I want people here to consider what happens when the current of the amplifier is constant at all frequencies. Looking at the flat impedance looks impressive and the reaction "this must make it easy on the amplifier" is making a comment that does make sense, but it misses out on the part that is really important. Let me try to explain.
I will not be able to show the complete picture in a single post and without not a single or two measurements, this will all be presented on paper that can be circulated and scrutinised cooly and not in a hot environment of social media where people mostly just want to parade their big egos. But even from them, I have learned something, so it is a mixed blessing.
1. An amplifier is defined by its output impedance. A low output impedance defines it as a voltage source, and a large output impedance defines it as a current source.
2. This means we can roughly model an amplifier as an amplifier with a series resistance on the output.
2. Pure zero-Ohm voltage-drive is not practical, but generally, if the insertion is no more than 1dB, which defines roughly a ratio of 10:1, then you have a practical voltage source.
3. If we follow a similar practice with current drive, then a ratio should also be 10:1 in the opposite direction. But Esa and I, about ten years ago, had a discussion where I asked him what he thought was the absolute lowest ratio (where I had in my own mind come up with 5:1 to be the absolute acceptable minimum) and I was pleased when he came back and also gave the same 5:1 ratio.
4. So the minimum impedance for voltage-drive for an 8 Ohm speaker should be 0.8 Ohm if 10:1 rule is applied, and the minimum for the same driver and ratio of 5:1, the output impedance for current-drive should be a minimum of 40 Ohm.
(At ETF17, Menno Vanderveen demonstrated an amplifier that could be switched between 0, 5 and 18 Ohm output impedances - and the ratio would have been 18R/6R = 3:1 and a room of people preferred the 18 Ohm setting and so did Menno - it was not that hard to hear the difference.)
5. We need to establish something that people give lip service to, but don't necessarily think it through. The only thing that causes the motion, what we call sound, is the current that flows through the voice coil and nothing else. What about the voltage? It only creates a potential for current to flow, but it should not be confused with the actual current that flows. Here we are speaking of the voltage of the amplifier. Often the voltage seen inside the magnetic gap is only 30% or even less the voltage of the amplifier, much of the voice coil is outside the gap (effectively a wire-wound resistor in front of the gap and another behind gap), so the gap never sees the full voltage of the amplifier anyway, and in fact it doesn't matter because it sees the 100% of the current of the amp that is what causes the coil to move.
(This may also help us to understand why we can get away with a lower ratio 5:1 with current-drive.)
6. Now I wonder if those here can ponder and analyse what happens when we use parallel passive components, create what looks like a nice and attractive flat impedance, what is really going on with respect to the current of the amplifier??? Keep in mind that an impedance is a function of current and not of voltage. The simple reason is that it is the current that is being impeded by an impedance, not the voltage. So when you see an impedance graph of a loudspeaker, you are looking at what the driver will do to the current of the amplifier. An impedance graph is a function of current, not voltage (sorry to sound so pedantic, but it must be made clear). In fact, when Neville Thiele measured the impedance of a driver, he used a 1000 Ohm series resistance creating a 'constant current method of measurement.'
7. So using appropriate passive components to construct an impressive-looking flat impedance, the really important question to ask now:
What happens on the current side of the amplifier, and how does that affect the driver?
That is a huge question. The ins and outs are massive, I admit it taxed my thinking for a long time and continues to do so.
If you have been following the above, you may have come to the conclusion that the amplifier is now producing the same current at all frequencies. So if it produces 3A at 100Hz, it will be the same at 1KHz, the same at 10KHz, even the same at 20KHz, and in my case, even up to 100KHz. The point is that the amplifier will do that at any frequency.
8. Now you have created an effect on the current side of the amplifier, that the output impedance of the amplifier will now look like zero at all times.
Please analyse this, think it through and realise that now a door of opportunity open up, one that you might have not thought about. You might be able to do stuff that you might now have considered before.
Whoah!
I will leave it there, because from here it gets a bit more complicated. But one of the spin-offs of what can be done is that you can use current-drive on the bass, something that was thought impossible before, because you have made the impedance of the amplifier look like zero.
To KSTR, now you may be starting to understand what I was getting at when I said that controlling current versus frequency, you can manipulate the sealed box Q of a driver turning it from a 2nd order Butterworth into a 2nd Order Bessel (increase real damping). What we have here is not breaking T-S equations, what we are doing (and we have indeed done it, it is not just a thought experiment) means we have to come up with compatible variations of those equations. This is beyond my pay-grade, but I can assure you that we have some very good mathematicians down here who will do that job. I can't wait to see what it looks like. I do know what the eqautions will show, I just don't know exactly what it will look like, but it will show that Re = infinity and adjust i with frequency will mean Re can be any number. That is quite a challenge.
To Steve: This is only scratching the surface. In the last three years, our understanding has grown, almost exponentially (and the good thing is that I am not a loner doing this). I would love to chat with you on the phone, I have access to free phone calls to the UK from Australia, so PM me your number, keeping in mind the difference in hours (yes Nicholas [local flat earth friend], the earth is really round), the time I can call. I will be able to further fill you in.
Cheers, Joe
I will not be able to show the complete picture in a single post and without not a single or two measurements, this will all be presented on paper that can be circulated and scrutinised cooly and not in a hot environment of social media where people mostly just want to parade their big egos. But even from them, I have learned something, so it is a mixed blessing.
1. An amplifier is defined by its output impedance. A low output impedance defines it as a voltage source, and a large output impedance defines it as a current source.
2. This means we can roughly model an amplifier as an amplifier with a series resistance on the output.
2. Pure zero-Ohm voltage-drive is not practical, but generally, if the insertion is no more than 1dB, which defines roughly a ratio of 10:1, then you have a practical voltage source.
3. If we follow a similar practice with current drive, then a ratio should also be 10:1 in the opposite direction. But Esa and I, about ten years ago, had a discussion where I asked him what he thought was the absolute lowest ratio (where I had in my own mind come up with 5:1 to be the absolute acceptable minimum) and I was pleased when he came back and also gave the same 5:1 ratio.
4. So the minimum impedance for voltage-drive for an 8 Ohm speaker should be 0.8 Ohm if 10:1 rule is applied, and the minimum for the same driver and ratio of 5:1, the output impedance for current-drive should be a minimum of 40 Ohm.
(At ETF17, Menno Vanderveen demonstrated an amplifier that could be switched between 0, 5 and 18 Ohm output impedances - and the ratio would have been 18R/6R = 3:1 and a room of people preferred the 18 Ohm setting and so did Menno - it was not that hard to hear the difference.)
5. We need to establish something that people give lip service to, but don't necessarily think it through. The only thing that causes the motion, what we call sound, is the current that flows through the voice coil and nothing else. What about the voltage? It only creates a potential for current to flow, but it should not be confused with the actual current that flows. Here we are speaking of the voltage of the amplifier. Often the voltage seen inside the magnetic gap is only 30% or even less the voltage of the amplifier, much of the voice coil is outside the gap (effectively a wire-wound resistor in front of the gap and another behind gap), so the gap never sees the full voltage of the amplifier anyway, and in fact it doesn't matter because it sees the 100% of the current of the amp that is what causes the coil to move.
(This may also help us to understand why we can get away with a lower ratio 5:1 with current-drive.)
6. Now I wonder if those here can ponder and analyse what happens when we use parallel passive components, create what looks like a nice and attractive flat impedance, what is really going on with respect to the current of the amplifier??? Keep in mind that an impedance is a function of current and not of voltage. The simple reason is that it is the current that is being impeded by an impedance, not the voltage. So when you see an impedance graph of a loudspeaker, you are looking at what the driver will do to the current of the amplifier. An impedance graph is a function of current, not voltage (sorry to sound so pedantic, but it must be made clear). In fact, when Neville Thiele measured the impedance of a driver, he used a 1000 Ohm series resistance creating a 'constant current method of measurement.'
7. So using appropriate passive components to construct an impressive-looking flat impedance, the really important question to ask now:
What happens on the current side of the amplifier, and how does that affect the driver?
That is a huge question. The ins and outs are massive, I admit it taxed my thinking for a long time and continues to do so.
If you have been following the above, you may have come to the conclusion that the amplifier is now producing the same current at all frequencies. So if it produces 3A at 100Hz, it will be the same at 1KHz, the same at 10KHz, even the same at 20KHz, and in my case, even up to 100KHz. The point is that the amplifier will do that at any frequency.
8. Now you have created an effect on the current side of the amplifier, that the output impedance of the amplifier will now look like zero at all times.
Please analyse this, think it through and realise that now a door of opportunity open up, one that you might have not thought about. You might be able to do stuff that you might now have considered before.
Whoah!
I will leave it there, because from here it gets a bit more complicated. But one of the spin-offs of what can be done is that you can use current-drive on the bass, something that was thought impossible before, because you have made the impedance of the amplifier look like zero.
To KSTR, now you may be starting to understand what I was getting at when I said that controlling current versus frequency, you can manipulate the sealed box Q of a driver turning it from a 2nd order Butterworth into a 2nd Order Bessel (increase real damping). What we have here is not breaking T-S equations, what we are doing (and we have indeed done it, it is not just a thought experiment) means we have to come up with compatible variations of those equations. This is beyond my pay-grade, but I can assure you that we have some very good mathematicians down here who will do that job. I can't wait to see what it looks like. I do know what the eqautions will show, I just don't know exactly what it will look like, but it will show that Re = infinity and adjust i with frequency will mean Re can be any number. That is quite a challenge.
To Steve: This is only scratching the surface. In the last three years, our understanding has grown, almost exponentially (and the good thing is that I am not a loner doing this). I would love to chat with you on the phone, I have access to free phone calls to the UK from Australia, so PM me your number, keeping in mind the difference in hours (yes Nicholas [local flat earth friend], the earth is really round), the time I can call. I will be able to further fill you in.
Cheers, Joe
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Addendum:
It even makes the amplifier look like zero Ohm when it comes to locking in crossovers. Think about that... now you can even use a current source and the crossover don't move. They stay with any source impedance from zero to infinity. And that just a glimpse, it virtually puts voltage-drive and current-drive on similar footing, but the same. Look where the current goes as you change the output impedance from zero up, and you will get some handle on it. I keep saying, this is but a glimpse...
I will wait till Steve is up, it is 4.20AM in Portsmouth.
It even makes the amplifier look like zero Ohm when it comes to locking in crossovers. Think about that... now you can even use a current source and the crossover don't move. They stay with any source impedance from zero to infinity. And that just a glimpse, it virtually puts voltage-drive and current-drive on similar footing, but the same. Look where the current goes as you change the output impedance from zero up, and you will get some handle on it. I keep saying, this is but a glimpse...
I will wait till Steve is up, it is 4.20AM in Portsmouth.
Collaboration on what? Based on your posts, past and present, you seem to have no questions, no doubts, no further needs regarding this topic, everything is on the right path for implementing and productizing your ideas. If I’m wrong, please list here your scope and objectives for a successful collaboration. Be SMART please.
P.S. SMART stands for Specific, Measurable, Achievable, Realistic and Timely.
I wonder what this is about? That I am on some ego trip to become famous? Nope! I am getting too old for that, will be seventy on Dec 3rd. I could have retired when 65 on a nice pension, but I am not finished yet, as long as my health holds up.
"You have no questions."
I have lots! The day I stop asking, it will be Alzheimer's or something worse.
"You have no doubts."
I only wish I did. I would be in heaven. But alas, that is not the case. The things I have learned in the past year convince me otherwise.
"No further needs regarding this topic."
What a strange thing to say. Define "needs" please. I am way too curious about life to stop at any time. And this particular topic is right on cue because of work done by others. I am a good student, I keep my mouth shut when others disseminate wisdom. But a subject often has to find its time in place, and what has happened in recent years, this is what is happening right now and I am not the only one sensing. I am excited!
This is my real vice: Curiosity!
You said: "If I’m wrong, please list here your scope and objectives for a successful collaboration."
That's fair enough. But I have to find others who have the same enthusiasm that I have. Thankfully that is working out very well. What is the scope? I hope it is wide - it might lead to better designed speakers and also better designed amplifiers, particularly voltage sources. There is something else, but I am going to keep my powder dry, and if my intuition (a la Feynman) proves to be true, then it will be big! But who knows what science leads to, what is around the corner?
"SMART means..."
"Specific."
I try very hard to be. Like Niels Bohr's famous quote about language being a limitation - ain't that the truth. I much prefer talking and even better with a scrap of paper and pen at the ready. Much better than here!
"Measurable."
Absolutely!!! I definitely believe in measurements. I have a few prepared and more to come (I have ordered a special driver with special characteristics) and I am hoping to do a measurement that I have devised in concert with an extremely knowledgable friend (very crusty and no-nonsense guy, also a very good businessman and mathematical background); and we are talking about measuring distortion. It's about further measurements that show up the difference in "impedance modulations" of the current of the amplifier. The hope is to prove the association between "impedance modulations" and what I have supposedly infamously called 'back-EMF impedance."
"Achievable."
Good one. I couple that with being practical, at times pragmatic (very selectively) and can it be understood? Or it's all an almighty waste of time. I am confident that publishable results may only be months away. Some people just have to be patient - but patience on [anti]social-media is an oxymoron. (That was a joke only.)
"Timely."
Another good one. The answer here is yes, look at the work done by Purifi on inductance causing "impedance modulations" and we are talking about the measurable distortion that originates on the current side of the amplifier - it seems that even reducing particular types of distortion from -80dB to -90dB is audible.
May I also point out that I have taken an oath that I will always give credit where it due. And I do that by name - and I document every quote by others, so that they can look them up and get the context. In this, I am scrupulous, even if others have quoted or used my work without naming me. I could tell you what they are, but I will then just be accused of aggrandising, sigh.
Now please, have I convinced you?
My number is not a secret, I am only a phone call away. Just search for it and you will find it. I get calls from all over the world, all I ask that they keep the hour difference in mind and I am GMT10+. So by all means call and chat. Nowhere to hide and you can ask ANY question and I will address it front on. Fair enough?
Cheers, Joe
[PS: That was fun, I enjoyed that. Please, I hope nobody has taken any offense, surely they should not have?]
"You have no questions."
I have lots! The day I stop asking, it will be Alzheimer's or something worse.
"You have no doubts."
I only wish I did. I would be in heaven. But alas, that is not the case. The things I have learned in the past year convince me otherwise.
"No further needs regarding this topic."
What a strange thing to say. Define "needs" please. I am way too curious about life to stop at any time. And this particular topic is right on cue because of work done by others. I am a good student, I keep my mouth shut when others disseminate wisdom. But a subject often has to find its time in place, and what has happened in recent years, this is what is happening right now and I am not the only one sensing. I am excited!
This is my real vice: Curiosity!
You said: "If I’m wrong, please list here your scope and objectives for a successful collaboration."
That's fair enough. But I have to find others who have the same enthusiasm that I have. Thankfully that is working out very well. What is the scope? I hope it is wide - it might lead to better designed speakers and also better designed amplifiers, particularly voltage sources. There is something else, but I am going to keep my powder dry, and if my intuition (a la Feynman) proves to be true, then it will be big! But who knows what science leads to, what is around the corner?
"SMART means..."
"Specific."
I try very hard to be. Like Niels Bohr's famous quote about language being a limitation - ain't that the truth. I much prefer talking and even better with a scrap of paper and pen at the ready. Much better than here!
"Measurable."
Absolutely!!! I definitely believe in measurements. I have a few prepared and more to come (I have ordered a special driver with special characteristics) and I am hoping to do a measurement that I have devised in concert with an extremely knowledgable friend (very crusty and no-nonsense guy, also a very good businessman and mathematical background); and we are talking about measuring distortion. It's about further measurements that show up the difference in "impedance modulations" of the current of the amplifier. The hope is to prove the association between "impedance modulations" and what I have supposedly infamously called 'back-EMF impedance."
"Achievable."
Good one. I couple that with being practical, at times pragmatic (very selectively) and can it be understood? Or it's all an almighty waste of time. I am confident that publishable results may only be months away. Some people just have to be patient - but patience on [anti]social-media is an oxymoron. (That was a joke only.)
"Timely."
Another good one. The answer here is yes, look at the work done by Purifi on inductance causing "impedance modulations" and we are talking about the measurable distortion that originates on the current side of the amplifier - it seems that even reducing particular types of distortion from -80dB to -90dB is audible.
May I also point out that I have taken an oath that I will always give credit where it due. And I do that by name - and I document every quote by others, so that they can look them up and get the context. In this, I am scrupulous, even if others have quoted or used my work without naming me. I could tell you what they are, but I will then just be accused of aggrandising, sigh.
Now please, have I convinced you?
My number is not a secret, I am only a phone call away. Just search for it and you will find it. I get calls from all over the world, all I ask that they keep the hour difference in mind and I am GMT10+. So by all means call and chat. Nowhere to hide and you can ask ANY question and I will address it front on. Fair enough?
Cheers, Joe
[PS: That was fun, I enjoyed that. Please, I hope nobody has taken any offense, surely they should not have?]
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I take it this is about more than impedance matching or a kind of zobel? I don't understand how you can have the advantages of current drive without current drive?
Hi Pavel
You showed something by your measurements and I sought your collaboration. I have a permanent link on my computer and have gone over it a number of times. I tried to point out something significant about those measurements, but you would have none of it. I am curious why?
Current drive of speakers and speaker distortion
Current drive of speakers and speaker distortion
Current drive of speakers and speaker distortion
Proudove buzeni repro a zkresleni repro
I think what you did was worth looking at very closely!
Maybe you think the discussion is done and dusted?
Were your pages the end of something, or the beginning?
Have you kept tabs on the work done by Purifi and others?
Have you considered that the distortion you made under voltage-drive and yet were significantly reduced under current-drive, that these could be due to "impedance modulations" named by Lars Risbo of Purifi? These are really current modulations of the amplifier, as was agreed to by him.
Are you not intrigued?
I know I am. Also, I have referenced your measurements to many people, to take a look at them, and then we had a good discussion. I would have loved you being there.
I actually need to thank you, so I thank you!
Cheers, Joe
You showed something by your measurements and I sought your collaboration. I have a permanent link on my computer and have gone over it a number of times. I tried to point out something significant about those measurements, but you would have none of it. I am curious why?
Current drive of speakers and speaker distortion
Current drive of speakers and speaker distortion
Current drive of speakers and speaker distortion
Proudove buzeni repro a zkresleni repro
I think what you did was worth looking at very closely!
Maybe you think the discussion is done and dusted?
Were your pages the end of something, or the beginning?
Have you kept tabs on the work done by Purifi and others?
Have you considered that the distortion you made under voltage-drive and yet were significantly reduced under current-drive, that these could be due to "impedance modulations" named by Lars Risbo of Purifi? These are really current modulations of the amplifier, as was agreed to by him.
Are you not intrigued?
I know I am. Also, I have referenced your measurements to many people, to take a look at them, and then we had a good discussion. I would have loved you being there.
I actually need to thank you, so I thank you!
Cheers, Joe
Nicely asked. But it is not just a matter of coupling some Zobels together.
I will try to answer: Knowing what current drive does and understanding how it reduces distortion (and there is no question here that it does), that we can then lower distortion of voltage sources.
Look at the post #7350 and visit those URL pages, and the answer is that current-drive reduces distortion.
But despite Esa's earnest efforts, we are not going to convert the world to so-called voltage-drive.
The answer is to apply the lessons of current-drive and find ways to reduce distortion in voltage-drive. But many don't even want to know there is a problem. There are now three ways that I know, that have been developed, to lower distortion of voltage-drive. Maybe not quite to a degree to that of current-drive, but still very audible and hence worthwhile.
Despite the nay-sayers, this topic will not go away. The horses have bolted out of the barn and it's too late to stop them. They will realise it later. History's a bit like that and I have been guilty too.
OK, one last try.
With current drive the voltage at the driver is allowed to move freely, it is equivalent to an unterminated driver, agreed so far?
When you tap it, it will ring a its high Q as Qes is not in place. There is no other damping other than mechanical from driver and cabinet.
What you are confusing is that steering the current to mimick the damping is not the same as real damping. As I said, a driver behaves basically identical when the voltage (or current) at its terminals is the same, regardless of terminating impedance. This is straightforward but let me explain it anyway:
Measure the impulse response of the driver current under normal voltage drive, using a small sense resistor. By this you have exactly the EQ required to get the same current injection into and thus the same acoustic response from the driver under current drive, just stuff that impulse response into a convolver feeding the input of a current output amp. You really end up to have the same system transfer function, the apparent Qtc and F3 in both cases.
But as explained, the driver is unterminated under current drive, the cone undergoes no electrical braking force and that means it will ring when exciting the cone, not matter what causes the excitation. The trick is now that the current is steered to precisely counteract the ringing so that it appears to be the same braking force.. but the main and all important difference is that the current is only steered, there is no control loop. When the movement of the cone is off for any reason (and there are a lot of reasons) the steering does not fix it because it simply makes an assumption of the state the system is currently in. We all agree that's actually a good thing at higher frequencies (as the feedback entity, the microphonic voltage, is corrupted) but not around resonance.
Agreed. The reason is that Re has become infinite.
Qes = (2Pi*Fs*Mms*Re)/(B*L*i^2)
We all know that equation - I have comitted it to memory and I never have to look it up.
If anything above the 'dividing line' is increased, then the Qes value will increase proportionally. So if Re is dopubled. the Qes will double. This is of course where current-drive has a problem, the Re increases dramatically and in pure theory Re becomes infinite and same applies to Qes. Of course, Qms remains unaffected, at least that is my understanding.
Indeed you have simulated current-drive by your illustration... sort of. Except there is no current, but never mind, you are correct.
I agree.
But wait, there is no excursion due to no current!!!
BTW, the argument is not knew to me, so let us continue.
I understand the argument very well. On the surface it can well be argued that way. Except the argument overlooks things that are not obvious and they are not that easy to explain to somebody who does not have the patience and try to understand.
I don't want to sound like I am fobbing anybody off, but what is your position on the reduced distortion (a known and measured fact) that we see under current-drive and yet is not reduced by voltage-drive?
Unless I know your position to that, I don't know how to proceed.
Let me put it this way, via two questions where the answer is either true or false:
1. A current source fixes the current, but to do that it must relinquish control over the voltage. True or False?
2. A voltage source fixes the voltage, but to do that it must relinquish control over the current. True or False?
Do you see the reasons for those questions and what is your answer?
I understand the argument, I have seen it before.
But it comes down to the two questions that I asked, as to how I proceed to respond.
For a start, the use of the word 'steering' is very interesting.
What I have been exploring is the proportionality of current versus the acoustic output. We are not talking about absolute levels here, but rather proportional change in dB, where a specific dB change in current causes the same specific level db_SPL changes. What can cause that to be interfered with (think resonances, think different inductance when the voice coil moves within it maximal allowed peak-to-peak excursions and more).
What I am asking you is to keep an open mind to something that you have not previously thought about.
Please, I am not the only one exploring this area. It is getting traction and a work in progress.
Cheers, Joe
PS: Re 'steering' this is one I came across when discussing with Lynn Olson many years back re current-drive description. It made me think.
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Current drive can reduce distortion in a driver, but it depends upon the driver, how does this relate to the distortion of a voltage source?
Joe,
You deserve an award for most likely breaking the DiyAudio Flux de Bouche record.
Just for fun I let my computer count the number of words you used over the last few days and the result is a staggering 6473 words, see image below
What came out of your postings so far is that:
1) the amplifier should preferably see the LS as a constant impedance over the whole frequency band and that
2) speakers where possible should be driven by current with some clever circuitry around to compensate for anomalies,
No math, no measurements no nothing to show that it makes sense to follow these ill defined roads.
So just as Syn08 wondered, I also don't get your purpose.
Hans
.
You deserve an award for most likely breaking the DiyAudio Flux de Bouche record.
Just for fun I let my computer count the number of words you used over the last few days and the result is a staggering 6473 words, see image below
What came out of your postings so far is that:
1) the amplifier should preferably see the LS as a constant impedance over the whole frequency band and that
2) speakers where possible should be driven by current with some clever circuitry around to compensate for anomalies,
No math, no measurements no nothing to show that it makes sense to follow these ill defined roads.
So just as Syn08 wondered, I also don't get your purpose.
Hans
.
Attachments
To my ears, the small experiment using the line matching transformer backward shows tremendous listening potential to this idea. The amplifier voltage output is converted to a current by a resistor. That current goes into a transformer winding and on the other side, a smaller current comes out of a high impedance source, driving a Wideband speaker.
My speakers are WAWs, so there's no resonance at Fs to wonder about; the wide-bands are crossed well above that. The woofers are run conventionally, with the full damping factor provided by the amplifier's ordinary low-Z output. Unsure why anyone would want to give this up by running woofers from a current source, but hey.
The difference I hear I'd describe as similar to going to a better DAC with more stable clocks - a soundtsage image focus improvement. I cant believe how easy it was to try and that I had the parts just laying around...
Now excuse me while I fall into Ella's very live sounding voice image back there on "Sweet Georgia Brown" - on an internet stream from WBGO - it's none the less fantastic to my morning ears. Cant wait to try it on the F15's.
My speakers are WAWs, so there's no resonance at Fs to wonder about; the wide-bands are crossed well above that. The woofers are run conventionally, with the full damping factor provided by the amplifier's ordinary low-Z output. Unsure why anyone would want to give this up by running woofers from a current source, but hey.
The difference I hear I'd describe as similar to going to a better DAC with more stable clocks - a soundtsage image focus improvement. I cant believe how easy it was to try and that I had the parts just laying around...
Now excuse me while I fall into Ella's very live sounding voice image back there on "Sweet Georgia Brown" - on an internet stream from WBGO - it's none the less fantastic to my morning ears. Cant wait to try it on the F15's.
Attachments
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