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.

 

[Jasonovich]

My comments is not in keeping with the main flow but;
It's worth taking the speakers out of the equation and take a peep inside the amp, just so, you've done the due diligence.
I had a Denon amp that kept blowing the fuse.
When I looked inside, I discovered two solder joints was a hair breath's apart.
I re-soldered the joints, ensuring these were fair distances apart.
This cured the problem.
Obviously if the amp is under warranty, I wouldn't recommend this.
Oh someone will mention this if I don't, make sure the mains is turned off 😊

 

[Rui]

i also use B&W speakers the CDM7 that have been working perfectelly and are 8ohms impedance ,this to allow the use of diferent types of amplifiers as mainly all have 8 ohms driving capability,

as an example some 87 tannoys i have they say in the manual from 4 to 8 ohms, the ohms law says the higher is the resistance the higher is the impedance , just some coments i didn´t understand what they meant saying ,as i use them as the amplifier in use is compatible with diferent measures of impedance,

the use of longer cables do increase the impedance of the speaker, but using them almost next to the system doesn´t make the speakers reveal it´s full quality as a stereo image,

they need to be installed a litle distant from the amplifier and depending on the room , the corners are maybe the best way to positioning them and a litle apart from the corners , as the use of bigger speakers in a small room might not release it´s better sound ,depending on the speakers quality but always far from their best sound release,

 

[davidf]

i also use B&W speakers the CDM7 that have been working perfectelly and are 8ohms impedance ,this to allow the use of diferent types of amplifiers as mainly all have 8 ohms driving capability,

as an example some 87 tannoys i have they say in the manual from 4 to 8 ohms, the ohms law says the higher is the resistance the higher is the impedance , just some coments i didn´t understand what they meant saying ,as i use them as the amplifier in use is compatible with diferent measures of impedance,

the use of longer cables do increase the impedance of the speaker, but using them almost next to the system doesn´t make the speakers reveal it´s full quality as a stereo image,

they need to be installed a litle distant from the amplifier and depending on the room , the corners are maybe the best way to positioning them as the use of bigger speakers in a small room might not release it´s better sound ,depending on the speakers quality but always far from their best sound release,

CDM7s dip to 4ohms. Virtually all manufacturers second range up will do so. Only entry level ranges will be 6-8ohms.

 

[Rui]

CDM7s dip to 4ohms. Virtually all manufacturers second range up will do so. Only entry level ranges will be 6-8ohms.

i thought they were 8ohms but not a problem s my amplifiers are all 4ohms driving capability or 4 to 8ohms ,only if i use two sets of speakers they have to be 8ohms but normally all that i have are 4 to 8ohms

 

[Rui]

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.

sorry but i think it makes no sense there are buildings made for people without much money that have big living rooms only the materials are cheaper , there are better speakers with small box that are much better than a lot of diferent brands tower speakers as an example the 761 mission speakers at 4ohms, from late 80´s or the cdm1 from B&W, i also have the cerwin-vega AT-100 from 89 with 400watts at 4ohms which sound amazing good and are huge, so not a matter of money when having a litle apartment or a bigger one, they are made at controled costs for people with less money to spend on a home, but giant speakers that cost each more than 50.000€ those doesn´t even make sense to put them on a litle house, but there are speakers for every wallet independent of it´s size

 

[Rui]

CDM7s dip to 4ohms. Virtually all manufacturers second range up will do so. Only entry level ranges will be 6-8ohms.

i just checked now and B&W CDM-7 they are 8 ohms speakers not 4 or from 4 to 8 ohms , as i have others who are as i said 4 to 8ohms,
entry level range 6 to 8ohms? it seems not correct or i don´t know them but sometimes in the 80´s amplifiers were 6 to 8ohms driving capability and were the top of the line
while have others from the 70´s who were the cheapest receiver pioneer had the 1979 SX-408 that were 4 ohms to 8 ohms capability and they had good sound and built with a very nice design,
to improve it´s power as the quality of sound was top you just had to buy a power amplifier and use the receiver SX-408 as a control amplifier, there no such thing as you described it ,i´ve checked as i had time to do so

 

[lacontrabarra]

Hi guys,

Sorry for the super late reply, didn´t follow the thread since my email kinda skipped on the updates from the post.

I obviously measured the impedance with the speakers disconnected, and I´m also aware that it changes with frequency. It´s a cheap method, but a straightforward one to check the "integrity" of the speaker.

B&W says 3.7ohm minimum...but again, not sure if that´s what the AMP should be seeing, or the Ohmmeter.

I´m trying to get the store to warranty the AMP, but so far they only suggested to change the fuses myself (WHICH OF COURSE, will keep on blowing if I continue to do so...). Twice is enough.

My question was only directed if anyone else have tried to compare "speakers" readings among the same pair.

Thanks to all!

 

[Fandango Andy]

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!

If you are measuring with a multimeter do it on the lowest resistance setting. The reading should be below the nominal impedance of the speaker. An 8-ohm speaker will probably read between 6 or 7 ohms. Most importantly, a pair of speakers should be about the same. Harbeth check each driver before installation to pick the best matched pairs. I don't expect other manufacturers are do precise!

If your speaker is reading 4 on a meter, it's going to go well below that at some frequencies.

How are the boxes sealed? Can you test individual components within the speakers to find the problem?

 

[Gray]

B&W says 3.7ohm minimum...but again, not sure if that´s what the AMP should be seeing, or the Ohmmeter.

You can be sure that what they've quoted as a minimum is the impedance that the amp will be seeing

 

[Rui]

Hi guys,

Sorry for the super late reply, didn´t follow the thread since my email kinda skipped on the updates from the post.

I obviously measured the impedance with the speakers disconnected, and I´m also aware that it changes with frequency. It´s a cheap method, but a straightforward one to check the "integrity" of the speaker.

B&W says 3.7ohm minimum...but again, not sure if that´s what the AMP should be seeing, or the Ohmmeter.

I´m trying to get the store to warranty the AMP, but so far they only suggested to change the fuses myself (WHICH OF COURSE, will keep on blowing if I continue to do so...). Twice is enough.

My question was only directed if anyone else have tried to compare "speakers" readings among the same pair.

Thanks to all!

that is very strange , if the fuses keep blowing it must be other matter as normally people i know that spend a lot of money in a new system normally they have non driveable capabilty to 4ohms speakers but they use them,

it never stops working but after some time the amplifier and the speakers get damaged not stop working but about the fuses normally aren´t for the impedance as it is a very low volatge in their magnetic specifications not sure now if are microvolts ,

the fuse normally is to protect the speakers against too much high´s to not blow a tweeter but it depends i never had seen that , but it can be just not knowing how it works for impedance

 

[davidf]

i just checked now and B&W CDM-7 they are 8 ohms speakers not 4 or from 4 to 8 ohms , as i have others who are as i said 4 to 8ohms

I don't really fully understand that sentence, but it's in the manual - 8ohms nominal, 4ohms minimum.

 

[davidf]

entry level range 6 to 8ohms? it seems not correct or i don´t know them but sometimes in the 80´s amplifiers were 6 to 8ohms driving capability and were the top of the line
while have others from the 70´s who were the cheapest receiver pioneer had the 1979 SX-408 that were 4 ohms to 8 ohms capability and they had good sound and built with a very nice design,
to improve it´s power as the quality of sound was top you just had to buy a power amplifier and use the receiver SX-408 as a control amplifier, there no such thing as you described it ,i´ve checked as i had time to do so

Generally, the entry level speaker range for most manufacturers are usually 6 or 8ohms, in order to widen amplifier compatibility. The next range up will more than likely be 6 or 8ohms and dip to 4, or be a 4ohm load. The electrical characteristics can be controlled in the crossover to an extent, but obviously involves unnecessary additional components, so better quality speakers tend to shy away from addressing the likes of impedance etc, as they're designed for better quality amplification. This is why we see most high quality speakers hovering around 4ohms, and some like Perlisten dipping as low as 2.2ohms. A sub £1k floorstanding speaker is likely to be used with budget amplification around £300-500, so is usually designed to be an easy load, which is why I don't get Q Acoustics approach with the 5040 being a 6ohm speaker and dropping to 3ohms. It might sound good, but owners will need to spend a couple of grand minimum to find a suitable, stable amplifier. I'm waiting for them to be packaged with Marantz PM6007s online, which will just show the money grabbing tendencies of online stores who have zero ability to offer genuinely curated packages.