Best sub design to go with maggies?

**iasonas** · **05-07-08, 02:24 PM**

Yes, something along these lines.. I'm talking about the interaction of the voice coil with the fixed magnet. I'm asking people on this forum who are more knowledgeable than me if this thought is of any value..

**mayhem13** · **05-08-08, 10:48 PM**

Quote:

DS-21, with all due respect to you, there has not been *any* concrete evidence that fast and snappy bass (subjectively or not) results from lower inductance in a subwoofer. This argument has surfaced way too many times in this and other forums and has been kicked around more than a dead horse. Unless there is empirical evidence from an accredited organization such as IEEE or even the AES showing that a reduction in inductance in a subwoofer's passband leads to said benefits, it is merely conjecture.

If on the other hand, said evidence has actually been released (and I don't mean that magic Adire paper talking about inductance in midrange drivers), then shoot me a link to it!

Best,
Mark

IMO the cleanest and most natural sounding subs include drivers with low Le and reasonable xmax. All that excursion usually leads to one thing-Audible distortion in the 40-80hz range. Makes high power subs undesirable for HT/Music dual duty use. Case in point-Dayton RS series-an excellent offering for Dual purpose listening. While technical data and graphs are always helpfull in determining the actual acoustic performance properties, actual listening has always been the best indicator for me. Coming from a Pro-Audio background, i've been pondering why most Pro audio sub drivers have low xmax. Parody, Conjecture, Speculation,anyone-Bueller.....Bueller?

**Ricci** · **05-09-08, 01:19 PM**

I come from a Pro audio background too. The reason that most pro drivers have 6-10mm xmax is because they are always highpassed at 30-40hz. You don't need 30mm xmax for 40hz bass. They would never use it. You need the big xmax for the <20hz stuff.

**bobgpsr** · **05-09-08, 08:23 PM**

Quote:

mayhem13 wrote:

IMO the cleanest and most natural sounding subs include drivers with low Le and reasonable xmax. All that excursion usually leads to one thing-Audible distortion in the 40-80hz range.

You need a very linear (flat) BL curve to keep distortion down over that big Xmax. Hence XBL^2, LMT, etc.

I agree that low Le is desirable to keep a flat freq response in the higher freq bass up to the point that is well beyond the sub crossover.

**Mike P.** · **05-09-08, 09:29 PM**

If a sub is crossed over at 80hz, would 120hz be "well beyond the sub crossover"?

**funky_waves** · **05-10-08, 10:22 AM**

It depends on the order of crossover, 1st order @80hz would only be 6db down @160hz, 12db@320hz.... a 4th order would be 24db down @160hz......

**mrogowski** · **05-13-08, 07:19 PM**

Quote:

mayhem13 wrote:

IMO the cleanest and most natural sounding subs include drivers with low Le and reasonable xmax. All that excursion usually leads to one thing-Audible distortion in the 40-80hz range. Makes high power subs undesirable for HT/Music dual duty use. Case in point-Dayton RS series-an excellent offering for Dual purpose listening. While technical data and graphs are always helpfull in determining the actual acoustic performance properties, actual listening has always been the best indicator for me. Coming from a Pro-Audio background, i've been pondering why most Pro audio sub drivers have low xmax. Parody, Conjecture, Speculation,anyone-Bueller.....Bueller?

Curious (and I'm not saying this to be a troll or anything), but were you able to measure the Le at the frequencies you were listening at? Coming from a pro audio background, it makes perfect sense that the drivers you listen to would have a lower Le than the big excursion monsters available today.

Best,
Mark

**mrogowski** · **05-13-08, 07:23 PM**

Quote:

bobgpsr wrote:

I agree that low Le is desirable to keep a flat freq response in the higher freq bass up to the point that is well beyond the sub crossover.

Not necessarily my friend. Remember the extremely narrow passband your sub is covering. A frequency response of the driver will tell you what it is capable of - not inductance.

**bobgpsr** · **05-14-08, 08:10 AM**

Quote:

mrogowski wrote:

A frequency response of the driver will tell you what it is capable of - not inductance.

Or modeling with software such as UniBox, BassBox, WinISD, etc. You then find that particular driver parameters have a significant affect on the modeled frequency response. My modeling experience shows that Le does correlate with the rolloff in subwoofer frequency response at the upper end of the desired passband for a subwoofer. Have you tried modeling different drivers that have a significant Le difference in a particular enclosure design?

**mrogowski** · **05-14-08, 09:34 AM**

Quote:

bobgpsr wrote:

Or modeling with software such as UniBox, BassBox, WinISD, etc. You then find that particular driver parameters have a significant affect on the modeled frequency response. My modeling experience shows that Le does correlate with the rolloff in subwoofer frequency response at the upper end of the desired passband for a subwoofer. Have you tried modeling different drivers that have a significant Le difference in a particular enclosure design?

Certainly I have. Have you done said modeling and then performed a frequency response of the driver? Then, have you tried to correlate what the modeling and response curves say to actual blind listening tests (against another driver - A/B testing) to see if you could actually *hear* the effects of inductance? Your ears after all, are the deciding factor here, not a modeling program.

I dunno. I guess I'm looking for actual scientific evidence showing a sub with a higher inductance is crappier than one with lower inductance. On a personal level I have listened to a pile (not pyle

) of drivers myself, run a variety of frequency sweeps, impedance curves, distortion measurements, modeling, box building, and have still been unable to point to a driver and say "Ah ha! There it is! There's that silly inductance playing tricks on me!".

One can dream though...

**elawton** · **06-12-08, 12:13 AM**

Okay here's an update from my research.

Enclosure - I found a simple slotted port 4 cu. ft enclosure design here - http://www.aespeakers.com/phpbb2/vie...php?f=4&t=1611

I feel confident I could tackle 2 of these to start me off. I like the front port design and the modularity so I can stack the 2 cabinets in my preferred corner placement, and add 2 more later if I feel like it for the look of a vertical array which I think is cool, or move them to a different location in the room. The size is just about right for my corner location and 12" drivers.

Material - MDF

Finish - Really all I will see of the enclosure is the front baffle. I just want a smooth glossy black finish. I was really impressed with the fiberglass finish and electroluminescent edging of Alvarez's build. See - http://www.hometheatershack.com/foru...ding-ib-4.html

I was blown away when I got to the end of that thread! The plexiglass addition could work, I think, with the above enclosure design sandwiched between the 2 pieces of the front baffle.

I would not attempt the curves and fiberglass like Alvarez's build. I will probably just leave the baffle flat and paint it, varnish it, no grill of course so the driver is visible.

I'm thinking of adding a sound-sensitive adapter for the EL wire. I'm sure it will put a smile on people's faces to see the light beat to the music. Perhaps I could experiment with placement of EL wire in the slot, which kind of accentuates that feature of the design.

EL wire here - http://www.elbestbuy.com/
Adapter here - http://www.elbestbuy.com/elwire3.html

The EL ring around the drivers would look complement my lighting design and the Emotiva LPA-1 amp and MMC1 pre-pro I've got my eye on. Emotiva - http://www.emotiva.com/mmc1.html.

Match that with a few neon signs from Foosign.com and other touches and it will all come together I think.

Drivers - I like the reviews and price ($148/driver) of the Infinity kappa perfect 12", as in - http://www.hometheatershack.com/foru...fect-12-a.html

Quote:

Quote:

This sub measures lightning fast, there's no ringing at all!
The distortion above 40 Hz is less than 5% at a flat 102 dB!
I bet this sub would be incredible for music.

Sub amp - not sure about this yet. I read a lot about the Behringer 2500, but I haven't made up my mind. The fan noise issue is holding me back.

Any comments are welcome.

**Mike P.** · **06-12-08, 04:07 AM**

Are you aware there is a fan modification for the EP2500?

http://www.hometheatershack.com/foru...er-ep2500.html

**willy-be** · **06-12-08, 09:12 AM**

Sorry I'm a little late to this party. I've run Maggies for a long time and would only mate them with a sealed box sub having a Qtc 0.50 aka a critically damped alignment

The rise time of ported box makes them a poor match for planar speakers.

Dipole or IB sub would be the best match, but most people aren't able to accommodate those kinds of designs.

**bobgpsr** · **06-12-08, 11:00 AM**

Quote:

willy-be wrote:

The rise time of ported box makes them a poor match for planar speakers.

Really? For what port tune? What about a port tune of 15 Hz? With such a design the port will only contribute for 25 Hz and down. Do you think the very low bass freqs (10 to 25Hz) rise time (aka phase delay) is heard easily with human ears?

I would agree with you for port tunes of 25 Hz or higher.

**elawton** · **06-12-08, 08:58 PM**

Willy-be, sorry I don't know what Qtc is or "critically damped alignment" is. Over my head. Care to explain?

You mentioned "rise time". I can think of a couple of things that might apply to...guessing in this context you mean the responsiveness of the sub driver to a signal compared to the responsiveness of the planar speakers? The reviews of the Infinity Kappa Perfect drivers indicate they are "fast".

So, are you saying the enclosure (slotted vs. ported vs. sealed vs. IB vs. LLT) can make that much of a difference with exactly the same driver? This is probably a sacrilegious remark here. I'm not discounting what you are saying, it's just that I don't understand why a sealed enclosure is preferred to the slotted/ported.

I still could do an IB design as stated earlier in this thread by opening a hole into the space below the stairs adjacent to my HT room. Would you recommend the vertical array with 2-4 of these Infinity drivers and simply cutting a large hole in the wall in the adjoining wall to add that volume? The hole will be invisible.

**willy-be** · **06-12-08, 09:34 PM**

http://www.geocities.com/kreskovs/Box-Q.html

You want a sub that has the best transient response (rise time) if the goal is to match your Maggies. The subs with the best transient response are dipole or IB, next best is sealed, then ported, then passive radiator.

The Infinity is an ok driver there better choices.

**mrogowski** · **06-14-08, 06:31 PM**

RLP's would fit this setup just fine...

**Ricci** · **06-15-08, 01:06 PM**

Elawton,
If you can do an IB I think that most would agree that this is the way to go. There are better drivers than the Infinity's for IB though. IB is all about massive displacement. 2 big long throw 18's would be a better and cheaper choice than 4 12" Infinity's. I'm not knocking the Infinity's. They are a good driver just not really the best choice for IB. 4 15's or 4 18's would be killer. Ficaraudio has some good ones. The Tempest X is a good choice too. The AE IB15 is available in lots of 4 for $400 I believe.

If you decide not to go IB, Rythmik Audio's servo kits might be worth a look. By all accounts they have great SQ.

**BB_SLO** · **06-17-08, 03:00 PM**

Hi!

I had Maggies with a ported Sub, and it was not the best choice.

After my first IB's was build it was a much better choice. I had only problems with Phase shift. So the next step was to buy an amplifier with Phase adjustment - better, but still not perfect. For Maggies with IB i suggest a location of IB's close to Maggies...

Greetings from Slovenia, BB

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