Direct Servo Subwoofers 

Who else thinks Paul should write, and narrate a children's book? "The Little Power Amplifier That Could" 🤣🤣🤣

That's exactly why I have a Rythmik. For the price they simply can't be beat. And that Rythmik sub will probably match very well with your new speakers Paul ;)

i have a ton of Rythmik coils and have been playing with them in custom drivers , the design actually works very well , both can achieve very good results to where the design of driver , enclosure and placement become a larger aspect to getting desired results

I have a Rythmik sub. It’s great, especially for the cost. Goes below 20Hz for less than $1k.

Nice one Paul.

From @5:50 Paul will leave no doubt by telling you twice in less than 5 seconds that your phone has an accelerometer 😊 listening to Paul is always so pleasant because he is very spontaneous and natural.

Cool information

Great video as always. Thanks! Could you give us your opinion about the Yamaha YST II . I mean is this another way of making a servo woofer? And generally speaking does servo woofer sound "faster" than the non servo ones?

My daily sip of education.

Paul, since we are on topic for servo woofers, I have a pair of Infinity KAPPA 8 Reference speaker columns, and was wondering can it's 12 inch woofers/sub-woofers be modified in any way to be servo controlled for better response??

Just another form of a feedback loop in an amplifier to reduce distortion. Only further down the food chain.

Channeling Borat here Paul, I Am Power Amplifier, Look at my powerful chair, I am King of Castle!

I remember I had a little subwoofer from...Mirage, I think it was. It had a long tube where all the air came out in the back, and when I played a heavy bass track it would blow so much air out that you could hear this muffler kind of whistle louder than the actual bass.

Yeah but what about the idea I had of an active control system of controlling the pressure inside the cabinet. The cabinet can control the overhang automatically and you can reduce pressure automatically just by using the natural energy of the driver.

What is that power amplifier is it a pass labs?

Quite enjoyed this explanation of servo subs but it raised more questions for me than it answered... The accelerometer (or secondary coil as you mentioned) is obviously a laggong indicator... How do you use that feedback loop to adjust amplifier power if the motion you wanted to correct had already happened? Is it some kind of predictive logic or is it straightforward? Lets say a kick drum (or explosion in a movie) happens... Big inputs decaying down quickly... How does the servo avoid overcompensating?

I deal with servos every day because they position all the axes in my CNC machines. I have built servo systems, both electronic and purely mechanical. I understand them pretty well. In a servo speaker system where does the feedback go? Is there an amplifier in the servo speaker? Or does the servo system attenuate the signal from the main amp and then ask for more depending on the cone position? Following error in a servo system must be kept to a minimum so your speakers must be pretty stiff in positioning at the frequencies desired. Anyway, just curious, this kind of technical stuff really appeals to me. Eric

So how Yamaha maneged to do a servo system with only 2 wires going to the speaker box. like on my YST-C10? This little Yamaha mini component pushes tons of air and the little 3" subwoofer barely moves. Bass reaches faraway.

servo subs a good fit for magnapans?

People need to check out Winers home theatre setup....all will become clear.

The next logical question will be on passive radiators...pros and cons to relieving sealed sub box pressures thus sub inertia?

"The problems we face with woofers". LMAO!

The input signal to the speaker, the voltage indicates how the amplitude is to vary with time. The transducer measures the actual motion generating an electrical signal that is compared to the input signal. The difference is distortion and the voice coil in a servo amplifier is driven by the negative difference between the two correcting for the dostortion. There are three generic types of motion sensors. Each has many ways to build them. The first one measures the actual position directly. It's called a strain gage. A second type is called a velocimeter. This type measures the change in position with time. Clearly it can't be directly compared to the input voltage, it's apples and oranges. The signal must first go.thtough a circuit called an integrator. It gets you back to position as a function of time. The third type is called an accelerometer. It measures the change in velocity as a function of time. It's signal must be integrated twice to.get to position as a function.of time.

Philips did it ?

I keep watching these servo videos in the hope of finding out how this signal from the accelerometer actually does anything. Great you have this signal, now what? None of my amps have an accelerometer input, so what magic transpires between the accelerometer and the amp to make this timing correction happen?

Question.. What is the best home cinema/hi-fi sub out there.. Paul never mentions Paradigm.. JL Audio.. Velodyne.. All make pretty mean beasts. SVS another big hitter!

I enjoyed becoming knowledgeable about the topic., which made me happy not to have ever sensed I have a problem with my sub (JBL B-380 powered by a Sony TA-N80ES). It sounds right. I think the bigger problem for most folks is sub integration, since the sub is not treated as a channel but instead a crossover matter. Of course with stereo material it will always be a crossover matter, unless amplification makes use of DSP to extract a sub channel. And that's what I'd like to see, DSP added to stereo integrated amps and preamps to make integration of passive subs a cost/effective solution to the sub chaos we have now.

Paul power amp animator

I don't really know how the corrections work, but I dont think an accelerometer is the best choice. An accelerometer measures acceleration and acceleration only. If it is not accelerating it outputs nothing. So if you are trying to get the current possition of the diaphram (which is what I assume you need), you will need to do some fancy math stuff to calculate the position based off of what the accelerometer has read over time. This is called an IMU and it works great for navigation in all sorts of vehicles including boats, planes, and even satelites. But for movemnt this high of frequency I highly doubt the accuracy you could get out of an IMU. I personally think you really should be using a laser or some other system to directly measure the position of the diaphram. I do think you could do the corrections in a way where it doesnt need to know the actuall position of the diaphram, just the acceleration, but I dont think it would be as accurate as if you knew the actuall postion. I am not saying the way it is already done is bad, but it could possibly be better. And once again I don't really know how the corrections work.

Is it a Watt or a Watt Puppy behind you maybe?

is your audio book finished? thanks Paul

Bad to the bone speaker piled up behind him.

I have a Velodyne FSR-15 with a frozen woof-woof (and I'm not sure if there is anything else wrecked). It died while given to someone else, and they said it just died one day (not under abuse). AFAIK, there's nothing that can be done with it - fishing for any suggestions.

How can my headphones produce low frequencies when they are so small ( the headphone )

How does a servo subwoofer motor work?

Sometimes it seems like speakers have been invented to death, but all we really need are a new set of variables to work with. Here's one. A semi-active port. One woofer, dual voice coil. Second woofer where the passive radiator would go but driven by the unused voice coil of the first. Here's another. A woofer with a parabolic efficiency curve to counter that caused by the suspension.

Criticizing Houston and Dallas while defending Austin? Very interesting.

Austin? Lol, Heck no! Too Lib for me

I don't wanna be an asshole, but how come a company that specializes in high end audio has such terrible voice recording quality on their videos?

I went along with all of that ... but I have to say this .... servo systems are and always will be a kind of necessary evil to correct another unavoidable evil so produced by inferior loudspeakers. I STILL maintain that a LF driver with a very stiff and low Mms ( diaphragm mass) also with a low Vas ( restoring force given by a given volume of air ) mounted in a well controlled potted enclosure will outperform any servo system ! The amplifier must have a very high damping factor and the bass driver must equally have a very high Bl ... PS audio should seriously consider this in their new speaker designs ...

I think I'm going to unsubscribe because of this..Paul has gone over all of these points before and many other questions it's just repetition, he's getting old dear love him, and he wants an easy life so why not just answer again the questions of the past instead of answering something new..Does he just do this because he couldn't be bothered or is his memory getting a little well less so. I'm really done here and it's sad but I really couldn't be bothered