Confused about Impedance

[Deezer]

Reciever and speaker impendance?I have a H/K AVR630 and looking at the Psb Image 45t-55t speakers.The speakers say impendance wise"6 ohm nominal and 4 ohm minimal".My reciever is rated at 75 rms@8 ohms,how much power would the speakers be getting?Image T45 Tower Specifications

Frequency Range
On Axis @ 0° ±1.5dB 48-20,000 Hz
On Axis @ 0° ±3dB 35-23,000 Hz
Off Axis @ 30° ±1.5dB 48-10,000 Hz
Lf Cutoff -10dB 30 Hz
Sensitivity
1w (2.83V) @ 1m, IEC-filtered Pink Noise, C-weighted
Anechoic Chamber 90 dB
Typical Listening Room 93 dB
Impedence
Nominal 6 Ohms
Minimum 4 Ohms
Input Power
RMS, Clipping < 10% of the Time
Recommended 10-150 Watts
Program 100 Watts
Features
Dual, 5-way Gold-plated Binding Posts
Bi-wireable/Bi-ampable

Here are the spc's for the 55t's

Frequency Range
On Axis @ 0° ±1.5dB 45-20,000 Hz
On Axis @ 0° ±3dB 32-23,000 Hz
Off Axis @ 30° ±1.5dB 45-10,000 Hz
Lf Cutoff -10dB 28 Hz
Sensitivity
1w (2.83V) @ 1m, IEC-filtered Pink Noise, C-weighted
Anechoic Chamber 91 dB
Typical Listening Room 93 dB
Impedence
Nominal 6 Ohms
Minimum 4 Ohms
Input Power
RMS, Clipping < 10% of the Time
Recommended 10-175 Watts
Program 125 Watts
Dual, 5-way Gold-plated Binding Posts
Bi-wireable/Bi-ampable

Should I try and and run my reciever to a 4 ohm load to reach the 55t's 125 watt rms ratting.I read a review were they said at 4ohms my amp was putting out 149 watts per channel.If I need a mono-block amp can you recomend a good but cheap amp for my needs.

Thanks for any help or suggestions.

 

[PENG]

Should I try and and run my reciever to a 4 ohm load to reach the 55t's 125 watt rms ratting.I read a review were they said at 4ohms my amp was putting out 149 watts per channel.If I need a mono-block amp can you recomend a good but cheap amp for my needs.

Thanks for any help or suggestions.

Did you read this review and lab measures of the 630?

http://hometheatermag.com/receivers/804hk/index2.html

The HK AVR630 is rated for 8 ohm loads. It can drive 6 ohm or 4 ohm loads but you will have to be extra careful and do not try to push it too hard. It will help a lot if you supplement the receiver with at least a 2 or 3 channel amplifier to drive the typically larger front speakers if their nominal impedances are 4 ohms.

 

[Deezer]

thats the article.By that article it didn't look like 4 0hms was a problem but it did't realy say too much on that topic either.What do you mean "don't push it"
what do you think is too far?as of now I'am using an older satalight speaker sytem by sony,with a 8inch sony sub.Can't remember sesitivity level on theses speakers but to play them loud I have to crank the volume to -20 never gone past that.

 

[3db]

Reciever and speaker impendance?I have a H/K AVR630 and looking at the Psb Image 45t-55t speakers.The speakers say impendance wise"6 ohm nominal and 4 ohm minimal".My reciever is rated at 75 rms@8 ohms,how much power would the speakers be getting?Image T45 Tower Specifications

Frequency Range
On Axis @ 0° ±1.5dB 48-20,000 Hz
On Axis @ 0° ±3dB 35-23,000 Hz
Off Axis @ 30° ±1.5dB 48-10,000 Hz
Lf Cutoff -10dB 30 Hz
Sensitivity
1w (2.83V) @ 1m, IEC-filtered Pink Noise, C-weighted
Anechoic Chamber 90 dB
Typical Listening Room 93 dB
Impedence
Nominal 6 Ohms
Minimum 4 Ohms
Input Power
RMS, Clipping < 10% of the Time
Recommended 10-150 Watts
Program 100 Watts
Features
Dual, 5-way Gold-plated Binding Posts
Bi-wireable/Bi-ampable

Here are the spc's for the 55t's

Frequency Range
On Axis @ 0° ±1.5dB 45-20,000 Hz
On Axis @ 0° ±3dB 32-23,000 Hz
Off Axis @ 30° ±1.5dB 45-10,000 Hz
Lf Cutoff -10dB 28 Hz
Sensitivity
1w (2.83V) @ 1m, IEC-filtered Pink Noise, C-weighted
Anechoic Chamber 91 dB
Typical Listening Room 93 dB
Impedence
Nominal 6 Ohms
Minimum 4 Ohms
Input Power
RMS, Clipping < 10% of the Time
Recommended 10-175 Watts
Program 125 Watts
Dual, 5-way Gold-plated Binding Posts
Bi-wireable/Bi-ampable

Should I try and and run my reciever to a 4 ohm load to reach the 55t's 125 watt rms ratting.I read a review were they said at 4ohms my amp was putting out 149 watts per channel.If I need a mono-block amp can you recomend a good but cheap amp for my needs.

Thanks for any help or suggestions.

Your Yamaha will drive them without problems. I have a pair of T45s, also rated at 6 ohms being driven by a cherapy Technics receiver and it drives them quite loud without breaking a sweat.

Impedance of the speakers changes as a function of frequency. The PSBs will be sitting at 4ohms for very short periods of time as the frequency changes unless your listening to a single tone for hours on an end. That would be harder on the receiver.

To simply this just a little, assume a single frequency that we can vary and that the amplitude stays constant over the frequency range. So as we vary the frequency, the impedance changes of the speaker. The amp is trying to maintain that constant voltage across the speaker terminals. So as the speaker's impedance drops, the amout of current that the amp has to deliver in order to maintain the constant voltage has to increase. Now the problem lies with the amp that can no longer deliever the current. That means the voltage has dropped which would cause the amp to clip the signal making it sound really bad and even worse, hard on the tweeters of the speakers.

H/K are grossly underspeced in terms of power output. The H/K will have no problems driving an efficient speaker like the T45s. I hope this helps

 

[PENG]

thats the article.By that article it didn't look like 4 0hms was a problem but it did't realy say too much on that topic either.What do you mean "don't push it"
what do you think is too far?as of now I'am using an older satalight speaker sytem by sony,with a 8inch sony sub.Can't remember sesitivity level on theses speakers but to play them loud I have to crank the volume to -20 never gone past that.

It is all relative, so when I said "don't push it", I meant don't push it as hard as you would as if you had 8 ohm nominal speakers. As 3 db said the impedance of a speaker varies with frequency but that's why manufacturers like to use the word nominal. A 6 ohm nominal speaker is generally (but not always because there are other factors) more difficult to drive than an 8 ohm speaker. That said, -20 volume is not pushing at all. If that's all you need, then you should be fine. I would say even up to -10 is fine unless you listen to something like 7 channel stereo.

In that article, the 4 ohm rating tested was for 2 channels driven, so understandably the power supply can handle the demand nicely. If you browse through the lab measurements for other makes such as Pioneer Elite, Denon etc., you will see other makes such as Denon, Pioneer Elite and Yamaha all do pretty good in the same kind of 4 ohm tests, in fact better than the 630. HK does tend to rate their output conservatively, but at the same price point they also tend to get you less output than Denon, Pioneer & Yamaha (the later year) models, though even a 30% difference is totally insignificant.

 

[j_garcia]

You have to factor in other things as well, such as sensitivity and the size of your room, as well as the volume level you will be asking of it.

 

[Deezer]

Thanks for the info and your guys time.room size is 15x19 if i can remember right.I just wanted to know if my amp was enough to push those speakers.As stated before out of all the mid-priced amps,the H/K 630 had the lower watt
per ch. ratio.Don't have money to up-grade speakers and amp at the same time.

 

[Deezer]

Just found the spec's on my currant speakers,sony ssv-531h satalight system with sub.Here the spec's:

MPN: SSV-531H

Product Type: Satellite speaker

Width: 3.8 in

Depth: 5.4 in

Height: 6.6 in

Weight: 2.9 lbs

Dimensions (WxDxH) / Weight Details: Satellite speaker : 3.8 in x 5.4 in x 6.6 in / 2.9 lbs

Speaker system
Speaker Type: 2-way - passive

Max (RMS) Output Power: 120 Watt

Input Impedance: 8 Ohm

Sensitivity: 85 dB

Output Features: Bass Reflex

Magnetic Shield: Yes

Connectivity Technology: Wired


with an 85db rating how much better should the psb's sound?

 

[3db]

Just found the spec's on my currant speakers,sony ssv-531h satalight system with sub.Here the spec's:

MPN: SSV-531H

Product Type: Satellite speaker

Width: 3.8 in

Depth: 5.4 in

Height: 6.6 in

Weight: 2.9 lbs

Dimensions (WxDxH) / Weight Details: Satellite speaker : 3.8 in x 5.4 in x 6.6 in / 2.9 lbs

Speaker system
Speaker Type: 2-way - passive

Max (RMS) Output Power: 120 Watt

Input Impedance: 8 Ohm

Sensitivity: 85 dB

Output Features: Bass Reflex

Magnetic Shield: Yes

Connectivity Technology: Wired


with an 85db rating how much better should the psb's sound?

Because the PSBs are way more sensitive than your Sony's, you'll find that you will not be turnikng the volume up as high with the PSBs to achieve the same loudness levels as your Sony's.

H/K also specs their amp with all channels driven where Denon and Yamaha do not. The H/K are more robust in the amp/power supply section than either Yamaha or Denon. Like I said before, I have a Trchncis receiver driving my entire PSB Image suite of speakers. They say use only 8 ohms speakers but I've had no problems whatosever. I';ve had this setup for the last 5 years.

 

[markw]

Just found the spec's on my currant speakers,sony ssv-531h satalight system with sub.Here the spec's:

MPN: SSV-531H

Product Type: Satellite speaker

Width: 3.8 in

Depth: 5.4 in

Height: 6.6 in

Weight: 2.9 lbs

Dimensions (WxDxH) / Weight Details: Satellite speaker : 3.8 in x 5.4 in x 6.6 in / 2.9 lbs

Speaker system
Speaker Type: 2-way - passive

Max (RMS) Output Power: 120 Watt

Input Impedance: 8 Ohm

Sensitivity: 85 dB

Output Features: Bass Reflex

Magnetic Shield: Yes

Connectivity Technology: Wired


with an 85db rating how much better should the psb's sound?

You make the common mistake of confusing specs with sound. Your specs in these posts just cloud the issues.

you can't really do that.

The sensitivity rating has no effect on how good or bad a speaker sounds. It's all in the "magical" combination of drivers, enclosure and crossover. there are good sounding abd bad soundingspeakers of both the high and low sensitivity variety. The problem is again compounded when you consider that "better" or "worse" is based on a personal preference, not a set of numbers.

Several things to consider:

1) A speaker's "nominal" impedance is basically an average. The true impedance varies by frequency and can go lower or higher. ...sometimes way lower.

2) Amps like a high impedance load better than a low impedance load.

3) You can't judge a speaker's sound by it's specs.

 

[PENG]

The H/K are more robust in the amp/power supply section than either Yamaha or Denon.

Sound like an opinion!

 

[3db]

Sound like an opinion!

Thats what all the Denon/Yamaha people say.

 

[Pyrrho]

Reciever and speaker impendance?I have a H/K AVR630 and looking at the Psb Image 45t-55t speakers.The speakers say impendance wise"6 ohm nominal and 4 ohm minimal".My reciever is rated at 75 rms@8 ohms,how much power would the speakers be getting?Image T45 Tower Specifications

Frequency Range
On Axis @ 0° ±1.5dB 48-20,000 Hz
On Axis @ 0° ±3dB 35-23,000 Hz
Off Axis @ 30° ±1.5dB 48-10,000 Hz
Lf Cutoff -10dB 30 Hz
Sensitivity
1w (2.83V) @ 1m, IEC-filtered Pink Noise, C-weighted
Anechoic Chamber 90 dB
Typical Listening Room 93 dB
Impedence
Nominal 6 Ohms
Minimum 4 Ohms
Input Power
RMS, Clipping < 10% of the Time
Recommended 10-150 Watts
Program 100 Watts
Features
Dual, 5-way Gold-plated Binding Posts
Bi-wireable/Bi-ampable

Here are the spc's for the 55t's

Frequency Range
On Axis @ 0° ±1.5dB 45-20,000 Hz
On Axis @ 0° ±3dB 32-23,000 Hz
Off Axis @ 30° ±1.5dB 45-10,000 Hz
Lf Cutoff -10dB 28 Hz
Sensitivity
1w (2.83V) @ 1m, IEC-filtered Pink Noise, C-weighted
Anechoic Chamber 91 dB
Typical Listening Room 93 dB
Impedence
Nominal 6 Ohms
Minimum 4 Ohms
Input Power
RMS, Clipping < 10% of the Time
Recommended 10-175 Watts
Program 125 Watts
Dual, 5-way Gold-plated Binding Posts
Bi-wireable/Bi-ampable

Should I try and and run my reciever to a 4 ohm load to reach the 55t's 125 watt rms ratting.I read a review were they said at 4ohms my amp was putting out 149 watts per channel.If I need a mono-block amp can you recomend a good but cheap amp for my needs.

Thanks for any help or suggestions.

I think everyone is making this way too complicated. If your receiver is rated to be used with those impedances (consult your owner's manual or simply look on the back of the receiver to find this information), then you probably will be fine.

If you want, we can keep it somewhat complicated, by observing that the amount of power an amplifier is putting out at any moment is dependent upon the input signal at that instant and the setting of the volume control. How much power you need is dependent on so many factors, that we cannot possibly tell you if you have enough. One of the relevant questions is, how loud do you like the music?

If you do decide you need more power, here is a cheap power amp that should fully take care of you:

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=248-749

But you most likely will have no need of an extra amplifier. If, when you hook up the speakers, it will play as loud as you want without noticeable distortion, then you don't need more power. And if you do have noticeable distortion, this could be due to a lack of power, or it could be due to the speakers being unable to handle as much power as they are getting. The only way to know would be with measuring with test equipment, or simply trying another amplifier or speaker to see if that corrects the problem.

 

[Janik]

For a second there, I thought this thread was posted on the wrong forum. But then again, I mistakenly read "Confused about Impotance"!!
Talking

 

[Deezer]

Thank you guys once again.When I built my first car stereo sytem 1 1/2 yrs ago, nothing was ever mentioned about impendance,just about ohms and getting more power from your sub.In light,I was led to believe by myself
that I had an Idea about home stereo.Thats probly why most of my post were about more power and speaker specs.Sorry for the lack of knowledge.I
can't wait to get a new set of speakers.