Jump to content



Sign up for a free account to remove the pop-up ads

Signing up for an account is fast and free. As a member you can join in the conversation, enter contests and remove the pop-up ads that guests get. Click here to create your free account.

Photo
- - - - -

What's harder for a receiver: 6 ohm or 8 ohm speakers?


  • You cannot start a new topic
  • Please log in to reply
12 replies to this topic

#1 of 13 OFFLINE   Stephen Gladwin

Stephen Gladwin

    Stunt Coordinator



  • 54 posts
  • Join Date: May 19 2005

Posted October 25 2005 - 11:39 AM

Simple question I know, but I've been wondering this for a while. Is it harder for a receiver to drive 6 ohm or 8 ohm speakers? It's been my assumption that the higher the impedence, the easier it is to drive, but I may very well be wrong. I'm wondering b/c I'm about to replace my 6 ohm surround speakers with 8 ohm JBL E10 speakers, and was thinking if they are easier to drive, my receiver wouldn't be as taxed. BTW: I'm using a Denon AVR-1705 receiver (75 watts/channel). Thanks!

#2 of 13 OFFLINE   John Garcia

John Garcia

    Executive Producer



  • 11,562 posts
  • Join Date: Jun 24 1999
  • Real Name:John
  • LocationNorCal

Posted October 25 2005 - 12:03 PM

Lower the impedance, the harder it is to drive because it draws (allows to flow) more current. Obviously there are other variables, but given two similar spec'ed speakers, the 6 Ohm will cause the amp to work harder. Impedance varies with frequency too, and what will be of significance is how low the speaker actually drops, but generically speaking, starting with a lower nominal impedance means the lowest it will drop will probably be lower than a speaker with a higher nominal impedance, but that's not a guarantee though. In your case, you may actually benefit from using 6 Ohm speakers if they are not stressing the receiver out, because they give you a little boost in output on those channels; the side effect of which though is the amp is working a little harder. If there's nothing wrong with the sound, I wouldn't bother switching them out.
HT: Emotiva UMC-200, Emotiva XPA-3, Carnegie Acoustics CSB-1s + CSC-1, GR Research A/V-1s, Epik Empire, Oppo BDP-105, PS4, PS3,URC R-50, APC-H10, Panamax 5100 Bluejeans Cable
System Two: Marantz PM7200, Pioneer FS52s, Panasonic BD79
(stolen) : Marantz SR-8300, GR Research A/V-2s, Sony SCD-222ES SACD, Panasonic BD-65, PS3 60G (250G)

Everybody is a genius, but if you judge a fish by its ability to climb a tree, it’ll spend its whole life believing that it is stupid.” – Albert Einstein

 


#3 of 13 OFFLINE   Steve_L

Steve_L

    Stunt Coordinator



  • 90 posts
  • Join Date: Nov 08 2004

Posted October 25 2005 - 01:14 PM

I went to electronics school a long time ago, but I remember the basic rule that maximum power transfer and efficiency was achieved when the output impedance of one circuit and the input impedance of the other were matched. Amplifiers are designed to drive speaker loads that ideally present a consistent 8 ohms load (impedance) across the audio spectrum. In practice, speakers will provide a much more complex input load to the amplifier, varying widely over the audio spectrum in impedance from something greater than 8 ohms all the way down to 2 ohms. Quality amplifiers can handle this variation in impedance while lessor amplifiers don't do so well. (Your Denon prolly will do just fine.) I wouldn't worry about the 6 ohm rating too much, but also wouldn't count on noticing much difference in output based on the impedance rating. What is much more likely to cause a noticeable difference in your perceived performance is speaker efficiency. Efficient speakers providing much more sound pressure level (volume) with less required output power from your amplifiers. Look for a high sensitivity rating in choosing speakers.

#4 of 13 OFFLINE   Shane Martin

Shane Martin

    Producer



  • 6,017 posts
  • Join Date: Sep 26 1999

Posted October 25 2005 - 01:43 PM

Ding Ding ding. This is the biggest difference. Check your sensitivity ratings.

#5 of 13 OFFLINE   John Garcia

John Garcia

    Executive Producer



  • 11,562 posts
  • Join Date: Jun 24 1999
  • Real Name:John
  • LocationNorCal

Posted October 26 2005 - 01:55 AM

That would be a speaker's sensitivity, which is not the same as efficiency.
HT: Emotiva UMC-200, Emotiva XPA-3, Carnegie Acoustics CSB-1s + CSC-1, GR Research A/V-1s, Epik Empire, Oppo BDP-105, PS4, PS3,URC R-50, APC-H10, Panamax 5100 Bluejeans Cable
System Two: Marantz PM7200, Pioneer FS52s, Panasonic BD79
(stolen) : Marantz SR-8300, GR Research A/V-2s, Sony SCD-222ES SACD, Panasonic BD-65, PS3 60G (250G)

Everybody is a genius, but if you judge a fish by its ability to climb a tree, it’ll spend its whole life believing that it is stupid.” – Albert Einstein

 


#6 of 13 OFFLINE   Steve_L

Steve_L

    Stunt Coordinator



  • 90 posts
  • Join Date: Nov 08 2004

Posted October 26 2005 - 03:59 AM

>>> That would be a speaker's sensitivity, which is not the same as efficiency. <<< John, do you not think they are related?

#7 of 13 OFFLINE   John Garcia

John Garcia

    Executive Producer



  • 11,562 posts
  • Join Date: Jun 24 1999
  • Real Name:John
  • LocationNorCal

Posted October 26 2005 - 07:35 AM


HT: Emotiva UMC-200, Emotiva XPA-3, Carnegie Acoustics CSB-1s + CSC-1, GR Research A/V-1s, Epik Empire, Oppo BDP-105, PS4, PS3,URC R-50, APC-H10, Panamax 5100 Bluejeans Cable
System Two: Marantz PM7200, Pioneer FS52s, Panasonic BD79
(stolen) : Marantz SR-8300, GR Research A/V-2s, Sony SCD-222ES SACD, Panasonic BD-65, PS3 60G (250G)

Everybody is a genius, but if you judge a fish by its ability to climb a tree, it’ll spend its whole life believing that it is stupid.” – Albert Einstein

 


#8 of 13 OFFLINE   Chu Gai

Chu Gai

    Lead Actor



  • 7,270 posts
  • Join Date: Jun 29 2001

Posted October 26 2005 - 08:22 AM

Well, efficiency is generally represented as a percentage but one can also express it as so many dB @ 1 watt @ 1 meter. Imagine a hypothetical source that is able to radiate 1 watt of acoustical power. One can calculate that the SPL on the surface of a sphere that is 1 meter from the imaginary source will be approximately 109 dB. This assumes 100% efficiency. Now take an actual speaker and pump that same 1 watt into it and let's say the measured SPL at one meter from the speaker is now 89 dB. Well, that's 20 dB less which means that this speaker is 1% efficient. This though, applies only to direct radiator type speakers and not horns.

Sensitivity is a convention that states that one uses 2.83 volts and measures the SPL at one meter from the speaker. Into an 8 ohm load, 2.83 volts happens to correspond to 1 watt of input.

Therefore, simplistically, one can use sensitivity to get a handle on which of two speakers can play louder. There really is no easy answer to which places less strain on your receiver and in fact, depending upon how you've set your crossover for your sub, where you sit in relation to the speakers, where you've placed them, how loud you listen to them, etc. can all have an effect on your receiver's ability to drive your speakers successfully. It's not hard to imagine scenarios where either of the two speakers present difficulty. OTOH, it's not hard to imagine scenarios where it doesn't matter a hill of beans.

#9 of 13 OFFLINE   Steve_L

Steve_L

    Stunt Coordinator



  • 90 posts
  • Join Date: Nov 08 2004

Posted October 26 2005 - 11:59 PM

Here's two definitions of efficiency plucked from the Home theater Glossary of Terms. http://white.homethe.../glossary.htm#e

Efficiency - The ability of an audio device to turn mechanical energy to electrical (microphones, phonograph cartridges) or vice versa (loudspeakers, amplifiers). For example, the more efficient a loudspeaker is, the louder it will play with a given input. A typical acoustic-suspension speaker may be anywhere from 0.5% to 2% efficient; some horn speaker systems surpass 20%. The leftover energy is dissipated as heat. Under most conditions, efficiency has little to do with sound quality, but with speakers, high efficiency allows one to use a lower-powered amplifier.

Efficiency Rating - The loudspeaker parameter that shows the level of sound output when measured at a prescribed distance with a standard amount of energy fed into the speaker. Efficiency rating standard is 1 watt at 1 meter and is measured in decibels.

#10 of 13 OFFLINE   John Garcia

John Garcia

    Executive Producer



  • 11,562 posts
  • Join Date: Jun 24 1999
  • Real Name:John
  • LocationNorCal

Posted October 27 2005 - 02:09 AM

The second definition is incorrect. There is no such thing as an efficiency rating for a speaker. The correct term for what they are describing is sensitivity as measured. Efficiency can be calculated from that measurement, but it is generally not used to describe speaker characteristics. IMO, I'd submit a correction to the author of that glossary.
HT: Emotiva UMC-200, Emotiva XPA-3, Carnegie Acoustics CSB-1s + CSC-1, GR Research A/V-1s, Epik Empire, Oppo BDP-105, PS4, PS3,URC R-50, APC-H10, Panamax 5100 Bluejeans Cable
System Two: Marantz PM7200, Pioneer FS52s, Panasonic BD79
(stolen) : Marantz SR-8300, GR Research A/V-2s, Sony SCD-222ES SACD, Panasonic BD-65, PS3 60G (250G)

Everybody is a genius, but if you judge a fish by its ability to climb a tree, it’ll spend its whole life believing that it is stupid.” – Albert Einstein

 


#11 of 13 OFFLINE   Shane Martin

Shane Martin

    Producer



  • 6,017 posts
  • Join Date: Sep 26 1999

Posted October 27 2005 - 03:30 AM

Stephen, Something to consider efficiency and whatnot. Klipsch are well known to be an efficient speaker and some question why Klipsch folks would use an external amp but it's been shown they have a major ohm dip to the point where it will drain you amp of its power pretty quick if you crank it. Your receiver should be ok for the JBL's but if you decide to crank it up, you'll hit the limits of your amp pretty quick. If you don't listen very loud, then I wouldn't worry too much.

#12 of 13 OFFLINE   Jerome Grate

Jerome Grate

    Screenwriter



  • 2,937 posts
  • Join Date: May 23 1999

Posted October 27 2005 - 04:39 AM

I've been running my Platinum Audio speakers all around 6ohms through the HK 500 with out an issue.
Listen Up People.., Rack Em and Pack Em.., We're Phantoms in 15.

#13 of 13 OFFLINE   John Garcia

John Garcia

    Executive Producer



  • 11,562 posts
  • Join Date: Jun 24 1999
  • Real Name:John
  • LocationNorCal

Posted October 27 2005 - 04:59 AM

I'm running three 4 Ohm (center and surrounds) speakers on my Marantz 8300 which is rated for 6 Ohms minimum, and it works, but the surrounds generally aren't working too hard, so the receiver can handle them without issue. My mains are handled by monoblocks. Here's what it comes down to: If you take two similar speakers with the same sensitivity, "A" being 6 Ohms and "B" being 8 Ohms and drive them to the same measured SPL, speaker A will draw more current than speaker B to achieve that same SPL.
HT: Emotiva UMC-200, Emotiva XPA-3, Carnegie Acoustics CSB-1s + CSC-1, GR Research A/V-1s, Epik Empire, Oppo BDP-105, PS4, PS3,URC R-50, APC-H10, Panamax 5100 Bluejeans Cable
System Two: Marantz PM7200, Pioneer FS52s, Panasonic BD79
(stolen) : Marantz SR-8300, GR Research A/V-2s, Sony SCD-222ES SACD, Panasonic BD-65, PS3 60G (250G)

Everybody is a genius, but if you judge a fish by its ability to climb a tree, it’ll spend its whole life believing that it is stupid.” – Albert Einstein

 





0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users