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Number of speakers a Connect AMP powers

  • 7 November 2017
  • 14 replies
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How many regular speakers can I hook up to the Connect AMP?
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Best answer by Lucid AV 7 November 2017, 21:12

The amp is designed to handle a 4-8 Ohm load per channel. i.e. left and right. You can run a higher Ohm load, it'll just make less volume per speaker. What you have to avoid is going below 4 Ohms. There's a risk to the amp and the speakers.



Check your speakers for their impedance rating. If the speakers are all 8 Ohm then you can wire two speakers per channel and connect them in parallel. That's the + / positive / red wire of both speakers going to the left red terminal. (repeat for the right speakers and right +ve / red terminal). Then the - / negative / black wires from both speakers going to the left black terminal. (repeat for the right channels speakers and right -ve / black terminal)



Wiring like this puts a 4 Ohm per channel load on to the amp. This is the lowest you can go with speakers directly connected.



For speakers with a 6 Ohm or lower rating do not connect them in parallel. The amp will see a lower load than 3 Ohms and this is bad.



If you want to wire any more that two pairs of speakers and do it safely then there are adapter boxes called Impedance Matching Speaker Switches which will allow more speakers to be connected. The good ones use a transformer to protect and isolate the amp from the speakers. The B-Tech BT913 4 Way Speaker Switch will allow the connection of 4x pairs (8 individual) of speakers to a stereo amp.



Check the instructions of any impedance matching switch before parting with your money. The impedance combinations will affect the total number of speakers you can connect.
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14 replies

Lucid AV
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The amp is designed to handle a 4-8 Ohm load per channel. i.e. left and right. You can run a higher Ohm load, it'll just make less volume per speaker. What you have to avoid is going below 4 Ohms. There's a risk to the amp and the speakers.

Check your speakers for their impedance rating. If the speakers are all 8 Ohm then you can wire two speakers per channel and connect them in parallel. That's the + / positive / red wire of both speakers going to the left red terminal. (repeat for the right speakers and right +ve / red terminal). Then the - / negative / black wires from both speakers going to the left black terminal. (repeat for the right channels speakers and right -ve / black terminal)

Wiring like this puts a 4 Ohm per channel load on to the amp. This is the lowest you can go with speakers directly connected.

For speakers with a 6 Ohm or lower rating do not connect them in parallel. The amp will see a lower load than 3 Ohms and this is bad.

If you want to wire any more that two pairs of speakers and do it safely then there are adapter boxes called Impedance Matching Speaker Switches which will allow more speakers to be connected. The good ones use a transformer to protect and isolate the amp from the speakers. The B-Tech BT913 4 Way Speaker Switch will allow the connection of 4x pairs (8 individual) of speakers to a stereo amp.

Check the instructions of any impedance matching switch before parting with your money. The impedance combinations will affect the total number of speakers you can connect.
K
There is also no such thing as a regular speaker. Even those of different makes marked as the same Ohms will not present the same Ohm load to any amp across the frequency range of the sound they deliver. Some will drop impedance to as low as 2 ohms at times imposing what could be an unsustainable load on the amp. Some will stay at the specified ohms across the frequency range, and if this is 8 ohms or above, are an easier load for any amp, not just Connect Amp.

In general adding a second pair or more to Connect Amp is inviting trouble best addressed by the impedance matching device referred above by Lucid. Unless you are very sure that both pairs present 8 ohms all the time to the amp.
Lucid AV
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Some will drop impedance to as low as 2 ohms at times imposing what could be an unsustainable load on the amp. Some will stay at the specified ohms across the frequency range, and if this is 8 ohms or above, are an easier load for any amp, not just Connect Amp.


Unless the speaker is playing only the exact frequency where the impedance drops to 2 or 3 Ohms then it's not going to be an issue.

Music contains lots of frequencies all playing at the same time. Some will have a low impedance, others a high impedance, and some will be in the middle as the speaker plays them.
K


Music contains lots of frequencies all playing at the same time. Some will have a low impedance, others a high impedance, and some will be in the middle as the speaker plays them.
My understanding is different. Frequencies don't have impedances attached to them as the quoted seems to say. Different speakers however need different amounts of current to deliver them as they arise in the music and those speakers that need more current will drop impedance to draw more current than those that do not need that additional current to play the same music content, and will not so drop their impedance. Which is why the latter are easier loads for any amp, other things being equal.
Lucid AV
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You're quoting out of context. Read the first para; I didn't say that the frequencies have impedances attached to them. The impedance is the speaker's response to playing music at a specific frequency. That's what an impedance curve is. It's a frequency sweep and the speakers response. i.e. a series of individual tones and the measured response to those tones. You can say that the impedance drop to a low of X Ohms at Y frequency, but you can't then say that this makes it an X Ohms impedance speaker.

Put it another way, take a random group of people and then count their teeth. Some have 32, some have their wisdom teeth too so they have 36, others have lost a few teeth. Then you find the one person with say 6 teeth. That person has the fewest teeth in the group. Now, would you say that the entire group has only 6 teeth each based on that one individual?

This is how the averaged impedance works when playing a broad spectrum of frequencies (music) rather than the specific frequency (a single test tone) that excites the lowest impedance response. The speaker impedance drops to a low of say 3.7 Ohms @ 90Hz, but at 1650Hz the impedance measures almost 20 Ohms. Depending on the rest of the curve then the manufacturer might say that this is a 6 or an 8 Ohm impedance speaker.

Whether a speaker is a difficult load for an amp depends on (a) how much of the frequency curve stays at a low impedance, and (b) what's happening to the phase curve at the same time.

For example, this is the impedance curve for a Dyne Audio Excite speaker



Although the impedance drops to a low of roughly 5 Ohms at approx 200Hz the rest of the impedance curve spends most of its trace above 6 Ohms. This speaker isn't a particularly difficult load for the amp based on what's happening with just the impedance curve.

Now compare and contrast with the Revel Ultima



This speaker presents a minimum 3.7 Ohm load but look at the graph. The curve stays at a low Ohms reading from about 20Hz all the way to approx 700Hz. Based solely on the impedance curve then this is a much more challenging load for the amp.



Quoted Impedance and the Nominal Impedance value are fairly blunt tools when dealing with a speaker's response. A Frequency response curve would be better, but if that's all we have then that's all we have. We have to take it as well in the context of the amp being used to drive the speakers. In this case it's a switch-mode amp (referred to as digital, but not really digital) which is capable of doubling its power at half the Ohms rating.

From the OP's point of view the question has been asked how many "regular" speakers can the Sonos Connect Amp drive, but regular hasn't been defined as you correctly pointed out. My reply has put some figures to the speakers (if they're 8 Ohm) and what might happen. I've also counselled against using anything lower. That's about as much as can be reasonably achieved given the lack of source information.




Acknowledgement to Stereophile mag for their images.
K
Since you know the subject, and you know Stereophile it will be helpful if you pull similar graphs from the Atkinson reviews of the zp120 available there online, and summarise your interpretation of these for an insight into Connect Amp quality. As compared to any other good quality modern day 50 wpc into 8 ohms stereo amp.
Lucid AV
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I wish I had the amount of free time you think I do, ha ha ha :)

What are you hoping such a comparison would reveal?
K
That a Connect Amp is just as good. More expectation than hope, based on how it sounds compared to many I have used/known. From brands like Quad/NAD/Rotel/Conrad Johnson/Yamaha.
Lucid AV
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You and I have already had this conversation. However, if you want to do the comparison then try something like the Rega Brio. It doesn't double its power like the Connect Amp/Z120, but in lots of other ways it measures much cleaner. Atkinson tried it with a wide range of gear including some very expensive speakers and it acquitted itself admirably in his view.

Sadly he didn't do a proper listening review of the ZP100/120 AFAICT. That makes it hard to gauge it against amps of a similar power.

In the end it comes down to a subjective assessment of whether the amp (any amp) meets the expectations of the listener.

I'm not sure if I've recounted this story here, but eight or so years ago I did an ad hoc demo of a ZP100 with some decent in-ceiling speakers but just propped up against a wall that blew away a customer's existing Bose Lifestyle system. He wasn't happy. He said, and I quote "The guy in the Bose store said this was the best". I'd just demolished his £2000+ Bose with a £400 amp and some £300 speakers not even installed in the ceiling.

Up to that point Stuart had been happy with the way the Bose sounded. It wasn't as good as the big system in the cinema, but for the games room he thought the Bose did just fine, and I guess most of his opinion wasn't his own. He'd been told this was good, and perhaps the salesman believed it too, so Stuart hadn't really questioned it because he'd never been to a store where something better existed. The Bose met what his expectations of what he thought "better" meant. For a lot of folk better means more forceful bass and 'brighter' treble. The kind of sound that grabs the attention, but doesn't really hold it.

It's a curious thing; I've been to a fair number of homes where people have Bose, but they never strike me as music lovers. They've bought it mostly on the marketing, which Bose does very well. They've just ticked a box. We've got the Range Rover on the drive, the Apple computers and tablets, and the Bose sound system, 2.4 children and a Labrador.

The point is that everyone makes subjective assessment of what they want from sound. Very few people get the broad range of experience with different bits of gear to work out what floats their boat and what doesn't. Beyond that there's learning about the different approaches of manufacturers in what they think makes really good Hi-Fi tick. Then you have to decide if this or that path is important to you.

Measurements and graphs only tell part of the story. They can show if a product is engineered well, but they can't differentiate between what should be an okay amp and one that really clicks with the listener. Part of the reason for that is that amps are not the perfect wire with gain. They impart a signature to the sound. Atkinson mentioned this briefly in his limited comments about the ZP100. He said it sounded lean. I think that's a fair assessment. It doesn't make the product bad. For a lot of people the ZP100 or the 120/Connect Amp hooked up to some reasonable speaker will be the best Hi-Fi they've ever heard.
K
Part of the reason for that is that amps are not the perfect wire with gain. They impart a signature to the sound.
I disagree, because of my experience with over 20 HiFi amps, including the Connect Amp, supported also by the lack of level matched single variable DBT established audible sound differences from amps that have a similar spec confirmed by honest measurement.
It is pointless to debate this subject, IMO, and I will not. I haven't the time.
Lucid AV
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Part of the reason for that is that amps are not the perfect wire with gain. They impart a signature to the sound.
I disagree, because of my experience with over 20 HiFi amps, including the Connect Amp, supported also by the lack of level matched single variable DBT established audible sound differences from amps that have a similar spec confirmed by honest measurement.
It is pointless to debate this subject, IMO, and I will not. I haven't the time.

You seem to be getting upset about something, but I'm not sure what.

I've said what any decent designer or reviewer will know as a fundamental truth, and this is that the perfect amplifier is a piece of wire with gain. However, they'll all acknowledge that no such amplifier exists in reality. All give something of themselves to the signal passing through.

You're disagreeing with that? Are you saying that the perfect amp does exist?

I'm trying to work out from the wording you've used what exactly it is you're trying say. It reads like "I disagree that amps add their own sound to the signal. Test and measurements confirm that amps do add their sound to the signal " which you can see is a contradiction of itself.
K
Are you saying that the perfect amp does exist?

I am saying that stereo audio amps that are perfect enough for their imperfections to not be audible to humans in the sound they deliver via well matched speakers in any listening room have existed in large enough numbers for decades now and that they are now commodities. Which is not the answer to the quoted question, but is a more meaningful one: perfect enough amps exist in large numbers. The wire with gain is now straight enough for it to be heard as such.

And no, I am not upset, just not willing to argue what is a beaten to the death subject, and IMO, a settled one. But because this is a matter of belief systems that never get bridged, so there is no point in attempting to do so.
Lucid AV
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Like you, I don't want this to become an argument. However, there what I see as some fairly basic flaws with your reasoning


Are you saying that the perfect amp does exist?

I am saying that stereo audio amps that are perfect enough for their imperfections to not be audible to humans in the sound they deliver via well matched speakers in any listening room have existed in large enough numbers for decades now and that they are now commodities.

Whilst I agree that Hi-fi (or at least some aspects of it) have become commoditised, if the perfect amp existed then it wouldn't matter about matching the speakers. It would drive anything.

The room plays a huge part in the final result of any system to the point where it can make very basic systems sound better than expected, or make a great system sound very broken.

Saying that an amp is good enough that a bunch of people can't tell the difference it makes isn't the broad brush solution you hoped. I can go out on any street and drag in folks who won't care they're listening to a £500 system versus a £1500 one.

If you didn't want to start this debate then why ask me to spend my time looking at comparative reviews of the Connect Amp versus other 50W amps?

You're happy with your Connect Amp. Great. Is there anything more that needs to be said?
K

If you didn't want to start this debate then why ask me to spend my time looking at comparative reviews of the Connect Amp versus other 50W amps?

I had very good reasons, but explaining them will result in more argument. So just accept my "sorry about that" and let's part ways agreeing to disagree.

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