Dayton Titan 15" subs plan  

Last week, a few moments away from ordering a well regarded sub, I stumbled across steve nn's Dayton Titanic 15" MKIII kit thread which has steered me to the DIY route. After evaluating my needs aided with the driver modelling program WINISD Pro I have pencilled out a plan of attack and am soliciting a little feedback to enlighten me of any errors or omissions of material importance.

Objectives:

-Maximize value/minimize cost
-Minimize boom (target Qtc of .58) and other distortions (60/50 movies music (20 % of movies are concerts)
-Sealed sub
-Forgo HP filters and EQ if possible.
-Achieve the most natural bass at spirited SPL's, (current room is 3750 cubic feet will likely be adding doors to seal off 1500 cubic feet of that.

I've decided to build two subwoofers each with an finished internal volume of 6.5 cubic feet, each housing one Dayton Titanic 15" driver. I chose this design after being intrigued by steve nn's posts on the Dayton kit but recognizing that his kit apparently suffers primarily in two areas: 1/ FR drop off below 25hz and 2/ distortion at/below the same frequency.

More than doubling box size flattens the response, achieving a relative increase of about 3dB at 20Hz. Additionally, modelling driver excursion in this box size indicates a power amp of approx 200 watts into 4 ohms need be used to prevent over-excursion. While the driver still exceeds XMAS at about 10 Hz, further modelling indicates the natural roll-off below 20Hz of the amplifier I have in mind will maintain the drivers excursion at approx 73% of it Xmas between 5-10Hz, 80% at 20Hz and 60% at 30Hz.

Employing two subs approximately halves the driver excrusion required to produce single box SPL"s below 50 Hz and this is where I trust large gains in sound quality will be achieved over the kit.

So it appears running two 6.5 cu.ft subs powered with perhaps a Crown XLS-202b will have the same potential maximum SPL output as Daytons kit (which I'm confident will produce satisfactory SPL's in my room) while offering 3dB better response at 20 hz, all this with half the cone excrusion helping to keep things cleaner sounding and with a cost only slighty above the price of one $688 kit. I should note my room adds gain all the down to 10 Hz so am confident the Dayton driver (even with the small box relatively steep roll-off) will work well in this configuration.

Now, I understand these drivers won't elicit ooohs and aaahs from the masses but the price is right and by all indications will suit my needs well. That's the plan, if need be I will add a HP filter or FBD but would rather avoid this if possible but obviously will take some time to make the final determination.

If anyone can identify any glaring issues with this plan I'd appreciate the feedback.

Thanks

Hi,

Correct, fill was not included in the design. I wish to achieve my objectives without employing "tricks", therefore no fill, PEQ, filters etc. While it may not be achievable I'll start with a simple bare bones plan and screw up the signal more as I go along if required to achieve greater SPL's or acceptable response.

The large box also keeps the "I required more SPL" option open by allowing room for adding another driver to each box in which case some stuffing may then be advantages.

I did take a look at the Soundsplinter driver and while it has higher Xmas therefore can handle more power, and should offer less excursion induced distortion at equal SPL's than the Dayton, the FR appears to be a little steeper as well. I would predict that should Steve measure the response of the Soundsplinter in a 3 cu.ft box may show relatively higher roll-off below 80Hz than the Dayton driver. While the Soundsplinter should have less distortion, assuming that higher SPL is not the goal but instead greater headroom, this advantage should become less relevant to the final SQ as more drivers are added to the mix, therefore I'm thinking that for my purposes the differences between the two may not justify the additional cost in drivers and box construction. (To achieve a Qtc of .58 the Soundsplinter requires an 8 cu.ft box while the Dayton 6.5.)

Regardless of the general responses the programs indicate and speculating on my part I've been searching for posts by Steve for some ITR (in the room) objective and subjective comparisons between the two but haven't seen anything yet.

Thanks for the DIY forum heads-up, I didn't know it existed. I'll ask the mods to move my post.

I think from a practicality standpoint if push comes to shove the idea of making the enclosure relatively smaller by adding more drivers is the way to go. ;)


I just put the figures in again (4ohm P) and get the same results, but now I'm starting to waffle, but I must resist the temptation to increase the budget.

I too am rather anxious to see how all this works out. At this point I'm determining suitable bracing and enclosure. Think I'll go thinner (1") on the exterior and spend more on the bracing reason being I've owned Yorkville Elite 18" pro bass bins used for gigging and I believe they were built from 15mm (approx 5/8") 11 ply birch but with extension bracing and these things were remarkably solid enclosures, rock-like in strength completely free of vibration or flex at silly SPL's. With that in mind I'm contemplating using 4 one inch thick shelf braces spaced every 6 inches (36" tall cabinet, 34" inside) on the horizontal plane all with one large central circular hole, the bottom brace further modified to make room for the drivers basket.

With luck I'll have a decent plan soon and start building next week.

Man I'm a little slow here, opened the link to reply with my previous post then walked away for a few hours.

That makes perfect sense and is consistant with the modelling. The Dayton has far less excursion headroom at any given SPL at 20 Hz compared to SS.

This is a tough call for me, I'm taking a bit of a risk with the Daytons in my large room they just can't handle gobs of power down low when in a large box. My primary concern is getting decent room response from 30-80 or maybe higher for music, loud SPL's below 25 or so are not as improtant to me and could live with that compromise if the setup is great elsewhere.

Regarding absorption, I wasn't planning anything at this point, any idea what high frequencies Thomas was referring to?

Thanks.

Thanks to everyone, I appreciate the replies.

I have looked at the Stryke AV15 and I'm not sure if the parameters are correct from Stykes site but WinISD shows that to achieve .582 Qtc the box must be about 11.5 cubic feet vs Daytons 6.5. This is inconsistant with strykes charts so I'm not sure where the error is, other than that I like what WinISD is showing.. Not a significant difference from the Dayton, but regardless, I really don't like the aluminum cone which would prompt me to build a grill therefore adding more cost into the project.

I'm still somewhat undecided, Daytons 12" reference series drivers look very interesting as well, 4 of them may perform admirably.... the AV15 isn't completely off the list either.

Next stop, the funny farm!