Back in the late 90's Linear Audio came out with a subwoofer package for use in car audio. The System came complete with the amplifier & 3 8" raw subwoofers that was designed with a Servo Feedback loop. Where this system shined brighter than anything else at the time was that because every car required a different design of enclosure built for the subs. Some boxes were extremely small and others larger and not always square or have 90deg walls. The genius of this Servo system was that the amp & subs could still play almost perfectly regardless. I built an SQ focused system in a GTI and when finished was amazing, space was very limited so I installed all three 8" subs into the spare tire and due to the feedback loop correcting bad harmonics the car ended up a top contender. I used that same servo system that Linear power product in multiple cars and would get perfect Bass every time. They worked well were no other sub could because of the small fitment requirements. I just wish one of the current automotive focused company would reintroduce the Servo package to the world again.
I am using a new subwoofer (I won't mention the company Paul on your channel) from a company that uses servo tech in the drivers of its subwoofer designs. The performance is amazing; fast, tight, and very deep bass extension in this case nearly flat response down to about 15Hz out of a 12" driver and a 370W AB amplifier. I use it in a typical medium size living room. Works great both for music and AV applications. Servo control is great for this application. I couldn't agree more.
I know this is an old video, I just wanted to chime in that I've been pretty impressed with Yamaha's A-YST II. I've found the subwoofers they produce with that technology are pretty clean sounding. Granted I've heard some lemons as well from them.
Once I ripped out the crossover in my Elac 121 Jet speakers and replaced it with three amplifiers (LM3886) and an electronic crossover with the exact same specifications. The improvement where so large that I never returned. My latest speaker construction contains two amplifiers special constructed with the speaker units in mind, and therefore they aren't not the same. The sound wery detailed, problerly due to the missing coils in the signal path.
Picked up Definitive Technology (Sandy Gross ) era speakers 20+ years ago.......... BP7001 Towers, BP7002 Towers and BP7006 towers back in the day and yeah........now paired with Emotiva XPA-8 GEN3 and Marantz SR7013. HELL YEAHHHHH!
you should develope electrostatic headphones with a laser servo control, lasers measure the distance between the cone and the case. you don't need a heavy accelerometer on the cone, and the entire amp fit in the headphone.
Active speakers (i.e., speakers with inboard amps) are not just "junk speakers." In contrast, most pro speakers are active because they are intended for use in studios or mixing rooms. These areas are only focused on supplying the "front end" (pre-amps and tape recorders) in the audio chain. To monitor sound in those areas, it is more cost-effective to put the amps in the speakers as you describe.
Actually here in Germany we have nubert producing absolutely amazing active speakers (nuPro series) at an affordable price point (not cheap though but worth). A pair of nuPro A-200 is right on my desk and the sound is just stunning. Unfortunately they only ship here in Germany, maybe Austria and Switzerland.
As you know, accelerometers are a 1970s solution.. More recent motional feedback woofers use a secondary coil to generate the feedback, signal which is far faster than a mechanical sensor.
When I was working for PAS in Harbor City CA more than a few years ago they used both active feedback and time offset correction in most of their upper end speakers but Ive always cringed a bit at manipulating the parameters artificially and thus forcing the driver to do things it couldnt do naturally. I know their Studio Monitors were great but not for the home environment at all and were made to be used with specific amps and electronics.It seems to me manipulating the natural parameters this way in itself would introduce distortion?
No that's not correct. You're thinking of push-pull amplifiers. These which use a particular electronic configuration. Almost all amplifiers have a push-pull output stage regardless of the type of speaker system involved. A servo system has a sensor(s) on the main driver which sends a signal back to the amplifier. This allows the amplifier to tell if the cone is in the correct place at any instant in time. If it isn't then the amplifier can try and correct for this. The amplifier therefore continually modifies the signal it would have normally sent. The idea is that imperfections in the cone movement can be partially corrected for to improve the sound quality.
I just ordered a Yamaha YST SW215 subwoofer that has an active servo. You mentioned that to your knowledge speakers today might have a "cheesy" servo set up. Are you familiar with what Yamaha has in their subs?
Sadly philips motional feedback (MFB) was never mentioned. Especially the 22AH587 is great and even has location filters! Its a great shame no one even knows about them.
The truth is that servo systems are today made again by Pirate Logic from the Netherlands. I got to discover them this early since I happen to live practically next door, but they're starting to make waves now.
As someone with Studio Monitors, active speakers are so much better than passives with separate amps. Never will I want to have a shelf of unnecessary audio boxes.
The real solution is to build your own active speaker system, requiring building speaker boxes with raw drivers, and driving those with external amps and external electronic crossovers. Phil Marchand makes a great electronic crossover for doing this, as do a few others. See my video on my active speaker system: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-4MNKxj6G_hE.html Paul is correct, active really is the way to go, but you have to build the system yourself.
This is a pro audio device intended for live sound applications. Generally speaking, such devices are a poor choice for home hi fi as they tend to have a high noise floor that is no issue in live sound but unacceptable for home hifi. Also, this device includes many features not suited for home use. And it offers a two way crossover only. For true hifi, a three way crossover is optimal, hence the Marchand recommendation. A better choice would be the mini DSP offerings, they make a version that offers two crossover points for a three way system. The issue with these digital devices is the A/D and D/A converters. No converter is sonically neutral, and each has it's own character. Building active speaker systems is an expensive proposition. If you really want to build an active system on a budget, then see my video, "Satellite/Subwoofer Speakers" in which I outline the building of a three way active speaker system using all car audio electronics, which performed remarkably well, and can be built for btw $700 and $1000. But you get what you pay for. I currently own four active systems and have built several others, and as expected, the more money a system costs, the better it sounds, much better in fact.
Gotcha. Yea, I figures that there had to be some major differences in pro audio shit versus the home stuff. The prices just don't make much sense. The Marchand stuff is really expensive. I guess I will just skip the whole thing. Is it possible to put a passive crossover in between a pre-amp and the amplifier, or is there not enough signal strength there for that to be feasible?
@@MeatPopsycle it has a lot of functionality for the price. you can replace it down the road with a high en dsp once you figured it's the weak link in the chain. depending on your speaker design you will appreciate the delay, and eq options. better spend your limited budget on better amps and drivers than expensive dsp is my experience although at some point the behringer dsp will become the weakest element..
Nice HP334 there atop your open reel machine, Paul, but I hope you are using something more up-to-date to measure THD from your designs and production gear....
At about 2:30 I feel the nail was hit right on the head. I've been an 'audiophile' since the 70's and been frustrated by the blinkered ignorance of, perceived, intelligent people. A lot of 'audiophiles' allow their opinions to be steered by what they read from other people consequently they poo poo active speakers,bi and tri-amping but are quite happy to negate the damping afforded by low O/P imp of amps by sticking long lengths of, 'low oxygen', speaker wire to connect them.
Servos correct a problem AFTER it happens. Doesn't work well with faster tempo music like techno and metal. The effect is weird. Doesn't matter, because with better drivers today- non servo-subs like SVS and HSU totally outperform old school servo like velodyne. That's thanks to superior drivers like TC Sounds and others with ultra light, rigid cones, massive voice coils and long xmax. Old "servo" subs had an 11mm xmax. New stuff will have 2" or more with 3" VC's and massive magnets.
The speed of correction of a control system is higly dependent on the control algorithm and processor used. Modern PID control algorithms are extremely fast and precise. Manufacturing robotic arms are controlled with PID logic.
Thoughts between a rythmik f12-300 and hsu vtf-2 mk 5? I'm really having a hell of a time deciding. I have a definitive super cube 1 in the room as well, and the room opens up to the kitchen. The overall room size is most likely over 3000 cubic feet. Not sure if I should go for the servo control (sealed) or for the ported non-servo controlled (hsu). Room is used for both 5.2.2 HT and 2.2 Stereo listening. Theil CS 2.2. main L./R. Can you solve my conundrum?
The most moronic comment I have read this year. All frequencies servo feedback is applied to (bass and sub bass) are SLOW. Periods of 10 ms to 33 ms. "Techno and metal" have nothing to do with it. Derp!
Indeed, the "audiophile" fraternity have been hoodwinked by and been spouting so much BS since the 60's that they should be ashamed by their own blinkered conservatism and gullability! Technically a powered speaker will always be better at controlling the drivers than a passive one hanging off the end of a few metres of "polarized low oxygen copper wire" (REALLY!?). I agree that servo speaker is most advantageous for bass speakers where, as you stated, the increased mass of the moving parts is more difficult to control. The electronics to do this is, these days, is very affordable. Conceptually, a cheaper speaker could be used as the control system could compensate for the speakers shortcomings.
