Adding an external power amplifier

[dlaloum]

Just to clarify my fronts are B&W 702s3 if that matters

Yes, I saw that, but could not find a 702s3 impedance chart to refer to...
I have no idea how different (or similar) the sensitivity and impedance of the s3 are vs the s2

 

[AcuDefTechGuy]

Yes, I saw that, but could not find a 702s3 impedance chart to refer to...
I have no idea how different (or similar) the sensitivity and impedance of the s3 are vs the s2

Knowing B&W, every generation is the same just with D1 vs D2 vs D3.

The 702S2 is 4-ohms. So S3, S4, S5 will be 4 ohms.

Bowers & Wilkins 702 S2 loudspeaker Measurements

Sidebar 3: Measurements

www.stereophile.com

 

[everettT]

Yes, I saw that, but could not find a 702s3 impedance chart to refer to...
I have no idea how different (or similar) the sensitivity and impedance of the s3 are vs the s2

The transition from mid range to the low woofers is the same, something like 3.2 ohms and around 200hz with sharp phase angle, something they've (B&W) been consistently bad at across all over their series beginning in the late 90s early 2000s but that's their thing, apparently.

 

[PENG]

Just to clarify my fronts are B&W 702s3 if that matters

In terms of amplifier requirements, they are probably very similar. B&W recommends 30-300 W 8 ohms for both models.

The Amp 10 is rated 200 W 8 ohms, 400 W 4 ohms, given that the 702 S3's impedance is 8 ohms nominal, 3.1 ohm minimum, the Amp 10 is adequate for them.

All else being equal, mono block equivalent of the Amp 10, that is one that is rated also 200/400 W 8/4 ohms will be better as they are more "separate" than a 16 channel "separate" power amp. However, in terms of audible difference there will be none. Very few power amps will sound audibly better than the Amp 10, based on specs and measurements.

Marantz AMP 10 200 Watt x 16CH Amplifier Bench Test Results | Audioholics

You can of course BTL the Amp10 with the 702S3, but I would suggest against it, because I don't believe they are truly 8 ohm nominal speakers, based on the very similar 702S2, in case the S3 might have worse phase angles. That said, if you don't push the volume, say if you typically listen to volume setting below -15, then there should be no danger. How much current your speakers need depends a lot on your listening habit, that is, you seating distance, and your SPL requirements/volume setting, and use of room correction. Impedance is just one factor, and as you know it varies across the audio frequency band.

If you are really bothered by using a 16 channel amp jammed in one box, then okay, for super extra/ultra peace of mind, go grab a monoblock Hypex or Purifi based 500 W 4ohm power amp and call it a day. It's your money, so...

I will never buy a 16 channel amp myself, to me it defeats the idea of using separates, may as well use an AVR such as the Denon AVR-A1H lol... That's just me though, and I do believe monoblocks won't offer audibly better sound quality than the Amp 10, if the listening are told they are listening to monoblocks only in a blind test.

 

[PENG]

Knowing B&W, every generation is the same just with D1 vs D2 vs D3.

The 702S2 is 4-ohms. So S3, S4, S5 will be 4 ohms.

Bowers & Wilkins 702 S2 loudspeaker Measurements

Sidebar 3: Measurements

www.stereophile.com

According to B&W 702S3 specs:

Nominal impedance8Ω (minimum 3.1Ω)

No measurements found, so yes I would agree the OP should assume it is more like 4 ohm, may be 5, 6 ohm nominal, but not 8!!

Regardless, as you know in my opinion (actually more than opinion as I know the theory haha), impedance specs, like power consumption, power output etc., are not very useful if only single point values are given.

The curves are better, though one has to know how to interpret and use them to size their amps, show them to someone who does not know enough about electrical and acoustical principle may not be helpful either.

@dlaloum knows my other opinions too, I guess, that while he's making valid technical points, most (not all) of the time it is better to just tell people to go with manufacturer's recommended "amplifier power requirements", or "power handling specs" and then may be double it for added peace of mind, or take the average and then double it.

In this case, recommended by B&W is 30 to 300 W, average = 165 W, so a 350 W 8 ohm power amp should be all he needs for those speakers, or go with 600 W 8 ohms, that would guarantee the amp can do 300 W 4 ohms all day long, or 150 W 2 ohms, or 75 W 1 ohm all year long.

 

[highfigh]

Just to clarify my fronts are B&W 702s3 if that matters

It doesn't- it would be the same with any speakers that have a way to disconnect the HP and LP terminals. If the amp has been bridged, the effective load is half of the load if it's in normal mode- this has been known for decades. It's also the main reason a lot of amplifiers have blown up.

Think of it this way-one channel is providing the positive phase and the other channel is providing the negative phase of a sine wave, with the negative of the channels providing the necessary link to the two. This only works in amplifiers with common ground, BTW. Don't try it with two monoblocks unless the manufacturer explicitly says it's OK and has provided a switch for Bridge Mode.

 

[highfigh]

In terms of amplifier requirements, they are probably very similar. B&W recommends 30-300 W 8 ohms for both models.

The Amp 10 is rated 200 W 8 ohms, 400 W 4 ohms, given that the 702 S3's impedance is 8 ohms nominal, 3.1 ohm minimum, the Amp 10 is adequate for them.

All else being equal, mono block equivalent of the Amp 10, that is one that is rated also 200/400 W 8/4 ohms will be better as they are more "separate" than a 16 channel "separate" power amp. However, in terms of audible difference there will be none. Very few power amps will sound audibly better than the Amp 10, based on specs and measurements.

Marantz AMP 10 200 Watt x 16CH Amplifier Bench Test Results | Audioholics

You can of course BTL the Amp10 with the 702S3, but I would suggest against it, because I don't believe they are truly 8 ohm nominal speakers, based on the very similar 702S2, in case the S3 might have worse phase angles. That said, if you don't push the volume, say if you typically listen to volume setting below -15, then there should be no danger. How much current your speakers need depends a lot on your listening habit, that is, you seating distance, and your SPL requirements/volume setting, and use of room correction. Impedance is just one factor, and as you know it varies across the audio frequency band.

If you are really bothered by using a 16 channel amp jammed in one box, then okay, for super extra/ultra peace of mind, go grab a monoblock Hypex or Purifi based 500 W 4ohm power amp and call it a day. It's your money, so...

I will never buy a 16 channel amp myself, to me it defeats the idea of using separates, may as well use an AVR such as the Denon AVR-A1H lol... That's just me though, and I do believe monoblocks won't offer audibly better sound quality than the Amp 10, if the listening are told they are listening to monoblocks only in a blind test.

I guess the photo of Gene holding it shows one of the reasons he works out.

Wow! I didn't know Marantz made a 16 channel amp- that would be great for a distributed audio system with in-ceiling speakers.

 

[highfigh]

Yes I have heard biwiring is useless. but the tech that helped me set up my room and the rep at B&W said biamping is beneficial in that it sends a separate channel to the high and mid and a separate channel to the woofer. So more efficient. I'm not sure if this is true but like I said mine is set to BTL. There's so many articles, reviews, vids, and recommendations on my amp10 and av10 as well as the av10 336 page manual lol, that it's kind of confusing what to think are the best connections?!

The only think Bi-wiring does is move the point where the upper and lower terminals connect (normally, it's on the speaker) and with Bi-wiring, it's at the amplifier, but someone who sells the speaker wire only makes money when people Bi-wire their speakers.

 

[PENG]

The only think Bi-wiring does is move the point where the upper and lower terminals connect (normally, it's on the speaker) and with Bi-wiring, it's at the amplifier, but someone who sells the speaker wire only makes money when people Bi-wire their speakers.

I understand many forum posters and youtubers had made that point, but in terms of electrical theories it is not correct (about what they said about the effects of "moving the point......."). One member Zilch, iirc had even do a YT demo proving that very point, but he used a voltmeter, so that demo was not valid. He later did use a clamp on meter to measure the currents in each wire; and if he did it right, he would have known that the currents would indeed be different between the current flowed in the wires feeding the tweeter, or tweeter+midrange driver, and the woofer, or woofer+the midrange driver.

So again, electrically there is a difference, but practically, I agreed there's no evidence that it would make any audible difference in probably 99.99% of the time/applications. I would leave that 0.01% chance, only because there will be a very minor electrical difference so there is always a chance, however low it is, in certain rare cases.

 

[philly]

So in summary my amp 10 and these speakers shouldn't "blow up" leaving it in BTL mode? Lol. if it's a risk I'll definitely change it

 

[philly]

It doesn't- it would be the same with any speakers that have a way to disconnect the HP and LP terminals. If the amp has been bridged, the effective load is half of the load if it's in normal mode- this has been known for decades. It's also the main reason a lot of amplifiers have blown up.

Think of it this way-one channel is providing the positive phase and the other channel is providing the negative phase of a sine wave, with the negative of the channels providing the necessary link to the two. This only works in amplifiers with common ground, BTW. Don't try it with two monoblocks unless the manufacturer explicitly says it's OK and has provided a switch for Bridge Mode.

So should I change the switch selection to biamp or normal instead?

 

[highfigh]

I understand many forum posters and youtubers had made that point, but in terms of electrical theories it is not correct (about what they said about the effects of "moving the point......."). One member Zilch, iirc had even do a YT demo proving that very point, but he used a voltmeter, so that demo was not valid. He later did use a clamp on meter to measure the currents in each wire; and if he did it right, he would have known that the currents would indeed be different between the current flowed in the wires feeding the tweeter, or tweeter+midrange driver, and the woofer, or woofer+the midrange driver.

So again, electrically there is a difference, but practically, I agreed there's no evidence that it would make any audible difference in probably 99.99% of the time/applications. I would leave that 0.01% chance, only because there will be a very minor electrical difference so there is always a chance, however low it is, in certain rare cases.

The best way to measure low Current, and this IS a low Current system, is to add a 1 Ohm resistor and measure mV- the Voltage on the display relates directly to the Current (I=E/R).

The current measured in the two tests would need to be added in order for the experiment to find a solution but the real questions are:

What difference was heard?
Did the listener know that something had been changed?
Did the person switching the wires know they were being changed?

Obviously, if the cables were changed manually and not by using an actual switch, they would know but if you think the extra wire was free from resistance and that it doesn't add to the total, go ahead and explain how that's possible..

 

[philly]

In terms of amplifier requirements, they are probably very similar. B&W recommends 30-300 W 8 ohms for both models.

The Amp 10 is rated 200 W 8 ohms, 400 W 4 ohms, given that the 702 S3's impedance is 8 ohms nominal, 3.1 ohm minimum, the Amp 10 is adequate for them.

All else being equal, mono block equivalent of the Amp 10, that is one that is rated also 200/400 W 8/4 ohms will be better as they are more "separate" than a 16 channel "separate" power amp. However, in terms of audible difference there will be none. Very few power amps will sound audibly better than the Amp 10, based on specs and measurements.

Marantz AMP 10 200 Watt x 16CH Amplifier Bench Test Results | Audioholics

You can of course BTL the Amp10 with the 702S3, but I would suggest against it, because I don't believe they are truly 8 ohm nominal speakers, based on the very similar 702S2, in case the S3 might have worse phase angles. That said, if you don't push the volume, say if you typically listen to volume setting below -15, then there should be no danger. How much current your speakers need depends a lot on your listening habit, that is, you seating distance, and your SPL requirements/volume setting, and use of room correction. Impedance is just one factor, and as you know it varies across the audio frequency band.

If you are really bothered by using a 16 channel amp jammed in one box, then okay, for super extra/ultra peace of mind, go grab a monoblock Hypex or Purifi based 500 W 4ohm power amp and call it a day. It's your money, so...

I will never buy a 16 channel amp myself, to me it defeats the idea of using separates, may as well use an AVR such as the Denon AVR-A1H lol... That's just me though, and I do believe monoblocks won't offer audibly better sound quality than the Amp 10, if the listening are told they are listening to monoblocks only in a blind test.

Just curious why you don't think separates are any more beneficial than an AVR? I thought 2 separate units offered a bigger power supply, shorter signal path, lower heat, etc.

 

[dlaloum]

I guess the photo of Gene holding it shows one of the reasons he works out.

Wow! I didn't know Marantz made a 16 channel amp- that would be great for a distributed audio system with in-ceiling speakers.

Gene's measurements shows that it is also an excellent performer....

 

[lovinthehd]

Just curious why you don't think separates are any more beneficial than an AVR? I thought 2 separate units offered a bigger power supply, shorter signal path, lower heat, etc.

I went from 2ch analog separates to avrs, while those are nice reasons in theory, generally just not that important compared to the feature set of modern gear. I'd just run your amp as normal, with one set of speaker wires. I'd also just concentrate more on using the gear rather than worrying about it.

 

[philly]

I went from 2ch analog separates to avrs, while those are nice reasons in theory, generally just not that important compared to the feature set of modern gear. I'd just run your amp as normal, with one set of speaker wires. I'd also just concentrate more on using the gear rather than worrying about it.

Gotcha

 

[PENG]

The best way to measure low Current, and this IS a low Current system, is to add a 1 Ohm resistor and measure mV- the Voltage on the display relates directly to the Current (I=E/R).

The current measured in the two tests would need to be added in order for the experiment to find a solution but the real questions are:

What difference was heard?
Did the listener know that something had been changed?
Did the person switching the wires know they were being changed?

Obviously, if the cables were changed manually and not by using an actual switch, they would know but if you think the extra wire was free from resistance and that it doesn't add to the total, go ahead and explain how that's possible..

The currents in the two bi-wire cables are due to the different impedances at the speaker end, when the crossover network would have been seprated into two parts when the jumpers are removed.

That's the "electrical difference", in terms of SQ, as I said, should be no difference in 99.99% of the applications unless the wrong cables are used.

 

[PENG]

Just curious why you don't think separates are any more beneficial than an AVR? I thought 2 separate units offered a bigger power supply, shorter signal path, lower heat, etc.

It is beneficial if your application needs the bigger power supply and output stages. In not, then no....

For, example, if you are getting ref level that is 105 dB peak at your seat with volume at -20, then even a 2000 W amp won't help you.

If you need to crank it up to say -5, then for sure you will benefit from an external amp rated 300/500 W 8/4 ohm.

You don't need to set your Amp20 to BTL, but there is no danger doing it, unless you have kids turning the volume too high.

 

[ski2xblack]

So in summary my amp 10 and these speakers shouldn't "blow up" leaving it in BTL mode? Lol. if it's a risk I'll definitely change it

Already answered upthread. Using the amp10 in bridge mode will effectively halve the load, so those dips to 3 ohms will present as 1.5 ohms. So, yes, when bridged, there is a greater chance to cook the amp. You really shouldn't use the amp10 in bridge mode on speakers that dip below 8 ohms. Your B&W's dip well below that.

 

[philly]

Already answered upthread. Using the amp10 in bridge mode will effectively halve the load, so those dips to 3 ohms will present as 1.5 ohms. So, yes, when bridged, there is a greater chance to cook the amp. You really shouldn't use the amp10 in bridge mode on speakers that dip below 8 ohms. Your B&W's dip well below that.

Ok thanks but I guess I'm getting mixed messages cuz right above, Peng says "there's no danger in doing it" unless i crank it up too high, which I don't?