B&W 706 S3 Impedance

[lacontrabarra]

Hi guys,

A quick question here (even though B&W states a minimum impedance of 3.7Ohm...)

I just measured my pair of BW 706 S3, and one measures 8ohm and the other 4,5. Is that common in a pair of speakers?? Wouldn´t it make the amp work "twice" as hard on one side than on the other?

Asking coz I just blew a fuse on my ATOLL IN80, and it keeps blowing...after just 3 months of use. Maybe it has nothing to do with it...but still gotta ask.

Thanks!

 

[davidf]

Shouldn't be that sort of difference - maybe the speaker has an issue.

 

[Integralista]

Hi guys,

A quick question here (even though B&W states a minimum impedance of 3.7Ohm...)

I just measured my pair of BW 706 S3, and one measures 8ohm and the other 4,5. Is that common in a pair of speakers?? Wouldn´t it make the amp work "twice" as hard on one side than on the other?

Asking coz I just blew a fuse on my ATOLL IN80, and it keeps blowing...after just 3 months of use. Maybe it has nothing to do with it...but still gotta ask.

Thanks!

Hi, this is not normal, one speaker may have some defect, which causes your Atoll is "welding" and blowing fuses. And B@W 706 with dips to 3,7 ohm means you need very very stable power amp, down to 2 ohm...You may send big thank you to B@W design department. These guys need to return to school to learn again to build speakers for "normal people". And not that even for their low cost 600 and mid cost 700 speakers you need "amp like Boulder" to sound right.

 

[nopiano]

Hi guys,

A quick question here (even though B&W states a minimum impedance of 3.7Ohm...)

I just measured my pair of BW 706 S3, and one measures 8ohm and the other 4,5. Is that common in a pair of speakers?? Wouldn´t it make the amp work "twice" as hard on one side than on the other?

Asking coz I just blew a fuse on my ATOLL IN80, and it keeps blowing...after just 3 months of use. Maybe it has nothing to do with it...but still gotta ask.

Thanks!

How are you doing this measuring, please? Impedance isn’t a static thing, it varies with frequency. Perhaps you are measuring resistance with an ohm meter?

However, even with static resistance I wouldn’t expect two correctly functioning speakers to differ that much.

 

[Gray]

These guys need to return to school to learn again to build speakers for "normal people".

😁 Your own speakers might even dip that low at certain times, when music is playing, if the truth's known.

B&W are only being honest and realistic with their spec.
I owned B&W for years - never any problem driving them (with quite modestly powered amps).

 

[manicm]

Shouldn't be that sort of difference - maybe the speaker has an issue.

It would also depend on the kind of music he's playing? Maybe a high level of deliberate stereo separation in a recording, which can cause left and right to fluctuate?

OP can you provide more details when you were measuring?

 

[Gray]

It would also depend on the kind of music he's playing? Maybe a high level of deliberate stereo separation in a recording, which can cause left and right to fluctuate?

OP can you provide more details when you were measuring?

You can be sure he won't have been measuring with music playing.
I'm sure he'll confirm that he was using the ohms range of a multimeter to measure resistance.

 

[manicm]

Hi guys,

A quick question here (even though B&W states a minimum impedance of 3.7Ohm...)

I just measured my pair of BW 706 S3, and one measures 8ohm and the other 4,5. Is that common in a pair of speakers?? Wouldn´t it make the amp work "twice" as hard on one side than on the other?

Asking coz I just blew a fuse on my ATOLL IN80, and it keeps blowing...after just 3 months of use. Maybe it has nothing to do with it...but still gotta ask.

Thanks!

Swop the speakers around, do you get the same measurements?

 

[Roger_A]

Hi guys,

A quick question here (even though B&W states a minimum impedance of 3.7Ohm...)

I just measured my pair of BW 706 S3, and one measures 8ohm and the other 4,5. Is that common in a pair of speakers?? Wouldn´t it make the amp work "twice" as hard on one side than on the other?

Asking coz I just blew a fuse on my ATOLL IN80, and it keeps blowing...after just 3 months of use. Maybe it has nothing to do with it...but still gotta ask.

Thanks!

Were the cables connected to the speakers when you measured the resistance? If so I would recommend disconnecting them and measuring the resistance again so you are only measuring the speakers themselves. If there is still a significant difference then something isn't right with the speakers. As others have pointed out the resistance you are measuring is not the same as the impedance the amplifier 'sees' when music is playing which will vary across the audio range.

 

[Deliriumbassist]

How are you doing this measuring, please? Impedance isn’t a static thing, it varies with frequency. Perhaps you are measuring resistance with an ohm meter?

However, even with static resistance I wouldn’t expect two correctly functioning speakers to differ that much.

Quoting to emphasize importance of this post.

 

[davidf]

Hi, this is not normal, one speaker may have some defect, which causes your Atoll is "welding" and blowing fuses. And B@W 706 with dips to 3,7 ohm means you need very very stable power amp, down to 2 ohm...You may send big thank you to B@W design department. These guys need to return to school to learn again to build speakers for "normal people". And not that even for their low cost 600 and mid cost 700 speakers you need "amp like Boulder" to sound right.

A bit like Q Acoustics producing a thousand pound speaker that dips to 3ohms - absolutely ridiculous. Most people are going to drive these with a Marantz PM6007. Any speaker below £1,000 should be 6 or 8ohms for wide compatibility, apart from the odd few like the original LS50 - which should've been a more restricted in my opinion. Many dealers had no idea how to set them up correctly, or which amps to pair them with, so couldn't even demonstrate them effectively.

 

[manicm]

A bit like Q Acoustics producing a thousand pound speaker that dips to 3ohms - absolutely ridiculous. Most people are going to drive these with a Marantz PM6007. Any speaker below £1,000 should be 6 or 8ohms for wide compatibility, apart from the odd few like the original LS50 - which should've been a more restricted in my opinion. Many dealers had no idea how to set them up correctly, or which amps to pair them with, so couldn't even demonstrate them effectively.

B&W are far from the only speakers that dip low. At least they're honest in their specs, as are Monitor Audio for their power requirements - they don't pussyfoot around like other companies.

I also disagree with you about £1000 speakers and below - even here it's become the NORM rather than the exception to dip so low. There's much hype about the new Elac Debut 3 standmount - until you read the specs.

So this picking on B&W is rubbish. Also HiFi News or HiFi Review recently reviewed the B&W 603 S3 floorstander - initially testing with a Denon Ceol N12 with no problems!

My slight issue is also with your inconsistency davidf. You espouse the design trend of speakers of the last 25 years i.e. narrow and deep, yet this design by default, along with stiffer and stronger materials, almost always necessitates lowish impedance, yet here you are not too keen on larger standmounts etc etc.

 

[davidf]

My slight issue is also with your inconsistency davidf. You espouse the design trend of speakers of the last 25 years i.e. narrow and deep, yet this design by default, along with stiffer and stronger materials, almost always necessitates lowish impedance, yet here you are not too keen on larger standmounts etc etc.

Not sure I've ever knowingly said anything against specific cabinet dimensions. I'm more for speaker array design and integration, so a loudspeaker works better in typical rooms. Whether a speaker is deep or wide, I'm not overly fussed. What I would be against is a deep cabinet that is also rear ported, which means a speaker that could be half a metre deep or more then needs another couple of feet (or more) for it to work well. I don't mind deep if it can work nearer a wall - most people don't have the space nowadays to allocate to perfect speaker placement. I still don't understand why more speaker manufacturers aren't designing speakers for close wall placement.

I get it with high-end speakers, as they're likely going into a property that has plenty of room for them to breathe.