[sapphari]

My subwoofer amp does not have a variable high pass crossover - it only has a 'subsonic filter', which is a high pass crossover pre-set at 25 Hz (presumably with a sharp dB/octave curve). My ported box is tuned to 34 Hz (recommended by woofer manufacture). My understanding is that a woofer can be damaged when reproducing frequencies below the tuning point of a ported enclosure. Am I setting myself up to blow my woofer because I cannot cross over at or above the tuning point of my ported box?

 

[Weigel21]

I've heard recommendations of setting within 5Hz below the tuning for the SSF, but I've also heard that a driver is unlikely to sustain damage from frequencies unless they are more than 1/2 an Octave below the tuning. I've followed the 5Hz rule personally, but the 1/2 octave thing may hold some truth. If such does, then you SSF would be set 1Hz below the allowance, which it it's not a very sharp slope of 24dB or more and you happen to play audio with frequencies that present a danger, damage may result.

Another, more knowledgeable, member may have more to say on the matter, so cross your fingers.

 

[Weigel21]

If we/I may, what are the models of the amp and sub? If you feed the sub less than rated power, like 2/3's or less, that would reduce the risk of damage dramatically, though who honestly wants to reduce potential output of their sub. LOL

 

[sapphari]

One-half octave lower than 34 Hz would be 25.5 Hz. I may just email Sundown and see what they say.

amp: Orion Cobalt CO24001D Mono Class D Car Amplifier
sub: WoofersEtc.com - SA-12 D4 - Sundown Audio 12" 600W Dual 4-Ohm SA Series Subwoofer

Sub is rated at 600 W RMS. In my wiring, I'll be giving it 800 W at 2 ohms, so not on the conservative side. Though I have read people routinely give it 1200 W. I'd get a new amp with variable pass crossover before giving the woofer less power

 

[Weigel21]

Yeah, I hear you, less power is the devil. LOL

Feeding the sub 800RMS and with the SSF .5Hz (1Hz) higher than 1/2 and Octave below the port tuning, I'd say you'd be pressing your luck, if you play a lot of music with deep lows.

I know I've read of people pushing the SA's hard as well and handling it well. What I don't know is how it is they know they are feeding it X amount of power regularly. 1200RMS sounds like a stretch of the imagination to me, but what do I know, I've never pushed any sub with twice it's rated power, even when a couple I've ran were "known to handle more".

Guess we'll see what sundown has to say.

 

[sapphari]

Thanks for the input. I'll reply back with the answer from Sundown. Hope I'm in the clear, don't really want to return the amp.

In the meantime, I'm interested to hear others' opinions.

 

[Weigel21]

In the meantime, I'm interested to hear others' opinions.

Ditto

 

[sapphari]

I have a hard time believing no one else has the answer to this question. Do I need to post this in the advanced forum? I thought it was a pretty basic question

I emailed Sundown, still waiting to hear from them. Grrr.

 

[snyderd758]

Sundown is probably going to tell you that you need a ssf especially if your overpowering the sub(keep in mind though that you probably will never see the rms you set the amp to depending on how you set it). You can buy stand alone ssf or back your amp gain down a little and probably be ok. The 2 options I think you really have are buy an outboard ssf or build a lower tuned box. If the sub is new and you damage it from unloading most company's wont cover I know sundown has stellar customer service and may cover it but most other companies would consider it user error.

 

[sapphari]

Thanks for the input, much appreciated. The port on my box is an aeroport, so I could swap out the tube for a lower tune. That would be cheap and easy. Another other option I have is to return my amp and get a new one that has variable high pass crossover. Unfortunately I overlooked this detail when I originally purchased the amp. Third option is the SSF - looks like Harrison Labs has some at line level that would work. Fourth option is just risk it

 

[snyderd758]

I have used the fmods they suck cut the output drastically. If you can return the amp that is what I would do your pretty limited in that price range. Ive seen some decent reviews on this amp though as far as budget friendly goes.
Precision Power PPI BA2600.1D 2600W Class D Car Amplifier

 

[sapphari]

I've read a lot of people run this with the SA-12 and are happy with it. It has the variable xover, same price as the Orion:

Hifonics BRX1100.1D Class-D Monoblock 1100W Brutus Series Amp

 

[sapphari]

Hifonics draws a lot less current too. Which means I could have gone with 4 gauge instead of 0 gauge power wire. Ugh.