Open Baffle Epiphany!
- Thread starter cptnCanada
- Start date
dan-c
Perpetual Lurker
This fellow Carolinian did the baffle-less speakers a few posts back. Now he's doing siamesed Grundigs over Heils I've got to pay him a visit.
Wonder how those sound wing in wing. Interesting.
Poultrygeist
Lunatic Member
2 Alphas 15a ( Parts Express #290-407 ) @ $65 each ( sometimes cheaper on ebay )
2 Betsy FR drivers ( Wild Burro Audio Labs ) @ $100 a pair
1 Yung SD200 class D plate amp ( Parts Express #301-504 ) $100
3/4 MDF - $20 ( quality is not as important as with resonant enclosures ) Plywood costs more but can be finished nicely.
Tweeters aren't needed for the Betsy's and the Yung is a better option vs the less powerful Dayton APA150. With this design the seller Zillaaudio elects to drive the Betsy's straight off the dedicated flea amp while the Yung plate amp controls the crossover on the Alphas.
http://www.diyaudio.com/forums/wild-burro-audio/156871-betsy-boomer-ob-speaker-kit.html
If a preamp with two outputs is not available to feed the signal to the flea amp and plate amp here's a simple option. Using Y cables from the CDP/source and feeding the two amps will often give a stronger signal. If you don't have a SET flea amp to drive the Betsy's another good choice is the amazing TPA 3116 chip amp which sells for $15 on ebay. Same chip set as TBI Mellenia.
I don't have the exact dimensions but you can eye ball them based on the 15" Alpha. Two L supports mounted to the back of the flat baffle is all that's needed to keep it standing erect or you can improv. Home Depot doesn't mind making the cuts even in MDF. But when cutting the speakers holes with your jig saw or router be sure and wear a mask as MDF is nasty.
This $350 set up is much the same as shown in post #26 and absolutely thrashed the Zu's I eventually sold.
I've spend time with my son-in-law's Meridians and a pair of Aerial 20T's and you may think I'm crazy but the OB sound is just more appealing.
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this has been posted before, but a great OB design that would work with the above parts list:
http://www.quarter-wave.com/Project09/Project09.html
http://www.quarter-wave.com/Project09/Project09.html
For those thinking of experimenting with different drivers before doing a "finished" build, here might be a thought starter.
This is a baffle made of cheap ply and finished with Danish oil. Remember...WAF can really help things! In interest of experimenting with not having edges to create HF problems, I did do an trial at rolling the baffle back...though that's not really necessary for beginning trials. But this has two cutouts to allow changing of drivers by cutting mating circle cutouts in the future. This provides for two speakers, one up to 8" as shown and one to about 4". This allows for a pair of drivers, likely which would need some low freq help.
You can't really see it, but this is simply setting on top of another quick baffle for the lows, here using a Hawthorne Augie. Or you could set the baffle on top of a chair (or other support) that provides a barrier to the lows wrapping around the bottom.
The Tang Band driver here is mounted on a very small wooden mounting ring...though painted black you can't hardly see it. Each cutout has a routed lip and any insert is made the same in reverse. I've also mounted in this same way a pair of the Dayton FR point source drivers and other slightly smaller too. The smaller circle is held in place by a simple screw through the center into a "cross bar" that is wider than the cutout. The bottom driver I just use 4 small blocks from scrap to go from the driver mounting screws past the edge of the cutout and use it to just hold it place.
I would encourage any tweeter dropped in to be cut off center so spacing could be minimized by positioning it close to the lower driver. A tip....While originally making and the cutout measurements in front of me, I go ahead and cut a few extra circle inserets for future drivers.
All this can be done with no more than a simple flat board with appropriate cutouts sizes for whatever sizes you're thinking of experimenting with. Plunge router and circle jig are your friend.
EV3
This is a baffle made of cheap ply and finished with Danish oil. Remember...WAF can really help things! In interest of experimenting with not having edges to create HF problems, I did do an trial at rolling the baffle back...though that's not really necessary for beginning trials. But this has two cutouts to allow changing of drivers by cutting mating circle cutouts in the future. This provides for two speakers, one up to 8" as shown and one to about 4". This allows for a pair of drivers, likely which would need some low freq help.
You can't really see it, but this is simply setting on top of another quick baffle for the lows, here using a Hawthorne Augie. Or you could set the baffle on top of a chair (or other support) that provides a barrier to the lows wrapping around the bottom.
The Tang Band driver here is mounted on a very small wooden mounting ring...though painted black you can't hardly see it. Each cutout has a routed lip and any insert is made the same in reverse. I've also mounted in this same way a pair of the Dayton FR point source drivers and other slightly smaller too. The smaller circle is held in place by a simple screw through the center into a "cross bar" that is wider than the cutout. The bottom driver I just use 4 small blocks from scrap to go from the driver mounting screws past the edge of the cutout and use it to just hold it place.
I would encourage any tweeter dropped in to be cut off center so spacing could be minimized by positioning it close to the lower driver. A tip....While originally making and the cutout measurements in front of me, I go ahead and cut a few extra circle inserets for future drivers.
All this can be done with no more than a simple flat board with appropriate cutouts sizes for whatever sizes you're thinking of experimenting with. Plunge router and circle jig are your friend.
EV3
http://www.leevalley.com/en/wood/page.aspx?p=40970&cat=1,43000,43001
Precision circle jig designed for speaker builders.
Lee Valley is your best friend.
No Affiliation.
Art
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Yup....that's the smallest of the Jasper jigs. You can also get them at Parts Express...
http://www.parts-express.com/cat/circle-jigs/338
...or your closest Woodcraft store.
http://www.woodcraft.com/search2/search.aspx?query=circle%20jig
Thanks for pointing the Jasper jig out. You can do such nice things with one. Like the recessing of the driver to be flush mounted.
BTW...if somebody wants to get started and has no woodworking skills, an option is available right now on Audiogon. Nice one in the California area for a decent price. Cut for a 15" woofer and a medium above that. Do a search for "open baffle" or Hawthorne to find it. No affiliation...
EV3
http://www.parts-express.com/cat/circle-jigs/338
...or your closest Woodcraft store.
http://www.woodcraft.com/search2/search.aspx?query=circle%20jig
Thanks for pointing the Jasper jig out. You can do such nice things with one. Like the recessing of the driver to be flush mounted.
BTW...if somebody wants to get started and has no woodworking skills, an option is available right now on Audiogon. Nice one in the California area for a decent price. Cut for a 15" woofer and a medium above that. Do a search for "open baffle" or Hawthorne to find it. No affiliation...
EV3
Poultrygeist
Lunatic Member
There's a difference of opinion regarding how best to use full range speakers with bass woofers.
Whether to run the full rangers unabated or to cross them actively with the woofers? While I currently use the latter approach and the Zillaaudio Boomers uses the former I found this interesting quote from Jacob George designer of world class Rethm Speakers.
"Use the wide bander as a wide bander with no restrictions whatsoever. No filters. And just bring in the bass to fill in what the wide bander cannot do."
There are those who feel that with crossovers/filters the magic of full range speakers in multi-ways is often exchanged for smoothness/better integration but with the loss of that sense of "aliveness". I have this debate with myself almost daily wondering if I'm missing some of the SET/FR goodness or is better to give up to get?
Whether to run the full rangers unabated or to cross them actively with the woofers? While I currently use the latter approach and the Zillaaudio Boomers uses the former I found this interesting quote from Jacob George designer of world class Rethm Speakers.
"Use the wide bander as a wide bander with no restrictions whatsoever. No filters. And just bring in the bass to fill in what the wide bander cannot do."
There are those who feel that with crossovers/filters the magic of full range speakers in multi-ways is often exchanged for smoothness/better integration but with the loss of that sense of "aliveness". I have this debate with myself almost daily wondering if I'm missing some of the SET/FR goodness or is better to give up to get?
dnewma04
The Healer
I think it depends on the driver and the output levels you are dealing with. If you are expecting a 3" fostex to work well without a high pass crossover at anything other than low levels, you are asking for distortion problems.
I find the idea that crossovers in some way kill some magic a little silly. I have had conversations with people about speakers that used drivers that required high order crossovers. They looked at a picture of a crossover and determined that it was too complex and responsible for their lack of appreciation for the speakers. I like to refer to people like that as fools.
I find the idea that crossovers in some way kill some magic a little silly. I have had conversations with people about speakers that used drivers that required high order crossovers. They looked at a picture of a crossover and determined that it was too complex and responsible for their lack of appreciation for the speakers. I like to refer to people like that as fools.
Poultrygeist
Lunatic Member
I suppose if I didn't have 2a3 powered Lowthers which are designed for use without crossovers I might think otherwise.
I have run my woofer + full range driver OB system with and without the crossover on the full range driver.
Without the crossover there is significant overlap between the woofer and full range driver which results in a bloom in the SPL curve over a fairly wide band of frequencies. At first it sounded appealing but after a while it started to sound wrong.
Adding the crossover to the full range driver has some additional benefits beyond just intergrating the output with the woofer's output. By removing the low frequencies the required deflections of the full range driver cone drops significantly. In my opinion/experience this seems to clean up the overall response. Most of the full range drivers are designed with very small Xmax, many as low as 1 mm. A true full range driver system will have an enclosure which will resonate at low frequencies to produce the bass output. The impact of the cabinet is to attenuate the driver's motion at low frequencies, like a driver placed in a bass reflex enclosure. Putting a full range driver, with a small Xmax, in an OB with no enclosure "pushing" on the back of the cone at low frequencies is not what was intended.
I believe you need the two sided crossover to get the most out of this type of OB system..
Without the crossover there is significant overlap between the woofer and full range driver which results in a bloom in the SPL curve over a fairly wide band of frequencies. At first it sounded appealing but after a while it started to sound wrong.
Adding the crossover to the full range driver has some additional benefits beyond just intergrating the output with the woofer's output. By removing the low frequencies the required deflections of the full range driver cone drops significantly. In my opinion/experience this seems to clean up the overall response. Most of the full range drivers are designed with very small Xmax, many as low as 1 mm. A true full range driver system will have an enclosure which will resonate at low frequencies to produce the bass output. The impact of the cabinet is to attenuate the driver's motion at low frequencies, like a driver placed in a bass reflex enclosure. Putting a full range driver, with a small Xmax, in an OB with no enclosure "pushing" on the back of the cone at low frequencies is not what was intended.
I believe you need the two sided crossover to get the most out of this type of OB system..
Poultrygeist
Lunatic Member
Martin,
I know you use solid state amps but have you listened to your Lowthers with a good SET amp using the two different options?
I know you use solid state amps but have you listened to your Lowthers with a good SET amp using the two different options?
I think there a several varibles as to the need for a crossover. But most of the time, you need one.
If it's a smaller driver, then driving it full range you are going to get more motion and increasing distortions as the level gets higher. So with a single 4" in a BLH cabinet and modest levels, maybe acceptable depending on your music preferences. In my listens, it didnt' do it for me. But a line level crossover, biamping with a seperate sub would lift these restrictions. But if you don't push it...you might maybe prefer the single driver, no augmentation and no filtering.
In my case, I tried 6 8" drivers in about a 22" wide folded back baffle. Total Q's of I think around .8. It really had LF drive, pop, and measured to be pretty flat below 40hz. If those cheaper drivers in that situation went high enough and had enough clarity, I'd have called it a day. Only the extremes of a few situations or movie tracks efx would have wanted for more.
With multiple Tang Bands run full range and bi-amped augmentation, I only start to hear negative effects when I get above my normal louder levels. My clarity is enough I don't have to go to extreme levels to get life...others might push it more. Which even when I do start to get some distortion starting to show up, could then be amps running out of steam as much as the drivers trying to do too much. I've went back and forth with inserting a line level crossover and think I have minor negative effects. Ultimately, as setup now, I settle for a crossover rolling in the bass and leaving alone the full range driver. I don't think that'd be typical.
EV3
If it's a smaller driver, then driving it full range you are going to get more motion and increasing distortions as the level gets higher. So with a single 4" in a BLH cabinet and modest levels, maybe acceptable depending on your music preferences. In my listens, it didnt' do it for me. But a line level crossover, biamping with a seperate sub would lift these restrictions. But if you don't push it...you might maybe prefer the single driver, no augmentation and no filtering.
In my case, I tried 6 8" drivers in about a 22" wide folded back baffle. Total Q's of I think around .8. It really had LF drive, pop, and measured to be pretty flat below 40hz. If those cheaper drivers in that situation went high enough and had enough clarity, I'd have called it a day. Only the extremes of a few situations or movie tracks efx would have wanted for more.
With multiple Tang Bands run full range and bi-amped augmentation, I only start to hear negative effects when I get above my normal louder levels. My clarity is enough I don't have to go to extreme levels to get life...others might push it more. Which even when I do start to get some distortion starting to show up, could then be amps running out of steam as much as the drivers trying to do too much. I've went back and forth with inserting a line level crossover and think I have minor negative effects. Ultimately, as setup now, I settle for a crossover rolling in the bass and leaving alone the full range driver. I don't think that'd be typical.
EV3
I have a 15 W EL34 based tube amp that I have tried on many of my speakers including a few OB designs. It sounded great on exactly one pair, unfortunately not mine, and weak on everything else. It has been sitting under an end table for the past few years in my listening room. I have heard a few other tube amps over the years and found that I really prefered SS amp performance.
Poultrygeist
Lunatic Member
I've tried several push pull tube amps with OB's but they didn't sound like SET amps.
tomlinmgt
Lunatic Member
I understand the requirement for (considerable) baffle area for the production of LF, but what is the general rule for recommended baffle area for a driver operating from approx. 125 Hz and up (specifically an Eminence Beta 12LTA)? And am I understanding correctly that no baffle is generally beneficial above 2-3Khz?
Thanks,
Michael
Thanks,
Michael
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