Open Baffle Basics pt.4

hey everybody welcome back we are today in The Listening Room here at gr research uh the temporary Listening Room as it is actually and we're going to continue talking about open baffle speakers we're going to go back and touch on some of the things that we've covered in the first uh three episodes and we're going to look at the in extreme here we're going to spin this thing around and understand now why it's made the way it is made and why this works and we're also going to talk about flat baffles H frames W frames and how those differ and how they load the driver differently how they affect the extension and we're going to look at this little beast around the corner here which is a triple stack of our Servo controlled woofers we're going to talk about those and that way everybody can understand exactly what the servo control system brings to the table in regard to open baffle so let's cut and I'm going to spin this stuff around so we can see the back side of it and we're going to dig into some cool stuff all right we're looking at the backside of everything now this is the n extreme again this is one of my all-time favorite speakers I love listening to this speaker this is usually what I have in my Listening Room when I want to sit and listen to music and as you can see it is a um u-shaped frame or a bit of a wed shape open baffle um the lower section and the upper section uh houses four of our m165 wolfers they're actually m165 16 ohm wolfers and if you notice they're they're completely enclosed on both sides and open out the back so it's just a wedge shape we got a wing on both sides you can do that and and you can get really good results that way with drivers that are not playing up very high um this wing on both sides is separating the front and back wave quite a bit so it's kind of like having a baffle that is um 3 and 1/2 fet wide it's creating that much separation and it's also loading the driver a little bit so it's increasing that low frequency extension on those drivers but keep in mind you can't do that to a driver that's playing up into the midrange or higher when you wall it in on both sides any of the shorter wavelengths that can propagate within that space are going to create a cavity resonance and it's going to create a shoutin um when you get up into the higher frequency ranges you have to take one side off so as you see here it's more of an L-shaped baffle as we get around the mid-range drivers here um that way you're not creating that megaphone effect and causing compression it's still open One Wing can't cause that type of compression so the one Wing though does separate the front wave from the back wave and the long wing with the little shorty is a way of tuning that roll off and that extension at the very bottom of its range keeping it flat and and making a gent roll off that means we have to use a minimal a number of crossover parts to try and control it because we're controlling the natural rolloffs with the shape and the and the size of the Wings and then of course around the Tweeter we have a scallop area there that is cutway so that um that higher frequency range isn't CED into a little area as well uh the little even the little short wing on this side is too much as it passes by the Tweeter we have to cut it out so that's the way this thing works that's the way we get the most out of it and get a neutral and flat response out of it without having to manipulate it a bunch we're keeping a narrow baffle which means minimal amount of surface Reflections minimal amounts of defraction uh edges are rounded all that kind of stuff so the Imaging and the transparency is a whole lot better A whole lot more open and Airy and three-dimensional than if the baffa were just flat if the baffle were just flat again it would have a a sound that's more perceived as if it's coming from the baffle forward now let's take what we've just talked about here we've got something in a U-shaped frame and talk about the differences in the roll off at the bottom end versus a flat baffle versus an H frame which is what the servo Subs are in over here and um I printed off some information uh I modeled the Eminence um beta 15 which is a big 15-inch woofer it and the alpha 15 are often used in open baffle applications and when you put it on a just a flat baffle uh maybe not much bigger than it is this is kind of the rolloff that you to actually get I don't know if you guys can see that that well I'll try to hold it up for you notice it starts rolling off up here around 200 HZ and it starts a long gentle rollof that's just the way drivers behave when you put them um in an open baffle if you put it into an H frame or a w frame where you're separating the front wave from the back wave a little bit and you're actually creating some loading on the driver you get a little more extension if you look at the bottom line that's the same line that was on the other graph the Top Line would be the output that you're going to get when you put it into an H frame or a w frame now of course an H frame is basically just if you look at it from the top it makes an H in other words the baffle is right in the middle and you have a side on each side so you have an H the W frame is the same but they're slanted so you have one slanted one way and one slanted the other so if if you look at it from the side it makes a w that's why they just call it a w frame W shaped frame and it works just the same as an H frame you're separating the front wave from the back wave the advantage in the W frame is it makes it a little shorter because you're folding the drivers a little bit instead of them standing up straight you're folding them over and shorting it down a little bit the con is that you're creating a larger unraced panel area in the middle of that wedge shape so you have to increase the thickness of your sidewalls uh to compensate for the fact that you're putting a whole lot more pressure on it um if you're using a flat baffle one of the things a lot of people do when they to try and get more output rather than putting it into a wedge or W frame is to add more drivers in other words you have a two-way or three-way you got a big mid-base driver and another another below it that's acting as a woofer what happens when you when you parallel two of those drivers you get the exact same response if you look at the response there at the bottom that again is the same Eminence beta 15 and an open baffle and this line above it here is the exact same response that you get when you parallel to of them it doesn't play any lower it just plays louder so you're not gaining lowend extension or anything you're just doubling your output but let's do this same situ situation um this this curve here that you see same curve that is one woofer and this one here is the second woofer and what you do on the second woofer is you just put a large inductor on that lower woofer when you put a large inductor on the lower woofer you're basically saying we're still going to let it play the very bottom end but as it approaches the higher frequency ranges we're just going to roll all that off so we're limiting it to just that lower output lower frequency range and if you notice it's pretty down in output it doesn't have that much output down low it has no more output than the single driver did but when you add that plus that you're gaining as much as 6db at the bottom because you have two of them paralleled at the bottom but as you approach the higher frequency range you don't gain as much output and in fact right at the crossover point you want them to sum and it goes back to the same output that you would have if you were just using a single woofer so that's a way of increasing that bottom end um keep in mind drivers like the Eminence um Alpha 15 or beta 15 are limited to less than 4 mm of xmax so you're not moving a lot of volume um drivers like our Servo controlled woofers these 12-in woofers have 18 mm of xmax so now you're talking a tremendous amount of output but uh you're moving a whole lot more air because the driver can sweep so much further um and with the servo control system you can make it do literally anything you want it to do what it does is the servo sens sensing system is always measuring cone movement versus input signal and it's comparing input signal to Cone movement constantly if the input says 20 her note what it does is it as gain as needed to maintain that linearity so that it's flat all the way to 20 HZ and it'll play the 20 H note the same level that it would a 40 or 50 H note so it maintains an unbelievable linear response and you can change that you can change the extension filters to tell it how far you want it to go how low do you want it to play and then the really cool part is once the input signal stops it says input is stopped therefore cone movement must stop and it electrically Slams on the brakes and stops that driver and it can stop it a lot faster than an uncontrolled driver so instead of those rolloffs that you saw with the first one there um you'll notice now it's flat all the way to 20 HZ with servvo woofers and then the rolloff is created by the crossover control that you have on the amplifier you can turn that thing up or down now the way that's doing that the woler is in an H frame as you saw from when the other examples the woofers still have a gradual rollof they have the same order rollof just the H frame is is loading the driver a little bit separating the front wave from the back wave and it's increasing the output in those lower ranges but it still has a rollof so what happens is we have on the amplifier that's driving these what's called a shelving circuit and if you measure the woofer right on the woofer if you get right up to the cone so you're not measuring out into the room you're just measuring the signal you'll see that is sloped a little bit to the bottom end this is the bottom end of the scale down here and this is the top end of the scale this is where the control of the crossover is pulling the top end of it down notice then there's three lines there there's one A Little Higher One in the middle a little lower those are differences that are created by changing the damping so we can go from high damping to low damping to medium level damping and we can change how tight how fast the woofers controlled and it's amazing what kind of difference that can make it can really slam on the brakes if you want it to um here's another one this curve is also again right on the woofer and you see three different lines there and the difference is the extension filters this top one here is the extension filter set to 14 Herz this one is the extension filter set to 20 HZ and the lower one is extension filter set to 28 Herz setting so what the shape of that is it's it's adding more power as needed to the lower end of the spectrum to mirror image the roll off that it's getting in an open baffle so when you actually get back into the room and measure you're getting a totally flat response down to into the teens if you want so you have a big variance there that's under your control you can do anything you want with the damping and the extension um it can be as little control or very similar to an uncontrolled driver uh even Ron Bernay mentioned in one of his recent videos he compared one of our kits with the servo Subs he compared it to the spatial audio uh sapphires that was the one he used and which was a great speaker you just want to buy an open baffle speaker open the box and set it in the in the floor plug it in and go that's probably one of the best ones I could recommend and Ron loved them and Ron actually said he thought the base was a little tighter on the larger Wolford Sapphire than with the servo Subs which everybody says what are you talking about and I then had to ask Ron so Ron you still have your extension filters set all the way to 14 and your damping set on low which he did which is where I have mine most of the time cuz I love for it to play all the way down into the Rock Bottom and the low damping allows it to do that even further it's a less control but a lot of extension and he said yeah yeah he did so had to remind him Ron you still got levels and levels of control that you're not comparing keep in mind with these if you have the extension filter set to 14 you're forcing that thing to play flat in other words you're pushing more amplifier power into it to keep a linear response way down into the teens so you're putting a lot more cone movement in motion and these have a long throw so you have a lot more in motion and when you have more movement it takes longer for it to settle and if the damping is set on low that's the least amount of control that you can add if you set the D the extension filters from 14 to 20 and then 28 going to 28 Hertz extension you've probably cut half of the cone movement out on that woofer because it's not having to play down as low it's rolling off so if you got a room that's boomy down really low you can change that filter back to 20 or 28 so that it can compensate for some of that room gain that you have and when you do that again uh less Excursion uh faster settling times and then start moving that damping Factor up to medium or high now you're really doubling and tripling the control on it to Make It Stop So it becomes really fast much faster than an control driver so I have no doubt Ron reported exactly what he heard but there's still a lot of functions and features that still allow more control and more damping and more tightness if that's what you want it also has a one band EQ built in on the amplifier so if you have a peak in your room or a dip in your room it can help solve that by allowing you to pull that Peak down or that uh pull that yeah pull the peak down or the dip up and it'll also allow you to decide if that's a narrow band Peak you can turn it down into a narrow band or if it's a wide band like a broad Peak you can set it to a wider band and you can pull that Peak up or down in a broad setting so you can you can change it like this or you can change it like this it's very flexible and just that feature alone is huge in allowing you to dial everything into a room um lot of power there you uh have dual Servo subs or triple Servo Subs with open baffle you can drop those things into any room uh especially like when we go to a show and have full range sound linear flat out to the teens and not be boomy it can be perfectly smooth balanced with the rest of your speaker because you have all those controls and functions to balance it out on a passive speaker if you put it into a room and you've got boominess only thing you can do is start adding room treatment start moving the speaker further out in the room and trying to find places where it's not as boomy but you don't have that kind of control with the servo systems you got a lot of control you can make it do anything you want so um if you guys are interested in that stuff it's there on the website if you guys have questions about it if you have questions about open baffle stuff in general or any of our kits shoot me an email on that stuff drop a comment in the me in the comment section down below and I'll try to answer any of your questions um be sure and hit the Subscribe button if you had hit the Subscribe button yet so you will be notified when we have new videos and hit that little uh Bell symbol I think that gives you more instant notification as soon as one comes out so help us click the Subscribe button and get those subscribes up and we appreciate you watching the videos very much I hope you guys like this section on open baffle now we did we've done four of them now um I think I've wrapped it up unless you guys have a lot of big questions I can always come back and do another segment on this if I need to but um open baffle stuff that's where it's at I hope everybody gets a chance to listen thanks and have a good one

Channel: GR-Research

Views: 50,809

Keywords: best loudspeakers, measurements, audiophile loudspeakers, crossovers, DIY Audio, preamplifier, audiophile, tube amplifier, fullrange driver, amplifier, audiophile speakers, Danny Richie, low distortion, drivers, subwoofers, Tuesday Tech Talk, open baffle, fast bass, loudspeaker, hifi, diy speakers, audiophile music, baffle step loss, crossover design, comb filtering, GR-Research, speaker upgrade, high end, audiophiles, bic dv62si, polk s20, kits, upgrade, lta, infinity, linkwitz, orion

Id: jUPslr_b6vE

Length: 17min 47sec (1067 seconds)

Published: Tue Oct 13 2020