How to DIAL IN your Servo Sub!

hey everybody thanks for tuning in i've had a lot of people ask me to do a video on this subject so we're going to get right to it we're going to talk about the servo subs and how to work the controls on the amplifier to integrate it to any speaker and there's so much flexibility built into this control system it's probably one of the easiest subwoofers to integrate to anything i mean literally anything you got you can dial these in to match the slope to match the the uh output levels the phase everything is completely adjustable at this amp so let's dive right in first of all servo control system this is not the servo control systems of old i know you've had i've had people ask me or say to me oh paul over there at ps audio says they're not even using servo subs anymore they're back to regular woofers but they think that's better and that may be better for them but this is not that type of servo system they're talking about old accelerometer based servo subs from the 1970s this is a whole different technology it's using a sensing coil that is much more accurate much faster and has a lot better control and literally will do anything you want it to do i mean you can change the damping settings the queue of the whole system on the fly with this thing it's awesome so with that in mind a little bit first how does it work what is it doing well the servo system works like this it's constantly comparing the input signal to cone movement so let's say it's receiving a 30 hertz note or a 25 hertz note it knows that a certain amount of excursion is needed to maintain that so in this case the amplifier due to the way that is set up will add gain as needed to maintain a linear response and then once that signal stops it says okay the input signal has stopped therefore cone movement must also stop so it electrically slams on the brakes and brings this thing to a stop really quick uh very quickly um typically about seven times faster than an uncontrolled driver so lots of control you you wind up hearing lots of detail and dynamics and things and texture of base that you normally won't hear with uncontrolled drivers and then with the open baffle application wow that takes things to another level this is the only servo controlled system out there for open baffles so the open baffle tends to not load the room like a typical woofer wheel you're moving air quickly from one side of the room to the other more of a velocity of the output rather than pressurization so you don't get a boominess in the room that you would normally get with a lot of other woofers you're just getting a quick movement of that output and then it dissipates real quickly so it's a whole different ball game even an open baffle those things will play flat to 20 hertz and they'll stop on a dime so um really unique um system now how to integrate it and one of the number one problems we see when people are trying to integrate it to their speakers is they try to measure their system measuring the whole system playing at the same time you don't want to do that you don't want to be measuring your left speaker and your right speaker at the same time and then trying to dial in your woofers to match that what you're going to get is you're going to get cancellation patterns that's going on between your left speaker and your right speaker and how that's reflecting in the room and you're going to have a response at the bottom that might be doing this when if you just look at a single speaker maybe it's not you want to you want to measure just your left speaker and then the servo sub for that left speaker or the the woofer for it and then you want to measure the right speaker and just the woofer for that one and then you measure each of them independently and then measure the sum and when you're measuring the sum you're looking for it to to create that balanced response and i'm going to walk you through the ways to do that and there are ways you can do that without measuring it there's ways you can listen by ear when we go to shows we don't set up a measuring system in the room and start taking measurements there's certain songs that i know and i know really well and i've measured and tested using those songs and i know what it takes to make a flat response and i know what it sounds like so we'll sit down and play some of those tracks and make adjustments pretty quickly to get a balanced response and it's it's not hard to do that at all once you kind of have a reference for how you know it's supposed to sound if there's something wrong there's adjustments on this to allow you to fix it so the first thing you're going to want to do is trying to figure out the phase relationship so your speakers you'll want those pulled out in the room to where they sound the best in your room so you want to position the speakers first get them to sound the best in regards to imaging sound stage layering three-dimensional field and things like that if you've got them too close to the wall you're handicapping all of that get those things out into the room a little bit enjoy what your speakers can really bring to the table and then you're going to want to do something similar with the woofers you want to move the woofers around to where they work best in your room if you've got a way to measure uh take measurements of just the woofers plan by themselves just if you've got a pair of them like we do here we've got triples on either side of us here you measure the left one independently of the right one and look at how it's interacting with the room and try to create a smooth response without having to use any of the controls to manipulate it so let's say you've got a speaker that's three db down at 60. so you're wanting to blend to that keep in mind you're not wanting to cross this where the speaker's 3db down if you're crossing where it's 3db down you're going to create a 3db hump in the response you want to cross the woofer over to the main speakers where each of them are 6 db down it's the same way when we design crossovers for different speakers the tweeter is 6 db down the mid is 6 db down where they cross is the crossover point and where they sum is the flat line so you're looking for that 6 db down point so if your speakers are 3 db down at 70 that 60 b down point may be 50 hertz or something so you're not going to want to set this at 60 or 70 hertz to form that crossover point remember the numbers on the dial referencing the crossover point on the amp are just numeric references to the slopes that are built into the amplifier that are electrical slopes it is not it is not in reference to an acoustic output keep in mind that the acoustic output completely changes whenever you put it into a room and it can change depending on whether it's sealed box or open baffle a lot of times in open baffle applications we've crossed at 180 hertz to some big open baffle line sources that have neotens in them that don't play down very low and to cross it 180 hertz we may have the dial set at 90 maybe 100 at the most to reach a 6 db down that's at that crossover point and it depends on the room gains too so don't think of this as these are my crossover points on the dial again electrical references you're going to have to listen or measure your room and see where the actual acoustic outputs are and most rooms will have some gains going on somewhere either just just the gains alone from overwhelming the room it may be increasing the output or there may be a hump in the room like when we used to go to rocky mountain audio fest a lot of those rooms that were 13 feet by 19 feet typically had a hump at 50 hertz you know or somewhere in there depending on their system you go room to room to room and your basement basement basement basement and it was awful it was really it really was just awful so when you have this kind of flexibility you can fix that and if you've got a peak in your room let's say at 50 then instead of running this up to where you think that crossover is you can pull the crossover point further away to compensate for that hump so there's a lot of flexibility going on here so keep in mind the numbers are just numeric references that is not your crossover point you're going to have to listen you're going to have to measure step one uh again let's say your speakers are three db down at at 70. what you want to do is set this dial to where you know it's going to be above that this is especially if you're listening and set this dial to 70. so they're on top of each other and then set the phase control which is a time delay feature set your phase at zero and listen play some bass heavy music and listen and then grab that phase control and spin it all the way around to 180. listen again decide which way has the greatest amount of output which one is the most base heavy that'll tell you which position on the phase control is most in phase and usually you want to start with either 0 or 180 go between the two and you'll know real quickly which one has a little more bass than the other if you're measuring it becomes a little easier you can measure the output of your speaker measure the output of the sub and then sum it and then try it with a phase in both directions see where you're getting that gain that's what you're looking for where is where does the phase control need to be and then of course if you need to you can adjust it anywhere between 0 and 180 and you can fine tune it and dial it in if you've got a way to take measurements in your room that's going to be really useful because you can really dial it into where it's in phase and it's it's a lot more useful than just a switch between 0 and 180 thing works really well so when we're going to want to find where it is in phase and then you're going to want to move that crossover point back to where it sums flat again if you can measure the speaker and then the woofer and then measure the sum you can see what it's doing with each other and see where you get the flattest sum and then if you've got a peak let's say you've got a you got a peak at 20 or 30 hertz you've got a low frequency bump in the room and some people like that you may want to leave it that way but what you can do is turn the overall level down and then turn the crossover point up to balance it out you can do the same going the other direction let's say you've got a dipped area down low your 30 hertz in your room is dropping off a little bit what you can do is bring that level up so that it's louder and then turn the crossover dial further back go back to 40 or 35 hertz and bring the top end down you can shape the slope by using just the volume control and the crossover point you can make it do just about anything you want once you kind of get it to where it's summed and it's flat with your speakers if you do have a peak or a dip there's a one band eq that you can turn on that'll allow you to make adjustments within a given area you can do you can take a range where you maybe you have a peak that's like this or maybe you have a broadband peak you can adjust how broad or how narrow of an area you're wanting to adjust with the one band eq you can create a narrow band peak or dip or you can create a wideband peaker dip and usually one band is plenty you're not going to have from 60 hertz and down you're not going to have multiple peaks you're not going to have a peak at 20 and a peak at 40. it doesn't work that way those wavelengths are too long usually you're going to have one big hump or one big dip and you can you can work on that to fix it so you can add a little bit of gain or you can take quite a bit out and try and fix one of those areas typically though with open baffle we we don't have a lot of that it loads the rim so evenly we rarely get big peaks and dips but if you do it's easy to adjust and of course these amps are available on our sealed version so you can adjust it on that on that version and do the same thing you can change any peak or dip in the room fix it do anything with it so once you've got a balanced response there's a lot of other features that are on this amp i'm going to put my reading glasses on here so i can look at it with you and there is first of all there's a there's a there's a switch here that's an ext 12 which is a when it's in the middle position that means the crossover slope is 12 db per octave roll off and it's completely controlled by that crossover control knob or you can select it in the up or down position and you can add another 12 db per octave slope at either 50 hertz or 80 hertz so you can help create a little more of a steeper slope by the manipulation of those two filters and you can do a lot with it you can have this adjusted a little above it and then cut it or you can have this adjusted a little below it and then cut it at that certain frequency so you can really make it do a lot just with those two positions it reducing output more in the higher frequency range if you need it to be steeper to match the roll off of some speakers like a little some of our open baffle speakers sometimes they're pretty flat down to 50 hertz and then they drop off pretty quick it's just the way it loads the rim so you can match the slopes with that real easily the other switch here is a rumble filter you can turn that on or off if you're playing vinyl you may have a lot of really low frequency information that's just fluttering the woofers just turn that rumble filter on and it'll start killing everything below 20. then over here you have extension filters you can determine how low you want the system to play there's 14 hertz 28 hertz and 20 hertz so you're basically just saying hey i want it to play this low that lower than not as low you can really adjust how low you want it to play and you can also use that as an eq system as well if you've got a hump in your room at 20 hertz well you can cut that back to 28 hertz and try to balance out your room with it a little bit the other control we've got over here is high medium and low damping settings that has to do with how much control you're hitting that woofer with how fast it is and it's not necessarily the best sound on the highest damping settings sometimes even the lower damping settings will allow a little more low in extension and it does a little to the sound stage it it can really change the size and the openness of the sound stage by changing those stamping settings i know that's kind of puzzling but it does we've even been at shows where we've had big open baffle servo subs up front and we've got sealed box servo subs in the rear corners of the room and they're set at 25 hertz and down so they're playing part of the bottom octave back there and we can adjust the damping settings on just the rear subwoofers and change the way the whole system is imaging it's kind of eerie but it really does do that so listen to it if you really want low low end extension set it to 14 hertz extension filter and set it to low damping that's going to let those things go down to the rock bottom if you don't need them going that low or if you're watching movies you may want to use a higher damping setting or reduce how low you're letting them play don't let them play all the way down to 14 when you're watching movies a lot of those movie soundtracks will really emphasize something down low a big explosion they're wanting to be that big wow factor and just when you think you've got things balanced all of a sudden a lot of subwoofers just completely bottom out and that that's just typical a lot of those movies so you on movies you may want to set it to to 20 or 28 hertz to minimize just how much excursion the whole system is going to see and when you start playing those big explosions and stuff um the other thing you've got speaker level inputs and you've got rca inputs here you got low level and high level so you can come right off your amplifier into the speaker level inputs it'll take a left and a right and it'll sum those internally so it works fine as a mono amp or you can just do left only or right only same goes for the rca input you can do a left only or right on there or you can feed left and right into it and it's going to sub them internally some of the amps also have a high level out it's got it'll show 80 hertz high pass filter which you don't really know what the high pass filter is because it has to do with the input impedance of your amplifier that you're plugging it into uh and what it's got is an electrolytic cap in the signal path we don't recommend using those because then the signal to your entire amplifier on your main speakers is passing through a little electrolytic cap there are better ways to do that and i want to show that to you as well if you've got let's say you got some mini monitors and you've got a big amp on those things which could easily bottom those things out and you want to blend it to your subwoofers what we do is we use little inline filters and we make them you can make them yourself too it's just an easy simple rca in rca out and we put a high quality capacitor inside these have sonic cap platinums in there i think this one is this group here or o47s these over here are some o33s and basically what you just do is you just plug that into the back your amplifier just like you plug it in there it's a nice tight fit you just plug it in plug your rca cable into it and it'll restrict the low frequency that's going to your speakers because it's restricting it to that amp what that does also is relieving that bottom octave so that the amplifier never sees any of that low frequency signal can really increase the headroom of your amplifier so that works great as well also we usually put a little bypass on it so you see there's two rca inputs this one's actually the input this is an output and it just bypasses the capacitor so that it's just a loop through so you can plug this into the back your amplifier and plug an rca cable here unrestricted low frequency and run it over your servo subs and your preamp then is just plugged into this one here so it's a y it's a splitter one leg's filtered one leg's not simple as that it's easy to make these i recommend some good quality connectors don't get anything cheesy these are happen to be some cardis inputs so they're they're decent inputs and there's some really high-end stuff out there you can use and those cap values are not very big you know oh 33 and o47 there's a pretty small cat base use good quality caps use a good film in full cap put a my flex copper full cap in there you can it's it's not expensive because it's it's a small value it's worth spending 40 bucks on a cap or 30 bucks on a cap because the entire signal to your main speakers is going to pass through that capacitor so you want it to be high quality so that's the way to do it if you're rolling off the lows on your main pair of speakers also if you got even a floor standing pair of speakers and they're boomy there's just too much going on there put an inline filter in line with it and roll the bottom off and then use your servo subs to pick that bottom up and you can use the controls on the servo sub to balance out the response so that it's nice and flat you know it's it's great to be able to do that i remember one of my colleagues at rocky mountain audio fest came to me and said man my room is so boomy it my big ht3s were just overwhelming the room i had i had to remove them and put my little song towers in there which wasn't another great speaker that he has but it was a smaller speaker and didn't love the room he said what what are you guys doing and i said i just turned the dials on the servos up down to where they're balanced real easy fix if you've got adjustability and you've got control over the bottom ranges then uh man you've got it licked because that's the tough part a lot of guys are trying to use dsp systems to control all that stuff they're trying to use many dsp and all kinds of crazy stuff and dirac which is actually a pretty good one to control that bottom end and and those can be effective but sometimes you don't want all that in your signal path you can keep that stuff out of your signal path and just handle it on the analog output much easier and without degrading the signal and something like this as an inline filter isn't going to degrade the signal to your main speakers this is the way to to filter that stuff off granted it's a low water filter but it works great on my preamp there's three outputs on my preamp and one of them two of them are full range one of them is restricted a little bit and again this the cap value that you need depends on the input impedance of your amp and the target 3 db down point you're trying to hit and keep in mind if you want to cross it at 50 then you need a cap that's going to be 3 db down at 70 or 80. remember it's a gradual slope and then use your subwoofer to balance it out so i hope all that made sense if you got questions if there's something i missed that i should have covered shoot me a message and we'll go over it and i'll try to answer all your questions hopefully that made things easier for you guys thanks for watching hit the subscribe button if you haven't and we'll see you guys in the next video

Channel: GR-Research

Views: 29,241

Keywords: Tuesday Tech Talk, audiophile, hifi, loudspeaker, fullrange driver, comb filtering, GR-Research, Danny Richie, crossover design, measurements, best loudspeakers, tube amplifier, preamplifier, diy speakers, audiophile speakers, audiophile music, amplifier, best voice, audiophiles, high end, baffle step loss, open baffle, fast bass, subwoofers, line source, drivers, high power handling, low distortion, the room, speaker upgrade, audiophile loudspeakers, crossovers, DIY Audio, soundstage

Id: 1HM7_OIgqwM

Length: 22min 41sec (1361 seconds)

Published: Sun Sep 19 2021