Topic: mis match impedance question

[imogen]

Good afternoon,

I have a pioneeer vsx-d511 with 8 ohm impedance.

recently i have auditioned wharfdale 9.1 with nominal impedance of 6 ohms.

Is there a problem with this? shall i look for 8 ohm speaker instead?

[Dracula]

Good afternoon,

I have a pioneeer vsx-d511 with 8 ohm impedance.

recently i have auditioned wharfdale 9.1 with nominal impedance of 6 ohms.

Is there a problem with this? shall i look for 8 ohm speaker instead?

I am using a 6 ohm speaker with my tube amplifier which has 4 and 8 ohm  inputs using the 8 ohms input...hindi pa naman nasira yung speaker or yung amp so ok naman...pero other members may have a more technical opinion...

[odyopayl]

Speakers doesnt have stable impedances when they are playing. The Impedance stated on the plate are just nominal impedance.

Amplifier sense this impedance as load when your amplifier rated 8 ohms output, still it can drive your 6 ohms speakers but you will noticed it will run hotter. Most amplifier rated as 6 - 8 but high -end amplifiers can carry as low as 1ohm load (imagine almost short).

[Dracula]

Speakers doesnt have stable impedances when they are playing. The Impedance stated on the plate are just nominal impedance.

Amplifier sense this impedance as load when your amplifier rated 8 ohms output, still it can drive your 6 ohms speakers but you will noticed it will run hotter. Most amplifier rated as 6 - 8 but high -end amplifiers can carry as low as 1ohm load (imagine almost short).

so should I be using the 4 or the 8 ohms output for my 6 ohm speakers?

[av_phile1]

Use the 8-ohm speaker setting.   Valve amplifiers are said to behave differently from solid state amplifers with impedance mismatch.  For solid state, when in doubt, use a higher impedance load.  For valve, when in doubt, use a lower impedance load.   

[av_phile1]

Good afternoon,

I have a pioneeer vsx-d511 with 8 ohm impedance.

recently i have auditioned wharfdale 9.1 with nominal impedance of 6 ohms.

Is there a problem with this? shall i look for 8 ohm speaker instead?

The receiver can drive your 6-ohm speakers, but it won't be able to achieve maximum power transfer due to impedance mismatch.  Using a lower load, even slightly, the receiver will heat up faster and could, on some current-hungry transient signals or at loud levels, go into protection mode so you hear nothing for a few seconds.

[hattori_hanzo]

I tried to toggle the impedance switch on my AVR loading it with my 6 ohms tower speakers. and measured the actual heat dissipation using a analog DON-NSF temp reader and heres what I got;

loaded with 6 ohms tower speakers:
set to 4 ohms switch - 90 deg. F
set to 8 ohms switch - 93 deg. F

sa sound naman, tama si sir av_phile wala naman big audibility difference ang dalawang setting.

kaya lang sir av_phile, para naman magkaroon ng kami ng sense of security ano po ba talga ang much safer to use na impedance setting using a 6 ohms load speaker? Thanks.   

 

[av_phile1]

For solid state devices, when in doubt, use a higher impedance load.  So if you set your receiver to 4 ohms and use a 6-ohm load, that should give you peace of mind. 

But....

You could be sacrificing sonic quality for peace of mind.     But if as you said, you heard no sonic difference between the two settings, then use the 4-ohm setting.

[Dracula]

Use the 8-ohm speaker setting.   Valve amplifiers are said to behave differently from solid state amplifers with impedance mismatch.  For solid state, when in doubt, use a higher impedance load.  For valve, when in doubt, use a lower impedance load.   

Thanks av_phile1  the seller also recommended the 8 ohm setting but couldn't give me a reason just that for him it sounded better....

[hattori_hanzo]

For solid state devices, when in doubt, use a higher impedance load.  So if you set your receiver to 4 ohms and use a 6-ohm load, that should give you peace of mind. 

But....

You could be sacrificing sonic quality for peace of mind.     But if as you said, you heard no sonic difference between the two settings, then use the 4-ohm setting.

thanks sir av! bilib talaga ko sayo boss...

[Roman]

1.) I too have 6-ohm speakers driven by a receiver that puts out "2 x 100 watts/8-ohms, minimal impedance: 2-ohms". Does this mean the receiver and 6-ohm speakers are safe if the receiver can put out enough power to  a 2-ohm speaker load?

2.) Separately, is there a correlation between impedance and sensitivity or efficiency? In ther words, does an 8-ohm speaker put out more sound for the same power output (and is therefore more sensitive or efficient) than a 6-ohm or 4-ohm speaker?

Thanks.

[bumblebee]

Assuming same sensistivity, a speaker with lower impedance will allow more power into it, therefore, go louder.

[Roman]

Assuming same sensistivity, a speaker with lower impedance will allow more power into it, therefore, go louder.

Just for my education:

By speaker with lower impedance, do you mean the one with the lower number of ohms (e.g., 4-ohm) or the one with the lower resistance (e.g., 8-ohm)?

Do I take it from your premise ("Assuming same sensitivity...") that sensitivity does not logically follow from a higher ohm number? In short, is an 8-ohm speaker not necessarily more sensitive than the 4-ohm speaker, even as the 8-ohm speaker has lower resistance? Or am I presuming strange things here?

Sorry for the pangungulit. I'm really no expert and would like to clarify the audio terms and concepts as I come across them.

Thnaks.

[hattori_hanzo]

Just for my education:

By speaker with lower impedance, do you mean the one with the lower number of ohms (e.g., 4-ohm) or the one with the lower resistance (e.g., 8-ohm)?

Do I take it from your premise ("Assuming same sensitivity...") that sensitivity does not logically follow from a higher ohm number? In short, is an 8-ohm speaker not necessarily more sensitive than the 4-ohm speaker, even as the 8-ohm speaker has lower resistance? Or am I presuming strange things here?

Sorry for the pangungulit. I'm really no expert and would like to clarify the audio terms and concepts as I come across them.

Thnaks.

Impedance is not really so much co related into sensitivity, sometimes there can be a speaker rated at 8ohms on 91db minsan meron din 6ohms on 89db, so hindi lahat ng may higher number na impedances are higher sensitivity speakers. 

[bumblebee]

Just for my education:

By speaker with lower impedance, do you mean the one with the lower number of ohms (e.g., 4-ohm) or the one with the lower resistance (e.g., 8-ohm)?

Do I take it from your premise ("Assuming same sensitivity...") that sensitivity does not logically follow from a higher ohm number? In short, is an 8-ohm speaker not necessarily more sensitive than the 4-ohm speaker, even as the 8-ohm speaker has lower resistance? Or am I presuming strange things here?

Sorry for the pangungulit. I'm really no expert and would like to clarify the audio terms and concepts as I come across them.

Thnaks.

Yes, by lower impedance, I mean the lower number of ohms. And yes, sensitivity and impedance does not relate to each other.

[Roman]

To hattori hanzo and bumblebee:

Thanks very much for the information, guys.

[squidball]

Mga masters tanong ko lang kung ok lang ba kung gagamit ako ng speakers na magkakaiba ang impedance to be used on one receiver? Would this cause problems on my receiver? Thanks.

[Erymel]

I would also like to add my interest to the answer for the last question. Would using mismatched speakers (in terms of impedance) seriously damage the receiver? Would it lessen the risk if you don't give it too much power (low volume lang)?

[av_phile1]

At low volumes, I don't see much of a problem.  Just a lot more heat than otherwise.

At louder volumes, it really depends on the receiver's recommended minimum load.  If the receiver explicitly cautioned you against using lower loads, then be guided accordingly.  Otherwise, in general, lower loads on SS gears will extract more current which the receiver may not be designed to deliver, and thus go into protection mode or bust a rail fuse.  Nothing really serious, that's what protection circuits and fuses do and if they were designed properly, shouldn't adversely affect the power transistors and will recover ( once fuse is correctly replaced) when the right conditions are detected at the amp's output. 

If the receiver is advertised to handle lower loads, impedance mismatch is no longer an issue. 

But it's always a good practice to load the receiver as recommended. 

[Erymel]

Thanks! Just got a Yamaha RX-V357 and while I'm shopping for matching speakers I'm really being tempted to try and hook up the Creative 5.1 speakers I currently use. Was thinking I'd just adjust the sound levels to the speakers but I can't find any data on their impedance rating and was afraid of damaging the receiver or the speakers.

[qctech]

to the experts: mga pre i have a marantz 4500 with impedance of 6-8 ohms and jbl speakers with 4 ohms rating. kaya ba yun?

[JojoD818]

Thanks av_phile1  the seller also recommended the 8 ohm setting but couldn't give me a reason just that for him it sounded better....

Power amps (both tube and ss) can be seriously damaged when using the wrong impedance loads.

For Tube amps, what causes the damage is underload. That's why tube amps should not be operated when there is no speakers connected. So if you happen to have a 6 ohms speaker and your tube amp has 4 and 8 ohms output taps then you better use the 8 ohm tap instead of the 4 ohms tap. Connecting a 6 ohm speaker to the 4 ohms output tap of your tube amp presents a slight underload condition to the secondary of the output transformer but should'nt be enough to destroy your output transformer.

Otoh, Solid state power amps can be easily damaged by overload conditions. That's why unlike tube amps, they can be operated for extended periods without any speaker load. Connecting a 4 ohm load to an ss amp designed for 8 ohms will not destroy it at once but will cause the output devices to conduct more current hence more heat. If you don't take care of this too much heat, then your ss amp will go to thermal runaway and destroy your output transistors. So to sum it up, an ss amp designed to run 4 ohms loads can safely handle 4, 6 or 8 ohms, but if the amp is designed for 8 ohms loads, it would be safer to at least use 6 ohms loads and never 4 ohms.

Now for 6 ohms speakers, I don't think it should be too much of a problem connecting them to any power amp, be it tube or ss.

Mixing impedances doesn't matter, such problems usually arise with HT setups. What I mean is your fronts can be 8 ohms, your center can be 6 ohms etc. What matters most is that all impedances should be within the output impedance specifications of the receiver.

Cheers

[Hot Mama]

... Connecting a 4 ohm load to an ss amp designed for 8 ohms will not destroy it at once but will cause the output devices to conduct more current hence more heat. If you don't take care of this too much heat, then your ss amp will go to thermal runaway and destroy your output transistors...

Talking about overheating... i used to connect 4 ohm speakers to my RXV357... and it really heats up!!! parang kalan... My question though is... if we take care of this too much heat, e.g. placing a fan to suck out the heat... will it prolong the life of the receiver? or will the effects just be the same?

Thanks!

[av_phile1]

Adequate ventillation will be good to your amp to further dissipate the heat, and prolong its life.  Aiming an electric fan on them is not uncommon.  Some models have internal fans.

[JojoD818]

I agree, the cooler theamp gets, the better.

Heat shortens the useful life of Solid State devices but that doesn't mean it can't operate at elevated temps. It's the "too much" junction temp that kills it.

[Hot Mama]

Dear Gurus,

Another impedance related question here...

Suppose i have a receiver/amp whose output is rated at 6 ohms... if i connect a lower 4 ohm speaker, the amp would really heat up right (see discussion below)... but what if i place in series two 4 ohm speakers, thus making it 8 ohms, would that not destroy the amp? The amp would "see" am 8 phm speaker right?

Thanks!

[av_phile1]

SS amps don't mind seeing a higher impedance than their rating.