Underground Sub

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
You need to separate front and back sub arrays to different back spaces with DBA, because back array is driven with inverted phase. With same back space to all drivers you wont get any output from sub, because of acoustic cancellation.

I guess DBA theory is based to rectangular room, so no one cant predict how it works in that shaped room. Probably still better than some other system.
 
Keeping the back space separate shouldn't be a major problem.

I have reworked the room a bit to restore a more rectangular shape and get the size down a bit. Current rendition is 12 meters long by 8 meters wide.

It means having to use a combination of back space and some under slab space to cut 2 meters off the width.
 

Attachments

  • Home Theatre Room 15.jpg
    Home Theatre Room 15.jpg
    79.2 KB · Views: 160
Hi,

worked with the 18" LMS Ultra and 15" LMS of TCSounds.
Both drivers are true Killers in their class. Unlike most of these very heavy and longthrow drivers, they show exceptional good lowlevel resolution. If pushed hard they will deliver.
After my taste they work best in CB. Their parameters are very well suited for rather small volumes and bass-eEQued (kind of ELF). Just keep it straight and simple. No fancy casings are required. CB in a inWall situation is perfectly ok.
You need a powerful amplifier though. A class-D amp comes top mind. See for example the Powersoft Digimod1500 and 3000PFC.
Powersoft also offers a interesting new motional feedback concept with specialised B&C drivers, dedicated amp and FB-sensor, the IpalMod.

jauu
Calvin
 
Hi Calvin, I have something similar to what you suggested already... I have 1 x RB1092 Home Theater System Surround Sound Amplifier DVD Player - Rotel PRODUCT SPECIFICATIONS and 1 x RB1091 Home Theater System Surround Sound Amplifier DVD Player - Rotel PRODUCT SPECIFICATIONS

To date I have yet to be impressed with the TC Sounds Pro 5100s but that is largely due to how I am using them, in a plain OB baffle the barely move more than 1mm or 2mm (perhaps too stiff).

I think in a closed box or something that provides a bit of resistance they could really shine. From what I have read, with the amp I have powering them, they should be delivering a lot more than they do. If I turn off the RB1092 I barely notice them gone (slight exaggeration but not too much).
 
Hi,

open baffle, or smaller sized folded dipoles are imo not really suitable for home cinema. The here regularly occuring very low signal frequencies would require impractically large membrane areas and excursions. Still though sonically a dipole can´t supply for the desired ´pressure´ and slam. A more classical approach as subwoofer, i.e. a monopole, just used below the lowest room mode (hence working under very efficient room pressurization, hence it should be a CB) offers all one could wish for. Precision, resolution, dynamic range and reasonable power efficiency.

I don´t wonder that You didn´t achieve positive results with the Pro5100 in a dipole configuration. It´s parameters suggest a BR casing or similar. The three only parameters suitable for a dipole useage would be its size, the long excursion and its Fs. Teh needed EQuing is quite heavy. Wo EQ I don´t wonder at all, that You hardly notice any difference betwen On and Off.
For a true Subwoofer playing from the infrasonic range up to max. 50Hz the 18" LMS Ultra5400 and the LMS-R15 feature a superior set of parameters.

I use 15" LMS15 in a small EQed CB (global shaped, monolithically cast concrete, see pic) driven by 1500W@4Ohms class-D modules and it seems this power is just sufficient. The 18" requires more, something like the afore mentioned Powersoft 3.4kW module.
500W is what I would try with a 12" driver.
All that of course with the idea of home cinema in mind. For home hifi I´d accept less powerful amps.

jauu
Calvin
 

Attachments

  • Subwoofer.jpg
    Subwoofer.jpg
    66.6 KB · Views: 141
Last edited:
Last edited:
I've heard the Dayton's in a closed box and they lack the clarity I am looking for in LF bass, I have no issues in buying a lot more of them to get depth with clarity / control I am looking for without the thumpiness normally associated with boxed speakers.

I really would like to keep the Pro 5100s in an OB / IB configuration but at $2500 landed with taxes I can't afford to buy a whole lot more of them to get results, but at < $200 each (plus freight + tax) for the Dayton's, that isn't so much an issue.

So while IB isn't the most efficient way to go, I do believe it will deliver the cleanest results.
 
Last edited:
Hi,

I haven´t worked with the Pro5100, since I was searching for a very capable driver in a rather small CB. So I tested the Ultra5400 even though it is terribly expensive. Cost and dynamic-wise a pair of the LMS15R are similar to a single Ultra5400. The pair of 15" requires slightly more volume than the single 18", but is easier in handling and allow for effective mass-momentum cancelation.
The 18" weighs incredible 36kg(!!) which asks for a mounting fixture and helping hands. The 16kg of the 15" are already something to really struggle with if You´re alone. It might also be easier to find good amps in the 1kW-1.5kW class than in the 3kW-4kW class.
So far I never pushed the pair of 15" to their 60mm excursion limits. Room, cubboards, closets and ears always gave up first.
The concrete casing, the sperical shape and the momentum-cancellation are so effective that one can´t sense any vibration of the casing by touching.
Probabely the ´quietest´ commercial Subwoofer.
These extreme-longthrow drivers enjoy and require a really really tight fixation to the casing and a extremly stiff casing with highest damping (in contrast to absorption). I´d rather discard wood as building material.
If You mount several of these drivers mechanically parallel into a wall, You need to waste some thoughts on how to keep the wall quiet.

jauu
Calvin
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.