The IRSV servo woofer system 

Paul's having fun playing with his toys again! :)

The IRS Vs are biamped. The woofers have their own dedicated amplifiers and crossovers and the user supplies the mid tweeter amps. Originally the speakers came with little boxes that had resistor/ capacitor networks in them to chop off the low frequencies for before the signal goes into the mid tweeter amps(most people use pass Labs, Bryston or some sort of crossover to separate the highs and lows around 100 Hz now). Along with these little boxes a parts kit was supplied with various capacitors and resistors that you would make in different combinations to match the amplifiers input impedance and the desired crossover point. Once the signal is sent to the mid-range tweeter panels the crossover in the speakers base is used to separate the tweeter and mid range frequencies (Bob at PS Audio has created updated crossovers with the help of Arnie Nudell to replace these older crossovers. There are also some adjustments that can be made to them if you have upgraded the magnets in the mid range drivers). The woofer's controller box takes the full range signal and chops off the hi frequency and sends the signal to the woofer amplifiers. The box has a bunch of controls to modify and contour the low frequency. It also supplys a 12VDC signal through a separate cable to the woofer amps to close a relay in the amp and turn it on. Most people now only use this box to trigger the amps on and off an use the external crossovers mentioned above to chop off the high frequencies. Once the low frequency signal gets to the woofer amp it is sent to the input of the amp where it is amplified and sent to the 6 12" woofers which are connected in parallel(that's where Paul is talking about a low inpedence load on the woofer amp). The third woofer from the bottom has an accelerametor that sends a low voltage signal back(the orange wire in the video) to to a circuit that inverts it, amplifies it and then ads it out of phase to the input of the amp. this is where the servo control comes in. The servos in the IRS are very reliable, unlike the Betas which were delicate, cheep and problematic. The woofer amps in the IRS III were 1500 watts, in the IRS Vs they were 2000 watts. That's where you will sometimes hear paul say 1500 or 2000. Most of the earlier IRS IIIs have had various upgrades done to them to make them into IRS Vs. I think Paul's were IIIs and still have the 1500 amps. The 2000 watt amps in the V's have a larger power transformer and more power supply capacitors. Greg Shugg told me the 2000 watt amps on the Vs were overkill and just upgraded to 2000 watts as a marketing thing( so they could say they had these massive amplifiers in there advertisements). The speakers are difficult to setup correctly because of the space required, also the woofers amps are single ended. Most audiophiles have balanced systems these days. There are many places for ground loop hum to pop up. Getting the amps, crossovers all set up properly requires patience. The system when it is hitting on all cylinders is something most people have never had the chance to hear. Imagine being third row center at a concert, super clean sound and will play so loudly you will want to turn it down. That is going to be tough for PS Audio to better.

Enjoy your conversational and even very candid talks . . . your honesty must translate into your business and products. Always appreciate honesty!

Your channel is absolutely fantastic, this was very informative and entertaining. (as always :)

I've never heard the V in a proper environment. Back in 1989 I heard the IRS Betas and those were simply amazing. Carver Silver 7T monoblocks driving the woofers and Conrad Johnson Premier 5B driving the HF section. Amazing clarity and soundstage. The bass did sound a bit rolling/warm but it was in control even at pants flapping SPL! Never heard bass levels with low distortion in a "home system" environment before. Though not exactly cheap, they were very good for asking price IMO. The V must be just breathtaking. I do love the revealing qualities of ES speakers but subs were required. The only system I heard that could pump the bass levels with quality in the price range of the IRS Beta was the VMPS Super Tower III biamped but opening with Pink Floyd's "Breathe" from DSOTM SACD, it was definitely taxing the limits of the dual 20A feeds!

Very interesting Paul. Thanks for sharing your knowledge with us.

Very interesting, and I'm looking fwd to seeing the amplifier upgrades of the IRS Subs.

I know that xover, it is your weak link, my friend did a Nelson pass diy xover years ago and it improved the sound a lot. I like that you are updating the amps to deal with impedance issues.:) . I like what you are doing. Be well .

You probably don't remember me, but you talked to me about audio for a long time on the phone once when I was 16. I didn't have any money and was just a budding audiophile then. Thanks Paul!! :-)

wow Paul, how fun thanks

thank you Paul

Hello Paul, thanks for a great channel. Met you in Denver (2013?) in the Soundlab/MSB room. Great sound. Back to the IRS, I had a pair of Genesis II.5’s driven by Jadis JA200’s, etc. Too big, too much. Too hot! Could you confirm that the woofers of the V’s are servo-controlled via accelerometers?

What is now called a servo system is actually an invention of Philips in the mid-70s of the last century and therefore some 45 years old concept. Philips called it Motional Feedback System and rightly has, at least in Europe, a large number of supporters. Even though they have not been sold for decades. With contemporary techniques, implementation could probably now be performed even better and cheaper.

I’d imagine you’d get so much more bass detail and depth out of a more modern and powerful amplifier, though the current amp set up would still be absolute bananas. Wish I could visit you in Colorado, I’d love to see this set up!

Now that was uber cool Paul...............

State of the art in simple words legends to be exact holly grial for collectors

So you run a full range signal to the Infinity’s and they have their own internal high pass crossovers for low frequency protection or they can play down real low safely? Or are they low passed at a certain frequency through the digital crossover to the subs?

I just realized you could probably hide a person in one of those IRSV subwoofers.

can't wait to see that video of when you've hooked up the Class D amps.

I can only agree that Greg Schug is an excellent power amp designer

Love the videos but still don’t understand how everything is connected, maybe a (wiring) diagram?

Nice, but I thought you would explain what a servo is and how it works, that rare sensor in the middle of a cone., you once showed it but it would be nice a further explanation of parts and function, thanks

can you elaborate on the servo electronics itself, that is, the signal from the sensor is sent to the crossover and from it to the power amplifier? And what are the sensors used in these woofers?

those technicians have some fun around there...

We can hear the fan?

Paul why did you remove the dust cap on one of the subwoofers ?

Might be nice if you could a before and after the mod video using the same music.

That's a proper sub stack.. 6 x 500w ICE class D amps wired to em will cause an earthquake! Might need some kind of remote volume control though as it might overpower on certain tracks.

Paul swap the fans for "Servo Gentle Typhoons" fans they do 900rpm to 1850rpm models, unbelievably silent and effective!, these are what we used in all our audio systems.

I believe that a standard 20 amp 120 volt wall outlet will only supply about 2400 watts. I hope that 3000 watt amp is per channel (6000 total). My plasma TV uses 900 watts and I don't have to heat that part of the house when it's on in the winter.

Great video, this much power just for woofers, this is to much, some people get lose in sound and forget to listen music. Regards Mr.Paul.

😍

Why aren't you Using Class A amplifiers? they seem the best choice for audiophiles in my head, since Ds can have noise due to the Pulse width modulation?

I guess I have to swing by PS audio someday and hear these Infinities. I know Paul gushes about them, but I have a hard time believing, given the line array design and their age, that they actually sound as good as advertised. Maybe someone that has heard them can chime in, but are they truly better than say a pair of Wilson Alexandria XLF or Focal Grande Utopia speakers?

I always hope for good audio videos. But then I see cables like that, that can carry, perhaps 40 amps, it's like we've forgotten Ohm's Law. "Well, how do you know big giant cables for audio are useless? Maybe the laws of physics will break down when you're listening to Peg through tubes on a turntable."

This dude is hysterical. He talks non-stop about Servo technology and all it's advantages but when he starts a speaker company he does not use the technology he says works. I don't understand this. He also once said there is no real difference between a HT sub and a sub for music- to which I completely disagree.

How can you power that many 12 inch woofers with only a thousand Watts? When there is a version of the little Sunfire true sub subwoofer that has a 2700 watt amplifier built into it?

Isreal...

Yamaha active servo and Sony DBFB is the best perlist at my ears. Too expensive for me audiophile.

wait Paul . .. .....did I hear class D? no it can't be who would put class D on That now I'll have trouble sleeping

Wha!...Hey Old Man, Did ya gET your new... Hearing Aids yET? Yours Truly, He that hath an Ear Let him hear 2;^D.

Bro... i feel like a girl in a group of guys that are talking about car parts.

Do you listen to music? or rather not.

Again about those woofers ? Yes once they were great speakers... About 40 years ago! Ppl Check Philips m.f.b on Google . They invented it!

Ughhh, "what we call..." Okay, you don't need to say "what we call..." It just is that thing, or it isn't. You call it that because it really IS that. So please just say the term straight and be done with it.

Not to be rude, but for an audiophile you use a really crap mic....these crackles are very annoying Paul, sorry. I think we can expect a bit better audio quality from PS right? A Go-Pro maybe?