 15" drivers compared to SVS using 16" diameter tube for 12" drivers.)

Tube subs are significantly lighter in weight and should be MUCH cheaper to fabricate compared to a custom made wooden boxes.

**ajpoe** · 13 July 2005, 19:32 Wednesday

I personally think the box subs like the PB Ultras look nicer than the PC cylinder subs, but I guess the price difference you speak of would be a deciding factor. Those sonotube subs look like monsters... I bet they sound amazing. Andrew, that down firing tumult that you have on your webpage... how many cubic feet are you filliing and do you get the effect I'm looking for?

**ThomasW** · 13 July 2005, 20:04 Wednesday

In your post prior to my last you stated

I think something on par with dual SVS PC Ultras would be good.

That why I brought up the idea of building a tube sub.

The cheapest option if you want a box is to use the 3 cu ft box from PE. It's roughly the same size as the PB-12 Ultra

**ajpoe** · 13 July 2005, 22:49 Wednesday

If I were to get the PE boxes, would I want to add feet and make it down firing? That box is only about 19" cubed which isn't too bad at all. The tubes would have about the same footprint but be quite a bit higher. I had only been mentioning the PC Ultras b/c they actually show a response curve on the site and I liked what I saw... the PB12 Ultra doesn't have a curve up yet. If they have the same response, I'd probably go with the 2 boxes for only $50 more each.

Looking at Andrew's FR from his down firing box sub, I'm thinking 2 of those would probably be really sweet and not have to stand so tall. You mentioned the new Ascendant drivers that will be out soon... how do you think they will compare to the Tumult? If I can save money by waiting for the new ones and maybe do 2 15" downfiring boxes like Andrew's, using the PE box, do you think I'll get the results I'm looking for?

**ThomasW** · 13 July 2005, 23:20 Wednesday

If I were to get the PE boxes, would I want to add feet and make it down firing?

It needs to be used as it is built, front firing.

We'll know about the new Ascendant drivers when they are released.

I think at $700 each, the Adire Tumult drivers are overpriced.

We can certainly design a sub that will equal the performance of a PB12-Ultra for a lot less than $1200ea + $99 shipping.

**Bent** · 13 July 2005, 23:25 Wednesday

Do we know if the suspension of the Ascendant stuff (this gen, as well as next gen) would even lend itself to a horizontal config?

**ajpoe** · 14 July 2005, 09:42 Thursday

It needs to be used as it is built, front firing.

Ok, that's cool... I didn't see mounting options for the Ascendant drivers. But, I certainly don't have an issue with a couple 15s staring back at me!

Since everyone keeps talking about waiting for the new drivers, I'm assuming you're expecting a leap in performance that will justify not just getting a couple of the closed out 15" avalanches at $225 each?

We can certainly design a sub that will equal the performance of a PB12-Ultra for a lot less than $1200ea + $99 shipping.

That makes me very happy!

On a side note... I called the guy I mentioned that does wood working. They have absolutely no experience building speaker/sub cabinets. They really sounded like they had no idea what they were doing as far as anything is concerned. I may be forced to use a PE box... which might be the most fun for me anyway. I think I can manage cutting some holes and adding extra bracing (and I can say I did it all! :lol: ). But if needed, I can call around and see if I can find someone else that can build a custom cabinet.

**ThomasW** · 14 July 2005, 10:03 Thursday

I'm assuming you're expecting a leap in performance that will justify not just getting a couple of the closed out 15" avalanches at $225 each?

If they have any 15"s left buy them. I don't expect the new ones to be tremendously better.

They have absolutely no experience building speaker/sub cabinets. They really sounded like they had no idea what they were doing as far as anything is concerned

If they are true cabinet makers they have all the skills needed to build subwoofers.

Show them this website as a general example

http://www.garagehobbies.com/thomaswoodcraft/Adire/tempestconstruction.asp

**ajpoe** · 14 July 2005, 10:30 Thursday

Yeah, I'm sure they have the skills to do it, but they were getting on my last nerve. They aren't cabinet makers, more like general woodworking. They build furinture, tables, etc. and have never built a speaker cabinet of any type. They kept wanting to talk about finishes and plywood when I kept telling them that I just wanted a box built out of MDF.

From the link you posted, I could maybe do something similar, minus some of the fancy detail work. What kind of tool do you use to cut the holes? I have a circular saw and jig saw and unfortunately no table to mount them to. Normally to do a hole, I just draw it on teh wood, start the hole with a drill or something and then use a jig freehand to do the cutout.

**Andrew Pratt** · 14 July 2005, 13:44 Thursday

Lets clear up a few issue first...

I really want to feel the bass. I would be very happy with a frequency response like you have though Andrew as it gets plenty of usable bass under 20 Hz. But I also want to produce enough SPL to really feel it hit you

Most of the bass you feel is actually well above 20 Hz. The gut wrenching stuff is closer to 40-60 Hz and there's actually very little truely subsonic bass on most DVD's so don't get too hung up on extending down to the single digits. Typically on a ported sub if you tune it low enough to extend its reach down below 20 hz it means giving up some SPL higher up where most DVD bass is. There's reasons to do that if protecting the driver is important but its not without its trade off's. For sealed designs that's less of an issue and room gain usually fills in the bottom end for free.

Andrew, that down firing tumult that you have on your webpage... how many cubic feet are you filliing and do you get the effect I'm looking for?

Tumults typically go into 3 cubic foot sealed box's though they can be used in other alignments as well if you so desire. 3 CU seems to be the common config though. As for the impact yes the tumult has finally satisfied by bass needs having gone through a number of different trials with various other drivers and alignments. One of the biggests changes was how clean the XBL motors are compared to others I've used. Its not always about sheer SPL. for reference my HT room is 12 wide * 25 long * 7 tall.

If I can save money by waiting for the new ones and maybe do 2 15" downfiring boxes like Andrew's, using the PE box, do you think I'll get the results I'm looking for?

Some drivers don't like to be downfiring while others are fine in that alignment. There's no acoustic benefit one way or another so its not an issue from that stand point. I like downfiring in my room since it helps protect the cone from the prying fingers my kids will likely inflict on it but there's a lot to be said of watching a front firing cone dance during a high impact movie scene

From the link you posted, I could maybe do something similar, minus some of the fancy detail work. What kind of tool do you use to cut the holes? I have a circular saw and jig saw and unfortunately no table to mount them to. Normally to do a hole, I just draw it on teh wood, start the hole with a drill or something and then use a jig freehand to do the cutout.

To do a proper driver cut out of the PE box you are going to need a plunge router with a circle jig attachement. You can get away with a fairly cheap model if you don't plan on doing much woodworking though they're handy to have around for other jobs around the house. Another option would be to borrow one from someone or possibly rent one from Home Depot etc. You would use your jigsaw to cut the plate amp hole or input cup if you go the external amp route. That said it is possible to do a reasonably clean circle with a jig saw if the material isn't very thick and you take your time but IMO for the cost of a plunge router its very much worth it to do it with the right tool. The PE box would be a good start and since they're local shipping wouldn't be an issue.

**ajpoe** · 14 July 2005, 15:19 Thursday

there's a lot to be said of watching a front firing cone dance during a high impact movie scene

I kinda like the idea of front firing drivers the more I think about it. It wouldn't require any extra steps to add feet and stuff like a down firing sub would. My room is about twice the cubic feet Andrew, so I'd probably want to stick with 2 subs.

Typically on a ported sub if you tune it low enough to extend its reach down below 20 hz it means giving up some SPL higher up where most DVD bass is. There's reasons to do that if protecting the driver is important but its not without its trade off's. For sealed designs that's less of an issue and room gain usually fills in the bottom end for free.

If that means the sealed is capable of reaching flat to 20 Hz like your response then the PE box and a sealed enclosure is sounding more and more like the best route for me. I'll have to look around to see if anyone I know has the tools you mentioned. If not, I'd just use the jig and be VERY careful and cut a smidge small and sand outward where needed.

Tumults typically go into 3 cubic foot sealed box's

Is this true for Avalanches too? Do you guys know how these 15" avalanche close outs for $225 compare to the SVS Ultra driver?

15" Avalanche (2) - $450 + shipping
PE 3.0 Cubic Box (2) - $300
PE 1000 watt plate amp (2) - $800

That's about $1600 for two subs. Do you think they would meet or beat a dual SVS Ultra setup?

**JoshK** · 14 July 2005, 15:46 Thursday

Have you checked to see whether the AV15s are still available, I read somewhere they weren't?

**ajpoe** · 14 July 2005, 16:02 Thursday

Originally posted by JoshK

Have you checked to see whether the AV15s are still available, I read somewhere they weren't?

They are still listed on the website... I haven't actually called to place an order or find out. If they aren't available then I can wait the 2 months and get the new ones. The Tumult seems a bit high for me... that would be $2500 for 2 subs.

**ThomasW** · 14 July 2005, 16:08 Thursday

That's about $1600 for two subs. Do you think they would meet or beat a dual SVS Ultra setup?

Certainly, they're going to be able to move more than twice as much air.

Normally to do a hole, I just draw it on teh wood, start the hole with a drill or something and then use a jig freehand to do the cutout.

For decades I used a compass to draw the circles, and a jig saw to cut the holes.

One thing you can't do without a router is recess mount the driver. Some of these high excursion drivers have very tall suspensions that can rub against the grill cloth unless the drivers are recessed. I've never had hands on the Ave 15" or the PE boxes, so I don't know if this the situation with them.

**ajpoe** · 14 July 2005, 16:24 Thursday

Ok, I just got off the phone with Ascendant and they said that a lot of people were under the impression that they are out of stuff, but they still do have 15s left. I just pulled the trigger on 2 of them. It's $488 shipped to my house for both. He said they are really low in quantity though so if you want to move on it move fast.

Ok Thomas and Andrew... I guess it's time to move on with the project! The guy I spoke with said he has used them in the PE 3.0 box and with that 1000 watt amp. Should I go ahead and get those? He also said that just getting cheap polyfil at walmart or something works the same and is a lot less expensive than the fill from PE. He said he recommends about 3 lbs per box. How's all this sound?

**Andrew Pratt** · 14 July 2005, 16:32 Thursday

Sounds pretty much on par with what I'd recomend. I'll let Thomas comment on the Ascendants volume requirements but with sealed designs you've got a lot of flexibility. One thing that I'd also budget for is the BFD. With this level of bass you'd be foolish not to go the extra step and EQ them. As you can see from the SPL plot I posted it can make a huge difference in working with the nulls and peaks. The only concern with the 1000 watt plate amps is that they tend to leak a little air when used with these high volume drivers. A seperate dedicated pro amp might be a better and cheaper option but fan noise can be an issue on some. Still for the cost of two 1000 watt plate amps you could buy a very nice pro amp.

**ThomasW** · 14 July 2005, 16:34 Thursday

Do you have your heart set on plate amps? IMO they aren't a very good long term investment.

If you can live with the cooling fan noise from one of the low buck pro-sound amps, you can save a ton of money and have lots of power.

Standard polyfill is fine, plain old fiberglass home insulation is even better for a sub. You certainly don't need the Acousta-stuff PE sells.

To reinforce what Andrew said, a BFD isn't an option it's mandatory!

**JoshK** · 14 July 2005, 17:35 Thursday

If your getting the BFD already, get a Behr Europower1500 for $249, just as much power basically (or the 2500 for $299), cheaper and better long term solution like Thomas said. The BFD will do the rest, so the other stuff on the plate amps is puffery.

**ajpoe** · 14 July 2005, 19:05 Thursday

I am definately getting a BFD. I've been quoted a price of $94 plus shipping for the 1124 I think. Is this not what I should be looking at? I'm certainly not set on plate amps. A separate amp is fine as long as the fan isn't too loud. I have an audio cabinet that will help with the noise somewhat. I have to run out for the night but anything you'd recommend, I'll take a look at.

**ThomasW** · 14 July 2005, 20:27 Thursday

Yes the 1124P is what you want. All the good low buck prosound amps are fan cooled. Is there a way to place the amp in a different room or closet? Depending on how loud you play these the fan can be pretty noisey.

The Behringer EP-2500 is rated at 750 watts/channel into a 4 ohm load. 800 watts is the Pmax for one Ave 15". So for ~$300+ shipping you have an amp that's a perfect fit for both your drivers.

**Andrew Pratt** · 14 July 2005, 20:45 Thursday

The fans on these area pretty loud so putting the amp in another room is ideal. There are resistors you can put on the fans to slow it down a bit but at the risk of voiding warranty and over heating the amp. If you can spend more there's air cooled pro amps (Crown K1 or K2) that are very nice but more expensive...but not too bad if you had budget for two 1000w plate amps.

**jdybnis** · 14 July 2005, 23:20 Thursday

I'd second getting a Crown k1 over a pair of plate amps. If you're patient you can find one on ebay for <$600. But there are always some up there for under $800 if can't wait. At least with the Crown you'll probably be able to sell it at any time in the next few years for close to what you pay for it now.

Those Pro Amps with fans can be pretty loud. But some of them keep the fan off most of the time. If they're good at regulating the fan it won't be noisy unless you're pulling a lot of juice. But then the fan noise will probably be covered up by the sound of a helicopter exploding or what not.

**ajpoe** · 15 July 2005, 01:08 Friday

The guy from Ascendant said they rated those drivers very conservatively. And while he doesn't want to say "go ahead and do it" for liability reasons, he said 1000 watts has never caused them any problems. He even has pro guys running several thousand watts through them, just punishing the driver but they stand up.

Is the K1 a more true rating than the other amps to justify the price difference or is it just the name? I know companies do their ratings different. Silent is good though... I'm just wanting to make sure if I do this, I do it with the right amount of power so I'm not wanting more and I don't know if 500 watts per channel will be enough. You guys know better than I. If the Behringer EP-2500 is really loud, it probably won't work for me. I don't have another room or closet to put it in... but I do really like that price!

**Andrew Pratt** · 15 July 2005, 09:23 Friday

The problem is if noise really is an issue there just aren't many options other then the Crown's in the pro amp range. There's a few like the Earthquake I mentioned that are pretty quiet but they don't always have the power the crowns have.

**ThomasW** · 15 July 2005, 10:06 Friday

It doesn't matter if the drivers are conservatively rated or not. No one needs to throw a kilowatt into a 15" driver. We're playing music here, not ARC welding .....:wink:

The Crown K1/K2 are the cream of the crop of high-end of prosound switching amps amps. They're light-weight, fairly compact and very powerful. Since the massively thick front panel is a heat sink, they don't reguire cooling fans.

The Crown and the Behringer amps are rated using the same standards for power output. I doubt that you'd actually 'hear' any audible difference bweteen the two when driving a subwoofer.

If you need/want a totally silent amp then you need a Crown

**Andrew Pratt** · 15 July 2005, 10:12 Friday

I'd also like to point out that there was someone that fried his XBL motor with too much power...the interesting thing is with these motors you don't hear them straining until its way to late unlike most subs where distortion kicks in early and gives you plenty of time to turn it down.

**ajpoe** · 15 July 2005, 10:28 Friday

Silent would be nice since the best spot for it will probably be my audio rack. It sounds like I need to start watcihng for the best price on a Crown.

Does anyone know about QSC amps? They have them at PE and rated at 700 x 2 at 4 ohms... looks like $850 after rebate.

Edit: Nevermind, I looked at the details of the QSC and see that they have fans. I'll probably just stick with Crown. I'm not sure if I should look at the K1 or K2. The K2 is rated the same as the driver, but it sounds liek you're saying I don't need that much power?

**JonMarsh** · 15 July 2005, 11:06 Friday

I'm not exactly impartial on this topic, but I'd go with the Crowns also-

If you want to wring the absolute last couple of db out of your drivers, then maybe the extra $350 for the K2 is worth it- but in 90% of the time, the K1 will do the job quite nicely- there's only about 2 dB difference in achievable playback level, based on power. If you're going with a Linkwitz transform style EQ in a 3 cu ft sealed box, the extra power in the deep bass might come in handy, but as others have very correctly pointed out, you need a little care with XBL style drivers (or any truly low distortion woofer) in that things sound clean and clear (compared to what you've been used to listening to) right up to the point of thermal distruction. It might be a little safer to have the lower power K1 and realize that when the clip lights are on, it's time to back off just a little bit....

Just my 0.02. I've found 500-600 watts to work pretty well for the big boy drivers. Especially since you'll have two...

~Jon

**ajpoe** · 15 July 2005, 11:43 Friday

If you're going with a Linkwitz transform style EQ in a 3 cu ft sealed box

I have no idea what that means.

ops:

All I know is that it will be sealed and I'll be using a BFD to EQ them. They will probably only be getting 60 Hz and below from my ICBM-1 which is where I currently have my subs. I'll have to test again, but I assume that won't change.

I'm guessing I'd probably never see the clip lights in any given situation as I don't listen to movies at reference volume. Sometimes I get close, especially when showing off, but that is rediculous loud. I usually listen to movies around 70-72 for DTS and 72-74 for DD on my Rotel 1068 using a Rotel 1075. When calibrating at 75 db using AVIA and my Processor, the volume was at 82 I think. I've never even attempted that during a movie.

**JonMarsh** · 15 July 2005, 12:17 Friday

A Linkwitz transform is a specific mathematical approach to the equalizatio needed for a woofer in small box to produce extended bass with well damped response- you can implement that pretty closely with the Behringer, as well as deal with other issues.

Here's a good explanation of how it works.

75 dB? Well, your subs will be coasting most of the time, and I think you'd do quite well with "just" a K1.

Keep in mind that if you're measuring average levels with an averaging meter, peak levels with program may be up to 20 dB higher, so I still think you're going to be in comfortable turf. Another thing that happens is as you get your system cleaner (lower distortion), you may find you have a tendency to listen at higher volumes than you expect or realize... unless, of course, you're in a situation with neighbors that requires the exercise of some self restraint.

~Jon

**ajpoe** · 15 July 2005, 12:43 Friday

Well, I think I calibrated the subs a bit higher... maybe 80 dB via the test tones. But, I'm thinking even at my listening level and with peaks, I should be fine with a K1. I can't wait for my subs to get here. Once they do I'll run down to PE and get the boxes.

For decades I used a compass to draw the circles, and a jig saw to cut the holes. One thing you can't do without a router is recess mount the driver. Some of these high excursion drivers have very tall suspensions that can rub against the grill cloth unless the drivers are recessed. I've never had hands on the Ave 15" or the PE boxes, so I don't know if this the situation with them.

The guy from Ascendant is supposed to call me today to let me know how soon those subs are going to ship. He has experience with the PE boxes so I'll ask him if the drivers need to be recessed or not. If so, I'm sure I can borrow a router from one of my friends.

**Andrew Pratt** · 15 July 2005, 12:51 Friday

For calibrating with Avia you should calibrate so that ref level is 85 dB not 75 dB like Video Essentials. Also the Rotel's LFE channel's test tone is 10 dB too low if you ever use the internal test tones.

As for the amps a K1 would be very very nice driving a pair of these monsters

**ajpoe** · 15 July 2005, 13:54 Friday

I think I have everything right the way it is, but who knows. I'll just recalibrate everything once I get the new drivers built and add the K1 and BFD. I'll probably have to move something things around in my rack too. Does the K1 generate too much heat to put the in bottom of my cabinet? I don't want to cause issues for all the compenents that are located above it. I may have to rearrange everything... I'm running out of real estate... that'll be a bizatch!

**ThomasW** · 15 July 2005, 17:00 Friday

Does the K1 generate too much heat to put the in bottom of my cabinet? I don't want to cause issues for all the compenents that are located above it.

This simply depends on how hard you drive it. I seriously doubt that at any sane SPL you'd find much heat coming off of a K1

**ajpoe** · 15 July 2005, 19:18 Friday

Awesome, then I might be able to get away with putting the K1 in the bottom of the rack and putting the ICBM on top of it... may be raising the feet up on the ICBM some if needed. That would keep me from having to rearrange EVERYTHING. Or, I might just throw it on top of one of the subs if that doesn't cause any issues.

I spoke the Ascendant today and they said that with the rubber mold, the driver does stick out over 1" so I'd either want to leave the grill off, remove the rubber mold, or recess the driver. I'm thinking that I may just want to leave the grill off and have these bad boys staring me in the face. If I recess the driver then I'm thinning the cabinet and I don't think I'd like to do that... the driver would probably still hit the grill on high impact scenes anyway.

**Dennis H** · 15 July 2005, 19:22 Friday

The K series idle at something like 90 watts so they are quite warm to the touch at low levels but they don't get much hotter when driven hard. Notice how the power vs. heat is nonlinear.

The page you were looking for doesn't exist (404)

http://www.crownaudio.com/pdf/amps/k1k2calc.pdf

**awm** · 15 July 2005, 20:50 Friday

WEll, having just built a JBL1500 sub, with an LT and...

having also just received my two Avalanche 15's, I'm going to comment here, however much it might seem like heresy and admitting up front that I have nowhere near the experience of the poohbahs on the board ;x(

First, I strongly recommend the PE higher end plate amps. The EQ DOES work (someone independent tested them, though I can't remember who at present, and the amps apparently did exactly what they were supposed to do...perhaps others know differently), and they're already sealed in the rear. Having seen and owned other plate amps, the build quality is quite high. This arrangement makes for one less piece of heavy, large, space-taking, heat-producing equipment.

Second, as some have said thus far, 1000w is an INORDINATE amount of max power, despite supposed power requirements to get max excursion and db down low. On my JBL 1500, which sounds quite nice, btw, I have the volume knob at 9 o'clock. Any more, and it becomes overwhelming and disproportionate. And, this is with the receiver settings dialed way down for the sub out. The PE 500 watt job would be PLENTY.

Third, I would consider it a given that you recess the woofer with a router and circle jig. Bracing the cab to make up for the "thinning" of it is easy, and probably desirable, regardless. Just epoxy some oak pieces, into which screws can go and not strip very easily, for support. Make sure the oak lines up with the woofer screw holes.

Fourth, I'd use an LT on top of the BFD. Just my $0.02. There are kits available for them. Maybe try it with a BFD solo first, but if you really want to get it down to 16hz flat, you'll probably need the LT on top of it. You will feel a lot physically (in the gut, pant legs shaking, house trembling, etc.) with 20hz flat inroom, btw... A LOT. :B Two Ava 15's in sealed boxes will probably be a threat to the integrity of your house. (I'm going to go IB with mine, so the threat will be less great...

)

Also, for Thomas W, the Avalanches structurally look almost exactly like the Tumults. (I know you've seen pics of Ava's, but I'm talking frame measurements.) The only thing I see different is the colored surround -- the Tumult's is a lighter gray, the Ava's, more charcoal -- and some cone, or dust-cap differences.

HTH,
Andy

**Adz** · 15 July 2005, 22:16 Friday

I saw a K1 for sale for $750, if you're interested.
Let me know.

DIY newbie looking at subwoofer options

DIY newbie looking at subwoofer options

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment