Stetsom 7KD protection issue

[Mtxplod 0]

I finally installed the stetsom 7KD (1 ohm 12 volt) and it ran very well but just yesterday it began going into protect.It throws a protect with one blink and the manual tells me that its a short circuit or below impedance.I'm running the amp at a half ohm nominal. It starts doing this when i roll into heavy bass. I triple checked all of my connections and everything is solid, voltage is in mid 13's when it cuts off. 

 

[Julian 641]

You answered your own question.

[ricksi30 923]

You answered your own question.

Yeah.....

 

1 ohm stable amp that is protecting from too low of a load. You are running a .5 ohm load. What is your question?

[Mtxplod 0]

that's only nominal impedance.  reactive should be close to 1.7 or so, im thinking?

[ricksi30 923]

that's only nominal impedance.  reactive should be close to 1.7 or so, im thinking?

You need to be concerned about your starting impedance. 

[ricksi30 923]

There are 2 major factors that I think will kind of help explain what you are asking(?)...

Normally, in a vented 4th order alignment (which is most of what we discuss on here) you are going to have 3 impedance peaks. The first 2, which will be domiant for most of our applications, are the peaks below and above the dip (trough) at tuning. The 3rd peak, and not quite as signifigant (or completely ignorable if you are totally out of the bandwidth) is the gradual peak that is caused by the inherent inductance of the voice coil.

So, an easy way to describe the first 2 peaks.... At resonance, the cone of the subwoofer is highly damped by the entire system attributes (mainly the Hemolitz resonation taking the load from the cone in an efficent manner) and due to the high amount of dampening (control) the reactive electrical properties are at a low point (null) and load is moved into a more resistive (reactance properties start cancelling each other out) realm... Above and below this point dampening suffers quickly and is immediately apparent due to the high amount of impedance shift... I am not sure if this is broke down well for understanding... I haven't really had to explain this many times and there are alot of people out there who could convey this better than I...

The 3rd peak is easy. The voice coil is an inductor, inductive reactance is proprtional to frequency. And a little food for thought, some overhung designs have 4-5mH of inductance, this starts raising impedance signifigantly as low as 100 Hz or so....

This is why I always say there is no such thing as "Impedance Rise".... You can see, the impedance goes up and down alot...

[Mtxplod 0]

that's only nominal impedance.  reactive should be close to 1.7 or so, im thinking?

You need to be concerned about your starting impedance. 

you wouldn't mind explaining to me how the amp sees that when its not putting out would you?

Thanks.

[ricksi30 923]

 

that's only nominal impedance.  reactive should be close to 1.7 or so, im thinking?

You need to be concerned about your starting impedance. 

you wouldn't mind explaining to me how the amp sees that when its not putting out would you?

Thanks.

Look up one post. A quote from someone on here much more knowledgeable than I am.

[ricksi30 923]

And here http://www.soundsolutionsaudio.com/forum/topic/30610-why-daily-systems-should-not-count-on-impedance-rise/

 

Plus from what I have heard those amps are pretty sensitive. 

[Mtxplod 0]

And here http://www.soundsolutionsaudio.com/forum/topic/30610-why-daily-systems-should-not-count-on-impedance-rise/

 

Plus from what I have heard those amps are pretty sensitive. 

you're very correct about them being sensitive. 

but i think that I'm starting to understand this.

The damping factor is killed when playing music at loud volumes and because of that the impedance can fall below the nominal load? 

[ricksi30 923]

And here http://www.soundsolutionsaudio.com/forum/topic/30610-why-daily-systems-should-not-count-on-impedance-rise/

 

Plus from what I have heard those amps are pretty sensitive. 

you're very correct about them being sensitive. 

but i think that I'm starting to understand this.

The damping factor is killed when playing music at loud volumes and because of that the impedance can fall below the nominal load? 

Impedance can fall to the nominal load, which in your case is .5 and too low for that amp.

[Mtxplod 0]

 

And here http://www.soundsolutionsaudio.com/forum/topic/30610-why-daily-systems-should-not-count-on-impedance-rise/

 

Plus from what I have heard those amps are pretty sensitive. 

you're very correct about them being sensitive. 

but i think that I'm starting to understand this.

The damping factor is killed when playing music at loud volumes and because of that the impedance can fall below the nominal load? 

Impedance can fall to the nominal load, which in your case is .5 and too low for them amp.

ok, ill wire it to two ohms and see what happens! 

now I'm butt hurt because I'm "that guy" that couldn't run his 7 K at a half ohm

[ricksi30 923]

Do you compete?

[Mtxplod 0]

Do you compete?

oh, no.  i just love car audio. i did this for sheer fun... and to scare deer away so i don't hit them at night ^-^

i would love to get metered though.

[djjdnap 78]

I dont see why ur hurt.

Im the guy that ran his at .5ohm for a day and it caught on fire and had to send it in for repairs.

id rather be you  at this point.

[Mtxplod 0]

I dont see why ur hurt.

Im the guy that ran his at .5ohm for a day and it caught on fire and had to send it in for repairs.

id rather be you  at this point.

Well thank you. that really boost my spirit. I guess i lucked out. 

good luck with that build though.

[ricksi30 923]

Do you compete?

oh, no.  i just love car audio. i did this for sheer fun... and to scare deer away so i don't hit them at night ^-^

i would love to get metered though.

You will be fine at 2 then.

[Mtxplod 0]

 

Do you compete?

oh, no.  i just love car audio. i did this for sheer fun... and to scare deer away so i don't hit them at night ^-^

i would love to get metered though.

You will be fine at 2 then.

Thanks, ill try 2 ohms and if i still have problems, squaretrade has my back.

[Mtxplod 0]

wired it to 2 ohms and still have the same problem. is this protection triggered by output only?