Really, you need to get a taste of yours truly; fortunately I cannot be bothered to pour vitriol in vacuum.
Hi Joe,
You are aware, we aren't necessarily. Only you can say exactly what is in your mind, and you are, by now, aware of the limits the average person will accept. You also know when you will probably see some push-back.
See ya, bed time!
-Chris
You are aware, we aren't necessarily. Only you can say exactly what is in your mind, and you are, by now, aware of the limits the average person will accept. You also know when you will probably see some push-back.
See ya, bed time!
-Chris
Do you guys find that DSD DACs significantly increase intermodulation distortion in a typical audio system?
I tried to understand the mathematics behind current drive.
As I understand the input voltage divided by voicecoil resistance translates to mechanical force according to the Bl which is nonlinear with excursion. Current drive doesn't correct for this first nonlinearity.
The back-EMF that is generated across the coil however is also distorted by Bl, and this distorted voltage is subtracted from the speaker input voltage. This adds additional Bl distortion when using voltage drive.
Is this about right?
As I understand the input voltage divided by voicecoil resistance translates to mechanical force according to the Bl which is nonlinear with excursion. Current drive doesn't correct for this first nonlinearity.
The back-EMF that is generated across the coil however is also distorted by Bl, and this distorted voltage is subtracted from the speaker input voltage. This adds additional Bl distortion when using voltage drive.
Is this about right?
DSD always drives me crazy after a while. I havent tried the higher sample rate DSD formats though, like 2xDSD or 4xDSD.
A shorting ring shorts out any attempt of the voicecoil to magnetize the gap otherwise than it already is. It only works at frequencies where the ring's resistance does not dominate over it's inductance coupling to the voicecoil (the ring's own inductance also poses a limit not unlike how the leakage inductance of common mode chokes limits their common mode rejection).
However the shorting ring does not keep the magnet's coupling to the voicecoil from changing as the fields mesh in the direction of excursion. This is a mechanical interaction that depends on the geometry of the magnetic fields.
As the cone moves the magnetic fields move in and out of each other and the effective Bl varies.
I'm not sure about the details of shorting rings. I think they can only make the magnet better, at the frequencies where they work. There may be dynamics with eddy currents through the ring doing weird stuff, skin effect, I don't know.
Last edited:
That is the coolest! I had a face to face with him once. He was nice to me too. Nothing like he can be portrayed to be.
Shorting rings do keep the inductance of the voicecoil more constant as it moves in and out of the magnet. But this is an exercise in getting two curves to cancel, and there is usually some residual left. It seems to me current drive would also be a good solution as voicecoil inductance would no longer matter.
I'm not expert, but I can't see a situation where having both would be worse than having either. I think it's possible though that current drive would eliminate the need for a shorting ring.
I'm not expert, but I can't see a situation where having both would be worse than having either. I think it's possible though that current drive would eliminate the need for a shorting ring.
Hi Chris
I thought we were friends? 😕
Have a good night's sleep. But I think there is a bit of an overreaction going on. I wasn't looking for an argument and just agreeing with comment:
Whoa! What did I do wrong?
I think it's because some people get bored with "riddles", to put it politely, it's not an original ploy, why don't you just say what you mean, or don't you know, that's ok too.....
Thanks! Yes, the D&D 8Cs do look like ingenious speakers. Getting more and more excited to receive them. Don't wait too anxiously for any omni/D&D comparison though... 🙂 I'm in the process of moving, and won't set up the omnis until we move to our new house late this summer. It's a pair of omnis from Morrison Audio. Differs somewhat in design from the more well-known omni brands (MBL, German Physiks, Duevel) in that it's omni in both the horizontal and vertical plane, and approximates a point source.
Hang in there Joe and Ridikas, it would be best not to give them something to blame us for. (whatever that is)
That was another part of Fremer's presentation: Talking about written insults on his website, and how he responded to them. Being in control of his website, he could answer with equal force, or even stronger. We could not get away with that around here. '-)
It seems that everybody who has a subjective opinion gets attacked, and in no small way, sometimes.
That was another part of Fremer's presentation: Talking about written insults on his website, and how he responded to them. Being in control of his website, he could answer with equal force, or even stronger. We could not get away with that around here. '-)
It seems that everybody who has a subjective opinion gets attacked, and in no small way, sometimes.
Last edited:
So, now that we are interested in time aligned speakers,
did I completely miss reference to Ed Long and his "Time Aligned" (TA) trademark?
His speakers, the CRM line and Urei line were using (TA) way back then
yes? Bill Putnum used Urei TA as they were pretty universally known very well liked?
They were accurate and sounded good. If they weren't I guess Harman wouldn't have
bought them out in the 80s after they go JBL. Somewhere there is or was the
Western Universal Studios.
did I completely miss reference to Ed Long and his "Time Aligned" (TA) trademark?
His speakers, the CRM line and Urei line were using (TA) way back then
yes? Bill Putnum used Urei TA as they were pretty universally known very well liked?
They were accurate and sounded good. If they weren't I guess Harman wouldn't have
bought them out in the 80s after they go JBL. Somewhere there is or was the
Western Universal Studios.
Close.
Terminal voltage is Ze*i(t) + BL*v(t), that is voltage accros the static VC impedance plus microphonic voltage proportional to velocity. Since Ze can be changed externally we can basically have any values here, from zero (velocity controlled operation) to infinity (force controlled operation, force is BL*i(t)).
Because of all of the nonlinearities of BL, Ze, Cms, various creep and drift effects, dynamic DC-offset etc operation at these extreme operating points (if even feasible) doesn't give stellar results.
Pure current drive suffers from nonlinear BL and Cms and more importantly, completely undamped mechanical system resonance which will be fully exited by any event external to the driver (forced movement by air pressure, but also the signals generated by its own distortion). Moreover, undamped high Q mechanical resonance may have chaotic "jump resonance" charactersitics.
OTOH, pure velocity controlled operation (effective impedance close to zero, full feedback in the driver) is hardly feasible at all because you need to synthesize a "counter-impedance" to Ze so that they almost cancel, but Ze isn't really static after all. If the synthesized effective impedance is unstable (signal dependant) this introduces extra errors.
But even if we assume the BL droop being the only error in the system, too much feedback in the driver will cause it to overshoot when BL drops as this drops the velocity signal as well (even if the momentary velocity still is at proper value), and the small effective impedance generates way too much current for correction.
So we clearly there must be an optimum damping somehwere in between, at a given frequency, that gives the largest Xmax.
Overall, there is a sweet spot effective impedance for any driver in a specific situation, actually a profile vs frequency, where the driver behaves "best" especially under large signal conditions and may also sport very high stability and low distortion at low/medium levels. This "best" is of course depending on your set of goals....
Am I reading it right that the dutch&dutch is using a similar approach to the kii3, but with the side drivers being replaced with a passive solution? Looks like their cardiod response won't go as low as the kii, but still looks nice.
You are misinterpreting the equation. Qes is not some existing damping factor which the amplifier then degrades, but the electrical damping which comes from the speaker plus amplifier plus cable. Hence it is quite meaningless to talk of "eroding" Qes, or the ampliifer only making things worse; in the absence of an amplifier there is no electrical damping and Qes is infinite - it might be closer to the truth to say that the amplifier can only make things better! Qes is what it is; it is minimised (i.e. maximum electrical damping) by minimising total resistance. In most cases an approach to voltage source is a practical minimum, but negative output impedance could push it down further provided that stability can be maintained. Qes is maximised by omitting the amplifier, or by using current drive.Joe Rasmussen said:
You must be reading a different thread.ridikas said:
- Status
- Not open for further replies.