dual voice coil, amp, ohm ....newb questions.

[evan 10+ year member]

Please forgive me if there is improper wording. Help me out, I'm a noob.

Answer the following questions with True(T) or False(F). If you answer false, please explain.

• 1. The number of ohm's being drawn from an amp is determined by the type of sub attached to it.
   
  
• 2. A dual 1 ohm sub draws 2 ohms.
  
• 3. Two 2 ohm subs wired together will draw 1 ohm from an amp.
  
• 4. Not all amps are stable for extended use at 1 ohm.
  
• 5. A dual 2 ohm sub draws 4 ohms.
   
  

Thanks.

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[azimuth 5,000+ posts]

Please forgive me if there is improper wording. Help me out, I'm a noob.
Answer the following questions with True(T) or False(F). If you answer false, please explain.

• 1. The number of ohm's being drawn from an amp is determined by the type of sub attached to it.
   
  
• 2. A dual 1 ohm sub draws 2 ohms.
  
• 3. Two 2 ohm subs wired together will draw 1 ohm from an amp.
  
• 4. Not all amps are stable for extended use at 1 ohm.
   
   
  

Thanks.

1.) the subs voice coil/coils determine the ohm load

2.) dual 1 can be wired to .5 or 2

3.)wiring them in parallel would present a 1 ohm load. series would be a 4 ohm load

4.) T

 

[evan 10+ year member]

• A. If a sub is a dual 1 ohm, but is actually 0.7/coil, that means it will be pulling 1.4ohms?
   
  
• B. Are most amps that are rated for 2 ohms capable of running at 1.4ohms?
  
• C. Should I compensate with an amp that is slightly over, or under powered to deal with the 1.4ohm instead of 2ohm load?
  

 

[evan 10+ year member]

OK, I just found this on another forum.

Zc is coil impedanceZt is total impedance

Parallel: Zt = 1/[(1/Zc)+(1/Zc)+(1/Zc)+ ....]

Series: Zt = Zc+Zc+Zc

Series/Parallel: Zt = 1/[(1/(Zc+Zc))+(1/(Zc+Zc))+(1/(Zc+Zc))]

The nominal impedances for those drivers are Dual 1ohm & Dual 2ohm... the numbers you are asking about at the DC resistances of the coil.

What I get from this is.... the coil impedance is .7, but when you factor in the real world you get the total impedance which is 1 ohm. Therefor, the total impedance of a dual 1 ohm coil sub will add up to 2 ohms.

Let me know if I'm off track.

 

[evan 10+ year member]

Until tonight I've just been using this forum for info, but there are others that are helpful too.

I found this on http://www.soundsolutionsaudio.com/forum/ and I thought I'd post this here since it was helpful to me.

The DCR of the coils is .7 or 1.4 Ohms, but the nominal impedance (what you really pay attention to for a daily application) is Dual 1 or Dual 2. The DCR is what you read with a multimeter. The nominal is what the amp actually reactively sees as an absolute minimum. Once in an enclosure, it will be well above even the nominal (but this rise is application dependant at that point).

Thanks...

Scott

 

[johnecon2001 5,000+ posts]

ok?

So what is the actuall question here?

 

[n2audio 5,000+ posts]

• A. If a sub is a dual 1 ohm, but is actually 0.7/coil, that means it will be pulling 1.4ohms?
   
  
• B. Are most amps that are rated for 2 ohms capable of running at 1.4ohms?
  
• C. Should I compensate with an amp that is slightly over, or under powered to deal with the 1.4ohm instead of 2ohm load?
  

You're trying to roll 3 speaker specifications/measurements into one.

Nominal impedance

DC Resistance (voice coil resistance at rest)

operational impedance

The resistance rating that is always given with a speaker's basic specifications is NOMINAL IMPEDANCE, and unless you're getting into SPL competition trying to milk every last bit of power from your amp w/o burning it up I'd suggest you disregard DC resistance and impedance.

You're trying to go straight to the more advanced stuff (ac impedance) w/o completely understanding the basics. If you have a dual 1 treat it like a dual 1 - at least for now.

• A. no, during real world operation a speaker will rarely (if ever?) present its measured dc resistance. It's usually quite a bit higher.
  
• Yes
  
• no need

 

[evan 10+ year member]

OK, thanks. I think I've wrapped my brain around it now.