Volunteer sir sanders zingmore Posted March 15, 2021 Volunteer Share Posted March 15, 2021 7 minutes ago, davewantsmoore said: It seems that many people don't really see the picture..... perhaps you guy get it, so this isn't directed at you, more in general. Speakers don't consume power (aside from small losses like heat dissipation) .... the current flows through the speaker back into the amplifier. People get confused when we say "a speaker is a hard to drive" .... and "a speaker takes lots of power" .... etc. etc. All the power flows back to the amplifier. When we have a "reactive" speaker load..... this doesn't mean that the speaker consumes more power in the way most people think. The extra power is dissipated inside the amplifier. You are correct to say I and V are just "two sides of the same coin" so to speak..... but in a (moving coil) speaker, it is the current flow, makes it move. The voltage in the speaker is of no relevance. So if I understand it correctly, it would be better to deliver the current flow that each specific speaker requires rather than just 'chucking' voltage at it. But the problem with this is that you can't generalise the requirements - the current requirements vary from speaker to speaker. A 'current drive' amp will not drive any and every speaker well, you need design the amp and speaker specifically to work together. In a world where amps and speakers are usually designed without reference to each other, a 'voltage drive' amp, whilst not the "best" way to drive a speaker is the best compromise because it cares less about the actual speaker it ends up driving. Or have I misunderstood what you are saying? Link to comment Share on other sites More sharing options...
davewantsmoore Posted March 15, 2021 Share Posted March 15, 2021 On 14/03/2021 at 8:18 PM, Ittaku said: I'm pretty sure the 135A is some theoretical ideal transient maximum Not as such.... it will depend on what voltage the amp is trying told up. It's all only rated to 4500w .... until it starts to smell bad. At 135w and very high power dissipation, the voltage side is going to be far away from its limit (90 something V from memory) .... so there shouldn't be any issues beyond the ability to cope with everything glowing white hot. Link to comment Share on other sites More sharing options...
anandpkumar Posted March 15, 2021 Share Posted March 15, 2021 10 minutes ago, davewantsmoore said: A speaker doesn't need any specific voltage to move.... it irrelevant. It is the current flowing through the coil which causes it to move. Whatever voltages are present are irrelevant..... it is only the resulting current which matters. A speaker is completely 1000% a current driven motor. .... it is sad that so many people in audio, people who should know better, seem to misunderstand this.... or at least get it very twisted around. Given all this confusion, I feel that there should be a better way of representing the specifications/requirements of both speakers and amplifiers. If current is so important, I see only a few amplifiers that have the max current/peak current values published. Speaker specs have no mention of current at all - only efficiency and max power requirements (whatever that means in the real world) Can the industry have a better way of representing the specs of speakers/amplifiers? Or am I opening up a can of worms here? Link to comment Share on other sites More sharing options...
davewantsmoore Posted March 15, 2021 Share Posted March 15, 2021 (edited) 20 minutes ago, sir sanders zingmore said: So if I understand it correctly, it would be better to deliver the current flow that each specific speaker requires rather than just 'chucking' voltage at it. Yes. When you chuck voltage (lol) at a speaker...... some current will flow. The crossover components and the impedance curve of the speaker dictate how much current flows for your voltage. BUT.... there is a huge problem. https://www.sites.google.com/site/drivervault/driver-measurements/tang-band-75-1558se/ae-speakers-td12m/le-x/Le(x)_7mm.PNG?attredirects=0 This is the impedance curve of a very high quality woofer. You can see 3 lines. This is the impedance of the driver at rest.... at full out excursion... and full in excursion. As the cone moves the impedance curve "dances" between these values. The impedance curve is the main thing acting as the "voltage to current converter" .... and it is the current signal which causes the cone to move. The current signal is polluted (distortion) by the unstable speaker impedance. If instead... the amplifier chooses a precise current output and lets the voltage be whatever it may be ..... (as opposed to controlling the voltage and letting the current flow be dictated) ..... then that amount of current will flow through the speaker irregardless of the (unstable) impedance. Quote But the problem with this is that you can't generalise the requirements - the current requirements vary from speaker to speaker. A 'current drive' amp will not drive any and every speaker well, you need design the amp and speaker specifically to work together. Yes.... mostly. It is possible to construct a speaker which would work consistently from any source impedance (ie. "voltage source" or "current source" ....... but noting that these terms confuse, as it's always current which is affecting the speaker) Joe Rasmussen (Custom Analogue) does this with his elsinore speaker. I'm still not a "put resistors, capacitors and inductors between my power and speaker" type of guy... so I've never bothered...... although it (what he is doing) does have some merits. Quote In a world where amps and speakers are usually designed without reference to each other It's very sad. A long time ago I read someone lamenting this.... and its what got me into "high quality" reproduction as I discovered how the SOTA was "doing it so wrong". (I hope that doesn't sound too arrogant). Quote a 'voltage drive' amp, whilst not the "best" way to drive a speaker is the best compromise because it cares less about the actual speaker it ends up driving. Or have I misunderstood what you are saying? No... I think you got it Edited March 15, 2021 by davewantsmoore 2 Link to comment Share on other sites More sharing options...
davewantsmoore Posted March 15, 2021 Share Posted March 15, 2021 7 minutes ago, anandpkumar said: Can the industry have a better way of representing the specs of speakers/amplifiers? Or am I opening up a can of worms here? It's complicated. Single numbers, or maximums, etc.... don't tell you what you need to know.... and people will interpret it all wrong. ... but we can see (hear) from the fact that sometimes amplifiers sound different to each other when they shouldn't......that we are abusing them by tortuous speaker designs. Misbehaving amplifiers really sound (at best) terrible .... so it's a sad thing. 1 Link to comment Share on other sites More sharing options...
aussievintage Posted March 16, 2021 Share Posted March 16, 2021 1 hour ago, davewantsmoore said: You are correct to say I and V are just "two sides of the same coin" so to speak..... but in a (moving coil) speaker, it is the current flow, makes it move. The voltage in the speaker is of no relevance. Except that you need the voltage to get any current to flow, yes 1 hour ago, sir sanders zingmore said: So if I understand it correctly, it would be better to deliver the current flow that each specific speaker requires rather than just 'chucking' voltage at it. As above, that's how you do it. A current source raises the voltage until the required current flows. 1 hour ago, sir sanders zingmore said: But the problem with this is that you can't generalise the requirements - the current requirements vary from speaker to speaker 56 minutes ago, anandpkumar said: Given all this confusion, I feel that there should be a better way of representing the specifications/requirements of both speakers and amplifiers. If current is so important, I see only a few amplifiers that have the max current/peak current values published. Speaker specs have no mention of current at all - only efficiency and max power requirements (whatever that means in the real world) The amount of current required to generate the required movement to generate the desired level of sound is related to the efficiency of the speaker because of the power term (W) in the db/watt/metre spec. 50 minutes ago, davewantsmoore said: The current signal is polluted (distortion) by the unstable speaker impedance. I like that way of putting it. 2 Link to comment Share on other sites More sharing options...
Telecine Posted March 16, 2021 Share Posted March 16, 2021 46 minutes ago, davewantsmoore said: It's complicated. Single numbers, or maximums, etc.... don't tell you what you need to know.... and people will interpret it all wrong. ... but we can see (hear) from the fact that sometimes amplifiers sound different to each other when they shouldn't......that we are abusing them by tortuous speaker designs. Misbehaving amplifiers really sound (at best) terrible .... so it's a sad thing. So the better way to think of this is as the speakers and amplifier being a circuit. The speakers draw current from the amplifier in response to the modulating frequency of the music signal and the impedance response of the speakers. Link to comment Share on other sites More sharing options...
davewantsmoore Posted March 16, 2021 Share Posted March 16, 2021 6 minutes ago, aussievintage said: I like that way of putting it. it's like using the speaker voice coil as a voltage to current converter. It's really really non-linear (distortion!!!!) 1 Link to comment Share on other sites More sharing options...
aussievintage Posted March 16, 2021 Share Posted March 16, 2021 5 minutes ago, Telecine said: So the better way to think of this is as the speakers and amplifier being a circuit. The speakers draw current from the amplifier in response to the modulating frequency of the music signal and the impedance response of the speakers. I know what you meant, but it's the instantaneous voltage or current that represents the music signal. How fast it changes is the frequency. Link to comment Share on other sites More sharing options...
davewantsmoore Posted March 16, 2021 Share Posted March 16, 2021 (edited) 21 minutes ago, Telecine said: So the better way to think of this is as the speakers and amplifier being a circuit. The speakers draw current from the amplifier in response to the modulating frequency of the music signal and the impedance response of the speakers. Yes.... but a better way to see it is..... the speaker doesn't "draw" anything. The speaker isn't "asking" for power.... it's not "consuming" power (aside from some small losses). The amplifier is pushing current out one terminal.... and it's going back in the other (through the speaker). In a (typical) voltage source amp ..... the music sets the voltage at the amp terminal ...... how much current flows through the speaker depends on the electrical impedance curve of the speaker In a current source amp..... the music sets the current at the amp terminal ..... that is the amount of current flows through the speaker and back to the amp. The voltages at the amp terminals and in the speaker, can be "whatever". It's of no affect on the amount of current which flows, and the speaker movement. In both cases.... it is the amount of current flowing through the speaker which moves it. Edited March 16, 2021 by davewantsmoore 1 Link to comment Share on other sites More sharing options...
Telecine Posted March 16, 2021 Share Posted March 16, 2021 (edited) 21 minutes ago, davewantsmoore said: Yes.... but a better way to see it is..... the speaker doesn't "draw" anything. The speaker isn't "asking" for power.... it's not "consuming" power (aside from some small losses). The amplifier is pushing current out one terminal.... and it's going back in the other (through the speaker). In a (typical) voltage source amp ..... the music sets the voltage at the amp terminal ...... how much current flows through the speaker depends on the electrical impedance curve of the speaker In a current source amp..... the music sets the current at the amp terminal ..... this same amount of current flows through the speaker and back to the amp. The voltages at the amp terminals and in the speaker, can be "whatever". It's of no affect on the speaker operation. In both cases.... it is the amount of current flowing through the speaker which moves it. It is a circuit isn't it? Technically, the amp is not pushing the current. Edited March 16, 2021 by Telecine 2 Link to comment Share on other sites More sharing options...
davewantsmoore Posted March 16, 2021 Share Posted March 16, 2021 2 minutes ago, Telecine said: It is a circuit Yes, that's right. 1 Link to comment Share on other sites More sharing options...
aussievintage Posted March 16, 2021 Share Posted March 16, 2021 3 minutes ago, Telecine said: Technically, the amp is pushing the current. Technically, current flows as a result of an EMF (voltage) in the circuit. The amount is determined by the impedance. 2 Link to comment Share on other sites More sharing options...
pwstereo Posted March 16, 2021 Share Posted March 16, 2021 Yeah, I'm not so sure about the terminology. Don't we say the load (speaker) draws the current from the source (amplifier)? 1 Link to comment Share on other sites More sharing options...
Telecine Posted March 16, 2021 Share Posted March 16, 2021 Just now, pwstereo said: Yeah, I'm not so sure about the terminology. Don't we say the load (speaker) draws the current from the source (amplifier)? Yes. Link to comment Share on other sites More sharing options...
aussievintage Posted March 16, 2021 Share Posted March 16, 2021 4 minutes ago, pwstereo said: Yeah, I'm not so sure about the terminology. Don't we say the load (speaker) draws the current from the source (amplifier)? The word "draws" implies some active involvement. I prefer to say, a certain current flows as a result of the electromotive force (EMF) or, more usually - volts. 1 Link to comment Share on other sites More sharing options...
aussievintage Posted March 16, 2021 Share Posted March 16, 2021 To use a plumbing analogy (always dangerous), saying it draws current, is a bit like saying a tank draws water from the hose that you are using to fill it, when in fact it's the water pressure causing water to flow into the tank. 1 Link to comment Share on other sites More sharing options...
pwstereo Posted March 16, 2021 Share Posted March 16, 2021 (edited) 7 minutes ago, aussievintage said: The word "draws" implies some active involvement. I prefer to say, a certain current flows as a result of the electromotive force (EMF) or, more usually - volts. I thought the terminology was: A potential difference exists between two terminals, a connected load draws a current from the terminals. An LED might draw 100 mA An electric heater might draw 8 A. Edited March 16, 2021 by pwstereo Spelling 1 Link to comment Share on other sites More sharing options...
aussievintage Posted March 16, 2021 Share Posted March 16, 2021 18 minutes ago, pwstereo said: I thought the terminology was: A potential difference exists between two terminals, a connected load draws a current from the terminals. An LED might draw 100 mA An electric heater might draw 8 A. It's not that what you are saying is actually wrong. Link to comment Share on other sites More sharing options...
Steffen Posted March 16, 2021 Share Posted March 16, 2021 3 hours ago, aussievintage said: Speakers run on electricity. Current and voltage have a relationship and you can't have one without the other. Yes. Voltage – current – power – resistance, pick any two and the other two will follow. AC doesn’t really change that relationship, we just need to consider the phase angle. For averaged values (RMS) we use the cosine of the phase angle (a.k.a. power factor) to get the effective resistance or power out of a given phase-shifted pair of voltage and current. The power factor is 1 for no phase shift (pure resistance), 0 for 90 degrees phase shift (pure inductance or capacitance), and anything in between for mixed impedances. 2 hours ago, davewantsmoore said: Speakers don't consume power (aside from small losses like heat dissipation) .... the current flows through the speaker back into the amplifier. Yes the current in a circuit is the same at every point. What goes in one speaker terminal comes out the other. But that doesn’t mean speakers don’t consume power. They do, and dissipate it as sound and heat. What they consume is voltage squared divided by impedance, multiplied by the power factor. 1 hour ago, davewantsmoore said: This is the impedance curve of a very high quality woofer. You can see 3 lines. This is the impedance of the driver at rest.... at full out excursion... and full in excursion. As the cone moves the impedance curve "dances" between these values. Yes, as electrical/electronic components go, speaker drivers are particularly non-linear. That’s why they distort. 31 minutes ago, davewantsmoore said: it's like using the speaker voice coil as a voltage to current converter. It's really really non-linear (distortion!!!!) Yes, very. However, the signal is a voltage level, not a current. We feed the speaker a voltage and measure the sound level it produces. We expect that relationship to be reasonably flat across the frequency range of the speaker. That’s what makes a quality speaker. Consequently, amps are designed as voltage sources. At any given output voltage they will supply the current determined by that voltage and the speaker’s impedance plus the amp’s internal resistance. On top of that, if the load has a large reactive component, the amp needs to work harder than the effective power delivered to the speaker would suggest. When voltage and current are way out of phase, the speaker will only consume RMS voltage times RMS current multiplied by the power factor (which is small when the phase shift is large). The amp though will still experience the full current, flowing through its resistive components (semiconductors, resistors), and causing voltage drop and power dissipation there. 1 Link to comment Share on other sites More sharing options...
GregWormald Posted March 16, 2021 Share Posted March 16, 2021 Thanks guys, I think. I may have to keep considering electrical theory to be a black art. When I talked to Stuart of SGR about the current drive modification to their amps/speakers, the only thing I really understood was that he said they sounded better. 1 Link to comment Share on other sites More sharing options...
ghost4man Posted March 16, 2021 Share Posted March 16, 2021 2 hours ago, anandpkumar said: Given all this confusion, I feel that there should be a better way of representing the specifications/requirements of both speakers and amplifiers. If current is so important, I see only a few amplifiers that have the max current/peak current values published. Speaker specs have no mention of current at all - only efficiency and max power requirements (whatever that means in the real world) Can the industry have a better way of representing the specs of speakers/amplifiers? Or am I opening up a can of worms here? That's a really interesting point to make. As a lover of all things maggies its interesting that Magnepan will nominate ideal amplifiers in terms of watts. But listening to @davewantsmoore during this conversation its really been impressed upon me how important current is in this. Dave I wonder why speaker manufacturers dont go to the trouble of identifying the sweet spot for the current required to get the best out of its speakers. I say this because its often the case that audiophiles will choose an amplifier on the basis of wpc capabilities at particular loads. As an example, how much value do we place on the available specs for the Magtech. I know Bill Mclean and I know he has probably tried more different amplifiers with maggies than probably anyone else but right now he is using the Rogue Audio Dark Mono's with his maggies ahead of the Sanders. Its clear that the Sanders delivers way way more wpc than the Rogue but that kinda tells us that watts is not the only determinant factor for a good pairing. Just to add Bill is also a big fan of using the autoformer transformers with the Sanders to ease the burden. Link to comment Share on other sites More sharing options...
Ittaku Posted March 16, 2021 Share Posted March 16, 2021 (edited) You can't make a current amplifier without it being a voltage amplifier as well. The voltage determines how loud the driver will play provided enough current is being delivered for the impedance. Likewise current determines how loud the driver will play provided enough voltage is being delivered for the impedance. It's the amplifier's responsibility to ensure enough current is provided at a voltage and vice versa. An amplifier that provided 1000A .1mV would produce almost no sound. Likewise an amplifier that provided 1000V at .1mA would also produce almost no sound. Power is intimately linked with both voltage and current. Whilst the product is intimately linked with both, they are also completely independent. In the same way that water in a pipe flow rate through a pipe's resistance is dependent on both pressure and speed. Our drivers are spec'd with respect to the voltage that hits them, not the current that runs through them, thus it has become the case that we define power output according to voltage, because we assume enough current is going to be provided. Saying one is more important than the other is missing the point, but I agree so much emphasis has been placed on just voltage that we end up with many many amplifiers that fall far short of what current's required for modern low impedance dynamic drivers. Edited March 16, 2021 by Ittaku Link to comment Share on other sites More sharing options...
pwstereo Posted March 16, 2021 Share Posted March 16, 2021 40 minutes ago, ghost4man said: ... I wonder why speaker manufacturers dont go to the trouble of identifying the sweet spot for the current required to get the best out of its speakers. Possibly because it would limit sales for those with very low impedance dips, etc. If you knew up front that the great sounding new speakers you heard at the shop were going to destroy your amp or at least render it not worth using, you might look at other speakers that present less difficulty to the amplification. Link to comment Share on other sites More sharing options...
ghost4man Posted March 16, 2021 Share Posted March 16, 2021 (edited) 46 minutes ago, Ittaku said: You can't make a current amplifier without it being a voltage amplifier as well. The voltage determines how loud the driver will play provided enough current is being delivered for the impedance. Likewise current determines how loud the driver will play provided enough voltage is being delivered for the impedance. It's the amplifier's responsibility to ensure enough current is provided at a voltage and vice versa. An amplifier that provided 1000A .1mV would produce almost no sound. Likewise an amplifier that provided 1000V at .1mA would also produce almost no sound. Power is intimately linked with both voltage and current. Whilst the product is intimately linked with both, they are also completely independent. In the same way that water in a pipe flow rate through a pipe's resistance is dependent on both pressure and speed. Our drivers are spec'd with respect to the voltage that hits them, not the current that runs through them, thus it has become the case that we define power output according to voltage, because we assume enough current is going to be provided. Saying one is more important than the other is missing the point, but I agree so much emphasis has been placed on just voltage that we end up with many many amplifiers that fall far short of what current's required for modern low impedance dynamic drivers. Con, Where do you include watts per channel in this equation because typically that's what amplifiers are measured against when listing specs? I get what you are saying about the intimate connection between voltage and current but it seems listening to Dave that current is everything. Apologies to Dave if I have misinterpreted the thrust of his statement. Invariably very little if anything in the specs for a Sanders emphasises how much current it can deliver. Its exclusively geared towards the wpc into specific impedance levels. BTW great thread guys. Have learned a lot! Edited March 16, 2021 by ghost4man Link to comment Share on other sites More sharing options...
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