Because almost nobody want to buy current drive, so nobody makes them 😁 who is first egg or chicken ? No demand because how many people know or tried current drive benefits? Only small diy fraction. Like all things there are benefits and drawbacks. Majority tend to go more simple path even they know they loose some fidelity. But most don’t even know that they loose some fidelity. If someone tried current drive down all the way to resonance and didn’t like it. They tend to dismiss current drive for all frequencies. Minority investigates and majority just follow the path. Thats my understanding why is not popular.Then why is everyone always trying sell me voltage drive up to 20kHz?
One need to compensate for the changed FR around resonance + output level, in order for a fair comparison - no?I made that experiment. Sound was so boomy in the bass, it was not bearable.
If there was a nice 15-25W current drive amp I would be interested. One that has a high output straight out of the silicon and not made by a resistor.
//
Yes, I compensated it with an equalizer. For bass, current drive is pure crap.One need to compensate for the changed FR around resonance in order for a fair comparison - no?
There is schematic of such amplifier in the post #1.If there was a nice 15-25W current drive amp I would be interested. One that has a high output straight out of the silicon and not made by a resistor.
Well, sorry my wording was poor. Depends on what the situation is, if electrical damping is eliminated completely possibly so. However, effect of small series resistor should be no problem based on two minutes on a simulator.Impossible.
Lack of damping in current drive can not be overcome by any possible manipulation of size, filling and leakage.
Simplified, a driver in a box makes single resonant system, manipulate either and the resonance is affected. Electrical damping is very effective way to dampen the resonance, or, resonance is very apparent unless damped.
Very easy test with simulator, but also in reality with a drumming test. Unhook your woofer from amp and drum it with your hand, and it sounds like a drum "boom" kinda sound. Now connect it back to the amp or short the driver terminals with a fork or something, and the sound is now "thump" instead of "boom". Now, amp still unhooked, use a resistor between the driver terminals and change it's size to vary amount of "boom", see how big you can use before you have the boom. Make the box leak and try again.
Or, just use simulator vary Rs, and then Qa and Ql parameters to introduce leak and damping.
If you manage to double circuit Re with series resistor, some of the motor distortion would reduce in half. Whether this sounds any different depends on the driver and how the system is used. Would dissipate some heat though, perhapsnnot wose fornwoofers. If electrical damping sound better then it does. When one understands the possibilities it's possible to make educated choise on any given project.
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This is another design then. Kartesian e.g. uses single layer voicecoils for their top drivers to fill the gap length and achieve desired Rdc with minimized inductivity (and also achieve a tight airgap then with sleek coil for increased B-field strenght)How about same number of turns but thin wire to increase Rdc without affecting Le. Not sure what else would change, mass and power handling at least.
I mean, when you keep the same winding crosscut and winding fill factor, and you change coil diameter vs. winding number sizing but keep all other parameters same. This is usually approximately done so with the often available 4- and 8-Ohm driver variants as stroke and gap width are same for both. Increasing BL by more windings will increase Le accordingly, and so the nonlinear contribution. Z_coil = R_dc + X_Le --> The fractions of Rdc vs. Le stay same with different coil sizings, and so the current distortion.
I would do it the other way around, at least for mids and midwoofers: driver with low impedance and low Qes --> strong magnet, then give it a series resistor (or make the lowpass air(!)coil of thin wire that makes it also cheaper) to come back to a useful impedance and Qts, and introduce a significant fraction of local current feedback to lower current distortion and thermal modulation by the series resistor. Here is an example that points to the direction I mean: https://www.diyaudio.com/community/threads/new-sb-acoustics-6-sb17nrx2l35-8.424648/post-7975493 Drivers with magnets else too strong for meaningful tuning can be used, with the advantage to saturate also the iron better against hysteresis distortion, and acheive higher BL but not by increasing turn nubers and so the inductivity. Rdc = 2,7 Ohm, Qes = 0,18 and Fs = 36 Hz would be a nice woofer / midwoofer parameter set, then give it ~3,3 Ohm series resistor...
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I have boards if you interested. Actually in two months i plan to have. Need to do some small adjustments and order the batch.If there was a nice 15-25W current drive amp I would be interested. One that has a high output straight out of the silicon and not made by a resistor.
//
found it here
https://www.baffless.com/analog-amp
mixed mode possible, voltage drive low frequencies, rest current drive
https://www.baffless.com/analog-amp
mixed mode possible, voltage drive low frequencies, rest current drive
Hi @Kwesi
Kindest regards,
M
You and @phase_accurate mentioned that the current drive as discussed would be beneficial for low Q drivers. Could you please explain for us less knowledgeable, why it that? The reason for asking is that I have a driver with similar parameters that you posted.Drivers with magnets else too strong for meaningful tuning can be used, with the advantage to saturate also the iron better against hysteresis distortion, and acheive higher BL but not by increasing turn nubers and so the inductivity. Rdc = 2,7 Ohm, Qes = 0,18 and Fs = 36 Hz would be a nice woofer / midwoofer parameter set, then give it ~3,3 Ohm series resistor...
Kindest regards,
M
OK, I have found information and a thread here - thanks!I have boards if you interested. Actually in two months i plan to have. Need to do some small adjustments and order the batch.
Is there the usual electrical measurements (THD, N, IMD, Multitone....) in to 8 ohm resistive available somewhere?
//
Find some answers here: https://www.diyaudio.com/community/...dback-interference.426685/page-3#post-7994266You and @phase_accurate mentioned that the current drive as discussed would be beneficial for low Q drivers. Could you please explain for us less knowledgeable, why it that? The reason for asking is that I have a driver with similar parameters that you posted.
Dialing in the correct natural Q is especially important for ported speakers to have a meaningful and well-controlled response from the port.
Hi @KSTR,
Thank you for the reference. So far, I have read only your response, but I will eventually read the entire thread, but as I understand it, you are referring to the overall Q of the driver/box system, while @phase_accurate and @Kwesi to the driver only.
To my lizard brain this seems to be a significant conceptual difference.
Kindest regards,
M
Summary: A speaker's error response is determined only by the natural Q of the alignent (as given per driver and box parameters together with source impedance). Tailoring the signal response with up-stream EQ to reach a given FR target does not affect the error response.
Thank you for the reference. So far, I have read only your response, but I will eventually read the entire thread, but as I understand it, you are referring to the overall Q of the driver/box system, while @phase_accurate and @Kwesi to the driver only.
To my lizard brain this seems to be a significant conceptual difference.
Kindest regards,
M
The use of a series resistor (or a simulted one) would still allow some damping around fs while showing significant distortion reduction. This could be interesting for the use of low-Q drivers in closed boxes.
Rdc = 2,7 Ohm, Qes = 0,18 and Fs = 36 Hz would be a nice woofer / midwoofer parameter set, then give it ~3,3 Ohm series resistor...
Good idea! Such very low Qes (Qts) woofers will work nice with current drive amplifier with output impedance equal to about Rdc - it can work well in vented boxes, not only in closed ones. But not with series resistor plus voltage drive amp - it is waste of power and efficiency!
The remaining question is - how big is the reduction of distortion with current drive amp with only 3 or 4 ohms output impedance?
It's also an absolute nightmare as a general-purpose system for driving speakersBecause almost nobody want to buy current drive, so nobody makes them
Not just because it varies case by case, but because it carries a much higher risk of seriously damaging the driver and/or amplifier.
This will become very evident when you take all speaker non-linearities in mind.
This has already been mentioned earlier in the thread btw.
There are hybrid solutions, but it's kinda looking for a solution for a problem that barely exists.
Instead you might as well as using two different amplifiers (voltage and current) with proper EQ and DSP in front of it.
That gives far better control and flexibility, while technically not being overly complicated.
Will try to measure more. Just my tools are not best for that.OK, I have found information and a thread here - thanks!
Is there the usual electrical measurements (THD, N, IMD, Multitone....) in to 8 ohm resistive available somewhere?
//
Is it generally assumed current distortion is a direct function of the Rdc/Le ratio?The fractions of Rdc vs. Le stay same, and so the current distortion.
NEXT UP:
KEF Reference 1 META
(2022 release) A veritable post COVID bargain at only at £7500 / $8999 / AU$15,000
The audiophile press love it
This time I will cut to the chase, but if you are uncertain about how to interpret these graphs please refer to this post
Most industries work on the "do the minimum" principle.
“We value feedback” but when you report it to your boss or line manager, guess who has to do more work?
The same with the industries that feed the audiophile industry. Buying the “reassuringly heavy” 100lbs amplifier to use with passive speakers, only to be unhappy with it and mix and match til the cows come home. But it doesn’t matter. It’s a great for the economy.
The CEO cannot see how to see to do it differently, only how to manage other people, and increase profitability.
If the high-tech industry were going what audio nuts and recording artists are like us are doing, mixing and matching speakers and mics and guitars and pedals and…
We’d be using computers the size of refrigerators, automobiles with hand cranks.
It's all a deep state of stagnation, locked away by patent monopolies like the first “Symmetric drive” patent in 1973, even though Philips had already had a product in the marketplace. And perpetuation of fiction like SD-1, Balanced Drive etc as discussed in "What is symmetric drive"
Someone should have patented enamelled wire!
It's do-it-your-selfers/ startups that are hungry that want to do things differently.
PS. Results have been passed onto @jackocleebrown @ KEF.
There are ways to reduce H3- current drive, or copper sleeve ?
KEF Reference 1 META
(2022 release) A veritable post COVID bargain at only at £7500 / $8999 / AU$15,000
The audiophile press love it
This time I will cut to the chase, but if you are uncertain about how to interpret these graphs please refer to this post
Comparison at 86dB
Comparisons at 96dB
Test conditions:
B&K 4191/2669/2690 mic @31.6cm, SPL shown for 1m
Audient iD24 audio interface
Hypex UcD400 mono amplifier
clean Mac mini (2024, M4); REW 5.40β80
@BafflessB&K 4191/2669/2690 mic @31.6cm, SPL shown for 1m
Audient iD24 audio interface
Hypex UcD400 mono amplifier
clean Mac mini (2024, M4); REW 5.40β80
Most industries work on the "do the minimum" principle.
“We value feedback” but when you report it to your boss or line manager, guess who has to do more work?
The same with the industries that feed the audiophile industry. Buying the “reassuringly heavy” 100lbs amplifier to use with passive speakers, only to be unhappy with it and mix and match til the cows come home. But it doesn’t matter. It’s a great for the economy.
The CEO cannot see how to see to do it differently, only how to manage other people, and increase profitability.
If the high-tech industry were going what audio nuts and recording artists are like us are doing, mixing and matching speakers and mics and guitars and pedals and…
We’d be using computers the size of refrigerators, automobiles with hand cranks.
It's all a deep state of stagnation, locked away by patent monopolies like the first “Symmetric drive” patent in 1973, even though Philips had already had a product in the marketplace. And perpetuation of fiction like SD-1, Balanced Drive etc as discussed in "What is symmetric drive"
Someone should have patented enamelled wire!
It's do-it-your-selfers/ startups that are hungry that want to do things differently.
PS. Results have been passed onto @jackocleebrown @ KEF.
There are ways to reduce H3- current drive, or copper sleeve ?
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This was theorised by @5th element already
“the potential to sink the HD3 down another 10dB, particularly between 400Hz and 2KHz would be welcome”
Reference: https://www.audiosciencereview.com/.../kef-r-meta-series-release.41420/post-1488047
“the potential to sink the HD3 down another 10dB, particularly between 400Hz and 2KHz would be welcome”
Reference: https://www.audiosciencereview.com/.../kef-r-meta-series-release.41420/post-1488047
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