I want to point out that while you are focusing on the suspension stiffness (cms), the mechanical variable that will create the most reactance is Qms, or the actual mechanical damping factor. The mechanical damping contributes to the reactive load that the speaker presents to the amplifier. Most people assume that the suspension stiffness is directly correlated to Qms, but it is not. You can have both soft and stiff suspensions that are Qms-agnostic. You will see this in the impedance peak of the driver at fs, and this is quantified essentially by the width of the peak. Higher Qms drivers will have a narrow peak, lower Qms drivers will have a wider peak. Cms, or the stiffness of the suspension, does not affect this. The lower the Qms number means the more mechanical damping the driver has, and the higher Qms number means less mechanical damping which equates to less reactance. The biggest contributor to Qms is the material of the voice coil former. Conductive formers like Aluminum or even some alloys of Stainless steel, even if they are not shorted, result in eddy currents on movement which is what creates more mechanical damping and a lower Qms. Also, inductance plays probably the most important role in the speaker itself creating a reactive load. Not only static inductance, but the inductance over stroke. In a Klippel lsi report this is what you would view as Le(x) and Le(i). I am a speaker engineer and the drivers that I design are both low inductance and high Qms, and we see marked improvements in system impulse response when using amplifiers with low damping factors, even tube amps. We also see this manifest in impedance stability of the amps, as there are some 8 ohm stable amplifiers that we are able to use with 1.5 ohm low-Le/high-Qms drivers without going into protect.
Love that you go in depth on the theory and method before you actually make the videos with the results. These videos are more interesting than the end result. Amazing work! Keep it up! :)
another great vid! my intuition says that the larger the voicecoil and the longer the excursion, ( and the more massive the cone/ dome) the more important the damping factor will be. thus, it would be more important for subs and less so as frequency goes up. i can't wait to see the results! this is the best car audio channel on youtube. you are a natural born teacher.
I feel like I'm walking into a college physics course every time your videos pop up. I love it. Very engaging presentation and I will learn something new by the end.
My Experience regarding Damping Factor is from the early 90s. Back then i built a pair of 15" backloaded horns equipped with Eminence EM 15-300. At first i ran them off of a home audio Aiwa Stereo Amplifier with about 2 x 120W RMS. It was nice and loud, after all it was 2 15s :) but at higher volumes, the Bass seemed to somehow "fall apart" in lack of a better term. Then i bought a PA Amplifier with 2 x 500W into 8 ohms. The Difference was absolutely huge. Not only in terms of achievable Output, but also soundwise, tested at roghly the same percieved loudness on both amps. Before, there was an undefinded rumble in the low end, which was completely gone on the PA Amp. Like night and day, literally. My only explaination back in the day was damping factor, made the most sense to me. So one could say, i have been wating about 30 years for you to enlighten me on the subject! Cheers! 😊😊😊
It's been said it was more of a marketing topic back then and is in reality not important at all. I posted a link in the comment section of Joe Hobart that kicker going into some detail about damping Factor.
The kenwood kac-1023 was a amp with a really high DF amd is still highly regarded today for its ability to control the driver. I never understood why kenwood amps with sigma drive dont get more attention.
Keep in mind that your impulse response IS your frequency response. A perfect impulse or square wave needs all the frequencies under the sun to be built up and alterations of that sharp on / off transient are alterations in frequency response. It’s just an FFT away. This point was driven home to me directly when I started testing speakers 30 years ago with the IMP audio analyzer. One little “click” played through the system and your FR appeared on the screen. (Yes, the MLS sequence of impulses was more efficient, but this was a great way to be introduced to Fourier.) If your cone’s motion to the impulse is affected by the amp’s high output impedance it IS directly altering the frequency response. FWIW, this I also why some IEMs now ship with little inline 10 ohm or so impedance adapters to let users tune the bass.
Great stuff, I knew about moving a magnet in a coil induces a current, I knew how a speaker's voice coil moves piston like, aligning to the (Faraday's?) 1 handed, positioned, strait thumb, index & middle fingerer held in (the only?) pointing perpendicular at right angles finger-directions (hope that made sense) & its analogy of magnetic, current & direction of voice coil movement BUT never ever once considered the (now obvious) reverse of those same electro' physical unchangeable laws relating to Damping Factor. I just noticed it seemed to proportionally relate to a power amplifier's output impedance. And I learnt something here that made absolute sense, very well explained & have a far fuller understanding of the speaker / amp electrical interactions. I suppose I'm saying "We must never assume we know it all"
When it comes to highly technical things like this, I have to defer to the experts. Kickers lead amplifier engineer, Joe Hobart, has talked about this. If you look through their Live videos Oct 3, 2023 titled "How clean is your amp power?". The question is posed at 44:44. I'll post a link below, but youtube frowns on that, so they might auto-delete it.
It will be interesting to see the results. Just as a note, I believe tube amps tend to have very low damping factor. Like low two-digit range. It's possible all the amps you have are "high enough" it doesn't make much difference. As a test, you could raise the amplifier's impedance by adding a resistor in series with the output. Obviously you'd have to increase volume to make much for the loss, but it might be an idea to control variables by using the same amp with different damping factors.
@@Mikexception The charts found on Wikipedia for "Damping factor". The amp shown PEAKS at less than 20 while the solid state amp is 20 at it's worst. I'm not sure about the "why". Perhaps it's the added resistance of the output transformer.
@@russellhltn1396 Thank you. Just wanted to know who eventualy tested it and how he did it. . Wijipedia is no name and gives no details .. . Output impedance of amplifier is created by feedback, not by speaker wires or resistance of windings which is comparable to transistore and bearing in mind output capacitor in solid often lower. Feed back in solid atate is adequately to damping factor tens times deeper. Tube amplifiers do not require such deep feedback due to tubes unique featers and it would be no reasonable to incerease just for damping.
@@russellhltn1396 . Just do not be too particular. For me in real technic 90% means takes resonsibility Only in theoretical dreams over 90% of dampiong factor is result which would be wrong to accept . I developed last time solution unknown to biggest world producers, in fact I patented some solutions in past and some I did not patent because I am only not interested any more to monetize audio ideas because people arer not interested in audio. only in quareeling about audio. . Unless you have also confirmed achievements You are not in position to change my opinions just with spotted articles . I do not use computer programs which are toys for boys. I used them betewen 1997 and 2017 . I learned about their value for audio enough .
ok wow always been curious about this spec. and has no idea it goes to such a high number via class D!! i’m just used to looking at vintage specs on amps where it’s rated 50 ish often.
The driver is acoustically (ie mechanically) coupled to the cabinet. This has a huge impact upon how the whole thing behaves. In some cases you will find negative impedance at certain resonant frequencies. Good loudspeaker designers will mitigate and minimise this. Buying cabs and mounting drivers isn't as simple as it first might appear.
Hello, i think the damping Factor is very important for a sub, my Hegel have 4000 and has a fantastic Controll. I think it is not easy to find an Class D amplifier with a high dampingfactor. Your videos are great, i learn a lot. Best Regards to England.
Maybe when you do the damping factor sub tests, set up the phone on a tripod in slo-mo mode. See if we can catch whats going on. I love what you're doing. I'm not a public speaker or I'd be trying to compliment your work with typical American equipment instead of european. This stuff needs to be tested like they do hi-fi over on Avsforum. Dyno means nothing especially without the rest of measurements.
Nice video on an interesting topic which a lot of people are interested in. The only point is your statement that class D amplifiers have higher dampening factor than class A/B. Class A amplifiers; yes, they have the lowest dampening factor. It mainly depends on the design of an amplifier, considering the dampening factor. I noticed in the German magazine HifiTest that class D amps have the lower (tested) dampening factor than class A/B amplifiers. But everything higher than 100 should be fine. In my experience, speakers that play the low notes are most beneficial of high dampening factor; keep the mass of the cone in control. High dampening factor are less important for mids and highs because of the lower moving mass; that's why sq guys use class A for mids and highs, and A/B or D for (sub)woofers. Even well regarded manufacturers engineer their multichannel amps this way (also because of the current draw of a sub channel).
We first suppose to buld speakers not producing acoustic resonsnces - then we do not need to care much for dampng their coils. Not all resonances produced by speaker system are contained and reversed by driver coil. . It is like we belive that all sound coming from grand piano comes from strings and we can make sound perfect by conditioning strings. .,
Very interested to see the impulse response results, since I've only seen damping factor discussed in relation to frequency response attenuation in dB. Since the effective damping factor is a combination of the amplifier output impedance and the speaker cable resistance, my guess is that in car audio the effects will be hardly noticable, as the runs from the amplifier to the subwoofer tend to be rather short and most people use common sense and aren't using 18 AWG cable for subwoofer connections
You left out the dominant factor in the control of the cone. The DC resistance of the voice coil, typically about 70% of the rated impedance of the speaker, is a part of the series resistance that in includes the amplifier’s output impedance, the resistance of the wire from amplifier to the speaker, and the resistance of the voice coil. The fact that part of the resistance is inside the speaker is not relevant to how damped the speaker’s motion is. Unless the wire running from amp to speaker is unusually high resistance, or the amplifier is an old tube amp with minimal negative feedback, the resistance of the voice coil winding is going to absolutely dominate. An amplifier with 0.1 ohms output impedance would have a much lower damping factor than an amplifier with a 0.01 ohm output impedance - and that wouldn’t make ANY practical difference, given that the resistance of the voice coil would be 30 or more times greater. BTW, FWIW I am a retired pro audio product design engineer.
What a tease. And here I thought I was gonna get a definitive answer to the question I've been wondering the last few weeks. My home audio monoblock power amps (Purifi Eigentakt 1ET400a) has an insanely low output impedance. The difference in bass was a night and day difference between those and my Class A/B monoblocks. The class A/B sounded more muscular, but not as controlled. Almost a bit bloated. The Class D Purifi's sounded lean in comparison, but ultra detailed. They didn't sound lean when I stopped A/B testing the 2 amps. My speaker cables also have a fairly low resistance. I wonder, if you have an amp with a crazy high DF, can that DF be negates by high resistance cables and binding posts? Can we hear the difference in that instance? I can understand people don't hear a difference with cable because of a low DF, but what about a high DF? 🤔 BTW, great video. When are you planning on posting the following video?
You can always stick a small value resistor in series with the speaker and find out! Though you may hear more of the resistor playing with the speaker impedance curve rather than damping factor of an amplifier
You can simulate output impedance with normal power resistors. Even wound power resistors work, as long as you parallel at least four-five to lower the added induction. Five 1ohm resistors is an added 0.2ohm output resistance, and gives a damping factor of roughly 20 into four ohms at the speaker terminals. At low power, you could also use normal metal-oxide resistors to get a more "pure" resistance. And I think you oversimplified for the audience - but there's no such thing "a single pulse" for a single frequency in physical reality. The only true "pulse" that exists is the Dirac pulse, and that has a real frequency response of +/-0dB from 0Hz to the upper limit of the system. It contains all frequencies the system can reproduce Try loading a Dirac pulse in REW and apply a bandpass 30-100Hz to simulate a bass driver, and look at what the resulting curve looks like. This is the theoretically perfect response that no real speaker will ever get even close to, and still it rings quite a bit. Especially if you bandpass with a fourth order lower and third order upper (like most ported subs)
I run class D amps I run a Stetsom Digital Bass 3000 2Ohm Version I also run a Stetsom HighLine 800.4 on my mids and highs. Both amps have internal fans.. Stetsom is more of an SPL company but I have to say the sound quality I am getting is phenomenal. The Mono amp puts out 3700 watts rms @2ohm @14.4v and 3000@ 2ohm at 12.6v I run three 1000 watt rms subwoofers in sealed boxes.. Dual enclosure in rear of suv and one in middle of 2nd row. S/N ratio: Dampening Factor and THD not really rated at time of purchase. Just saw amp dynos verifying power and foot print. I wired my 3 subs to 2.67 ohm and with ohm rise I am probably close to 3 or 4ohm load and this amp sounds phenomenal! The low freq's sound so clean down to around 24hz... I broke my sunroof (now sealed) from the roof flex that the sound reproduces. My windshield wipers shake at full tilt But it also sounds nice and clean at low volumes not overpowering the rest of the music but blends very well. The higher the ohm load the better the dampening imo.. If your amp sucks at 4ohm its not a good amp.. Wire down to 1ohm or .5 ohm and you can get really loud but no control. Then ppl wonder why they have to recone subs all of the time lol.. The 4 channel puts out 125 wrms @4 ohm under 12.6v and 165wrms at 4 ohm on 13.6v. it has a fan on it, so I hear slight sound from small tweeters when hooked up but changed to 3.5 full range speaker and no more slight hiss. Both amps run cool and sound amazing. I get compliments all of the time. Running a mono amplifier at 4ohm or better (If it has the power) will almost always provide a high dampening factor and much better control of your subwoofers vs wiring down to 1ohm or .5ohm with little much less control. Again, If your amp sucks at 4ohm its not a good amp..
I am a bit experienced about those problems and I like to notice that it is not easy to know not theoretical but real impedance of spaeaker ZL for any harmonics which are interersting fo you. I see drivers without enclouser which is braking conditions of assesment . . You promise to measure output from amplifier when loaded with resistance 2 or 4 ohm. but what frequency are you going to apply? Most amplifiers work with output capcitors and it will affect results - amplifier may have higher output impedance in low range. At the same time higher harmonisc may be damped better than expected and i in my opinion is much more important then for lowest range hich you consider when talking about membrane main resonance. . It may be even a good factor if our spaker is not very big and may work good or bad in phase shifts produced by enclosure , That frequency without enclosure it is unknown. .Impedance ZL varies depending on many factors also on enclosure. which is not here. , but i couldn't find how you solved it. When this is positively solved I am interested how does sound is affected by ear when two amplifiers have damping factor different as much as 100 and 460 s. How much better is when it would be say 600? Because I do not receive sound based on calcultions which may be ipressive in numbers but on what I hear.
i have heard a difference myself. a better lower wattage amp with higher damping factor and slew rate sounded better than higher wattage lower damping and slew rate amp.
I feel this is a much more important factor for tweeters and upper midrange. . it's a lot more audible when the mids and highs are smeared and ringing. A water fall graph across the entire frequency response would be Interesting to test this theory
@@carlosoliveira-rc2xt but can you audibly hear it I'm not saying it does not matter at low frequency I'm saying it's going be a lot more audible at higher frequency when wave length is shorter and the cone has to stop and start faster that low damping factor would be very audible. As far as ohm loads can drop no matter the size the driver I seen 8 ohm drivers have a 1.7 ohm impedance at some point of the frequency sweep. But also maybe as you said I'm completely wrong with I don't see how that is going be possible both things we both said could be true I just saying it would be very nice to see that tested to see if you can see a measurable difference
@@paulgood2218 I've read elsewhere that generally damping factor over 200 is "the same". It's mainly when you get tube amps that have damping factors of 1 that you can hear more to do with it
if the softness / stiffness in woofers has a lot to do w dampening characteristics then for modern stuff a vintage amp w dampening factor or 50 is probably very fine. if assumption is accurate does this work in reverse w class d working fine w soft vintage woofers i wonder..
You didn’t need to get a bunch of different amps. You would get EXACTLY the same results by using one amplifier with extremely low output impedance (damping factor 800) and then adding a low value resistor in series with its output to see what effect a lower damping factor has. Assuming a nominal 8 ohm speaker, an output impedance of 0.01 ohms gives a damping factor of 800. Put a 0.1 ohm resistor in series and the damping factor would be 80. Put a 1 ohm resistor in series to simulate a super low damping factor of 8. Put a mike in front of the speaker and put a very, very low frequency square wave into the amp. Observer the actual acoustic output. Put the mike as close as possible to the cone, and hang the speaker in free air as far from any reflective surfaces as you can, so you aren’t just observing reflections off tables and walls.
You don't even need a mic. You can clearly hear a difference in bass and an amp with a low damping factor at lower impedances will have less control over a woofer and said woofer will bottom out more easily.
@@carlosoliveira-rc2xt I bet you're wrong about that. Unless the output impedance of the amp is really high (several ohms) it is unlilkely that you could detect, in a fully blind test, the difference between a damping factor or 20 and any higher damping factor. Once the amplifier's output impedance is 5% or less of the speaker impedance, the DC resistance of the voice coils is absolutely the dominant factor in how much electrical damping occurs. Or more accurately, that dc resistance working with the coupling between the voice coil and the manetic field the voice coil is in. There is also coupling between the cone and the air, of course - that's the whole point of a speaker. And that also damps the motion of the cone. And in a ported enclosure, the mass of the air in the port has inertia, and once it's moving in one direction, it doesn't want to stop. That moving air mass fights the damping on the speaker. Factors other than the damping factor of the amplifier (once the amp is even sort of decently low output impedance) are far, far more in control of the transient response of the speaker.
@@jimmurphy5355interesting all the details of something that’s not really noticeable? also must be about how the music was produced regarding compression. assuming damning is synonymous w ASDR namely the decay and release aspects of lower freqs. for dub music low dancing slower release is probably better; metal kick drums faster makes more sense. so i guess maybe a spec is not useful too if it’s actually context / genre dependent. but yes blind testing no clue how much confirmation bias is involved but. usually it’s everything! w audio folks
i have tested one yamaha home theatre amp which had the damping factor about 70-80 i think and compared it to a small rockford fosgate car amp which had the damping factor over 200,...the speaker were a pair of floor standrs,...with very soft mid bass drivers,...the difference was quiet obvious,...the rockford was much more precise and punchy,...where the yamaha was much slower,....and the rockford was half the power of the yamaha,...so he couldnt get even near as loud as the yamaha,...but was much more precise and punchy even with hald the power
My question is why not also test some home stereo amplifiers, I own a couple of Adcom amplifiers, one has 260 and the other has 500 damping factor. How do you compare those to car stereo amplifiers running off 12v dc batteries. I've really wanted to buy a crown class d amp to compare and see if its worth upgrading.
It's been stated that around 80 is good enough for home stereo systems but it depends on the speakers too. I had an amp known for power output but low damping around 43 df and it made my speakers bass too flabby, slow and undefined (there were other issues as well such as graininess in the mids). My lower powered amp has around 150 df and surprisingly a rising frequency response rising up to 1.5db slowly starting under 90 hz and provides tight, strong and decent quality bass. The added response might help bass a bit, not much but also sucks a bit of energy too. But the amp works fine on even 4 ohm speakers. The difference in bass is minor between that amp and my upscale amp which probably averages well over 500 df., so at moderate SPLs, you may not gain much unless the speaker driver really needs to be heavily controlled and requires power and whether one listens at higher SPLs. Then a higher df may help. There are higher powered amps with a low df too whose bass is appreciated by alot of people producing a warmer sound, one that may add to the mids, but I prefer a fast, tight bass with definition over that. System synergy. Also, some have stated that speakers of higher sensitivity/efficient speakers can play better with amps with lower df while those that need power for output SPLs can benefit from higher df. But there is more to this I suppose. A nearfield speaker that can only take 50 watts but outputs say 83dB at 1 watt/2.83v or however they get measured today, may or may not sound better to someone due to df. So, there's more to it such as distortion, SNR, how well a signal gets amplified along the whole frequency curve, room, source, recording, etc. In my experience, if an amp has sufficient df to not sound flabby on a particular speaker I have, its good enough. Can one have too much df? Yes. It can make a speaker sound a bit thin in certain ranges, from what I have heard. Adding a sub can change the whole presentation as well. If one uses a good sub that blends in the bass without seeming off, too fast or too slow, etc., it's going to cover up or fix some of those low end deficiencies when set appropriately at a certain low frequency point, especially if you can cut the poorest response off from the speakers. Say setting the crossover point somewhere between 50 and 100 hz. I run my small bookshelves full range with a sub adding in at and below 80 Hz and it mostly works without hearing the sub. Perhaps 2 subs would help that for balance but it isn't worth it for me as I am satisfied with the results.
@@RAW-CAt La fuerza que entregan los dos es la misma❗️❓❗️ No me sentiré faltando bass❗️❓❗️ Ya tengo instalado MRV F407 y para subwoofer tengo jl audio 500/1 v2 y jl audio 10w3 …
@@chinmeyswayessentially it’s a baffle mounted to an area that goes over an area that you cut out in your vehicle, your subwoofer will be out in the open and technically makes your whole vehicle the box. There is a few videos that are pretty cool I suggest you look them up they are very musical setups and others can explain them better than I can.
You werent taught the underlying reason. And its not your fault..some of this is correct. Some isnt. Lets get to the truth. Look at the rail voltages. If the voltages move at aĺl. The output has been compromised.
Unfortunately it's not that simple as I can't just "grab" any amp I want. I have to work with what I have. If you have that amp and are willing to send it to me for testing, I can gladly measure it.
The class of an amplifier has no direct bearing on the damping factor. Any kind of amplifier can be designed to have a very low output impedance.The bandwidth of the semiconductors available now makes it trivial to build an amplifier with very wide bandwidth and lots of open loop gain. That in turn allows for lots of negative feedback. Lot of negative feedback lets the amplifier hold the output at a precise voltage independent of the current flowing into or out of the output.
@@KaranDeep-e4c Better or worse are not words I would apply to the concept of negative feedback. Negative feedback is a tool. Conceptually it means comparing the output of an amplifier to the input. The difference (if any) represents an error. It means the output is not a perfect (amplified) copy of the input. A portion of the error is inverted (that's where the word "negative" originates) and mixed with the input to partially cancel the error. Sending the output of an amplifier back to its own input in inverted form is a powerful tool in the arsenal of amplifier designers, but like any powerful tool has dangers. There is an ever present possibility for the negative feedback to become positive feedback and trigger ringing or outright oscillations. This generally happens at far above audio frequencies, but can occur intemittently under particular combinations of load current, output voltage and load characteristics. And signals do not propagate through an amp instantaneously. Whenever the input changes suddenly, there will be some brief interval when the error between the input and output is very large, because the input has changed, and the output has not yet changed. This can overload (clip) internal stages of the amplifier for a few microseconds. If and how much that matters depends on all sorts of details beyond the scope of this already long comment. Bottom line: negative feedback is a nearly universally used technique, and applies to any kind of amplifier. Proper engineering makes it very beneficial. Poorly done, it can cause subtle problems. And that is true for any kind of amplifier. BTW - I am retired from the audio business, but over many decades I designed audio amplifiers for some big name companies. Mostly for pro audio, not home hifi. But the principals are the same...
Pay attention. Math only explains physics. Dc resistance isnt imp.. all amps can drive low imp if rails dont move. Yes Im david stevens Im the master of audio
