Good, less bad blood for you, strike “ripped you” and replace it with “didn’t credit you”. You still claim the invention and first publishing of the [complementary] CFA in 1980. Good luck with the history
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Did i said the opposite, while I was in total agreement with you on the technical point of view. Who is misunderstanding ?
Or, again, an effect of my poor English ?
With all these aggressive behaviors, paranoia is installed on the forum and I'm surprised by your reaction. I was just trying to situate your input in a larger landscape.
I did not question it. Don't you had seen the smiley after "you killed-me" ?
Tip: On my side, the first thing I look for, when i'm looking at a speaker, is its impedance curve where we can feel, with a little habit, near everything we need to know: The resonant frequency, the Q factor, the frequency where the membrane begin to fractionate, the spider and surround defects.
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Good, less bad blood for you, strike “ripped you” and replace it with “didn’t credit you”. You still claim the invention and first publishing of the [complementary] CFA in 1980. Good luck with the history
what makes you think they needed to credit me? If you bothered to read the whole story you would know they had a similar topology done and was going to patent until i published. Kinda blew things for them until they did the mods which salvaged thier work. It wasnt only the circuitry but the mode it was operating in gave it the unusual characteristic we know as Current-Mode.
The usual VFA characteristics didnt apply under these operating conditions; Traditional voltage-feedback amplifier configurations, both discrete and integrated, have always suffered from the severe disadvantage of drastically restricted bandwidth at high gains due to the problem of constant gain-bandwidth product.
With CFAs, the amplifier gain may be controlled independently of bandwidth. This constitutes the major advantages of CFAs over conventional VFA topologies.
Internally compensated VFA bandwidth is dominated by an internal dominant pole compensation capacitor, resulting in a constant gain/bandwidth limitation. CFAs also have a dominant pole compensation capacitor, but due to using current feedback instead of voltage feedback, the resulting open loop response is different. VFA stability depends on the ratio of open loop gain to feedback gain; CFA stability depends on the ratio of open loop transimpedance to feedback resistance. VFAs have a gain/bandwidth dependence; CFAs have a transimpedance/feedback resistance dependence.
In VFAs, dynamic performance is limited by the gain-bandwidth product and the slew rate. CFAs use a circuit topology that emphasizes current-mode operation, which is inherently much faster than voltage-mode operation because it is less prone to the effect of stray node-capacitances. When fabricated using high-speed complementary bipolar processes, CFAs can be orders of magnitude faster than VFAs. This is largely due to most VFAs being compensated for stability at unity gain. Decompensated VFAs can be just as fast as CFAs. With CFAs, the amplifier gain may be controlled independently of bandwidth. This constitutes the major advantages of CFAs over conventional VFA topologies.
See Google.
They had done the same things as i did on their own, independantly. I just published first. Now this basic topology is like the Wright brothers airplane vs F-35. Things are much more refined now.
Whats with you any way. Whats your major malfunction with all this?
THx-RNMarsh
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Please, explain how (or why). And, about your "1 db", don't it vary with the speaker's efficiency ?
I have often shared a similar thoughts, but the earlier posts do now go back some while and hence you may not be aware of the context. I am aware that "back-EMF impedance" has become controversial, but it goes with the territory. Indeed that "impedance" is where all the complexities of the driver (the bad stuff) shows up and corrupts the current of the amplifier. I now have a fool-proof way of explaining it and have tried on a few people I know and trust (offline and in person), and it seems to work very effectively.
Question, if you produce the voltage of the amplifier and put it on Channel 1 on your scope, then reproduce a sine wave (using a small value current sense resistor) and put that sine wave on Channel 2, if they don't line up at say 2KHz and about 30 degrees lag in current (the same 30 degrees will show up in the impedance/phase plot), then the speaker must be producing one of these sine waves, it cannot be producing both. The truth is that we are listening to the current of the amplifier, not the voltage of the amplifier. The argument then goes from there, because the "back-EMF impedance" can be calculated at that frequency as the excess impedance above the DC resistance of the voice coil. Maybe you can see where this is leading to, because we can measure distortion on the current side of the amplifier that is not on the voltage side.
This is about distortion and figuring out how and where it comes from, the mechanism, and the "back EMF impedance" is at the heart of that mechanism, and the "0.1dB" challenge is also.
Over the next few weeks I will be doing some measurements that will answer Scott's challenge, so maybe wise to cool it down till then.
BTW, Pavel's (PMA) measurement on his website is very interesting, except he draws the wrong conclusion that the driver produces less distortion under current drive compared with voltage drive. It is in fact quite different, the amplifier produces more distortion, but on the current side - and there is measurable distortion there. That is what he captured and it shows up best with IMD measurements than THD.
It will all come out, it will be explored properly and I have a peer group to look at it, so as far as I am concerned, it looks good, and may the chips fall where they may.
Cheers, Joe
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What's funny about that? Surely it just confirms that price means very little, similarly when it comes to whether something sounds better to a particular individual?
Is not it obvious to everyone? (As long the speaker is an electrodynamic one and not an electrostatic one.)
So, the solution to reduce distortion should be to add the RLC+RC networks I use with all my speakers in order to linearize their impedances curves down to their DC value (amp side). And to drive them in current (high impedance source) that I never tried for bass speakers because we are looking for max damping at the resonance frequency. Happily, I use horns for medium treeble, that are > 10dB more efficient and are powered across a serial resistance.
To tell the truth, across an attenuator. You gave-me the idea to use the B circuit instead of A as a start.
A funny video in topic with Jean Hiraga about "paramagnetism": YouTube (He explain that the phenomena is the same with a magnet inside a copper tube (shorted coil ?)
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That was exactly the point......so why should someone have to prove an opinion?
It’s totally up to whomever absorbs the info.....ignore,digest,archive,laugh,cry....both! Whatever, but to criticize opinions because they were not achieved under a certain protocol is ridiculous.
In other news...... It’ll be ok EH
I’d also like to add that I have no superior hearing skills but do like to think a lifetime of honing listening skills should at least qualify an opinion.
Agree too. Some kind of "Choose your poison".
If you refer to my previous schematic, I'm not manipulating the bass response curve. Only the impedance curve.
About damping, if you hit a bass speaker (unconnected to a ~O Ohm amplifier) with your finger, you will hear the huge effect of the RLC on damping its resonance. Similar to the one provided by the low output impedance of an amp connected to the coil.
About " in this day and age", it has been a long time since series resistance has been added to compression chamber motors in order to reduce distortions.
Opinions are fine. What I'm saying is what does better mean, and does it only mean what it means to you? Perhaps the way something is distorting the sound sounds better to you, how is that of value to someone else. Richard Marsh, Mark and others throw around the word better as if because they are saying it it should have meaning/value to other people, why should it? There are far too many variables in the system, and I include the recording as well as their auditory systems and expectations of what sounds better.That was exactly the point......so why should someone have to prove an opinion?
It’s totally up to whomever absorbs the info.....ignore,digest,archive,laugh,cry....both! Whatever, but to criticize opinions because they were not achieved under a certain protocol is ridiculous.
In other news...... It’ll be ok EH
I’d also like to add that I have no superior hearing skills but do like to think a lifetime of honing listening skills should at least qualify an opinion.
I totally disagree (which does not matter), on an human point of view with this. As well as your names dropping.
The goal of hifi reproduction is to bring pleasure and emotions. To reproduce (or produce) music in the most believable way. And, as you say, recording included. The goal of producing records is not hifi. It is, most of the time, lot better than reality.
As-you says, there are "so many variables in the system".
Some people (and all the sound engineers) are listening in a very subjective way trying to discover things that seem to work better than others (increase of emotions) in this system that goes from the musician to our ears.
It seems to me you are mistaken about this approach. Nobody I know pretends what he feels have any universal value. "Subjective and personal" is included by essence.
Just, if many people seem to have the same experiences and feelings than us (you ?), even when their are not supported by maths or scientific explanations, you can begin to think you are not totally mistaken and some "tip" can have some interest for some others.
When you are behind a mixing desk, you are obliged to find a good balance between your own tastes and the ones that you suppose to be the ones of your global audience. And the only way is to can hear, read, have access, to their 'impressions' and feelings. It is fragile. never definitive because human subjectivity and tastes, not obvious.
Listening requires learning and a culture as great as the ones needed to make correct measurements. It appears to me that the names you quoted have the same king of attention to some details of reproduction than me, and, often, reach to the same conclusions.
If they do not join yours, where is the problem? Continue your journey with your own scale of values. Sharing them with others. But why to impeach others from climbing on their owns ?
With all due respect for your own opinions.
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From a technical point of view, this seems unlikely to be the mechanisme behind what you percieve.
With the loudspeaker terminal open, there is nothing inside a regular crossover of any order that presents a DC path as seen from the bass driver side. In other words, for the relevant low frequencies, the bass driver sees an open circuit when it looks into an unterminated crossover.
So no electrical damping at all.
Er no. Fallen at first hurdle. High fidelity and pleasure are sometimes exclusive. If everyone WAS after fidelity then we would have a far easier job of it.
Matt,
Well I can’t speak for all, but in my case an opinion comes from a wealth of accumulated knowledge of what sound others prefer over another. Of course there’s the odd man out here and again but I’ve found way more than not what I prefer in a sound system most everyone else does also. And I’m not talking just having tin eared friends over for beers, I mean designing and setting up systems for others, setting up sound for shows, recording and mastering, etc.
That’s what I meant by coming at home audio from a sound engineering viewpoint, setup the sound as if it were a live production......you know, listen.
And I’ll save you the trouble of hitting on the mono vs stereo thing, I have recently been in awe of decent mono recordings......I suppose I’ve just never appreciated them up until now.
I think a lot of it has to do with the delivery (tidal high fi and dsp).
I never had a decent turntable, my early days of high fidelity started with reel to reel recorded live at the local fm station which I know were recorded in stereo (I helped set it up) they even played around with quadraphonic for a few years. My mom was station manager which allowed me access at a young age, later on they let me make copies from the master tapes (which I found out were all thrown away when the station got bought out) my copies are all long gone now.....I wish I would have had the foresight to save this stuff, there were many one off performances and interviews by ‘soon to be famous’ people coming in to advertise local performances. Closest I’ve come to vinyl was my uncles collection, I used to make copies of some to high quality cassette tape but at that time didn’t appreciate any music that would have been in mono (still hate the Beatles!)
To make it short i’ve dedicated my entire life to sound.....just now (last couple years) trying to get a handle on the EE end of things, have certainly noticed it’s a odd collection of personalities for sure......not a bad thing though!
Hopefully I don’t annoy you fellers too bad in my quest for knowledge.
Bob
Edit......and like TT says above emotional connection is a big part of what makes a good representation a great representation. I’m still saying this emotional connection is made in the phase relationships.....you know the ones people can’t hear.
Well I can’t speak for all, but in my case an opinion comes from a wealth of accumulated knowledge of what sound others prefer over another. Of course there’s the odd man out here and again but I’ve found way more than not what I prefer in a sound system most everyone else does also. And I’m not talking just having tin eared friends over for beers, I mean designing and setting up systems for others, setting up sound for shows, recording and mastering, etc.
That’s what I meant by coming at home audio from a sound engineering viewpoint, setup the sound as if it were a live production......you know, listen.
And I’ll save you the trouble of hitting on the mono vs stereo thing, I have recently been in awe of decent mono recordings......I suppose I’ve just never appreciated them up until now.
I think a lot of it has to do with the delivery (tidal high fi and dsp).
I never had a decent turntable, my early days of high fidelity started with reel to reel recorded live at the local fm station which I know were recorded in stereo (I helped set it up) they even played around with quadraphonic for a few years. My mom was station manager which allowed me access at a young age, later on they let me make copies from the master tapes (which I found out were all thrown away when the station got bought out) my copies are all long gone now.....I wish I would have had the foresight to save this stuff, there were many one off performances and interviews by ‘soon to be famous’ people coming in to advertise local performances. Closest I’ve come to vinyl was my uncles collection, I used to make copies of some to high quality cassette tape but at that time didn’t appreciate any music that would have been in mono (still hate the Beatles!)
To make it short i’ve dedicated my entire life to sound.....just now (last couple years) trying to get a handle on the EE end of things, have certainly noticed it’s a odd collection of personalities for sure......not a bad thing though!
Hopefully I don’t annoy you fellers too bad in my quest for knowledge.
Bob
Edit......and like TT says above emotional connection is a big part of what makes a good representation a great representation. I’m still saying this emotional connection is made in the phase relationships.....you know the ones people can’t hear.
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Thanks, I was aware of what Wikipedia says about: Current-feedback operational amplifier - Wikipedia A link could do nicely, no need to copy/paste here. Or at least copy/paste the entire paragraph and indicate the source.
No, it doesn't bother me that you think Dan can provide itHopefully I don’t annoy you fellers too bad in my quest for knowledge.
Bob
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