Brainstorming needed: WANT to ADD resistance without changing woofer.

[BassAddictJ 5,000+ posts]

Oh man, here we go....

So I've had my amp worked on a few times by a very reputable specialist, and the problem seems to be my 0.8ohm DCR load going to my rated 1ohm amp. I have okay (not ideal, but not bad) current on tap, and the amp components that keep failing are consistent with running below rated imp. Sure there's imp rise, but that only happens after cone movement and a bit of playing. When that signal first hits it's stressing those parts that aren't rated for under 1ohm. I realize most woofers (custom or OEM) come with DCR's a bit lower than the nominal rating...but what I'm told makes sense and I want to keep my amp in it's rated stable range. This guy sees the same problems and ALLLL kinda of amps (sundowns, AB, us amps, RD's, you name it) they all pop eventually running under rated imp in time, its just a matter of when.

I have WAAAAY too much time and money put into my sub and sub amp. Changing them out for something else really something I'm trying to avoid. And I cant afford to keep fixing it every other month. So aside from beefing up mybattery bank a little, I have an atypical idea....

I'm thinking about finding a spool or wire, say 20ft or whatever of 8awg or something...something with about .2ohm resistance, and put it in series between the amp and sub. It'd have to be wire that'll handle that kind of current, and it'll need to have proper heat dissipation....I'm just wondering if anyone knows a specific reason why this would be a terrible idea? I know it's not ideal, none of this is....but if I can just get my load to the amp to sit a tad higher safely, I'll be happy....and I'm skeptical there's any dummy resistors out there that'll do the resistance AND current capability I need without being a fire hazard.

Thoughts??

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[Haunz 10+ year member]

Ideally the amp should have been repaired with more powerfull fets that can handle a little more current... Although thats not always possible...

The easiest fix is to simply turn the gain down and ask the amp for less current... trying to use a resistor to change the subs impedance is a bad idea and probably wouldn't work anyway... (you would need a pretty big resistor and would just be wasting power, not to mention messing with the damping factor which could become audible - why not just turn the gain down)... Using a long piece of speaker wire is almost just as silly...

The only feasible way to change the load the drivers present to the amp without changing the drivers themselves, is to use a transformer.. accumatch and some other company make autoformers designed for audio use but IIRC they are made to double or halve the impedance, not change it just a little bit, and can only handle a limited amount of power... you could try and find yourself a 1:1.1 transformer or something similar yourself, but IMO you would be further ahead to just change out the gear for something else...

ON THAT NOTE: A 1ohm stable amp should have absolutley no problem with a set of subs that have a DCR of .8ohm... my suspicion is you have an intermittent short going on somewhere... check your wiring and make sure the sub's tinsel leads are not shorting on eachother or the basket.. if you suspect that could be a problem coat them in liquid electrical tape...

 

[BassAddictJ 5,000+ posts]

Leads should be fine. here's the sub:

Spencers TRF-Ti 15" monster - Car Audio Classifieds

Last time around the repair guy (ampmedic) was able to put better quality mosfets in than were in there before. Don't quote me but I want to say it was just the diver board that went out this time (first time the driver board and mosfets went). I was getting proper rail voltage on one side but nothing on the other. I'll get more accurate details when I speak with him next. The guy know's his amps though. He works his *** off and basicaly lives inside these big amps. I believe him when he says the amp isnt liking the .8ohm load.

I figured it'd be fine too, and maybe my gain is too high. Input voltage is like 2v so I needed the gain kind of high to begin with. But it wouldnt hurt to draw it back a tad. I'm sure more battery juice would help too. I'll go back and double check my connection to and around the amp to make sure there isnt a minor short making big issues.