First Subwoofer question

**Dennis H** · 30 September 2006, 21:58 Saturday

The Soundsplinter driver or the equivalent one from TC Sounds are much better drivers than the Dayton Mk 3. Steve Callas's LLT design is a proven winner. I forget the specifics of his design but you've got plenty of volume with your proposed boxes to match his design. I'm sure Steve will chime in with specific volume and port suggestions.

**WillyD** · 30 September 2006, 22:18 Saturday

That 2x2x3 enclosure would work well, generally speaking. The SS Rl-p 15 or the TC Sounds TC-2000 are the preferred drivers at the moment.

**ThomasW** · 30 September 2006, 22:55 Saturday

Unless it's bent like a pretzel (bad idea) a 6" or 8" port won't work in downfiring configuration in a 2' tall coffee table style box tuned to 15 Hz.

Something taller like a hutch will give the required height for a bigger port.

Why don't you post the largest external dimensions you want to live with, then we'll do the rest..... :T

**chasw98** · 30 September 2006, 22:58 Saturday

The one thing to think about is if the height is 3 feet and you use a 27 inch port, you will have a hole in the top, plus the driver (RL-P15) will get a bit crowded. If you are using 2 foot height, 3 feet wide, you wil have a hole in the side and room for the driver. Or you might make it sealed.

**Dennis H** · 30 September 2006, 23:24 Saturday

Thomas and I have agreed to disagree about ports with bends in them. Personally, I think they work fine as long as the port velocity is kept low -- no problem with an 8" port. Imagine if tuba players insisted on straight pipes for their instruments -- Ricola!

**woodfiend** · 30 September 2006, 23:54 Saturday

Dennis....Talk about horn loaded!...... :W :lol: Ha Ha sorry bad joke.

I will go with the SS or TC if you recommend that. Isn't the TC way more expensive than the SS though?
I think 2x2x4 is about the max I would like to go. That gives me about 16 cubic feet before subtracting for driver and bracing. So in a 2x2x3 enclosure I would need about a 27 inch port? What about cutting an oval or eliptical hole and running the port at a 45 degree angle across the inside of the box. Kind of like almost corner to corner. That would allow you to get a few more inches in length. That may be a completely ridiculous idea but it just popped into my head. You wouldn't be able to use a store bought flare but you could still round it over with a router. That would actually make the exit opening larger....almost like having a 6 inch port and a 7 inch flare. You guys would know better if that would cause chuffing or resonant problems. The idea (be it good or bad) just hit me and I didn't know if that had been discussed before.
My wife would prefer the smaller enclosure but I am willing to do the larger if it gets me as low as I would like. Would a 6 inch or 8 inch port work better?

**Inu_Yasha** · 01 October 2006, 00:34 Sunday

I have my sub built as a box, and when it's finished I want to make it into a table for me to put some of my stuff on. My setup is going to be down firing, but I don't have the tools right now to add the base plate. You probably could integrate the sub into something to hide it better. I have my sub ported to 16hz with two pipes that have dual 90 degree elbows.

**---k---** · 01 October 2006, 00:35 Sunday

Woodfiend,

Welcome to HTguide.

First, what is your location? I'm crossing my fingers and hoping you're western burbs of Chicago so maybe you can help me out with my current project. I'm a great rough carpenter, but need some help with the finish work - still struggling with the width of the saw blade thing.

Like Dennis said, a handfull of people are real happy with Steve's SS RL-p15 D2 design. Stevenn is real happy, and he's done a lot of experimenting with differnt sizes and shapes with the RL-p15 driver. I think his current design is a effective enterior volume of 260L and tuned to like 15hz. If I got all the math right, that's an 6" port 28" long in a box that is 24 x 24 x 38 (I subtracted out 40L for the port/driver/bracing).

Check my math. But, that should do you.

The RL-p15 D2 is a little cheeper and proven winner. The TC-2000 is just an updated version of this driver. It is a little more expensive and out of stock. I'm also not sure what is up with the 3ohm insted of 2 or 4 - odd to me, but what do I know.

I don't think you'll go wrong with either one.

**SteveCallas** · 01 October 2006, 01:17 Sunday

Hmm, I don't really understand why there would be any problem fitting the needed port in this enclosure. If one dimension is 4', that will provide enough room. For the RL-p15 D2, I'd go with 260 effective liters with a 6" diameter port that is 30" long being fed with 600-900 watts. Use a roundover bit to create flares for the port - the larger the better.

As for specific dimensions, it doesn't really matter, just make sure it equates to ~260 effective liters (after subtracting port and bracing volume) and you have one dimenison long enough to fit the port length + provide enough clearance for at least the diameter of the port in all directions.

**Inu_Yasha** · 01 October 2006, 01:55 Sunday

Ah, didn't see the 4' in the post. I thought it was 2'X2'X2'. Yeah, with a 4' you wouldn't have any problems with a ported design.

**ThomasW** · 01 October 2006, 02:11 Sunday

Originally posted by Dennis H

Thomas and I have agreed to disagree about ports with bends in them. Personally, I think they work fine as long as the port velocity is kept low

I'll be happy to take the tuba recommendation into consideration once we segue into building musical instruments....

If you go with 6" ports I really recommend paying the extra $50 and getting the AeroPort flares. They're much better than a DIY flares made with a round-over bit.

**WillyD** · 01 October 2006, 02:15 Sunday

I'm also not sure what is up with the 3ohm insted of 2 or 4 - odd to me, but what do I know.

I think they are just using the DC resistance of the voice coil for the rating instead of "rounding it up". For instance, the DCR of the VCs on the SoundSplinters arent exactly 2 or 4ohms either.

But what do I know.

**woodfiend** · 01 October 2006, 03:45 Sunday

Sorry ---K--- I am in Nebraska. That might be a bit of a drive. 8O
Alright I will look for the RL-p15 D2 to purchase. So to summarize 260 L enclosure, 30 inch port (6 incher) and a lot of wattage. Any better recommendations on the amp or would behringer 1500 be okay? I hear fan noise is a problem. Would it be louder than my Infocus 4805 projectors fan noise??

**Inu_Yasha** · 01 October 2006, 06:10 Sunday

Originally posted by woodfiend

Sorry ---K--- I am in Nebraska. That might be a bit of a drive. 8O
Alright I will look for the RL-p15 D2 to purchase. So to summarize 260 L enclosure, 30 inch port (6 incher) and a lot of wattage. Any better recommendations on the amp or would behringer 1500 be okay? I hear fan noise is a problem. Would it be louder than my Infocus 4805 projectors fan noise??

If money isn't too much of an issue, I would get the EP2500 over the EP1500. More wattage = more headroom. Right now I'm running my RL-p15 on one channel of my EP2500. Fan noise definately is an issue with the EP2500! I would say do the fan mod if you don't mind opening the case. I personally haven't had the time to switch my fan out, but it definately beats my home computer in terms of loudness.

**---k---** · 01 October 2006, 10:15 Sunday

Be careful, more watage means it is easier to blow it up.

There arn't any amps that are better values than the EP2500. You get the most power for the $$, but yes fan noise is a problem and needs to be delt with by either swapping the fan of adding a resistor to the fan.

Steve is a big fan of Carver amps, say they are quieter, but still have a fan. The butt kicker amp is another option that is fanless. Both are more expensive. It is up to you which you use, just get enough wattage.

**SteveCallas** · 01 October 2006, 11:00 Sunday

Steve is a big fan of Carver amps, say they are quieter, but still have a fan

*Carvin

A bridged mono Carvin HD900 would do the trick if you have no plans of building any more subs in the future. If you want to leave yourself the window to possibly build another down the road, I'd get the EP2500 (in which case you'll definitely want to do a resistor mod).

**woodfiend** · 01 October 2006, 14:02 Sunday

Is there an online tutorial on swapping out the fan or modifiying the ep2500? I think I will get that amp and try and place it where noise isn't an issue or I could build a hush box for it like some people do with their projectors. Thanks for all your input so far guys I really appreciate it.
Now say I build a 260L box and have a 30 inch port is it going to be self limiting if I drive it with the ep2500? I know I have seen in other discussions about how your overall design can actually keep you from overdriving your sub. Or am I going to need to watch my volume levels to keep from blowing it up? Sorry if I am asking a bunch of noob questions but I did just get bitten by the home theater/audio bug recently so a lot of this is new to me.

**ThomasW** · 01 October 2006, 14:22 Sunday

There are posts and threads about the fan mods. A search will bring them up.

Common sense is the best amp output limiter. A single RL-p15" can handle in excess of 1000 watts (the figure published on the SS website is to error on the side of safetly). 1000 watts is VERY loud.

The amp has input level controls, those can be used to throttle back the incoming voltage = lower output

**SteveCallas** · 01 October 2006, 14:33 Sunday

Yes, you will be amp limited with 750 watts - with actual material, you'll be well protected. Just don't get foolish and try running single digit sine waves ta loud levels or anything like that.

**woodfiend** · 01 October 2006, 15:01 Sunday

Great! I will have to experiment with the right levels when I calibrate it to the rest of the speakers. I am glad to know it has an input adj. so I can limit it. I wanted to be sure I could "set it and forget it" without worrying about a particularily strong bass scene coming along in a movie and driving it past excursion.
Are there any negatives associated with building your box with plywood? I have a lot of maple,oak, and birch plywood. I also have mdf if needed as well. I will put ample bracing but I didn't know if plywood had any inherent problems since I don't often see box construction using it.

**ThomasW** · 01 October 2006, 15:06 Sunday

Yes, you will be amp limited with 750 watts - with actual material, you'll be well protected.

I'm sorry to disagree, but there's no such thing as protection by 'amp limiting'.

Regardless of rated output power, the amp will attempt to amplify any level of input voltage. If the input voltage is too high the amp will clip the signal. If it's driven into gross or 'hard' clipping it will dump DC and that will destroy the speaker. This can happen with 100 watt amp or 500 watt amp. Neither inherently offer protection to the speaker.

**ThomasW** · 01 October 2006, 15:41 Sunday

Originally posted by woodfiend

Are there any negatives associated with building your box with plywood? I have a lot of maple,oak, and birch plywood. I also have mdf if needed as well. I will put ample bracing but I didn't know if plywood had any inherent problems since I don't often see box construction using it.

The primary reason you see MDF is it's low cost, also it machines well if one wants to paint it..

The idea is to use a void free or relatively void free material. This of course eliminates the cheap 5-7 layer plys. 13 layer ply is THE material of choice if one's budget can handle the hit.

**SteveCallas** · 01 October 2006, 17:14 Sunday

I'm sorry to disagree, but there's no such thing as protection by 'amp limiting'.

Regardless of rated output power, the amp will attempt to amplify any level of input voltage. If the input voltage is too high the amp will clip the signal. If it's driven into gross or 'hard' clipping it will dump DC and that will destroy the speaker. This can happen with 100 watt amp or 500 watt amp. Neither inherently offer protection to the speaker

Seeing the red clipping lights is essentially the protection - that means turn it down or get more woofage. The odds of going straight to hard clipping without any "warning" ahead of time (which would be in excess of a conservative ~112db in most rooms with this design) are slim to none. You'd just have to really be asking for it to damage the driver in this design, throwing caution to the wind and ignoring all warnings along the way.

**Inu_Yasha** · 01 October 2006, 17:22 Sunday

Originally posted by woodfiend

Are there any negatives associated with building your box with plywood? I have a lot of maple,oak, and birch plywood. I also have mdf if needed as well. I will put ample bracing but I didn't know if plywood had any inherent problems since I don't often see box construction using it.

I didn't see anyone else with a hardwood sub before I built mine. I did however see someone with hardwood (birch) speakers in the dayton 3-way thread. My sub is built out of birch plywood. I think homedepot carries the 13 ply birch and oak if you need extra.

**ThomasW** · 01 October 2006, 18:06 Sunday

Seeing the red clipping lights is essentially the protection - that means turn it down or get more woofage.

I believe that's called human interactive limiting, not amp limiting...

The odds of going straight to hard clipping without any "warning" ahead of time (which would be in excess of a conservative ~112db in most rooms with this design) are slim to none.

Testing done shortly after the launch of CD's, showed musical transients capable of drawing an instantaneous 500% increase in power. This was of course decades before the existence of subsonic material on DVD soundtracks.

Yes RL-p15" are very stout drivers...but... there are numerous extreme bass transients in modern soundtracks that would destroy (probably oil-can) an Rl-p15" even with a low tuning.

**SteveCallas** · 01 October 2006, 19:41 Sunday

Testing done shortly after the launch of CD's, showed musical transients capable of drawing an instantaneous 500% increase in power. This was of course decades before the existence of subsonic material on DVD soundtracks.

Yes RL-p15" are very stout drivers...but... there are numerous extreme bass transients in modern soundtracks that would destroy (probably oil-can) an Rl-p15" even with a low tuning.

Ehhh - owners of this design have had no such problems to date, it's really a non issue. I'd be more worried about this susceptability you speak of when using other alignments.

**Dennis H** · 01 October 2006, 19:47 Sunday

Originally posted by SteveCallas

Seeing the red clipping lights is essentially the protection - that means turn it down or get more woofage. The odds of going straight to hard clipping without any "warning" ahead of time (which would be in excess of a conservative ~112db in most rooms with this design) are slim to none. You'd just have to really be asking for it to damage the driver in this design, throwing caution to the wind and ignoring all warnings along the way.

Depends on your standards for very low frequencies whether 112 dB is "loud" or not. Quoting Bruce Thigpen from the AVS thread:

These are the sound levels you experience when you sit in your car and close the door, windows rolled up, also not a door slam. The doors represent the equivalent of a very large woofer cone, in effect you are sitting inside the woofer box.

I think the goal should be to reproduce these sounds at actual levels. (The measurement system is calibrated to 1Hz).

If that's what a car door does, 110 dB at 1 Hz, imagine a cannon.

And those kinds of signal levels can be present on some disks. Tzucc is going for 125 dB down as close to DC as he can get it.

**Inu_Yasha** · 01 October 2006, 19:57 Sunday

I keep hearing the word oil-canning, but what does that mean?

**SteveCallas** · 01 October 2006, 21:38 Sunday

Dennis, sensitivity rises exponentially as frequency decreases, and you're talking about single digits. When playing at calibrated reference level (master volume of 0), the subwoofer can potentially be asked to reproduce 115db peaks at the seat, and reference level is pretty darn loud. If the OP's desire is to be able to comfortably play his subwoofer at reference levels, he'll want to build two of these. That will get him there from ~14hz on up in room, assuming an average room.

**chasw98** · 01 October 2006, 22:28 Sunday

Originally posted by ThomasW

If you go with 6" ports I really recommend paying the extra $50 and getting the AeroPort flares. They're much better than a DIY flares made with a round-over bit.

Not to hijack this but.....
What will the audible difference be between using some sewer pipe with a roundover and using an Aero Port?

**ThomasW** · 02 October 2006, 00:55 Monday

Originally posted by Inu_Yasha

I keep hearing the word oil-canning, but what does that mean?

When the cone moves forward with so much force the suspension isn't able to stop it, as a result the VC pops out of the gap.

Below are examples of what happens when a driver in a ported alignment 'unloads' as a result of not having a proper high pass filter. BTW this driver had a 1400 watt Pmax and was powered by a 600 watt amp.

And no I didn't do this....

In the first pic the driver bottomed so hard the alu dustcap is embossed with the profile of the VC.

Image not available

In the next pic, the cone shot forward so quickly it oil-canned.

Image not available

Originally posted by chasw98

Not to hijack this but.....
What will the audible difference be between using some sewer pipe with a roundover and using an Aero Port?

If the DIY has the same flare it will function the same. But the router bit needed to get a 6" tube to flare to 9" dia is $pendy and more than a bit tricky/dangerous to operate.

**Bent** · 02 October 2006, 09:52 Monday

Ahhh, Bing's 12"er.

**woodfiend** · 21 November 2006, 21:08 Tuesday

Update

Okay finally making some progress now on the sub. Actually two of my friends decided they wanted to make one as well so all three of us are building them at the same time. We just ordered 3 TC Sounds 2000 Dual Voice coil drivers. I am working on purchasing 3 buttkicker amps. 6 inch shedule 40 pvc sewer and drain pipe will be purchased tomorrow. And we picked up 3 sections of 24inch sonotube this afternoon each of which is 4 feet long. So I believe that will give us plenty of volume for the subs. So do I need to make any modifications to the design due to the fact that I went with the TC's instead of the Soundsplinter? I am still trying to figure out my exact volume with a 4 foot length. Will a 30 inch port still work well? Or what will that volume do for my tuning?

I decided to go with a sonotube as well instead of my original box idea because both of my friends like the look and design of the tube. So since we are making them all at the same time I figured for simplicity's sake better to have them all identical. My one friend is going to lay his on its side in his theater he has a 70 inch flat screen HD tv and it is just over 2 feet off the floor and he thinks it may work perfectly there. Mine will be a bit different since I plan on making some beefy cabriole legs and probably veneering the sides. If I decide I don't like the sonotube look I can always whip out a new box some weekend. I can't wait for the drivers to hurry up and get here! They look gorgeous in the online pictures.

First Subwoofer question

First Subwoofer question

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