Because almost nobody want to buy current drive, so nobody makes them š 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 donāt even know that they loose some fidelity. If someone tried current drive down all the way to resonance and didnāt 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.
One need to compensate for the changed FR around resonance + output level, in order for a fair comparison - no?
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.
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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.
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)
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.
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.
Kindest regards,
M
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?
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Find some answers here: https://www.diyaudio.com/community/...dback-interference.426685/page-3#post-7994266
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
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