Monster magnet meets subwoofer...

[@robertgaines-tulsa]

The basket may have become magnetized disrupting the magnetic field. Running a sine wave through the speaker for a while at moderate levels might help restore the magnetic field strength. I wouldn't know if the magnets were permanently changed. Neodymium magnets are usually used for small speakers, not large ones. It might be interesting to repeat the experiment with a field coil speaker. With and without the field coil working.

[@DJSNT]

The subwoofer appears to have a machined aluminum frame. Not to say it couldn't gain some magnetism with the presence of the large neodymium magnet, but it would primarily function as a shorting device to the magnetic circuit. I could see this easily being the case with a stamped steel frame, which would already cause some stray flux to travel up the basket to the surround landing. Secondly, it's more likely that the larger neodymium magnet was just pulling some of the magnetic charge from the subwoofer, as it is possible to do not only with magnetism itself, but heat as well. (More susceptible in Neodymium though.) • Brainiac75 is actually doing something "similar" on a larger scale that Digital Designs does offer as an upgraded package to some of their subwoofers, which is known as 'Supercharging", where a slug of Neodymium can be added to the top of the pole-piece to improve BL (Thus BL²/RE) Also, there as several larger format subwoofers that do utilize rather large neodymium magnets, such as the B&C iPAL 21". If you search "B&C iPAL 21 magnet" on Google Images and locate the following post; "B&C 21-IPAL Driver and Measurements Discussion - Page 3 - Bass Gear - Data-Bass Forums". If I recall correctly, the B&C iPAL uses a 6" O.D. N48H, though, is information that is not publicly available to my knowledge. Other Companies that provide large format Neo subwoofers include but are not limited to Harbottle, Sundown, Digital Designs, Ground Zero, Pride, Eminence, Massive Audio, etc.

[@kylevanwinkle2081]

@@DJSNT DD audios supercharging option doesn't really change the bl much but it does raise the inductance significantly which allows the sub to play higher in the octaves with a smoother response curve

[@Margarinetaylorgrease]

Neodymium magnets don't like to get hot, they lose their magnetism. I worked in a club were the bass speakers magically just stopped making sound.

[@Audysseus]

@@Margarinetaylorgrease i dont think the neo got hot there at all lol

[@Margarinetaylorgrease]

@@Audysseus It was a response to Neo's being used in small speakers. When your running 600w + drivers heat is a thing. Hope that clarifies.

[@minekrafines]

Maybe the weird results with the 20hz test have something to do with the selected frequency? Try using a white noise signal (frequency flat) with longer time duration (at least 10-15 seconds, but longer is better), and later analyze the frequency response differences. Perhaps you find that, for that particular frequency, the response is lowered, but increased for others. I'd like to see you try something like this in a future video.

[@SpudicusMaximus]

I agree, I think testing at Fb might produce a more interesting result as well. Though the demagnetizing is a bit of a problem. So all results will probably be inconclusive. Unless he picks himself up a magnetizer. That way he can re-charge the ferrite after each test.

[@jonnyreverb]

This is what I was thinking too. You could be creating some sort of resonance at certain frequencies and their harmonics.

[@coastersaga]

Yeah, because the music used isn't just 20Hz bass

[@brett4264]

I took an acoustics class in college where I earned a degree in electrical engineering. It was VERY high level. You would not believe all the the theory and math analysis that goes into optimizing a speaker's design. It doesn't surprise me that you didn't really improve the speaker. It is designed to tight tolerances with the parts that are there. The math in that class killed me. I almost didnt pass.

[@TheMetalShed]

An interesting alteration to the last test you did would be to play a sine wave sweep from 20Hz to 20KHz, and comparing the frequency response of them with/out the magnet

[@LabdalockVelheimr]

i love how you show what types of dangers the experiment can cause in the beginning, keep up the cool experiments

[@blockbeata09]

I think you changed the impedance rise on the 20hz cycle. If you could get power reading in real time I bet the subwoofer is receiving more power depending on the orientation of the neo magnet. If you have a clamp and multimeter you could get a power reading while playing the 20hz.

[@CrashPCcz]

This might be the actual right answer. Higher Bl will cause more electrical damping. At and near resonance frequency, this gets rather criticsl.

[@OfficiallySnek]

The difference is probably due to the fact that the simulation isn't taking into account may things. For example, just a simple screw somewhere could slightly change the magnetic field leading to a different reading that then one you where expecting. If you were to get the real life setup as close as possible to the simulation, you would probably get closer results to resemble that simulation.

[@justlooking6898]

Just my thought - Attaching the monster magnet to the actual speaker free-air/no cabinet with nothing butt a strong piece of duct tape between them for easi(er) separation would be the biggest change I'd make...the gap of the inside of the cabinet, the thickness of the cabinet, the fear of never getting them apart, etc. Could not NOT comment, lol - I love these experiments. 🤗

[@Wobochacha]

My cat was coming near me during the video. She was purring then exploded.

[@brainiac75]

Oh boy, never knew infrasound could have that effect ;) Thanks for the early watch!

[@Jannesmitderwelle]

Same Here 😲:-D

[@user-if2jq8vr8y]

horifying

[@dorhocyn3]

They’re always free replacement cats on craigslist, we have two that we got from craigslist and they are pretty good.

[@corinnemuir1542]

Social Media

[@DJSNT]

Hey Brainiac75, The most critical evidence of performance changes would come from the Thiele Small Parameter; Large Scale Parameters via Klippel would provide the most information as to the effect on BL over Excursion, and what impact this has on inductance, but that would be a pretty penny to accomplish. Typically, a shift in the BL will directly impact the Q parameters (Qts & Qes). The Lower the BL figure, and therefore a lower BL²/RE, would result in Higher Q parameters. Typically, the lower the Q parameters become, the more adequate a subwoofer becomes for bass reflex enclosure designs, whereas, the higher the Q parameters become, the subwoofer yields better performance in a sealed and/or Infinite Baffle alignment. If the Q parameters were being lowered, a bump also occurs in the response above the tuning frequency of the bass reflex enclosure as the driver becomes more resonant. Measurement of bandwidth before the magnet is applied, then post-application of the magnet being attracted to, and repelled from the magnetic structure of the subwoofer would certainly be the cherry on top.

[@OlafurArons]

I love your mixes. Your answer was exactly what I was thinking, albeit, you did a much better explanation than I could've.

[@vladimirmikasinovic2374]

It's a good explanation, but one thing you've written is very wrong: If Bl is lower, then Qes and Qts and higher.....If Bl is higher, then Qes and Qts is lower.......You know that speakers with strong magnets usually have low Q factor, because stronger magnet means more electrical damping, and more damping = lower Q. This is the formula for Qes: Qes = Res / (Bl * Bl) * sqrt(mms / Cms).

[@DJSNT]

@@vladimirmikasinovic2374 I am actually aware of this, but in my haste to respond I swapped around higher and lower in the explanation. It has sense been corrected. Just like the old saying, measure twice, cut once. I should have reread the response more thoroughly. 🤦‍♂

[@Thumper68]

Yeah he’s got 30k or whatever a klippel cost lmao

[@CrashPCcz]

In days of powerful cheap processing, Bl, and Qes values might not have much to do with a speaker choice. You just straighten it out. The elephant in the room is true efficiency, heating and power distribution. Rule of thumb if all else being equal, you have DSP, and an amplifier with more voltage swing, get lowest qes/highest (bl*bl)/2 driver possible. Flat natural frequency response is not needed anymore. Just being that guy, poking. 🤣

[@anthonyvolkman2338]

That's actually a very nice subwoofer that you have. The box rise (Impedance rise) could have actually been affecting it. A very good way to tell if a magnet/magnetic field effects a speaker would to do the test while using shunt resistors in series with both coils (each coil having an independent shunt) and oscilloscope to see if the current increases or decreases while while watching the current waveform to see if anything changes.

[@davelowets]

Or just simply run the driver at a single frequency..

[@rayoflight62]

It is more than 50 years that I operated in the electronic sector. When I begun, ferrite loudspeakers were still part of the future. The speaker at the time used iron magnets, and the most powerful commercial speaker was 4 Watt of power - which coincidentally was the same power delivered by a single ECL82 or 6AQ5 (beam tetrode) working in class A. 10 W speakers were reserved to Hi-Fi systems utilising a push-pull of two EL84 per channel. Again, there were no ferrite around. The speaker were reasonably efficient even with iron magnets, because a loudspeaker is designed as a system, where the moving coil mass and excursion is balanced against the magnetic field. Changing only one parameter can't bring improvements; the whole system must be re-dimensioned and re-optimised. With a stronger magnetic flux in the same air gap, you can increase the coil mass so it can handle more current, you can have wider excursion (which require higher damping factor) and a wider cone area, which in the end increases - in a non-linear fashion - the amount of power transferred to the air. In all of this, η (efficiency) varies wildly. Designing a speaker is a feat of engineering and, notwithstanding the existence of models and simulators, is still done manually because there are many competing factors. It useless to make an extremely efficient speaker if it is not linear. Neodymium speakers can be very small for a given power, but their linearity & bandwidth outside a speaker box can make you cry...

[@randomtube8226]

Now this is the magnet content I can get behind! We need more speaker magnet test videos 😂

[@MAGGOT_VOMIT]

Since I said with my experience, crushed ice in a tube would be the safest way to bring magnets together, I always wondered how much it would affect a speaker with just one these magnets. 🤣

[@AJBtheSuede]

1) A 10% increase in magnet gap strength is only about 0.4dB SPL increase... 2) A resonant system is dependent on Fs and Q to get a response level. Way above the resonance, efficiency should scale with magnet gap field strength. At or below - you have to calculate the resonant behavior to get SPL difference. Lower field strength might give higher SPL at a certain frequency depending on the resonance function. Especially in a fouth-order system like a ported sub

[@zenvir1680]

As far as I can guess, the big magnet would have messed up the TS parameters of that driver to some extent, and bass reflex enclosures are sensitive to those changes.

[@igxniisan6996]

Ez.. the monster magnetic field over powered the little ones and because of it's massive field the entire area was already filled with dense magnetic flux lines.. hence sound increased instead of decreasing.. In the repelling set up the fields were almost erased away from the ceramic due to the super strong repelling force of the monster hence the entire magnetic strength of the ceramic decreased (may even demagnetized a bit permanently), resulting into lesser amplitude.

[@Pulverrostmannen]

you should have checked how much power was going into the speaker during the test too because I am pretty sure the impedance of the speaker changes with the magnetic field too so you probably had different amounts of power into the speaker during the test

[@bolwem50]

At low frequencies, the speaker impedance is mostly back EMF generated from the voice coil moving in the magnet. The voice coil has to move further to generate the same back EMF when the magnet is weaker, increasing the volume. it will also increase the current draw from the amp and reduce the speaker efficiency.

[@ohanneskamerkoseyan3157]

I guess with a weaker field you get less back emf, increasing the terminal velocity of the coil, which increases the volume in the end. This could be the case if the back emf in a speaker is not negligible.

[@victortitov1740]

yep, and if the port is tuned to a frequency higher than 20 hz (which it very likely is), 1) the speaker is essentially flapping around, and likely approaching this terminal-ish velocity, 2) the second speaker+port resonance may be contributing to even eliminate surround return-spring action, leading to even more likelihood of approaching this terminal velocity. it's like an unloaded dc motor, which will spin faster if one reduces the strength of magnets...

[@mernokimuvek]

@@victortitov1740 Shouldnt it act like a synchronous motor with a fixed 20 Hz input?

[@WXSTANG]

The magnet glued to the back of some speakers is to aid in magnetic shielding for near electronics by compressing the fields. Should make little difference in the output sound. ;)

[@globaldeception7414]

0:42 You forgot about the radiation risks

[@Apti-Erhan]

from what i know, if the polarity of the speaker is correct, the speaker should vibrate outside, maybe that influences somehow

[@westelaudio943]

False, the cone will move outwards and inwards at the same rate, given the coil is within it's linear region, and a sine wave with no offset.

[@dinitroacetylen]

2:25 -- summing like this only works when you consider that Z is actually a vector! To get the ohmic value, you calculate the vector length Z = sqrt( X^2 + R^2 ). Z is a vector, similarly to a complex number in the coordinate plane of real and imaginary components (swap them for resistance and reactance, respectively). The angle in which Z is pointing equals the phase difference between voltage and current. Oh yeah, and X can actually be negative (a capacitor). Try wrapping your head around that. 9:25 -- I think that here we need to consider that the monster magnet is conductive. Every time a magnetic field reversal occurs in the coil, a respective field oscillation occurs in the magnet itself. Such magnet re-magnetisation cannot occur instantly, and it also consumes the energy of the external field. This effect gets stronger at higher frequencies. And it gets particularly strong with conductive magnets due to the eddy currents. At high frequency, a significant portion of the coil energy can be absorbed by the monster magnet, lowering the sound volume. At low frequency, this magnetic loss is insignificant. And as for the volume gain, I have not a clue. Did you position the monster magnet so that its edge (where the field is stronger) is aligned with the speaker axis, and the monster's field strength actually takes priority?

[@fezy9417]

Watched your content some 9 years ago and this is finally being recommended back to me after making a new yt account, forgot this gem of a channel existed (sry). Great content as always I've always enjoyed the magnet experiments. Thx for all the childhood inspiration!

[@johnniewalker39]

Oh, i can't wait for the audiophiles' expert opinions!

[@lunam7249]

my audiophile expert opinion is the big magnet is way way to far away....+ the magnetic circuit or the woofer is already "perfect"....any additional magnetic field will not add much energy

[@datutturugang666]

audio engineer here,you said that it wasn’t a huge difference with the magnet near. keep in mind that dBs are a logarithmic scale, for every 3 db more the volume doubles, so it was a pretty large difference

[@jojohnson215]

I never thought I would be sitting here on a Sunday morning binge watching videos from a fellow from Denmark and learning so much in a cool way. Thanks brother. May God bless you and draw you near to Him.

[@kellypg]

That is the most strange subwoofer design I've ever seen

[@axmaz_lazy]

Oh boy this might go wrong. Speaker going BRRRRRRRRRRRRRRRRRR

[@Jwn5k]

We need a dedicated video on your home theatre setup, it looks quite serious!

[@Aaron48219]

Different frequencies induce a different impedance on the voice coil. I suspect this has something to do with the 20hz test. You should repeat the test at 20,30,40,50 and 60hz. Also do a sine wave sweep from 20hz to about 120hz.

[@theCidisIn]

It seems like their is a point when the magnet makes it louder with the South pole facing it, then it gets more quiet as it gets too close. Maybe it was nothing.

[@fentonryan]

Just a layman interpretation here: Stronger forces input don't necessarily mean more force goes into the vibrations - you'd need both stronger forces AND a bigger or more robust vibration chamber in concert to have that work cleanly. Otherwise, the vibrations would 'step' on eachother more, converting to other forms of energy (heat, deformation) instead of going into the air as vibrations. It's like slapping on a small drum. Within a range, the drum will react to stronger slaps with more sound, up until a limit. Approaching and passing that limit, you start just changing the pitch of the sound without increasing volume, then you start just damaging the drum, or having more of the energy just making the drum 'hop' after you hit it. But make a bigger drum, and then you can raise that limit up further, depending on the materials used. How about you try using a panel big enough and shaped to take the vibrations of the big magnet, and turning THAT into a speaker? Might need a friendly sound engineer, like the kind that set up big churches to help with that though.

[@brainiac75]

Thanks for the input. I believe I may have messed with the Thiele/Small parameters of the speaker with the external magnet... Measuring at only one frequency (20 Hz) really only tells you something about the speaker at that frequency. I may need to revisit with white noise and some spectral analysis of the output. Much to learn for me yet :D

[@Thales_WH]

The explanation is simple: you are not measuring just the speaker, but the entire speaker system, speaker volume and bass reflex tuning. By adding a magnet, you not only affect the speaker's sensitivity, but also its other electromechanical parameters (for example, Q factor, EBP, etc.). As a result, there is a different mutual interaction between the loudspeaker, the speaker and its tuning (using the bass reflex) - for example, the balanced or optimal tuning changes. A new tuning then brings different results. reproduction with other parameters would then require a different enclosure with other parameters to make it work as it should again. It can be beautifully and easily simulated, just measure the speaker parameters before and after and then insert them into the simulation. however, the measurement is not performed with a microphone, but with the help of a PC sound card and specialized software (for example, ARTA Limp). The output of this measurement is then inserted into one of the simulation software. Not completely accurate, but WinISD is the simplest, but it is sufficient for a basic understanding of how it works.

[@neutronenstern.]

My guess before watching the video: The added magnetic field will cause a stronger Lorenz force acting on the coil, for the same current flowing through it. However, with it being AC the current flowing through the coil is not determimed by its ohms resistance only, but mainly by its impedance. And while at zero elongation of the membrane the acceleration might be a lot bigger with the added magnetic field, at some point the membranes elasticity will push back, and this will cause an added impedance to the normal impedance of the coil, cause it cant move freely through the magnetic field, and thus due to the law of lenz, this will cause and opposing reaction, which in this case will result in a higher impedance. So after all the amplitude might get a little bit bigger with a bigger magnetic field,cause when theres no elongation at all, theres only a resistance due to inertia of the membrane itselve, and thus overall the force and thus the acceleration of it should be bigger than normal, and thus overall its pushed more, but i think this effect is tiny. But the frequency peak of the speaker and thus its sound characteristic will probably change dranatically due to it,because of the changed average impedance. Also at some point, the membrane cant flex that much anymore,and thus at this point the membrane and thus also the coil will come to an almoust sudden stop, which will cause a voltage spike, that might damage the driver. Also the membrane might get damaged. I think its magnet fits its purpose in strength and size pretty perfectly, cause they designed it,and thus more magnetic force probably will be more bad than good, cause else, they would have chosen a stronger/bigger magnet or a more suitable coil, or arrangement. I think they choose a sweetspot, that you cant improve that easily.

[@engjds]

Just to clarify Impedence (Z) is a combination of resistance and reactance, and this impdence is a combination of electrical and mechanical. The compliance of the spider+surround (Cms) and the Mass (Mms). As you rightly say, acceleration will increase due to increased magnetic field strength. IF the magnets were aligned perfectly, IMO they would work, I do not understand your argument for them not.

[@vincentrobinette1507]

The explanation is actually quite simple. When you increase the magnetic field in the coil gap, it actually increases the impedance of the speaker. That means, the velocity of the coil is slower for the same amount of voltage. The coil will draw less current, so it won't draw as much wattage from a given amplitude. When you use a low frequency test tone, the speaker operates in 'compliance mode'. That means, the excursion is proportionate to current, rather than velocity, therefore, no EMF. At a frequency well below the free air resonance of the cone, the impedance of the speaker drops to approximately the DC resistance of the voice coil, drawing more current from the amplifier. A stronger magnetic field produces more force, for a given current. The result is, the speaker becomes less sensitive to high frequencies, but, has much more force at low frequencies. The frequency has to be low enough, that the improvement in EMF doesn't raise the impedance, lowering the power the speaker will draw.

[@wvogel57]

Changing the magnetic field in the air gap will also change the back EMF. It is important to know how the speaker is electrically driven, with a constant voltage source or with a constant current source. The source impedances are zero Ohms or infinity Ohms. Or you can drive the speaker with another source impedance, this can also be a negative impedance, This will seriouslly affect the frequency response of the speaker!

[@verdatum]

I lost count of how many speaker coils I wrecked in my childhood. They sounded great until they sounded terrible 😂

[@maverick9708]

thanks for the music timecodes haha and thank YOU for providing readily accessible and low abstraction level edutainment

[@cappoisepic]

I rewatched ur merging monster magnets like a million times

[@cyborg97Oficial]

very interesting, try sticking more rings from the magnetic ones on the speaker and maybe it will increase its performance.

[@volactic8495]

I've seen neodymium magnets used on small speakers, most of the ones I've seen are less than 4 inches in diameter and are used in places where space is constrained, such as Bluetooth speakers. I've also seen them used in headphones. Also, Dayton Audio uses neodymium magnets on their ND series of speakers, with the biggest speaker in the series being 5 - 1/4" in diameter.

[@bensonak47]

Check out fi car audio with their subwoofers :)

[@anon_y_mousse]

I love these crazy experiments. Though I actually expected these results given the way most speakers and microphones work, it's still great to see it tested anyway. I keep wondering why electromagnets aren't used more these days. As we all know, permanent magnets aren't.

[@engjds]

Only good reasons are cost and convienience, no one wants to connect their speakers to the mains, the extra power supply would incur costs. However if you drove both voice coil and electro magnets in a push pull configuration, in theory you could lower distortion.

[@anon_y_mousse]

@@engjds True, it would make isolation harder, and thus cost more in terms of components. Though, a company that makes professional grade products likely wouldn't care. They could just charge more and their customers would take it.

[@engjds]

@@anon_y_mousse Yeah, speakers are a funny technology, they havent changed at all nearly in decades, just slightly better materials, more rare earth magnets used. I think the biggest advancement will be made when spiders and surrounds are replaced by magnetic suspended systems where you can control compliance. Electrostatics good, but they are poor at low frequencies, same with planar(mags). You can buy 2nd speakers now at around £500 from 4 decades ago that will blow anything new up to 5 grand.

[@test-rj2vl]

I would have wanted to see you open the speaker case and put the neodymium directly against speaker magnet so that magnets touch.

[@magneticpulseengine3605]

you can't expect the additional magnet to do anything because it isn't part of the magnetic circuit and the real magnetic density in field lines exists in the pole gap where the magnetism is at it's highest a good thought experiment.

[@AstarOfDavid]

I think the problem was that the 2nd test you did not place the magent in the center - it was placed lower (There for it was a differnt magentic field affecting the test in the 2nd test)

[@Nobe_Oddy]

The Speaker is a DUAL VOICE COIL!!!!! So the modeling you did is NOT THE SAME! - That is the ONLY thing I could think of 🤷‍♂

[@Thumper68]

I was hoping you were actually going to make a subwoofer with the monster magnet

[@christopherleubner6633]

To use a monster magnet, you need a pancake style voice coil. The flux is too high for a regular voice coil because it will experience an undue amount of eddy currents.❤

[@MrDanielknew]

You need to measure the speaker impedance while playing with true rms volt meter and a/c clamp to determine real time output power because it will change when you have a more/less BL or a stronger motor force. If the woofer impedance had even a slight increase then your output from the amplifier will be reduced. If you turned up the amplifier to maintain the same rms output power from the amplifier the speaker could see an ever larger spl increase.

[@omsingharjit]

Megnetic circuit in it is closed, so external magnetic will not affect it much.

[@iridios6127]

Until you slap magnet onto the rear metal flange.

[@GiesbertNijhuis]

Ha, I have tried that long time ago, also did not find a sweet spot to add more magnetic force to the speaker. You HAVE to be in the magnetic loop, replace the black magnet (or part of it).

[@kalags2644]

I loved this video. Please do a part 2!!

[@pressorv]

Your tests should be done with an app of approximately 750w rms at 4 ohms to get the maximum output. This 1.5 times the rms value is typically what professional sound engineers use for low end powering

[@Random_4400]

In most cases increasing the motor force near the voice coil will indeed improve performance however it's not as easy to do and isn't always successful by just adding an extra magnet to the already existing magnet,in fact in most cases that might actually decrease the magnet strength at the voice coil.

[@ogxbox]

20hz was too low of a freq to be testing. You were testing at too low of a volume to notice slight differences in gauss. Your bucking magnet was too far away from the speaker's motor to repel stray flux back into the motor in any noticeable amount. Try 40-80hz. Use a higher volume well above the noise floor. Don't do peak and hold on your meter. Take an average over a period of time so it filters out any noise anomalies in the room. Use a strong wooden crate for the bucking magnet. This allows you to remove it from the motor with opposite poles and allows you to force it into position with same poles. Allow the voice coil to cool between runs. Measure gauss when the subwoofer has been off for a while and is cooled down.

[@damic.489]

Depending on the frequency generated by the coil, you will create a resonance in the envirement. It is possible that the induction force in the coil will affect the ressonant circuit of the speaker and then variate your results. I dont know but it is possible that when mannufacturing neodimium magnets, some elements tend to migrate to north or south pole. The difference between chemical composition can change the inductance of the coil.

[@Synthematix]

Path of least resistance at play, the large neo magnet overcomes the ferrite and reduces its magnetism, in a nutshell its creating magnetic fields in unwanted areas

[@trevorcrowe7571]

I knew it would be quieter with a more powerful magnet at 20hz. You want to know why? It’s basic speaker design parameters. Magnet strength is known as BL. As BL goes down, QTS goes up, which is used for designing an optimal enclosure type and tuning. Generally, very powerful magnet woofers have better control and mid-bass, good for sealed, while small magnet woofers trade it off for less cost, deeper extension in a reasonably sized bass reflex enclosure.

[@KnowName33]

That's pure coincidence that mid-based drivers have IPL in comparison to subwoofers that play low. Except for with a very high BL is desired for trying to hit high SPL levels at low frequencies never will a subwoofer with a lower BL outperform a subwoofer with a high bl given that the suspension is the same in an SPL application

[@daviddanh1772]

That sub is 500wrms.. dvc @ 4ohms..thats gonna need a lil more than 60 watts at 6ohms. Around 150-175w at 4 ohms would give you a increased out put , in which the subwoofer would be easier to notice the difference

[@justynpryce]

I know this is pretty long after the video came out, but my guess as to why the pure sine was louder when attracted rather than repelled is because with the lower field strength you're effectively lowering the resistance felt by the speaker, so it moves more air in the same amount of time with the same amount of energy. This comes from just treating the system like a harmonic oscillator, where if you decrease the spring constant you can increase the amplitude for the same energy. However this does mean you'd expect a decrease in frequency and if this was not observed this may be a poor model

[@kyra03200]

Measuring the displacement of the cone with and without the 'Monster' might show some better results. However, its a little hard to do so.

[@ПётрБ-с2ц]

01:59 "more watts needed from the amplifier" - are you sure about that? Does the efficiency of the speaker change somehow?

[@Fk8td]

You aren’t taking account for impedance rise and tuning frequencies. By adding the magnet you actually alter these factors and can actually throw off the frequency. You need to test within the tuning frequency of the speaker. You should test at 40hz not 20hz where the speaker can put out sound efficiently. Playing below the frequency can alter the phase output which will have dramatically different effects.

[@NVMDSTEvil]

FEMM not taking into account the metal of the driver basket holding all the soft parts. A bucking magnet on top of the motor structure might be interesting but might need to change how the coil sits to play well with it.

[@Oystein87]

I have this subwoofer driver laying around😝 It has done an impressive job over the years in use

[@FSXgta]

That enclosure is probably tuned high, you would want something tuned lower for home theater

[@brainiac75]

You may be right. But given enough watts and maybe with some simple port tuning/blockage, I think it could add some impressive vibrations. Especially if placing the slanted sub box up against the back of my couch :D Thanks for watching!

[@crime_tostig149]

20Hz is such a low frequency that it is boosted via bass reflex ( the hole on the left side of the box). It makes sound when the speaker membrane is retracting (so it's pushing the air out of the box) thats why monster magnet in an attractive position helps it. (At least I think that's why)

[@iridios6127]

You should have slap (but gently) this magnet onto the rear metal flange - this would have given a significant increase in volume. 😉 Maintaining attractive polarity.

[@Cautionary_Tale_Harris]

When I was shopping for a home to buy these loud car audio systems provided a quick and invaluable indicator of what properties to avoid.

[@MikeDaveYapOfficial]

Thats why some car subs are using neodymium magnets instead of ferrite magnets as there will be a 2 to 4 dB gain

[@GGPlaysCDT]

Don’t let the magnet eat you. Magnet: nom. You: aaAaAaAaaAAaAAaaaAaaaa!!!

[@joelnash13]

You measured the magnetic field of the speaker magnet backwards, the north needle of a compass is it's south pole, so the speaker performed as expected even tho it looked like it was backwards

[@ganjasage420]

Coil saturation and magnet saturation are likely culprits. The monster magnet saturates the ferrite material, and during dynamic (music) the quick changes in magnetic field are affected. This a wild educated guess, I could be very wrong with what is actually going on.

[@Skarfar90]

Some subwoofers (Most notably models made by Digital Designs) can have an option to have a ring of neodymium fitted on top of the ferrite motor, to help increasing magnetic force in the pole-gap. This will in turn increase the efficiency of the subwoofer, since you can achieve higher output with less input power. There are also subwoofers that have full neodymium motors instead of ferrite ones.

[@engjds]

That might enable more amp power, but the main bottleneck on most subs is cone excursion (how far it can move), so that would achieve very little for most systems.

[@Skarfar90]

@@engjds Typically neo-subs are designed for high excursion. Like the Sundown Nightshade series for instance, with its 4" mechanical limit.

[@engjds]

@@Skarfar90 As long as you test for it not going over excursion you will be fine, but I would just turn up the power to compensate and ditch the magnets, unless efficiency is really important.

[@alleycatsphinx]

Do a signal sweep. Every frequency will have a harmonic relationship with the amount and velocity of air the speaker pushes due to the inertial moment of the magnetic coupling.

[@DallasG83]

I always wanted to try this when I was a kid but the strongest magnets I could find were other speaker magnets.

[@overloader7900]

Have you tried testing with different frequences? Also, try using a simple piece of iron instead of magnet

[@engjds]

Iron? that makes zero sense.

[@enderlore1337]

This dude deserves 1 million subs guys

[@brainiac75]

Thanks! Almost three quarters of the way after making videos for over 13 years :D

[@PerMejdal]

@@brainiac75 subs grows expontial. You will pass 1 million within a year.

[@jonevk]

Since the output (loudness) of the system is primarily dependent on the input power being pumped into the voice coil, I do not see how the external magnetic influence would affect the perceived loudness in an audible way. The purpose of the permanent magnet is to provide an opposite force for the voice coil to react upon. So your actual result (no difference in volume) seems to me to be the logical result.

[@stevefox3763]

The prolonged exposure to loud volumes warning instantly disregarded lol, i run four 12's in my car and pound my ears on a daily basis ha ha!

[@brainiac75]

I haven't been above 2x12" in my cars over the years. More than enough for small European cars x) Thanks for watching!

[@stevefox3763]

@@brainiac75 My four 12's are in the boot of a mondeo, i still want more bass lol but boot space limits me to four and my electrical system also means im on the limit of what i can run :(

[@EatonEmmerich]

The attracting field on low hertz pulls the coil back easier, so there would be a frequency that the pull of the coil doesn't make the sound louder.

[@alexandergraf8855]

Burn holes into the center spiders to make them more flexible and also Burn holes into the Membrane into the inside between dustcap and voicecoil. Speaker will have more gain compared to the magnetic Drive and less compression. Resonance frequency will be like 5hz 😎

[@TimpBizkit]

20 Hz test. This is probably well below the tuning of the subwoofer and maybe similar to the driver's free air resonance. Increasing the BL product of a speaker's magnetic gap can sometimes hold the cone back, providing a braking effect. Motor strength is good for providing pressure where the speaker is acoustically loaded (e.g. the tuning frequency of the port in a vented box, or the quarter wave resonance of a horn enclosure). At both the vented box driver's combined passband resonance, and also frequencies well below the tuning, the high strength motors provide back EMF and the driver doesn't actually move as much and thus is not as loud! Technically the efficiency is not reduced as if you measured the driver's impedance, it would have increased with the more powerful magnets and is not drawing as much power from the amplifier. But when the driver is resonating in some way, you can often get more sound (time domain neglected) with a weaker magnet! Often sealed boxes prefer a bit higher electrical Q and heavier driver cones, so the loudspeaker is free to "get its swing on" in the lower frequencies. This does ruin transient accuracy a bit, but does allow the enclosure and driver to produce deeper basst extension more loudly. With a ported box, electrical Q is somewhat a balancing act. Too low (strong magnets), and the box becomes a one note wonder, driving the port hard, but held back by its own braking effect everywhere else. Too high (weak magnets) and the speaker can swing back and forth easily in the middle resonance, but is completely gutless at driving the port resonances. It's similar to electric motors, where weaker magnets give a better top speed (for the voltage) but less torque. If you just want to flap lightweight air around as fast as possible, sometimes the light cone and weaker magnet does better. If you want to compress air to drive a horn (which converts low displacement high pressure into a high displacement low pressure), then the stronger magnet and longer low resistance coil does better.

[@pratikpurandare]

Increasing magnetic flux in speaker coil gap, increases the Fs (resonant frequency) of speaker. Efficiency of speaker below its Fs significantly low. So try with 150-200Hz+ signal and results will be opposite. *as you expected

[@Wobochacha]

The spider cone and surround as well as excursion plays a role in the way the subwoofer reacts. When you start messing with the parameters as well as the ported box you change the whole thing. Like putting a bigger v8 motor in a Honda Civic without charging the suspension

[@brainiac75]

Yeah, Thiele/Small parameters is something I struggle to understand... May have to experiment more at different frequencies - including using a more realistic bucking magnet ;) Thanks for the early watch!

[@JoshuaBarrio]

Just make your own speaker with off the shelf or parts of other speakers. Use a crazy magnet.

[@schizophreniagaming4058]

"Today on recreating the Skullcandy Crushers in a subwoofer..."

[@youkofoxy]

Get a small woofer, one of 8, 6 or even 4 inches and place it on top of the monster magnet.

[@Mr.Unacceptable]

If you ruin a speaker they can still be useful. A thumper speaker mounted in my couch has changed my movie watching life. Needs to be subtle though, lower level than the subwoofer but higher pitch.

[@andrewpienaar4522]

The Monster Magnet is not acting as a bucking magnet, as it is completely overpowering the existing internal magnetic field. The Speaker magnet is able to pull the Compass Reading away from the Earth North, because the Speaker magnet is much stronger than the magnetic field of the Earth. In the same way the Monster Magnet is overpowering the Speaker Magnet, in stead of creating the Bucking effect. Increasing the magnetic field correctly will have a bigger effect on peak power rather than on efficiency (sensitivity) At peak output the magnetic field becomes saturated. A stronger field will saturate at higher power levels. The size of the voice coil has a big effect on how much heat can be dissipated and therefore how long it can play at peak volume. You can restore the Magnetic field of the Speaker Magnet, by using the Monster Magnet correctly. (Maybe even make it stronger than is was after 10 years of use)

[@humanbeing7938]

magnets are cool

[@G1ZQCArtwork]

Did you account for the resonant frequency of the speaker.? Maybe its around 20Hz. Perhaps a higher frequency may be more accurate.

[@kaotictouch345]

What kind of amplifier would you use to power that subwoofer in your home?

[@MAGGOT_VOMIT]

If they're like my pair of HK BU-2's, each sub has it's own built -in, high-current amplifier.

[@kaotictouch345]

I need an external amplifier

[@brainiac75]

The subwoofer is inexpensive and not really highest quality, so I would probably match it with an inexpensive PA amplifier and only let it play very low frequencies. The amplifier should be several hundred watts and preferable a bridgeable stereo (or mono amplifier) stable at 2 ohms impedance. Place it behind my couch to get some kicks close up ;)

[@MAGGOT_VOMIT]

@@brainiac75 I need to add that to mine as both my BU-2's are 12in floor-firing in the front corners of my den. I bet adding another pair behind my couch would sound ...err......I mean, feel awesome when they hit!! 👍

[@MAGGOT_VOMIT]

@@kaotictouch345 Each one of my BU-2's not only has their own built-in high-current amp but each has it's own volume and Rolloff controls plus a polarity inverter switch.

[@x189player4]

Stronger magnet means more to push against = speaker handles more power before being overwhelmed. Did you test to see if the speaker would handle more output with the additional magnet added?

[@williamdowling7718]

It would be interesting to do tests on a range of frequencies. I wonder if the low frequency allowed the monster magnet more time to influence the speed of the cone than it would at higher frequencies.. and maybe that could have some impact on the difference between the music test and the 20hz test.

[@RannekMusic]

I am a music producer, and i love speakers too! Great video!

[@Blackwing2345635]

You simply changed the electrical Q(uality) parameter of speaker, that's why unexpected result in single frequency test. Speakers are tuned with resonance in mind, especially subs. And speakers really, *REALLY* don't want to play even on all frequency range. Changing Q changes frequency response, because you are "detuning" speaker, making it perform differently. Actually when someone is trying to change electrical Q factor of speaker in DIY fashion - they usually use resistors to change electrical part, not permament magnet) In this case lower field gives less damping, not only less (potentially) power to the motor, it means speaker will wobble more with the same power input. So on some frequencies it will have bigger effect, than power loss (e.g. natural frequency of speaker), on others - opposite. There are also mechanical Q for suspension, Q for air spring of closed box, or even more complex behavior of phase invertors and other openings. So you will see different effect of added magnet with different boxes or with bare speaker.

[@dantan205gaming2]

i always heard that adding a magnet to a speaker will add more bass which might be it sounded slightly quieter in normal music yet louder playing 20hertz