Basic starter build. Newbie no clue

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Hi, I am going to try a simple build but I am pretty clueless! Ive decided to try a small subwoofer which I will either use as a nearfield subwoofer in a home cinema setup with a 15 or 18 subwoofer to come in the future to handle more of the low end or maybe to supplement my pc based music system in the office if the cinema application doesnt work out. The main subwoofer is in a far corner and gets a lot of gain from 35 down but creates a null between 50 and 60 depending whereabouts on the couch you sit. For light tv and music it will probably be the only sub turned on and the bigger sub engaged on movienights.
I bit the bullet and bought 2 RSS210HO-4 (8 inch) subwoofers (RSS210HO-4 8" Reference HO Subwoofer 4 Ohm Specification Sheet) but now am not entirely sure what to do with them! After lots of unconvincing playing with winisd I am probable not that much the wiser but I am keen to get going in the garage actually doing some building.
The aim is for a subwoofer that can be crossed at 100 with some MK speakers and produce (for lack of a better word) clean bass down to 30. The room is less than 1500 square feet. It is going to be driven by a stageline amp (sta-225) which should give 750w bridged into 8ohm or 2x350w into 4 oh rms.
A narrow long shape would fit well into the space I am thinking of which is right next to the which is the MLP and in will pretty much be an inch away from brick walls on two sides.
So I was thinking dual opposed (in phase) and wired for 8ohm load.
Box size 20x15x10 using 18mm mdf and double baffled at each end. Maybe two pieces of bracing in using 18mm mdf with holes cut in. Size wise I could go bigger but dont want the width to increas from 10 inches. It can go higher ore longer.
I have a minidsp to eq.
Does this sound anything like sensible or am I going about it in the wrong way.
Not a very interesting build I know but would appreciate your thoughts.
Thanks
 
Thanks Dan, I did consider ported but think it may be more of a complication for me at this stage so I was going to go sealed so less can go wrong. Maybe move on to a ported slot in the future.
Basic question, I have the drivers now. What is the best way to test them for faults.
Should I run them in free air for a while and if so is that at low power with a test tone or music? Thanks
 
Well its been a while but I have made a solid box.
Wired it up for the first time.... and destroyed everything!
It may be salvageable but what happened is I wired the 2 woofers in series with the + going into one woofer. then the - connecting to the + in the second woofer with - then going back to the amplifier. Or at least I think that's what I did.
The amplifier is a stageline sta 225. It was set in bridge mode and I wire the woofers to the two + outputs as the manual describes for bridged output.
My aim was to create a 8ohm load supplied by the amps 750 rms bridged output (at 8 ohm) The daytons have a rms 300w capacity and 600 peak individually.
I did it in a rush and played some heavy bass scenes. The subs were firing in phase but didn't seem to be outputting much bass even though there was a lot of cone movement. Instead of checking wiring etc I turned it up and the drivers started to overheat and then cut out. Followed by a burning smell from the drivers so thought the voicecoils were fried.
I was in a bit of a rush at the time so presumed I had killed the drivers and disassembled and put in garage.
I have today got it all out again just to double check and have discovered that the stageline amp is turning on fine but is not actually outputting any signal so that looks fried. I tried the subs in free air with a behringer a500 and they both actually seem to be working. Well at least with low level music. My concern is they still have a burned smell if put nose close up close to the bottom of drivers. This was before I tested them and it doesn't get worse when testing them.
What is the most likely damage I have done to the drivers and are they safe to test further or should I write them off.
Any help is appreciated
 
Thanks GM, got the paper copy of the manual and in the first section in German it has a folded back page and within there it does indeed have different ratings for wiring two subs together. In the english section it just has a table saying 8ohm bridged is 750. I didn't realise wiring in series was any more complicated than what ohm they show and the rms capacity of the combined subs. Sounds like it was my bad. Drivers are now showing 2 ohm readings so looks like they are damaged. Along with getting the box right on the third attempt this has been a learning experience just a pity I don't have a working sub at the end of it!
 
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