DIY sub blowing fuses

[Haaspac]

As stated in my other thread, I finally finished building my 18" sub. The cone is a Monacor SPH 450TC. The amp is a RCM acoustik Detonation DT300 plate amp. I originally hooked up the amp/speaker in 4ohm config and the fuse blew in the amp in about 5-10 minutes. I replaced the fuse and the amp blew again. I replaced the fuse AGAIN, bridged the 2 voice coils for an 8ohm load, redid room equalization, fuse blew in about 5 minutes. I am throwing my arms up right about now cursing the speaker gods for not allowing me to shake my house and my neighbors houses with my new 18" sub. I am getting just a small taste of the power and then the fuse goes. It is plugged into an APC power conditioner and replaced my SVS PC12 NSD which worked for years without failure.

Is my amp undersized for the speaker? is the fuse (4a125v) too small? Is the amp just toast? Is the speaker cone bad? I don't know what else to do other than buy a new plate amp and resize the hole in the back, or plug up the hole, add a terminal, and get a rack mounted sub amp to sit somewhere.

If I am just screwed and I have to buy a new amp, can someone recommend me a proper amp to fit my speaker?

 

[fuzz092888]

If it's a DVC sub, then if wired properly you had them in either series or parallel. In series you should have an 8 ohm load and in parallel you should have a 2 ohm load. I don't know what size box you have that in or what it models best in, but at 300/600peak you could very well be overtaxing the amp which is causing the fuse to blow.

Then again, I just saw that you had the amp repaired. If they simply repaired anything they saw, or perhaps did not make sure the amp was operating to spec and only testing power on, they may not have fully solved the issue. In any case, I'd be looking at a new amp before you possibly damage the driver.

 

[Haaspac]

http://www.parts-express.com/dayton-audio-spa1000-1000w-subwoofer-plate-amplifier--300-809#lblProductQ&A
If I am to be looking for a new amp, then what wattage should I be looking for? This is the biggest plate amp that PE sells.

speaker specification:
http://www.monacor.de/en/products/speaker-technology/pa-bass-speakers/18/sph-450tc/#

The box I built is 750mm wide x 700mm deep x 610mm tall with 28mm wall thickness MDF or roughly 30inch x 28inch x 24inch box. I for sure wired it correctly to bridge the 2 voice coils into a 8 ohm load just like this :http://www.the12volt.com/12voltimages/1_4ohm_dvc_8ohm.gif

 

[fuzz092888]

So it is a sealed box. Is the front baffle doubled or are all walls 28mm?

With those dimensions and 28mm wall thickness all around, I'm getting a pretty peaked response that looks like it needs a bit of EQ to get it flat. However, in terms of power, you should be fine with 300 watts, depending on how low/how much EQ you plan on adding to it. It will also depend on what what the volume of the space you are trying fill is and what kind of output you are shooting for in that space.

 

[Haaspac]

Not sealed, 4 ports on the front. all walls are 28mm thick. the Volume dial goes from 7oclock for 0 and 5oclock for full volume, I had the knob set between 8 and 9oclock on the sub amp for my receiver to do its auto room equalization and never touched it again. played music for a couple of minutes and blew the fuse.

the room is the first floor of my house, its pretty open, no doors except on the bathroom door and washer/dryer room.

My SVS pc12 nsd subwoofer works absolutely fine and sat where my new 18" sub sits for the past 3 years without any problem at all.

 

[fuzz092888]

Ported is a different ballgame and should have less power requirements than sealed. Just get a new amp and you should be all set.

 

[Haaspac]

what amp would you suggest? something from Parts express?

 

[fuzz092888]

what amp would you suggest? something from Parts express?

Personally I like pro amps to run my subs. Right now I have a Peavey IPR2 and a Crest Pro Lite 5.0 and I've had AB International amps and Crown XLS. I've never been a huge fan of plate amps, especially since if something goes wrong you have a big whole in your sub box that you have to find a replacement for that has to fit that cut out.

PE sells crown XLS, one of those should be more than enough. I'd probably go with the 2500 if you can afford it, but the 1500 would most likely be enough as well.

 

[ARES24]

I got a Crown 1002XTI from PE I will definitely be a repeat customer when I am looking again. Just my $0.02.