Man cave subs to compliment Maggie 2.7OR's

[dracoskeeper]

I'm planning on building some subs for the man cave, I have these items that are left over from projects over the years.

1 pair (or two) of these Parts-Express.com:*Dayton ST255-8 10" Series II Woofer | woofer st255-8 10" woofer midbass dayton series II series 2 dayton audio dayton loudspeaker series 2 10" subwoofers

1 pair of 12" passive radiators (forgot the brand)

My problem is that I'm very good with tools and not very skilled with computers! I just need some direction to figure out box size. I want to have upright boxes with as little footprint as possible. These will be driven with adcom 565's that were driving the Maggies before I went to tubes. They will be used mainly for music and TV never for HT. I realize without specs for the passives it will not be an exact science and I'm not looking to go that low just clean and tight.

[zora]

Those subs really won't do justice to the fine sound from the maggies. You really want some drivers that can go deep with low distortion. I would look into the designs for the AV12's or AV15's from Acoustic Elegance or the Rythmik/GR Research servo subs.

JP

[zobsky]

rythmik servo subs are overhyped , l've listened to a couple of different variations

I'll see if I can draw up a feasible / easy to build low distortion tapped horn or "reverse" tapped pipe for your drivers

[littlemike]

This driver models well in a simple tapped horn. A pair models even better.

My model was very quick with very little refinement. I am sure it can be improved upon/further optimized. I'd be happy to post it if others want to mess with it.

Limit the low bandwidth to 30 Hz to control excursion. You will run out of linear excursion, but still should be within the mechanical limits of the drivers at rated power (15 mm @ 500 W to the pair). I've driven Dayton 10" woofers past this level of excursion without scary noises. SPL output should be more than adequate, approx 125 dB @ 500 watts ground-plane, significantly louder if placed near a wall or corner.

At over 12 cubic feet, the box will be large, but it should be an easy build and will fit through doors. The simplest tapped horns can be constructed with 7 boards and no angle cuts. I'd recommend some bracing, so you're up to 9 boards if you keep it simple. Different shape cabinets require different folds, potentially getting complicated.

Sound quality - well, I do not know. I have listened to tapped horns with several direct-radiator systems and they blend well. Magnepans may be a bit more of a challenge, I don't know, I've never had the pleasure of listening to a pair.

[littlemike]

Here is the model inputs and results.

Remember - this is just a first, rough model of a simple (single taper) tapped horn. I am sure it can be improved.

edit - Attachments....

[dracoskeeper]

I appreciate the suggestions, zora: just for *****&grinz I asked AE what they would suggest but I don't have much of a budget for drivers (it went towards tubes!). The reason that I need a small footprint is this room is 12'X24' with Maggies 7' apart on the one long wall. The right short wall has my desk (5.5'X6.5' corner) and the other short wall has a 8'@300 gal. aquarium. Down the road I plan on putting the Maggies in a dedicated listening room when/if I can move! I wouldn't rule out building nicer subs but they would be for music first. I've got a SVS up in the theater and it shakes the house but I don't care for that type of bass in two channel. I have a diy sub that I built with my original SVS driver when I updated drivers but I've been told I need some way to raise the gain feeding the 565 from the avr because even at max setting on the preout it is not enough. It is nice clean bass just not enough, originally I thought of building two of these but now I may sell both SVS's and build two killer musical subs powered by the 565's.

[zobsky]

Here's a reverse tapped pipe (dual driver version) that should get you into the mid 30 Hz in room. This could be split into two enclosures (each half the starting and ending cross sectional area).

I've had magneplanars (borrowed MMG and owned vintage MG1) in the past and regular box subs just didn't cut it. Horns (low distortion) blended fine and added the punch that these lacked, somewhat. From my experiments a few years ago, I'm guessing open baffle dipole woofers would work okay too (apart from being somewhat SPL limited, unless using multiple drivers)

If you're handy with tools, you owe it to yourself to try this or the other tapped horn enclosure (check with the experts first that there are no glaring flaws in this design )

[dracoskeeper]

Zobsky, What type,size box would that call for?

[littlemike]

Hmm - looking at the two sims, either Zobksy or I have a typo somewhere, our driver parameters do not match for Cms and Mmd. I used the information provided in the Parts Express PDF data sheet. I think I got the info typed in right (unless my typo is staring me in the face).

Similar to Zobsky's design, the tapped horn can be split into two cabinets, with one driver per and about half the total volume. Even with a stereo pair, I'd run them mono. With a single fold (like Cowan's tapped horns), floor footprint would be minimal (2 sq feet). If you have 4 drivers, use two per cabinet. With the typical fold I envision, the drivers will be low in the cabinet so it should be relatively stable.

You can make the single or dual driver enclosure considerably smaller, peak SPL capability drops and excursion goes up a bit, but unless you're looking for that last dB, it really does not matter. I got the enclosure down to 8.5 cubic feet for two drivers, which is about 0.75 by 2 by 6 feet, though layout of the fold may change this a bit.

Based on my experience designing, building, and measuring tapped horn subs (some documented over in the collaborative thread), the large spike the model predicts just after the passband is attenuated in reality. Some of my subs have not had the spike at all, though the model predicted a 10 dB spike in the response. The rising response after the first peak is usually present, and can be easily tamed with an electronic crossover.

[zobsky]

Originally Posted by littlemike

Hmm - looking at the two sims, either Zobksy or I have a typo somewhere, our driver parameters do not match for Cms and Mmd. I used the information provided in the Parts Express PDF data sheet. I think I got the info typed in right (unless my typo is staring me in the face).

I'm probably the one with the typo since I manually entered data based on your input. Will re-check at home.