 Re: Difference between impedence specs
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Joined: Feb 2004
Posts: 1,863
connoisseur
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connoisseur
Joined: Feb 2004
Posts: 1,863 |
Punisher, if your looking at speakers that are 2 ohm's you will need a serious amp to power them. The way that amplifier companies make the amp stable to a lower impedance is by adding transistors, the more transistors the more power and the lower the impedance the amp will be stable to.
Depending on the speaker manufacture, some label the normal impedance, others will give you the normal, and minimum at the frequency that the minimum occurs at.
Any average receiver will have a onboard amp powerful enough to power a 6 or 8 ohm speaker. Some receivers can power a 4 ohm load, Denons are popular.. for a 2 ohm speaker, most receivers will not have an amp powerful enough to power those, you will need to find a dedicated amp that is stabile to 2 ohms. Plan on spending some cash for one.
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Re: Difference between impedence specs
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Joined: Feb 2006
Posts: 6,471
axiomite
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axiomite
Joined: Feb 2006
Posts: 6,471 |
Maybe I should have Mark talk to the women for me.
Bears, beets, Battlestar Galactica.
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Re: Difference between impedence specs
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Joined: Apr 2009
Posts: 40
buff
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OP
buff
Joined: Apr 2009
Posts: 40 |
Thanks for the responses. Not quite clear about the explanations. I should probably explain the issue I'm having - I have a pair of Senheisser HD650 cans that are rated at 300ohms. I have Logitech Z5450 speaker which I sometimes listen to through my headphones.
The problem is I have the volume turned all the way up and it's not loud enough (sound is about average volume but not loud enough for me) through the headphones. Its probably because the Z5450 has a crappy amp for the headphone jack (even my iPhone is louder at higher volumes).
So presumbly I need a headphone amp to boost the volumes. And I'm trying to figure the proper impedence I would need on the amp. The nominal impedence on the z5450 is in the 1000s. But this won't drive those headphones.
So going back to my original question I am confused about how impedence is measured? Speakers in general are rated in single digit ohms. My headphones are rated at 300ohms. My speakers nominal impedence is rated in 1000s. Why is the metric so vastly different for different devices?
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Re: Difference between impedence specs
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Joined: Feb 2009
Posts: 3,466
connoisseur
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connoisseur
Joined: Feb 2009
Posts: 3,466 |
Yeah, sometimes it helps to actually ask what you want to know.  Here's something from a website: Impedance: One issue that's especially important when choosing a pair of headphones is impedance. So called low impedance and high impedance pairs should not be intermixed.
Low impedance headsets may vary from 75 ohms up to about 150 ohms. Phones in this impedance range may be directly plugged into the headphone jack routinely found on recording and playback equipment.
Higher impedances sets normally have an impedance of around 600 ohms; these are more useful in studio installations where many units may be wired in parallel for studio monitoring applications.
The 600-ohm models are more rugged than low impedance ones in that the higher resistance coils are less susceptible to burn out than low impedance models. On the other hand, high impedance sets require a higher driving signal to produce the same level of sound output in comparison to low impedance headsets.
This means that low impedance headphones will sound louder when plugged in devices with low output voltages such as portable CD players, etc. In reality, because of the limited power available from portable players, headsets for portable use should have a maximum impedance of 64 ohms.
Worth keeping in mind here that the lower the impedance, the more efficient headphones are in converting the incoming electrical energy into sound. On the contrary, the higher the impedance, the more electrical energy is required to drive the headsets tiny speakers. So basically the amp can't drive the higher impedance of the semi-pro phones to the volume level you want. You need to get an amp designed to drive higher impedance levels.
Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs
-Chris
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Re: Difference between impedence specs
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Joined: Dec 2003
Posts: 10,420
shareholder in the making
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shareholder in the making
Joined: Dec 2003
Posts: 10,420 |
I am not sure why you are looking at the input impedance on your Z5450 when you are looking to drive(output) to your headphones, 2 different things.
I will guess the Z5450 headphone jack is a very low line level voltage(0-3V) out for headphones and not passed through it's amp at all. So yes, you could use a headphone amp.
Last edited by jakewash; 03/25/10 06:46 PM.
Jason
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