Explain Speaker Impedance to me

[JkSpinner 24]

Hi all

can someone explain speaker impedance to me please, especially how it relates to an amp.

I have a Denon 3312 that has includes two impedance specs in the specifications

8ohm, and 6 Ohm

does this mean the amp will not power 4ohm speakers?

 

I have a mixed bag of speakers, bought for a purpose, ie, dipole speakers for the side wall, and thin speakers for the rear wall, not matching.  My front three are matching though

 

I also have several speakers

some are 8 ohms normal

others suggest 8 ohm normal, and 2.7 ohms minimal

what does this mean in relation to my amp

 

i am considering a Rotel 1555 5 x 120w amp anyway, but trying to get an understanding of what all this means, as I am looking to make several upgrades

 

thanks

 

Edited April 2 by JkSpinner

[Quark 890]

You can think of impedance as the AC equivalent of resistance. Speakers with a lower impedance will draw more current. At higher volumes an unsuitable amp will run out of current capacity and clip - essentially send DC to the drivers - this is likely to fry them.

 

2.7 Ohms is quite low (and likely to be problematic with your 3312), but often low impedances are in bass frequencies and if your AVR's crossover is set to the typical 80Hz AND your speakers are set to Small in the AVR, much of the problematic low impedance won't be loaded on your AVR. What make/model are your speakers? Often there will be reviews that measure the impedance curve at different frequencies.

[stereo coffee 405]

On 02/04/2021 at 1:24 PM, JkSpinner said:

Hi all

can someone explain speaker impedance to me please, especially how it relates to an amp.

I have a Denon 3312 that has includes two impedance specs in the specifications

8ohm, and 6 Ohm

does this mean the amp will not power 4ohm speakers?

 

I have a mixed bag of speakers, bought for a purpose, ie, dipole speakers for the side wall, and thin speakers for the rear wall, not matching.  My front three are matching though

 

I also have several speakers

some are 8 ohms normal

others suggest 8 ohm normal, and 2.7 ohms minimal

what does this mean in relation to my amp

 

i am considering a Rotel 1555 5 x 120w amp anyway, but trying to get an understanding of what all this means, as I am looking to make several upgrades

 

thanks

 

When amplifier manufacturers rate power amplifiers they do so into a variety of resistance loads, loudspeakers as @Quark informs are different,  in that they present to a amplifier a reactance which stores some of that energy and later releases it. Impedance differs to resistance as it is the contribution of both resistance and reactance.

 

Here is a graph showing a solid state amplifiers ability into a number of resistance loads. it can provide some indication if we fall for thinking loudspeakers represent resistance, but that is not the case, as few of us enjoy the heat of a resistor, rather there is expectation a loudspeaker will be used. 

 

Also within this is the need to look at the contribution of the crossover network and two way vs three way

which has its own thread

You could choose to use planar speakers which typically have very high impedance at lower frequencies

and very low impedance at high frequencies. See the Quad ESL 57 impedance graph

https://medialux.blog/2018/04/25/erster-blogbeitrag/

 

At this point its good to keep in mind that there are fundamental differences between solid state and valve amplifiers, stated here http://education.lenardaudio.com/en/14_valve_amps_7.html

• Valve amp       power is directly proportional to speaker Impedance
        therefore   power increases as the speaker Impedance rises.
   
• Solid-state     power is inversely proportional to speaker Impedance
        therefore  power decreases as the speaker Impedance rises.

 

The reason for amplifier manufacturers not taking the further step to test with loudspeakers is that  they are presently voltage amplification devices which only indirectly affects the current flowing in a loudspeakers voice coil.

 

The future for amplifiers is to be current driven, and have sensing of the loudspeaker as part of its feedback path, but until then, I think Martin Colloms famous words that " all amplifiers sound different " needs  to be reflected upon vs Peter Walker of Quad,   words, "all amplifiers sound the same"   Auditioning of methods of attenuation,  power amplifiers and the speaker you intend to use, is absolutely essential.

 

 

 

 

 

 

 

 

[andyr 6,063]

16 hours ago, stereo coffee said:

 

You could choose to use planar speakers which typically have very high impedance at lower frequencies

and very low impedance at high frequencies. See the Quad ESL 57 impedance graph

https://medialux.blog/2018/04/25/erster-blogbeitrag/

 

 

Perhaps you should've used the term "electrostatic speakers" instead of "planar speakers", Chris.

 

Here is the impedance curve for a Maggie 1.6 which has a series passive XO instead of the stock parallel XO:

 

 

Pretty flat all the way through!

 

Andy

 

[stereo coffee 405]

1 hour ago, andyr said:

 

Perhaps you should've used the term "electrostatic speakers" instead of "planar speakers", Chris.

 

Here is the impedance curve for a Maggie 1.6 which has a series passive XO instead of the stock parallel XO:

 

 

Pretty flat all the way through!

 

Andy

 

Hi Andy

You are right , yes I was associating planars , thinking of them just as electrostatics, when there are many varieties of planar speakers.  The Maggies  as you show being exceptional with their impedance, that part of impedance related to resistance,  being very flat indeed.  

[Ittaku 4,719]

19 hours ago, stereo coffee said:

The future for amplifiers is to be current driven, and have sensing of the loudspeaker as part of its feedback path

That's just how you see it and wish for it to happen. Unfortunately no matter how much you wish for it, I'm quite sure that apart from perhaps some exceptional examples, won't be happening any time soon, if ever.

[Addicted to music 7,150]

13 minutes ago, Ittaku said:

That's just how you see it and wish for it to happen. Unfortunately no matter how much you wish for it, I'm quite sure that apart from perhaps some exceptional examples, won't be happening any time soon, if ever.

Most if not ALL conventional A and B amplifiers apart from Class D etc  driving speakers are Voltage source amplification.   Constant voltage across the 20-20k when a input is applied for the said freq Unfortunately a speaker is a reactive RCL device that varies with freq.   The best out there such as Dan D’Agostino etc, his designs are no different.....    So your best bet for SS amplification is to have as many BJT devices to handle the toughest of loads, that’s loads where current is demanded.   Note I said BJT, as there are positive temp coefficient,  

[stereo coffee 405]

16 minutes ago, Addicted to music said:

Most if not ALL conventional A and B amplifiers apart from Class D etc  driving speakers are Voltage source amplification.   Constant voltage across the 20-20k when a input is applied for the said freq Unfortunately a speaker is a reactive RCL device that varies with freq.   The best out there such as Dan D’Agostino etc, his designs are no different.....    So your best bet for SS amplification is to have as many BJT devices to handle the toughest of loads, that’s loads where current is demanded.   Note I said BJT, as there are positive temp coefficient,  

However current drive amps, with advantage of eliminating major distortion,  can be obtained https://www.integeraudio.com/

or DIY built  https://www.current-drive.info/9

[Addicted to music 7,150]

3 minutes ago, stereo coffee said:

However current drive amps, with advantage of eliminating major distortion,  can be obtained https://www.integeraudio.com/

or DIY built  https://www.current-drive.info/9

I hate to say it and I’ll say it once; “stop linking marketing BS”.    Do some research and look at how some of the most the respected designers and you’ll see how to design something that can be a “spot welder” 

[ray4410 820]

22 minutes ago, Addicted to music said:

I hate to say it and I’ll say it once; “stop linking marketing BS”.    Do some research and look at how some of the most the respected designers and you’ll see how to design something that can be a “spot welder” 

you mean something like this

[Addicted to music 7,150]

18 minutes ago, ray4410 said:

you mean something like this

Yep

[stereo coffee 405]

3 minutes ago, Addicted to music said:

I hate to say it and I’ll say it once; “stop linking marketing BS”.    Do some research and look at how some of the most the respected designers and you’ll see how to design something that can be a “spot welder” 

 

There is very little marketing in a well written 342 page book, rather more so an enormous passion by its author to solve why voltage drive is far from complete, even at welding type currents. Would  you like me to send it to you ?

 

Having read it it you can reflect on the all too common welding approach, and perhaps better see why it is incomplete,   vs current drive.

 

A simple example is if we consider the resistance portion of a high impedance loudspeaker as being a simple form of current drive, as its resistance portion is partially allowing current driving of a normal voltage amplifier. The infamous L/S 3,5a provides 15 ohms, and is far from being unpopular. 

 

There is no doubting voltage amps are good at what they do when measured with a resistor, but the next step of making a current drive amp,   is not too much of a departure,  from what is already being provided, if we aspire to achieve it.

 

Perhaps we can both find some graphs and measurement of actual amplifiers when attached to a loudspeaker, we would then see what was BS. 

 

 

 

 

 

[stereo coffee 405]

3 hours ago, Addicted to music said:

I hate to say it and I’ll say it once; “stop linking marketing BS”.    Do some research and look at how some of the most the respected designers and you’ll see how to design something that can be a “spot welder” 

 

There is very little marketing in a well written 342 page book, rather more so an enormous passion by its author to solve why voltage drive is far from complete, even at welding type currents. Would  you like me to send it to you ?

 

Having read it it you can reflect on the all too common welding approach, and perhaps better see why it is incomplete,   vs current drive.

 

A simple example is if we consider the resistance portion of a high impedance loudspeaker as being a simple form of current drive, as its resistance portion is partially allowing current driving of a normal voltage amplifier. The infamous L/S 3,5a provides 15 ohms, and is far from being unpopular. 

 

There is no doubting voltage amps are good at what they do when measured with a resistor, but the next step of making a current drive amp,   is not too much of a departure,  from what is already being provided, if we aspire to achieve it.

 

Perhaps we can both find some graphs and measurement of actual amplifiers when attached to a loudspeaker, we would then see what was BS. 

 

 

I found Stereophile admitting something is missing with amplifier tests, when they are conducted when not using actual loudspeakers   https://www.stereophile.com/reference/60/index.html

 

and reference to a Audio Engineering Society article, which is also at research gate, which I have requested a copy of, which may be subject to copyright. 

 

Failing that I might have to set up my spare oscilloscope, and run a sine wave signal with and without speaker 

so we can see the effect on a scope of a few speakers.

 

As a collective of persons interested in audio IMO we should always expect actual loudspeaker loads to be part of amplifier testing, and reject as having as much less meaning resistor loads, as being nice, but not too meaningful.  

 

 

[sir sanders zingmore 12,371]

2 minutes ago, stereo coffee said:

As a collective of persons interested in audio IMO we should always expect actual loudspeaker loads to be part of amplifier testing, and reject as having as much less meaning resistor loads, as being nice, but not too meaningful.  

Which loudspeaker should we select to replace resistor loads for amplifier testing?

[stereo coffee 405]

2 minutes ago, sir sanders zingmore said:

Which loudspeaker should we select to replace resistor loads for amplifier testing?

Good question, I think a three way design and a two way design, and electrostatic where available  should form

part of all amplifier tests. The tables would begin to turn to show preference I think for simple crossover networks. 

 

A standard reference with two way being the LS /3,5a, i don't think any speaker other than maybe the ESL57 has received so much research.  With 3 way lets plumb for a Yamaha NS1000 , and electrostatic the venerable ESL57

 

As long as testers were testing with each type ie 2 way, 3 way and a electrostatic  is the emphasis, rather than  resorting to resistor measurements,  as they presently get too easily away with.

 

 

[andyr 6,063]

On 02/04/2021 at 11:24 AM, JkSpinner said:

Hi all

can someone explain speaker impedance to me please, especially how it relates to an amp.

I have a Denon 3312 that has includes two impedance specs in the specifications

8ohm, and 6 Ohm

does this mean the amp will not power 4ohm speakers?

 

I have a mixed bag of speakers, bought for a purpose, ie, dipole speakers for the side wall, and thin speakers for the rear wall, not matching.  My front three are matching though

 

I also have several speakers

some are 8 ohms normal

others suggest 8 ohm normal, and 2.7 ohms minimal

what does this mean in relation to my amp

 

i am considering a Rotel 1555 5 x 120w amp anyway, but trying to get an understanding of what all this means, as I am looking to make several upgrades

 

thanks

 

I'm not sure you have so far received the direct answer you were hoping for, JkS ... so I thought I might try.  

 

The specs for your Denon 3312 don't include a 4ohm rating.  That suggests to me ... the amp doesn't perform well into 4 ohms.    (Coz if it did - they would trumpet it!   )

 

An "ideal" amp doubles output power as you halve the load - most amps don't achieve this.  With a good amp ... you might see figures like "500w/8 ohms, 900w/4 ohms, 1500w/2 ohms".

 

What are the figures quoted for the Denon 3312, at 8 & 6 ohms?  Is the 6 ohm power rating 1/3rd more than the 8 ohm power rating?

 

As you've found from your own collection of spkrs - just because they say it's an 8 ohm spkr doesn't mean it doesn't drop to a much lower value somewhere during its frequency range.  So the one that says "8 ohms nominal, 2.7 ohms minimum " is going to be a harder load for an amp to cope with than one that said "8 ohms nominal, 4 ohms minimum ".

 

In general AVRs and multichannel amps don't handle difficult spkr loads as well as good stereo amps - simply because in a multichannel situation, the one power supply is feeding all channels (whereas in a good stereo amp, each channel has its own power supply).

 

The specs I saw for your Denon 3312 say 7 channels at 125w per channel; so in what way is the Rotel 1555 better (given you say it is 5x 120w)?

 

Andy

 

[JkSpinner 24]

41 minutes ago, andyr said:

 

I'm not sure you have so far received the direct answer you were hoping for, JkS ... so I thought I might try.  

 

The specs for your Denon 3312 don't include a 4ohm rating.  That suggests to me ... the amp doesn't perform well into 4 ohms.    (Coz if it did - they would trumpet it!   )

 

An "ideal" amp doubles output power as you halve the load - most amps don't achieve this.  With a good amp ... you might see figures like "500w/8 ohms, 900w/4 ohms, 1500w/2 ohms".

 

What are the figures quoted for the Denon 3312, at 8 & 6 ohms?  Is the 6 ohm power rating 1/3rd more than the 8 ohm power rating?

 

As you've found from your own collection of spkrs - just because they say it's an 8 ohm spkr doesn't mean it doesn't drop to a much lower value somewhere during its frequency range.  So the one that says "8 ohms nominal, 2.7 ohms minimum " is going to be a harder load for an amp to cope with than one that said "8 ohms nominal, 4 ohms minimum ".

 

In general AVRs and multichannel amps don't handle difficult spkr loads as well as good stereo amps - simply because in a multichannel situation, the one power supply is feeding all channels (whereas in a good stereo amp, each channel has its own power supply).

 

The specs I saw for your Denon 3312 say 7 channels at 125w per channel; so in what way is the Rotel 1555 better (given you say it is 5x 120w)?

 

Andy

 

Thanks Andy,  well said.  I have been doing heaps of reading, and posted a few specific questions.  I am looking to upgrade several pieces, but want to make sure I understand most things first.  It’s not just the amps, many  speakers only quote nominal, and do not quote minimal.

but in the end, I think if I get a 5 channel power amp, all should be fine, just need to worry about my 2 channel stuff then

your comment about the 8/4 ohm.  If the power doubles, I am lead to believe that it is a higher current Amp.  Without trying to get into the mathematics of things, I am lead to believe that if an amp is able to produce twice the power at half the resistance, it could be considered higher current amp, and that could be useful.

thanks, you were right, I don’t think the question was answered 

[DrSK 455]

1 hour ago, JkSpinner said:

Thanks Andy,  well said.  I have been doing heaps of reading, and posted a few specific questions.  I am looking to upgrade several pieces, but want to make sure I understand most things first.  It’s not just the amps, many  speakers only quote nominal, and do not quote minimal.

but in the end, I think if I get a 5 channel power amp, all should be fine, just need to worry about my 2 channel stuff then

your comment about the 8/4 ohm.  If the power doubles, I am lead to believe that it is a higher current Amp.  Without trying to get into the mathematics of things, I am lead to believe that if an amp is able to produce twice the power at half the resistance, it could be considered higher current amp, and that could be useful.

thanks, you were right, I don’t think the question was answered 

 

That covers some basic pointers, but high current often refers to peak current as well. 

 

I have these, and the max current is in arc welder territory but they don't follow the rule of thumb about doubling power for halving resistance. 

 

https://www.theaudiotailor.com.au/products/electrocompaniet-aw180-mono-block-power-amplifier-pair

 

Based on their 250W at 8Ohm this would give just under 6A.  Or just under 18A at 2Ohms. But this rating is for continuous power and in part relates to thermal overload. 

 

However the peak output per channel is over 100A. This gives plenty of head room for drum hits etc so they don't get clipped.

 

Most amplifiers at lifestyle consumer stores etc effectively clip. Eg my 130W per channel $2k-$3k AVR (among many other things, and even at moderate listening levels) could not reproduce vocal dynamics, drum hits, double base string plucks, and low register piano strings as they were struck by the hammers, yet my 100W Metaxas stereo power amp could. 

 

 

Edited April 4 by DrSK

[JkSpinner 24]

9 minutes ago, DrSK said:

 

That covers some basic pointers, but high current often refers to peak current as well. 

 

I have these, and the max current is in arc welder territory but they don't follow the rule of thumb about doubling power for halving resistance. 

 

https://www.theaudiotailor.com.au/products/electrocompaniet-aw180-mono-block-power-amplifier-pair

 

Based on their 250W at 8Ohm this would give just under 6A.  Or just under 18A at 2Ohms. But this rating is for continuous power and in part relates to thermal overload. 

 

However the peak output per channel is over 100A. This gives plenty of head room for drum hits etc so they don't get clipped.

 

Most amplifiers at JB Hifi etc effectively clip. Eg my 130W per channel AVR could not reproduce vocal dynamics, drum hits, double base string plucks, and low register piano strings as they were struck by the hammers, yet my 100W Metaxas stereo power amp could. 

 

 

I get it, there’s watts, then there are watts, then there are watts, but how does a novice work this out.  Then many people talk about high current amplifiers, which appears even harder to work out

[DrSK 455]

1 minute ago, JkSpinner said:

I get it, there’s watts, then there are watts, then there are watts, but how does a novice work this out.  Then many people talk about high current amplifiers, which appears even harder to work out

It shouldn't be this hard. It is in part because specs are often hard to come by or not well defined. 

 

I'm rather cynical in that it is to many in the industries benefit that this is so. No good if we could simply just read the specs and buy exactly what we needed to match gear perfectly to our needs first time. 

[sir sanders zingmore 12,371]

3 hours ago, stereo coffee said:

Good question, I think a three way design and a two way design, and electrostatic where available  should form

part of all amplifier tests. The tables would begin to turn to show preference I think for simple crossover networks. 

 

A standard reference with two way being the LS /3,5a, i don't think any speaker other than maybe the ESL57 has received so much research.  With 3 way lets plumb for a Yamaha NS1000 , and electrostatic the venerable ESL57

 

As long as testers were testing with each type ie 2 way, 3 way and a electrostatic  is the emphasis, rather than  resorting to resistor measurements,  as they presently get too easily away with.

 

 

It seems to me that there is huge variance even within your suggested subset of speaker types. Enough of a difference that the measurements for one set of two/ways (for example) would not be nearly as useful for any other. So unless you are considering that particular combination, you wouldn’t gain anything more out of this style of measurement. 

[stereo coffee 405]

53 minutes ago, sir sanders zingmore said:

It seems to me that there is huge variance even within your suggested subset of speaker types. Enough of a difference that the measurements for one set of two/ways (for example) would not be nearly as useful for any other. So unless you are considering that particular combination, you wouldn’t gain anything more out of this style of measurement. 

It does encompass quite a few owners of speakers, are yours 4 way ?   what would you suggest ?

[sir sanders zingmore 12,371]

13 minutes ago, stereo coffee said:

It does encompass quite a few owners of speakers, are yours 4 way ?   what would you suggest ?

How are my particular speakers relevant to this discussion?. 

[Addicted to music 7,150]

11 hours ago, stereo coffee said:

 

There is very little marketing in a well written 342 page book, rather more so an enormous passion by its author to solve why voltage drive is far from complete, even at welding type currents. Would  you like me to send it to you ?.  

 

 

you keep it for your own entertainment 

 

 

11 hours ago, stereo coffee said:

 

 

Having read it it you can reflect on the all too common welding approach, and perhaps better see why it is incomplete,   vs current drive.

 

A simple example is if we consider the resistance portion of a high impedance loudspeaker as being a simple form of current drive, as its resistance portion is partially allowing current driving of a normal voltage amplifier. The infamous L/S 3,5a provides 15 ohms, and is far from being unpopular. 

 

There is no doubting voltage amps are good at what they do when measured with a resistor, but the next step of making a current drive amp,   is not too much of a departure,  from what is already being provided, if we aspire to achieve it.

 

 

 

 

 
 

Basic ohms law says for current to flow you MUST have a potential difference between 2 points in a close circuit...  so you must provide a voltage that’s different between 2 points: Hence the term: Voltage Source 😉

How do ALL amplifiers work?   They convert a small signal to a large one or a large signal from a small one!  😃  How do All amplifiers do this?  Usually involves switching on/off  a larger power supply with some 3 legged devices that’s attached to the PSU voltage rail in series with the transducer in series with ground 😉. How do you have enough current capability to drive the hardest load that involves low impedance so the the 3 legged devices don’t self destruct and remain in SOA,  you increase the number of devices on the end so it provides more current from the power supply voltage rails, a basic technique that’s referred as current sharing!  note the output impedance of the device doesn’t change, its constant at all frequencies unless it’s neg temp coefficient mosfets .... Basic Electronics, all comes under the term: Voltage Source 😉

if you want to reduced the variation of reactance to get consistant volume at all frequencies,  you need to correct the transducer reactance when designing/calculating  the equivalent electrical circuit of the transducer to all the freq required which no loudspeaker manufacturers will do..  The different reactance in a LCR of a transducer is  the job of the loudspeaker designer to correct not the electronics engineer for the electronics driving it!  
It’s like making a AC motor to run at 50hz 230VAC....  I bet you won’t be lodging a complaint to a power company to say that they have to do a power phase  correction to the mains so your AC motor will work!   You’ll be correcting it with an equivalent LCR circuit to the correct power factor for the motor so it runs on the mains....basic circuit theory!  The mains has to drive many different components with different LCR!  Why should it be different or unique to drive what you have.   That’s basically what you’re asking as an analogy for speaker/amp design.  Amplifier manufactures won’t make there products drive every speaker in the market, it wouldn’t be feasible, they make a range to cater for price and the more capable the more it costs.  Usually the better capability involve a huge power supply with  higher DC voltage rail and multiple 3 legged driver devices for current capabilities!  
 

See what I did there “high DC voltage rails “ Voltage source 😉

 

Edited April 4 by Addicted to music

[stereo coffee 405]

 

7 hours ago, Addicted to music said:

 

 " The different reactance in a LCR of a transducer is  the job of the loudspeaker designer to correct not the electronics engineer for the electronics driving it!  "

 

 

 

Trouble is they don't usually meet to discuss each others requirements.  Not discounting there may already be products  seeing the current drive method as beneficial, particularly products from active speaker manufacturers.

 

Rather generally  presently physics wins, and few of us presently benefit, as EMF deriving from the voice coil motion, sums with the voltage applied to the driver, resulting in a mixture of the original signal and spurious signal corrupted by the speakers own mechanical electrical and acoustic properties. 

 

It goes without saying a current driven amplifier should also cater to the loudspeaker, and vice a versa.       

[davewantsmoore 6,720]

On 02/04/2021 at 11:24 AM, JkSpinner said:

I have a Denon 3312 that has includes two impedance specs in the specifications 8ohm, and 6 Ohm does this mean the amp will not power 4ohm speakers?

 

The short answer is yes.

 

The long answer is it will probably work (for not high SPLs) but the amplifier may misbehave, which could include distortion, over heating and/or shutting down.

 

If you want to drive speakers < 6ohms to any serious SPL (or at all) you should change the amp to one which is designed to drive a <6ohm speaker.

[davewantsmoore 6,720]

21 hours ago, Ittaku said:

That's just how you see it and wish for it to happen. Unfortunately no matter how much you wish for it, I'm quite sure that apart from perhaps some exceptional examples, won't be happening any time soon, if ever.

 

 

Why do you say that?

 

There is a lot (!!!!) of current (pardon the pun) work in this area including everything from giant subwoofers, right through to the speakers you would find inside a mobile phone.

 

[davewantsmoore 6,720]

19 hours ago, stereo coffee said:

There is very little marketing in a well written 342 page book

 

I'm not sure I agree the book is "well written"   

It's a tough read..... but it's heart is certainly in the right place.

 

I think it misses it's mark for it's "taregt market" though (those under the 'delusion' of 'pure voltage drive').

 

Anyways.... it's a complex discussion (huurrrr... I did it again)

[davewantsmoore 6,720]

13 hours ago, JkSpinner said:

I get it, there’s watts, then there are watts, then there are watts

 

No.... This misleads people (especially a "novice").

 

What you need to do is find an amplifier which is rated to drive the minimum imedance of your speaker, with enough power to drive the speaker to the SPL you want.

 

Just follow the above and foget things like "does the impedance double with a halving of impedance", etc, etc.... and "is this a high current amp"?

 

 

You might need help figuring out the above things.... like whats the minimum impedance of my speaker?.... or how much power do I need to reach my desired SPL? .... or what is my desired SPL?

 

.... but that's what you should focus on...... ask.... or ask your speaker and/or amp manufacturer(s).

[davewantsmoore 6,720]

1 hour ago, stereo coffee said:

Trouble is they don't usually meet to discuss each others requirements.

 

This is very true and a very big problem.

 

You know the funny thing though.   "HiFi" is basically the ONLY place where this problem exists.

 

In professional audio.... or embedded audio (like a phone, or TV, or portable speaker), etc. etc.....  the people making the transducers, enclosures, and amplifiers, are highly intertwined, if not one and the same people.

[betty boop 15,959]

On 02/04/2021 at 11:24 AM, JkSpinner said:

Hi all

can someone explain speaker impedance to me please, especially how it relates to an amp.

I have a Denon 3312 that has includes two impedance specs in the specifications

8ohm, and 6 Ohm

does this mean the amp will not power 4ohm speakers?

it will JK we have a older 3series denon powering old 4 and 6 ohm Richter’s abs has done for years .. keeping in mind limits to what will achieve and denon rearranged their line up in 2011 so really they moved the range up a notch to include lower rung 1 series. So really current 3 series is more like 2 series level from  2008 and back ...

 

On 02/04/2021 at 11:24 AM, JkSpinner said:

i am considering a Rotel 1555 5 x 120w amp anyway, but trying to get an understanding of what all this means, as I am looking to make several upgrades

do without hesitation this amp is a refresh of the old rotel 1075 (look similar under hood) that was good honest engineering using decent components and will be a very decent upgrade over the 3312 internal amps. Many folk have combined the denons over the years for their processing and rotels as power amps ... work great. Think said in other thread you had a michi 2ch amp ? In which case this would be a great match !

 

Avrs in power amp stage do get better as go up the range but then they still heavily compromised in the greater amount of channels and processing trying to squish in leaving little room for essential things like heat sinks and such

 

you certainly couldn’t squish the power amp like like rotel  1555 or even older 1075 ! So makes sense to add on ...for the benefit

[Ittaku 4,719]

21 minutes ago, davewantsmoore said:

 

 

Why do you say that?

 

There is a lot (!!!!) of current (pardon the pun) work in this area including everything from giant subwoofers, right through to the speakers you would find inside a mobile phone.

 

Because I see effectively nothing happening in the general purpose amplification for home hifi which is what we're ultimately discussing here?

[davewantsmoore 6,720]

2 hours ago, Ittaku said:

Because I see effectively nothing happening in the general purpose amplification for home hifi which is what we're ultimately discussing here?

 

Yeah, I think it's unlikely to be "general purpose".... but I see it coming.   The world of speaker and amplifier manufacturers being different people (or not heavily intertwined) it very very last century.

[sir sanders zingmore 12,371]

20 minutes ago, davewantsmoore said:

 

Yeah, I think it's unlikely to be "general purpose".... but I see it coming.   The world of speaker and amplifier manufacturers being different people (or not heavily intertwined) it very very last century.

It may be changing with the likes of  D&D, SGR, Kii etc but there are still big obstacles which make it hard (and which are usually completely unrelated to sound quality). 
 

EDIT: apart from SGR I’m not sure which of the “all in one” manufacturers are using current-drive in their devices. 

Edited April 5 by sir sanders zingmore

[almikel 1,649]

@JkSpinner did your original question get answered? the thread seemed to go in multiple directions...

 

On 02/04/2021 at 10:24 AM, JkSpinner said:

I have a Denon 3312 that has includes two impedance specs in the specifications

8ohm, and 6 Ohm

does this mean the amp will not power 4ohm speakers?

possibly not - especially at high volumes

Most of the below has been said above in one way or another, but I'll summarise:

• Speaker Impedance is the load presented to your amp - the amplifier you have (Denon 3312) will attempt to deliver a constant voltage to the speaker load for a constant input. The lower the load/impedance, the higher the current your amp needs to deliver based on Ohms law V=IxR (Voltage = current x resistance).
• Speakers/drivers aren't purely resistive, they also typically have inductive (eg cone drivers) or capacitive (eg electrostatic speakers) characteristics, and the inductive or capacitive part of the load is called "reactive" - so your amp has to drive both the resistive load and the reactive load
• Ohms law still applies, ie V=I x R, except R becomes a combination of resistance and reactance, and is termed "impedance"

Getting a bit more technical

• once you have reactance in the load, the voltage and current get out of phase with each other (called phase angle)
• inductive loads (eg normal cone drivers), have a positive phase angle and generally don't prove to be a difficult load for solid state amplifiers like your Denon as long as the impedance/resistance doesn't drop too low for the amp to provide the current - in your case the amp is designed for 8 and 6 ohm loads.
  At low volumes your amp will likely be fine with a 4 ohm load, but at high volumes your amp may not be able to maintain the voltage (V=IxR) to deliver the current into the 4ohm load
• capacitive loads (eg electrostatic speakers like ESL57s), have a negative phase angle - some solid state amps don't like capacitive loads, as it will send the amp into oscillation.
  Some amps more than others - Naim amps seem to have a reputation for disliking capacitive loads.
  Good design of the amplifier removes this limitation.
  There are plenty of great solid state amps that will happily drive a capacitive load - but generally these are amps that are able to deliver high current into a low impedance
• If you have cone speakers, the only thing you need to worry about is whether your amp can provide the volume you want without distortion

cheers

Mike

 

 

[andyr 6,063]

Great summary, @almikel!  

 

Andy

 

[davewantsmoore 6,720]

On 05/04/2021 at 1:20 PM, sir sanders zingmore said:

EDIT: apart from SGR I’m not sure which of the “all in one” manufacturers are using current-drive in their devices. 

Kii do

[davewantsmoore 6,720]

On 05/04/2021 at 10:07 PM, almikel said:

• If you have cone speakers, the only thing you need to worry about is whether your amp can provide the volume you want without distortion

 

This.

 

... or shutting down and/or overheating, which can be an issue in AVRs and similar.    That being said, it's super unlikely to break anything (eg. driving 40hm speaker from 6 ohm rated AVR) .... it just might not sound as good.

[sir sanders zingmore 12,371]

22 minutes ago, davewantsmoore said:

Kii do

 

Thanks 

 

I see this in their website

Unique to the implementation used in the Kii THREE is a combined voltage/current control loop that goes beyond merely a better amp – it actively improves the distortion performance of the drive units which contributes significantly to the extreme resolution of the speaker.

 

So presumably they aren't using the same nCore modules that you can buy off the shelf?

[davewantsmoore 6,720]

20 minutes ago, sir sanders zingmore said:

So presumably they aren't using the same nCore modules that you can buy off the shelf?

Correct.

 

 

Sorry OP - Most people will consider this off topic  (it's very related to impedance.... but a bit far out from the question which was being asked)   

 

My loose interpretation of it is, simply an extension of what Bruno has said loudly for a long time.   Feedback isn't bad..... unless it is used poorly (it's a powerful tool, with great responsibility, etc).    The whole simple argument of "current drive" is the question of what is it that we are trying to control.    The voltage?  No (it's borderline irrelevant) .....  the current is what is relevant.

 

Well designed voltage feedback... is great and all (better than badly designed)..... but trying to control the wrong thing is quite daft.

 

Voltage controlled amplifier exist for nothing more than convenience.... it is not what any smart person would go to if beginning with a blank sheet of paper.

Edited Thursday at 12:27 AM by davewantsmoore