Open Baffle Epiphany!
- Thread starter cptnCanada
- Start date
Poultrygeist
Lunatic Member
I was disappointed with this mono sub amp I put together to drive my Alphas. It's also a TPA3116 class D and has good power but it's adjustable crossover is not good. The fixed crossover amp you linked from Amazon should be better and you only need one to drive two Alphas. I drove four with mine.
In my search to use the gear I own already, and to try to keep my experimentation as simple as possible, I decided to maximize use of my Yamaha AVR. Today, I ordered a highly rated but inexpensive SMSL TDA7492 50WX2 stereo amp. I bought a male RCA to split male RCA cable. I also bought 2 sheets of 3/4" walnut ply, 24"X48" for delivery. The plan will be to:
1) build baffles similar in style to Caintuck, but with a much wider bottom "barrel" portion to accommodate the Eminence Alpha 15As I have on order, positioned directly under the Betsy drivers. The baffles will then taper toward the top where the Betsys will be positioned;
2) the AVR speaker outs will run directly to the Betsy drivers;
3) I will connect the AVR's mono subwoofer LFE output to the SMSL amp, using the split RCA so the same mono sub signal is directed to L/R inputs of the small SMSL amp. The SMSL is very small and will sit directly on top of the back corner of the Yamaha AVR with the volume set up high;
4) the SMSL outputs will be connected to the Eminence 15A drivers;
5) the AVR will be set to drive the Betsys as the "front speakers" and the 15As as "subwoofer". I'll run the YPAO room correction, which will attempt to set the crossover and to balance the volumes of the respective drivers;
6) All of this should allow a fairly simple arrangement that maximizes the equipment I already have. The crossover will be further adjustable from within the AVR menus between 40 hz and 200 hz, and I also have a Behringer EQ unit that I can use to tweak if needed. I'll probably start with the crossover set at 200 hz and adjust down based on needs. If need be, I can always tweak the output of the 15As using the volume control on the SMSL amp, assuming I'm not happy with the AVR YPAO settings.
I'm extremely excited to take delivery of the bits and pieces I'll need to build these. I'm not sure if any other users have configured their OBs as noted above, but I have this AVR that can accomplish a lot of the driver management that will be needed, so it'll be cool to see how it works out. More to follow.
1) build baffles similar in style to Caintuck, but with a much wider bottom "barrel" portion to accommodate the Eminence Alpha 15As I have on order, positioned directly under the Betsy drivers. The baffles will then taper toward the top where the Betsys will be positioned;
2) the AVR speaker outs will run directly to the Betsy drivers;
3) I will connect the AVR's mono subwoofer LFE output to the SMSL amp, using the split RCA so the same mono sub signal is directed to L/R inputs of the small SMSL amp. The SMSL is very small and will sit directly on top of the back corner of the Yamaha AVR with the volume set up high;
4) the SMSL outputs will be connected to the Eminence 15A drivers;
5) the AVR will be set to drive the Betsys as the "front speakers" and the 15As as "subwoofer". I'll run the YPAO room correction, which will attempt to set the crossover and to balance the volumes of the respective drivers;
6) All of this should allow a fairly simple arrangement that maximizes the equipment I already have. The crossover will be further adjustable from within the AVR menus between 40 hz and 200 hz, and I also have a Behringer EQ unit that I can use to tweak if needed. I'll probably start with the crossover set at 200 hz and adjust down based on needs. If need be, I can always tweak the output of the 15As using the volume control on the SMSL amp, assuming I'm not happy with the AVR YPAO settings.
I'm extremely excited to take delivery of the bits and pieces I'll need to build these. I'm not sure if any other users have configured their OBs as noted above, but I have this AVR that can accomplish a lot of the driver management that will be needed, so it'll be cool to see how it works out. More to follow.
Poultrygeist
Lunatic Member
Here's an inexpensive SET amp that would be a great choice to drive efficient full range speakers in OB. The APPJ is currently on massdrop for $99.
https://www.massdrop.com/buy/appj-mini2013-6j1-6p1?utm_placement=4&referer=ZU39SC&mode=guest_open&utm_campaign=Automated Daily Promotional 2018-04-20&utm_source=SparkPost&utm_medium=email&utm_term=Daily Promotional&utm_content=1524205357819.115067130630754875568575
https://www.massdrop.com/buy/appj-mini2013-6j1-6p1?utm_placement=4&referer=ZU39SC&mode=guest_open&utm_campaign=Automated Daily Promotional 2018-04-20&utm_source=SparkPost&utm_medium=email&utm_term=Daily Promotional&utm_content=1524205357819.115067130630754875568575
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Yeah I've got a happy little Chi-Fi amp in a home office, which I love! I may go that route in this application, but not initially. I'll be slumming it with my AVR, partly because it will simplify the setup, assuming things go the way I think they will with AVR settings, crossovers, etc.
Here's an inexpensive SET amp that would be a great choice to drive efficient full range speakers in OB. The APPJ is currently on massdrop for $99.
https://www.massdrop.com/buy/appj-mini2013-6j1-6p1?utm_placement=4&referer=ZU39SC&mode=guest_open&utm_campaign=Automated Daily Promotional 2018-04-20&utm_source=SparkPost&utm_medium=email&utm_term=Daily Promotional&utm_content=1524205357819.115067130630754875568575
My OBs are quite small... one pair is about 10W x 14H, and the other pair are 8W x 10H. The size of the open baffles affects the bass output. I run a subwoofer (actually two) to augment the bass. Works very well for me. The listening space is about 12x20 but the actual room is 24x20. Even when I'm not "in the listening space" and in the kitchen, the sound is great.
OB is easy to play around with without having to spend lots of coin.
+1. I am playing around with OBs using Betsy drivers in barrel-shaped ply pieces, the shape cribbed from Caintuck Audio. They are roughly 22" X 18" and supported by a small subwoofer. The low-slung barrel configuration brings the drivers close to the floor, an idea that at first I thought would make for terrible sound. I was wrong, because the bass is enhanced by the low driver position and the stereo image fills the center of my room.
Moving them around and playing with toe in make very large differences in the way they sound. I have found relative sweet spots in which they sound fantastic, large, expansive and detailed. There are positions though where they sound way too reflective and create a distracting echo effect, which is also exactly when they sound tinny, or transistor-radio-like. I find that using them without sub support brings a very tight and articulated bass but without any punch, a visceral sense which I've learned to need over the years. So, for me, the extra bass support is required, even if its only role is to gently flesh out the bottom end.
The OB sound is a thing that I love but I can see how others might not enjoy it. It creates a very large sound image but one that is not "pinpoint". I've decided I like that largeness. Another poster earlier in the thread made a good point when he asked when the last time was that anyone heard a "pinpoint" image at a live show or in a large space. It was a great point. For example, with orchestral music, I prefer a wide open sound, which sounds more life-like to me than any narrowing of the image.
FWIW, The OB sound reminds me a lot of a great version of the stereotypical Bose "direct-reflected" sound. In my current application, a large finished basement room in which I exercise, the OB concept is perfect. I can position the speakers easily wherever I need them, with ease. I can tailor the sound with positioning and when I get it right, it almost freezes me in place for a few minutes because it sounds so enveloping. When I'm finished I simply place them against the wall next to the equipment rack. It's been a sort of personal proof of concept for me, inspired by this thread.
Now, I have materials in transit to make baffles+, which in my case will mean slightly differently-shaped "barrel-style" plates that will house Eminence Alpha 15A and Betsy drivers in 3/4" walnut-faced ply. I'm hoping to do away with the powered sub, gaining the power and support of the 15As, which should create a better and more coherent image with more articulate bass that's less boomy. I hope I like it. Speaker flexibility and positioning should be the same, the only real difference being the addition of a small TPA amp and an extra run of speaker wire, which should bind together nicely from amps to speakers.
I'm excited, so much so that I already have my eye on my main system, in which I currently use Focal floorstanders with a large sub. The WAF may make it impossible, but it seems likely that I could create better sound in that room, with only slightly more imposing size, with OB. The focals are very good in their own right, but create their lower-end sound with dual 6.5 woofers and reflex port. On the one hand, I know response can be crafted, extended and shaped with ports, horns, etc., but I love the idea of cranking large woofers, 12" to 15", and had been looking at the Klipsch heritage line, partly because I love that vintage large-driver concept. I may be wrong about all of this, but it will be telling how these eminence/Betsy units sound. If I enjoy the sound of large diaphragms moving in free air, it will be hard not pursue that sound in my main system.
Moving them around and playing with toe in make very large differences in the way they sound. I have found relative sweet spots in which they sound fantastic, large, expansive and detailed. There are positions though where they sound way too reflective and create a distracting echo effect, which is also exactly when they sound tinny, or transistor-radio-like. I find that using them without sub support brings a very tight and articulated bass but without any punch, a visceral sense which I've learned to need over the years. So, for me, the extra bass support is required, even if its only role is to gently flesh out the bottom end.
The OB sound is a thing that I love but I can see how others might not enjoy it. It creates a very large sound image but one that is not "pinpoint". I've decided I like that largeness. Another poster earlier in the thread made a good point when he asked when the last time was that anyone heard a "pinpoint" image at a live show or in a large space. It was a great point. For example, with orchestral music, I prefer a wide open sound, which sounds more life-like to me than any narrowing of the image.
FWIW, The OB sound reminds me a lot of a great version of the stereotypical Bose "direct-reflected" sound. In my current application, a large finished basement room in which I exercise, the OB concept is perfect. I can position the speakers easily wherever I need them, with ease. I can tailor the sound with positioning and when I get it right, it almost freezes me in place for a few minutes because it sounds so enveloping. When I'm finished I simply place them against the wall next to the equipment rack. It's been a sort of personal proof of concept for me, inspired by this thread.
Now, I have materials in transit to make baffles+, which in my case will mean slightly differently-shaped "barrel-style" plates that will house Eminence Alpha 15A and Betsy drivers in 3/4" walnut-faced ply. I'm hoping to do away with the powered sub, gaining the power and support of the 15As, which should create a better and more coherent image with more articulate bass that's less boomy. I hope I like it. Speaker flexibility and positioning should be the same, the only real difference being the addition of a small TPA amp and an extra run of speaker wire, which should bind together nicely from amps to speakers.
I'm excited, so much so that I already have my eye on my main system, in which I currently use Focal floorstanders with a large sub. The WAF may make it impossible, but it seems likely that I could create better sound in that room, with only slightly more imposing size, with OB. The focals are very good in their own right, but create their lower-end sound with dual 6.5 woofers and reflex port. On the one hand, I know response can be crafted, extended and shaped with ports, horns, etc., but I love the idea of cranking large woofers, 12" to 15", and had been looking at the Klipsch heritage line, partly because I love that vintage large-driver concept. I may be wrong about all of this, but it will be telling how these eminence/Betsy units sound. If I enjoy the sound of large diaphragms moving in free air, it will be hard not pursue that sound in my main system.
Ah, the joys (read horror) of endless purchasing to support this hobby. I bought the APPJ through MassDrop this morning. My thought is to use it in my home office to drive a pair of Klipsch R-15Ms. I've been using a Gemtune X-1 EL34-based unit, but (1) have started to have fuse problems that are causing me to have to correspond with the seller for return or repair, and (2) once that issue gets worked out, I can use the Gemtune's 8W per channel in my OB setup.
The Gemtune has really much more power than I will ever need in near field on the desk top. The APPJ's 3 watts will be best served there, where its smaller footprint will also be welcomed. The APPJ isn't slated to ship until the end of May, so I'll have plenty of time to build, test and tweak the OBs I have planned.
I'm starting to understand hobbyists who have endless bits and pieces related to the hobby sitting in their houses.
The Gemtune has really much more power than I will ever need in near field on the desk top. The APPJ's 3 watts will be best served there, where its smaller footprint will also be welcomed. The APPJ isn't slated to ship until the end of May, so I'll have plenty of time to build, test and tweak the OBs I have planned.
I'm starting to understand hobbyists who have endless bits and pieces related to the hobby sitting in their houses.
Here's an inexpensive SET amp that would be a great choice to drive efficient full range speakers in OB. The APPJ is currently on massdrop for $99.
https://www.massdrop.com/buy/appj-mini2013-6j1-6p1?utm_placement=4&referer=ZU39SC&mode=guest_open&utm_campaign=Automated Daily Promotional 2018-04-20&utm_source=SparkPost&utm_medium=email&utm_term=Daily Promotional&utm_content=1524205357819.115067130630754875568575
45rpmspinner
Super Member
DavidTT,
How far out from the wall do you have your OBs?
How far out from the wall do you have your OBs?
Poultrygeist
Lunatic Member
Almost ten years ago - this is what started it for me. Folding baffle Betsy's powered by an APPJ ( Miniwatt S1)
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Poultrygeist
Lunatic Member
Listening to OB's can be highly entertaining but not far behind is the fun of experimentation. These showed promise but were far to heavy and clumsy to move around. Sadly they never made it out of the garage.
They sound best to me when out from the front wall about four feet and at least three feet from side walls. They sound like people describe them, very sensitive to placement. I love that aspect of OB.
I hope so. I'm particularly interested to hear what many of you describe as "articulated bass" with less chuffing and boom at the low end. I'm hopeful that the large diaphragm moving in free air will really be something new in my application. The days of large speaker cones faded in my youth and I want to get back to them. The 15As should arrive today, the ply tomorrow. Yeah! And to PG, yes indeed, the experimentation is a huge part of the fun.
So, for those of you who have been at the OB thing for several years now, where exactly has it led you? What has become your long term answer, or is the answer simply that the experimentation is the thing in itself?
So, for those of you who have been at the OB thing for several years now, where exactly has it led you? What has become your long term answer, or is the answer simply that the experimentation is the thing in itself?
Poultrygeist
Lunatic Member
Will you keep the S.L.O.B. configuration?
