Pictures of my Tri-amped Open Baffles

[Poultrygeist]

The main driver ( Beta 12LTA ) is powered by 2a3 SET mono-blocks. The Alpha 15 inch H-frame woofers are powered by solid state Dayton APA150 mono-blocks. The super tweeters are powered by a Dayton DTA100 tripath amp. That's a total of 5 amps driving 6 speakers. Pictures of amps to follow and I'll explain how I do it.

http://gallery.audioreview.com/data/audio/500/medium/P5120005.JPG

[Poultrygeist]

Here on the top rack are the 2a3 SET mono-blocks that drive the mains ( Beta 12LTA ). On the floor are the Dayton mono-blocks that power the two H-frame bass woofers.

http://gallery.audioreview.com/data/audio/500/medium/P5060001.JPG

[Poultrygeist]

The Dayton T-amp ( glaring blue light ) drives the super tweeter with only a 1uf cap on the positive terminal. There are no sound robbing XOer's in the entire system. It's not rocket science that the preamp has two outputs, one which feeds the 2a3 amp and the other feeds the solid state mono-blocks on the floor. But how do I get a signal to the T-amp which drives the tweeters? The Dayton mono-blocks which are daisy chained together each have one input and one output. So I took the second Dayton amp output and pass it to the T-amp. It really works nicely and it's great to be able to control the super tweeter with it's own amp. Best of all my SET now sees an 8 ohm load rather than 4 ohms. The only downside is the maze of wiring to pull this off.

http://gallery.audioreview.com/data/audio/500/medium/P5120003_2.JPG

[Feanor]

The Dayton T-amp ( glaring blue light ) drives the super tweeter with only a 1uf cap on the positive terminal. There are no sound robbing XOer's in the entire system. It's not rocket science that the preamp has two outputs, one which feeds the 2a3 amp and the other feeds the solid state mono-blocks on the floor. But how do I get a signal to the T-amp which drives the tweeters? The Dayton mono-blocks which are daisy chained together each have one input and one output. So I took the second Dayton amp output and pass it to the T-amp. It really works nicely and it's great to be able to control the super tweeter with it's own amp. Best of all my SET now sees an 8 ohm load rather than 4 ohms. The only downside is the maze of wiring to pull this off.

http://gallery.audioreview.com/data/audio/500/medium/P5120003_2.JPG
Well done, PG. I'm glad it's working to your satisfaction.

Come come you're using a T-amp for the super tweeters instead of more tubes?

[Poultrygeist]

The T-amp works well, makes no heat and takes up so little space.

If I couldn't have triodes I'd have T-amps.

[E-Stat]

Wasn't the Dahlquist DQ10 somewhat similar to this approach?
Not really. It was a five way monopole rather than a hybrid dipole. The upper drivers were mounted on small baffles independent of the acoustic suspension (Advent) woofer, but were sealed.

Some pics (http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=3758)

[Mash]

Wasn't the Dahlquist DQ10 somewhat similar to this approach?

The Dahlquist died & went away but I forget why.

[Poultrygeist]

I received an email today from Doc the owner of Bottlehead. He's selling his fully shunt regulated 45 amp mono-blocks. This dream SET with great iron makes 1.75 watts and was only used to drive a pair of tweeters.

Imagine driving a pair of tweeters with a amp that he's selling cheap for two grand. I think it would put my tweeter driving t-amp to shame.

[BoJonJovi]

Could a person go from the signal source to a DAC to
AV splitter (http://www.amazon.com/AV-400-Composite-Distribution-Amplifiers/dp/B000BLJE8W/ref=pd_cp_e_3) to ampsdirect to speakers and eliminate the crossover?
Just trying to understand how you eliminated the crossover.

[Poultrygeist]

You can use a pair of one-into-two RCA Y cables and split the analog output signal from a DAC, CD player or other source and feed it to two different amps. There is no loss of signal strength using Y cables. There is no crossover needed at this point as it's still up stream of the amp and speakers. The speakers in this case would have built-in passive crossovers unless they were full rangers.

With my 3 way set up there is no XO on the main drivers as they are full range. They run directly off the tube amp. The bass woofers which need to be low passed ( receive just the lower frequencies ) are powered by Dayton amp(s) with a built in XO control ( active ) as you would find on a powered sub. The tweeters use a single cap which filters out unwanted frequencies and are driven straight from the T-amp.

The link below gives information on an electronic/active crossover which in this case is accomplished at the preamp level.

electronic crossover, PLLXO, passive crossover, active crossover, custom amplifier (http://www.marchandelec.com/xovers.html)

[BoJonJovi]

With the current price of Tang Band W8-1808 would you make that purchase again? You seemed to be very taken by them. I wonder if I shouldn't grab a pair in case the price continues to rise. I am thinking I could incorporate them into the Betsy's and build/experiment around them.

Interesting I was looking at a pair of no baffle speakers you built. Decades ago when I was in high school one of my buddies worked in an auto salvage yard. He took a set of speakers and suspended them in a frame with springs from each corner and powered them with a salvaged car stereo. He used these in his house for a few years and they sounded great. We always commented on the sound. Perhaps he was ahead of his time.

[Poultrygeist]

I think the current price for the TB's is $200 each which I consider steep. If you could get a pair for $300 I'd say go for it as that's what I paid a few years ago. The Betas are a better buy at $79 each and you'll need tweeters but they cost very little. The TBs are fantastic drivers in OB but I can say the same for the Betas. The TB's don't really need a super tweeter and they would work great as the main driver in flat baffle like my Betsy's.

The reason those car speakers sounded good is because they are full rangers and don't need much of a baffle. Lots of homebrew OB's use car speakers.

[BoJonJovi]

I have been reading ferociously. For simplicity of build, cost, and my live room it seems the road keeps coming back to something similar to, if not your system. I have looked at the more complicated horn builds but I am not sold on that idea as the OB with full rangers seem to be a better match for the hard surfaces of my listening room and lower volume listening. I also like the simplicity of your crossover or lack of crossover network. I can tell you did your homework.

[BoJonJovi]

Are you talking about the 12 inch Betas?
I was also looking at the Dayton Audio DCS450-4 18" for H frame woofers.

[Poultrygeist]

Yes, the Beta 12LTA ( 12 inch ) are my favorite for the time being. With OB, room acoustics are much less important that with conventional speakers.

The Dayton 18 inch sub would not be a good choice for OB as it's Qts rating of .47 is more suitable for a conventional enclosure. A stiff cone woofer ( low Qts ) is not loose enough to move much air in open space. I would recommend the full range Eminence Alpha 15 which seems to be the favorite bass woofer for H-frames. It's Qts is well above 1.00.

[Mash]

Two thoughts on your OB's, Pg....

1. A curved & shaped structure to move the cone forward of the baffle plane so as to discourage early reflections.

2. Work up a feedback control system to clean up the sound from the cones. [Tweeters usually do not need this since their moving mass is small w/r/t the "motor's" power.] Visit Mackie.com and look up the diagram for the HR824Mk2, which has an elegantly simple feedback control system. The resistor in the cone's ground circuit only has to be large enough to generate a preamp-level voltage.

[Poultrygeist]

I take no credit for this MJ King design. I only build what others have had success with. I don't have the software or knowledge base yet to simulate what baffles/enclosures work best with a given driver. The link below has been a great resource for me. MJK has done some amazing work with a host of different designs.



http://www.quarter-wave.com/Project08/Jordan.pdf

[thekid]

The main driver ( Beta 12LTA ) is powered by 2a3 SET mono-blocks. The Alpha 15 inch H-frame woofers are powered by solid state Dayton APA150 mono-blocks. The super tweeters are powered by a Dayton DTA100 tripath amp. That's a total of 5 amps driving 6 speakers. Pictures of amps to follow and I'll explain how I do it.

http://gallery.audioreview.com/data/audio/500/medium/P5120005.JPG

Beautiful work!
I have never had the opportunity to listen to any open baffle speakers but the concept is intriquing.

[Poultrygeist]

Thanks kid,

These have been real game changers for me. If you like the openness of Magnepans you'd love OB.

[thekid]

Thanks kid,

These have been real game changers for me. If you like the openness of Magnepans you'd love OB.

Yes. I see the similarity in the concepts.
A local gentlemen I sold some gear to is very big on OB's and has apparently built a few himself.
I suppose I have enough "spare" drivers laying around that I could give it a shot at some point but my guess is that drivers designed for a traditional cabinet speaker is what you need/use for OB's.

[Poultrygeist]

Full range drivers are a must for OB. Conventional drivers just don't work well.

As you well know dipole bass can be weak so in order to get good bass an efficient woofer with a high Qts ( like the Eminence Alpha 15 ) is necessary for OB.

A stiff cone woofer ( low Qts ) works great in a sealed enclosure but won't move enough air in open space. Hence a looser cone ( high Qts above 1.0 ) is needed. The 15 inch Alpha is a high efficiency ( 97 db ) full range bass woofer with a Qts of 1.26.

Folks on this forum think nothing of spending $300 on high end cables while for the same money they could build these puppies which more than likely would put their own system to shame.

[BoJonJovi]

Yes, the Beta 12LTA ( 12 inch ) are my favorite for the time being. With OB, room acoustics are much less important that with conventional speakers.

The Dayton 18 inch sub would not be a good choice for OB as it's Qts rating of .47 is more suitable for a conventional enclosure. A stiff cone woofer ( low Qts ) is not loose enough to move much air in open space. I would recommend the full range Eminence Alpha 15 which seems to be the favorite bass woofer for H-frames. It's Qts is well above 1.00.

Thanks, that helps.
I think I will start heading this way. It may take a while so I can spread the bill out a bit.

[Feanor]

Full range drivers are a must for OB. Conventional drivers just don't work well. ...
Fanciers of the Linkwitz Orion would beg to disagee with the full range part; (HERE (http://www.linkwitzlab.com/orion-rev4.htm)) ...

http://www.linkwitzlab.com/images/photos/O4Sapele-a.jpg

... Or those of the Legacy Whisper, (HERE (http://www.legacyaudio.com/products/view/whisper-xd/)) ...

http://www.legacyaudio.com/images/made/images/uploads/products/Fronts-Mains/WhisperXD%20MAPLE%20PAIR_434_571.jpg

[E-Stat]

Fanciers of the Linkwitz Orion would beg to disagee with the full range part.
As would Carl Marchisotto of Dahlquist and Nola.

After many an hour of listening to his Grand Reference (http://nolaspeakers.com/products/exoticagr_b.php) using equally commensurate gear, I would too.

[Poultrygeist]

Linkwitz "must" use complex crossovers which is thankfully avoided with multi-amped full range drivers in OB. With no crossover you get to hear all of what's normally burned off as heat.

E-Stat, those monoliths of excess, the Grand Reference, I'm sure sound fantastic with your gorilla amps but I see nothing relative to crossover-less full range drivers in OB. Apples and cumquats?

[Mash]

Well, Feanor... that Linkwitz Orion looks complicated..... Monopole tweeters, dipole mid and a series woofer? The Legacy Whisper I encountered some time ago but I remember nothing about them. But they look very complicated...... maybe too much so.... a violation of KISS.

These are both far beyond Pg 's DIY project, and they seem hardly appropiate as anyone's DIY projects.

[E-Stat]

Linkwitz "must" use complex crossovers which is thankfully avoided with multi-amped ...It is an eight channel active design. Now using an H-frame for the woofers.


I'm sure sound fantastic with your gorilla amps...
You have no idea. And none of it is mine. That system recalibrated my notion of what an audio system can do many years ago. Sense of authority. Walls disappear. Spooky.


...but I see nothing relative to crossover-less full range drivers in OB.
You seem to think open baffle is a single design concept. That's like saying all electrostats are designed the same way. Some are hybrids. Some use frequency specific panels to achieve full range. Others use single panels or multiple identical panels. Not all are dipoles.

Vive la difference!

[E-Stat]

that Linkwitz Orion looks complicated..... Monopole tweeters, dipole mid and a series woofer?
Full range dipole on latter versions with the additional tweeter in rear. Dipole woofers driven with separate amps.


... they seem hardly appropiate as anyone's DIY projects.
You can buy the package as a kit here. (http://www.linkwitzlab.com/orion_construction.htm). Including the active crossover with 44(!) op amps.

[Poultrygeist]

E-Stat, you seem so knowledgeable of DIY builds I'm anxious to see and read about yours. And please post some pictures.

[E-Stat]

E-Stat, you seem so knowledgeable of DIY builds. I'm anxious to see and read about yours. And please post some pictures.
Aware of many designs, yes. My DIY projects are now limited to room treatments and attenuators for the digital front end in the main system. There is no way to DIY a U-1. The last electronics I built were Dynakits when I was a teenager.

SE-2 (link to details) (http://db.audioasylum.com/mhtml/m.html?forum=tweaks&n=79584)


http://home.cablelynx.com/~rhw/audio/se2.jpg
http://home.cablelynx.com/~rhw/audio/se2_rear.jpg

The twelve bass traps used this recipe. (http://www.teresaudio.com/haven/traps/traps.html)

http://home.cablelynx.com/~rhw/audio/reartraps.jpghttp://home.cablelynx.com/~rhw/audio/rear.jpg

I'm still using the original owner's Kenwood receiver to drive speakers throughout the house and to the outdoor patio / pool with access to the digital library on my server along with internet radio of various sorts. It's nice having music indoors and out.

[Poultrygeist]

Any basic speakers?

[E-Stat]

Any basic speakers?
No,. Just rebuilt parts of the Advents. New wiring, crossover caps, felt tweeter diffraction.

I bid on a pair of Acoustat 1+1s on ebay, but they guy had too high a reserve. That's what I'd really like to replace the Advents in the garage.

[BoJonJovi]

The TB's look good and reviewed highly over many builds. They are out until September. Just nosing around I ran into the Goldwood GW-8003/8 8" Full Range Driver w/Whizzer for 26 bucks. What are your thoughts on the Goldwood GW-8003's?
I thought they might offer an ultra cheap introduction to OB while the TB come.

[Poultrygeist]

The Goldwoods look good but at 87 dbs will need power. I have a pair of these GRS below which are even cheaper and more efficient at 91dbs. They replaced the famous Pioneer BOFU full ranger that was a Nelson Pass favorite. I have a pair of those as well.


GRS 8FR-8 Full-Range 8" Speaker Pioneer Type B20FU20-51FW 292-430 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=292-430)

[BoJonJovi]

The Goldwoods look good but at 87 dbs will need power. I have a pair of these GRS below which are even cheaper and more efficient at 91dbs. They replaced the famous Pioneer BOFU full ranger that was a Nelson Pass favorite. I have a pair of those as well.


GRS 8FR-8 Full-Range 8" Speaker Pioneer Type B20FU20-51FW 292-430 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=292-430)

Glad you mentioned those. I was considered them as well. I think they can be had for around 14. I think I saw the qts of .40 vs .79 for the Goldwell and figured the Goldwell might be the better option.

[Poultrygeist]

Here's a link to an interesting enclosure using the Bofu ( GRS drop in ) but the GRS should work fine in OB. A qts of .40 is not bad for OB if you're using bass support ( H-frames ). The TBs are right at ,40

Pass The Bofu Building a transmission line cabinet for the Pioneer 8-inch full range driver. Article By Jeff Poth (http://www.enjoythemusic.com/diy/0710/bofu_pioneer.htm)

[BoJonJovi]

Just curious. What do you think of the Tang Band W8-1772 for OB? I got one off ebay for $116 with the option to return it. I thought it might also make a cheap pair of voight pipes. Unfortunately PE will not have them in stock until August for me to finish the pair.

[Poultrygeist]

The wife has not been a happy camper with my large OB's. I brought this old single bed down from the attic and converted it into a garden bench. I cut the foot board into and used it for side arms. With the brownie points earned I can build more speakers in peace.

http://gallery.audioreview.com/data/audio/500/medium/P6050005.JPG

[BoJonJovi]

It looks lonely without a Gazebo. Hmm..., a gazebo would keep an amp out of the weather, and a pair of OA (Open Air) yard speakers disguised as yard art. You are brilliant.

[Poultrygeist]

I almost did a gazebo but instead did a screened porch where strange full rangers propagate.

The 1772 will work in OB as long as you augment the bass with H-frames.



http://gallery.audioreview.com/data/audio//500/PA2900021.jpg

[BoJonJovi]

Nice. Like the wine as well. Brewing wines and ciders is one of my other avocations. I have 60 gallons of various brews going. I guess a lifetime of working with at-risk kids, the mentally ill, and big bureaucracies makes one want to blunt the memories by indulging the other senses.

[Poultrygeist]

Between the two Tang Bands and the Beta, I think I'd go with the Beta. Reasons: cheaper, more efficient ( by 4dbs ) and much larger sound stage. A friend who has heard the TB's and Betas in my home wants me to build him these same Betas over H-frames. I trust his ear and as a professional violinist it feeds his family. He has owned Omegas, Tektons and Zu's but is enthralled with the Betas.

[BoJonJovi]

OK I am ready to pull the pin on the 12inch Beta.
Was there a reason for the alpha over the 15 inch beta for H frame woofers?
Seems like I might have read somewhere that there was a reason.

[Poultrygeist]

The 15 inch Alphas are just a better choice for H-frames. They have very high Qts and will move more air in open baffle. Even though the Alphas are efficient they'll still need 50 to 100 watts of solid state power. Actually they can handle even more if it's available. The Betas OTOH need only a couple of watts and preferably tube watts or t-amps watts.

If you build this you'll eventually end up driving the Betas with a SET. The $200 Miniwatt/APPJ on ebay is a great choice if you're on a tight budget. SETs and high efficiency full range drivers are a match made in heaven.

[Poultrygeist]

BoJon,

FWIW I too worked with at-risk kids for much of my career. My first job out of grad school was in a mental health hospital. I recently retired from a state agency serving children with SED/BD.

[BoJonJovi]

I started in public education working in lower economic class schools and alternative schools as a Special Ed teacher for Emotionally Behavior Disorder Kids.Then as school principals in schools that needed help to clean up problems. I retired from the Colorado Mental Health Institute as the Director of Patient Education. I really enjoyed the patients and kids in all settings but the bureaucracies were soul sucking; not too much PTSD but some.

Not on a real tight budget if I drag it out. I would like to build a SET as I get a little more experience.


I am going to go ahead and order the 15 inch alphas and the 12 betas. I thought about the cheaper full rangers but then I thought the 12 inch betas were not really budget breakers. I think I can still manage to keep the water and lights on and the wife should not beat me too bad.

[Poultrygeist]

The Betas over H-frame Alphas are good enough to be a final destination system.

Unless you use the Dayton APA150 amps with built in crossover controls you'll need to buy two 8 ohm 80hz low pass crossovers from Parts Express. I believe they cost $17 each. To save money on shipping and use their online discount coupon it's good to order everything from PE at the same time.

What amps will you be using?

[BoJonJovi]

I have the Class-D Audio 250x2. I am building the other Sure amp 250x2. It is about ready to go but I think I have something amiss with the polarity. I have not had time to fiddle with it. So I am thinking one amp for the top end and one for the bottom end. I am also thinking of the Dayton 150 in the future but cannot do it all at so I should probably get the low pass crossovers.
I am also thinking I need some tweeters. I was looking at the planer and ribbon tweeters from parts express but kinda have a jones for a horn as well. Any suggestions for tweeters? I will also need some caps for them.

[Poultrygeist]

If you drive them with their own amp you can use 4 ohm tweets with lower efficiency but if you run them off the same amp as the Betas I'd stick with 8 ohms and slightly higher efficiency than the Beta's 98dbs.

My 108 dbs 8 ohm super tweets were a PE buyout and no longer available.

I would consider: Eminence ASD1001 horn driver ( 8 ohm 103 dbs ) @ $29 each plus Dayton H45E wave guides @ $6.35 each or perhaps the Pioneer AHE60-51F @ only $12.32 each ( very good reviews but looks a little cheap - 100 dbs )

I have had good luck with these vintage Realistics ( see link below ) but they're only available on ebay and at flea markets. They are said to be the same as the highly regarded Fostexs. You can remove them from their pods and easily flat mount them in baffles. You can often find them for around $40 a pair.

Radio Shack 40-1310 Super Tweeter (http://diyaudioprojects.com/Drivers/40-1310/40-1310.htm)

[BoJonJovi]

After spending the moring reviewing tweets I am leaning toward the ASD 1001 with Dayton Waveguides.
However the Foster 025N03 Cast Aluminum Horn Tweeter caught my eye for a second and perhaps cheaper build.

Is there a reason you went with the 15" H-frame rather than the Goldwood-1858 H_frame?

[Poultrygeist]

The Goldwood is not as highly regarded as the Alpha. If you check out the other forums the majority of H frame builders use Alphas.

[Poultrygeist]

This $189 APPJ/MiniWatt N3 sounds incredible with the Betas. LeRoy, a member here just PM'ed me about how great his N3 is sounding with new tubes. Says it beats his high dollar Rogue.

Small Mini Tube AMP Audio Amplifier APPJ EL84+12AX7B (Original Miniwatt N3) 1set | eBay (http://www.ebay.com/itm/Small-Mini-Tube-AMP-Audio-Amplifier-APPJ-EL84-12AX7B-Original-Miniwatt-N3-1set-/251007931870?pt=Vintage_Electronics_R2&hash=item3a713d15de)

[BoJonJovi]

Regarding the 18" GW that is what I noticed as well. I could not find as much on the GW but the Alpha was well covered. Also the few reviews of the GW speaker alone were not great while the Alpha reviews were much better. GW was also more expensive. Taken together it kinda tips the scale to the Alpha.
I have the N3 in my ebay cart but it is going to be a while. I have to finish a few projects first. I am a good starter but a very poor finisher. I am working on that.

[BoJonJovi]

I am planning on pretty much copying your system. I am planning on purchasing the Dayton DTA-100 to run the Eminence ASD1001 horns. What uf capacitor would you suggest for the high pass filter on the ASD's?

I will probably buy the Dayton 150 in the next month or two rather than put the money in crossovers. In the mean time I can be building the speakers.

[Poultrygeist]

The DTA-100 is almost too good for super tweeter duty and would be a good choice for the Betas. I think you've already invested in some class Ds which will probably sound even better than the DTA-100. I went with the DTA-100 as I had it on hand and wasn't using it.

Before spending your hard earned cash on the DTA-100 just to drive the tweets I'd first try running the ASD1001 off the Beta terminals. Your class D amps are much more 4 ohm friendly than my flea tube amps which like a 8ohm load. The PE Lepai t-amp would also drive the ASD1001 which are even more efficient than my Peavey tweets and would be a good bit cheaper.

I'd go with a 1uf cap on the positive tweeter terminal of the ASD1001 but also pick up some .68 uf in case there's more sizzle than you want. You don't need to buy the top shelf caps. I usually go with the audio grade ones one step up from the bottom. Don't forget to buy the wave guides for the ASD1001.

One Dayton APA150 will drive two H-frame Alphas and it could be enough depending on your bass tastes. Maybe get one to start with. If you've got an extra solid state amp with good power you could save a ton using it for the H-frames with two low pass 80hz crossover ( $17 X 2 ). I do this on two of my other systems and don't feel I'm missing anything. FWIW I keep the crossover controls on the Dayton APA150s set at 80hz.

Being of Scottish decent I'm tight and love going cheap and then adding to as I see the need. I bought the Dayton APA150s before I discovered I could use solid state amps with the 80hz crossovers which function as filters and not crossovers. The APA150s do offer more flexibility with their variable XO controls and allow another preout to drive the super tweets independently from but it costs.

You're gonna love the Beta/Alpha OBs. They bring tears to my eyes I kid you not.

[BoJonJovi]

Sounds like a plan and thank you.

Now I need help to understand capacitor selection for this project.

If I understand correctly, a capacitor in series with a driver is a 1st order crossover.

If I connect the betas to the horn in parallel with the capacitor in series between them I should be be at 4 ohms.

If I make the crossover point say 7500 at 4 ohms, the web based crossover generators say I shuld have a 5.3 uf capacitor.

If I run the horn directly from an amp I should have an 8 ohm load. If I cross it at 2500hz as suggested in the PE webpage I should have a 7.95 uf cap. (Recommended crossover: 2.5 kHz, 18 dB/octave)

Also I do not understand the (Recommended crossover: 2.5 kHz, 18 dB/octave), particularly how the 18dB/octave figures in. Is that utilized in some formula?

If I use a 20000 hz crossover point at 8 ohm I get a 1 uf cap. Maybe that is where the crossover should be.
I am not sure I am understanding the 1 uf capacitor selection and if I have any of this right.

Maybe the over 105 temps and all the smoke in Colorado has smoked my mind. Can you help me understand some of this?
Teach me fish.

Speaker Crossover Calculators by V-Cap (http://www.v-cap.com/speaker-crossover-calculator.php)

[Poultrygeist]

You are reading too much on what others are doing in different systems, getting bogged down in terminology and making it more complicated than it is. Forget all that as mine is much simpler and mirrors a successful build on the DIYaudio forum.

I soldered one end of a 1uf cap to the + terminal of the super horn tweet and the other end to it's hookup wire and that's it. With your horns you can try going up or down a little in cap value but not much. I'd start with 1uf and go down first.

The Betas use no caps or crossovers. The super horn tweets are connected to the two extra terminal tabs on the Betas terminals ( + to + and - to - ) and your amp will see a 4ohm load which class D amps like. You will need to buy blue crimp-on female connectors as all the drivers use the same size.

If you use a single amp for the super tweets you will still use a 1 uf cap on the + terminal and the Beta will present an 8 ohm load.

The Alphas each need a 8 ohm low pass 80hz crossover from PE if you use a regular amp and nothing if you get the Dayton APA150 with built in crossover controls.

If you aren't using a preamp with two outputs then you can still split the CD player's analog output signals and share it between the two amps. If using a third amp ( for tweeters ) the digital signal from the CD player needs to be converted by a DAC to analog before passing it to that amp. The other option would be using the Dayton APA150's preouts to feed the 3rd amp.

In another system I use an old Denon AV receiver ( built in DAC ) which takes the digital signal from the CD player and converts it to analog and drives the OB Alpha woofers.

This build takes 4 to 6 pair of binding posts which can get pricey at PE. I buy mine by the pack at Lowes. They are high quality and designed to be used in keystone wall plates and I just break off the plastic keystone keeper. They accept banana plugs and have a set screw for the hookup wire.

.

[BoJonJovi]

Thanks Poultrygeist
My email signature ends with "I suffer from analysis paralysis".
I pulled the pin and sent my order.
I ordered a set of each of the caps you suggested.

I really appreciate the help.

You have been awesome!

[Poultrygeist]

You are certainly welcome. Let me know how it goes.

[Poultrygeist]

BJ,

You will be driving the 98 db Betas with lots of power although the ratings on those class D amps has always seemed inflated to me. My Sure 100X2 is in reality about 20X2. I drive the Betas with 3.5 watts ( SET running in class A ) which will play them very loud. You probably won't get above 9 o'clock on your class D with the Betas.

The Alphas on the other hand and despite their high efficiency will take lots of power. I know one guy on another forum who drives his H-frames with 250 watt plate amps.

[BoJonJovi]

Any recommendations for baffle size? The dimensions seem to be all over the place.

I have been reading a little bit abut Tone Tubbys and Alnico OB. Not really full rangers but they might make some pretty cool speakers, particularly for blues. Maybe down the road.

[Poultrygeist]

The H-frame dimensions aren't so critical as long as you get the Alphas fairly close to the floor. My H-frames are a cube measuring 17 inches on the insides. 3/4 ply or MDF works well. The baffle is mounted in the center of the cube. The bottom of the inverted T should be the same size as the H-frames. My top baffle is 24 inches high. I used that size as it worked with the half sheet I had on hand.

My Beta is centered about 9 inches down from the top and 7 inches over from the short side. I think it may be better to drop it another 1.5 to 2 inches so the tweeter could then come down to normal ear level depending on the chair you listen in. My chair sits high and I'm tall but you might want to get the tweeter down a little. You can adjust these as you see fit or defer to what MJK uses in his OB papers.

I'm sure you have a router but you may not have a Jasper jig for hole cutting. Buying both sizes is worth the investment but there are probably other options out there that I'm not aware of.

[Poultrygeist]

These OB's have helped me make the leap from high dollar commercial builds with all their hype and bling to what really counts in audio and that's the music. It will allow you to get the highest level of enjoyment without spending a king's ransom. It will not impress with it's looks but it will impress with it's sound. Once you listen to them every box speaker will come off limited, directional, compressed and boxy sounding. I'm so spoiled I keep trying to improve the Tektons ( my last pair of monkey coffins ) which have about reached their point of diminishing returns.

[Poultrygeist]

The 3 way tri-amped OBs look nicer when the lights are low but don't we all?


http://gallery.audioreview.com/data/audio/500/medium/P7140010.JPG

[Poultrygeist]

http://gallery.audioreview.com/data/audio/500/medium/P7140004.JPG

[Poultrygeist]

http://gallery.audioreview.com/data/audio//500/3Way1.jpg

[Poultrygeist]

If using thicker 3/4 plywood or MDF then you should increase all 17 inch dimensions above to 18 inches. The Solenium ST2000 should be Solenium ST200.

[Poultrygeist]

I didn't realize that the $4,000 Emerald Physics CS2.3 open baffle speakers use the same Eminence drivers as these < $400 3 ways............. but the Emeralds aren't tri-amped.

6moons audio reviews: Spatial/Emerald Physics System Review (http://www.6moons.com/audioreviews/emerald/1.html)

[Poultrygeist]

A friend at AC built these after being inspired by mine. He's a true craftsman with great wood working skills and loves the sound of these OBs. He went with the more expensive Eminence super tweeters.


http://www.audiocircle.com/index.php?action=gallery;sa=view;id=81976

[Poultrygeist]

Here's his system. He uses a SET to drive the Betas and dual high power plate amps for the Alpha H-frames. Notice all the matching wood.



http://www.audiocircle.com/index.php?action=gallery;sa=view;id=81977

[Poultrygeist]

I just ordered a pair of Bohlender Graebener Neo 3 planar tweeters to try with the OBs. I'll need to remove their back cup for them to radiate in both directions. I was reluctant to buy them at first as they are 4 ohm and the Dayton DTA 100 is not recommended for 4 ohm loads. Then I discovered that my Topping TP21 is rated for 4 ohm speakers. I'll swap the Dayton for the Topping which is currenting driving a pair of compression horns on top of the Tektons. The German B&G's I purchased on ebay are shipped from China but what else is new?

Bohlender Graebener Neo3-PDRW Planar Tweeter w/Back Cup 264-735 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-735)

[Poultrygeist]

In preparation for use in open baffles here I'm prying off the back so these planars can radiate to the rear.

http://gallery.audioreview.com/data/audio/500/medium/P9110003.JPG

[Poultrygeist]

The planar configuration is the same for front and back but since most people use these in conventional enclosures they ship with backs glued on. They are certainly worth the minor surgery.

http://gallery.audioreview.com/data/audio/500/medium/P9110005.JPG

[Feanor]

The planar configuration is the same for front and back but since most people use these in conventional enclosures they ship with backs glued on. They are certainly worth the minor surgery.
...
I used this tweeter in a center channel speaker I made a few years back; the result was very good although my speaker is monopole. Removing the back ought to work well, though.

http://gallery.audioreview.com/data/audio/500/medium/199052DIY_center_channel.jpg

[Poultrygeist]

Good work Bill I know yours sound good. They've gone up in price at PE but I was patient and ordered them from China. Here they are mounted atop the OBs.

http://gallery.audioreview.com/data/audio/500/medium/P9110006.JPG

[Poultrygeist]

http://gallery.audioreview.com/data/audio/500/medium/P9110004_2.JPG

[Poultrygeist]

http://gallery.audioreview.com/data/audio/500/medium/P9110008.JPG

[Feanor]

Good work Bill I know yours sound good. They've gone up in price at PE but I was patient and ordered them from China. Here they are mounted atop the OBs.

http://gallery.audioreview.com/data/audio/500/medium/P9110006.JPG
Looks good!

[Poultrygeist]

After experimenting with different mountings I think I've finally found the one where the Neo 3 planar tweeters sound the best. I settled on this simple lollipop mount with no mounting legs to influence the rear wave.

http://gallery.audioreview.com/data/audio/500/medium/PA010001.JPG

[Poultrygeist]

http://gallery.audioreview.com/data/audio/500/medium/PA010002.JPG

[londo1dw]

I've lost the specific thread, but I remember you offering to share your plans for your take on Martin King's H-frame OBs. Of course, your tri-amped version is also of great interest. I'm a newbie on audio review, but I've thoroughly enjoyed following your adventures in the OB world.

[Poultrygeist]

WOW it looks like all the pictures evaporated from this thread???

My Beta/Alpha H-frame OB's have continued to evolve but the basics are unchanged. The H-frames are an open ended cube with all interior dimensions measuring 17 inches. Martin King's is a little larger as he uses an 18 inch woofer rather than the 15 inch Eminence Alpha 15A. His dimensions can be found at his quarter wave website.

The Alpha is mounted in a 17 X 17 inch flat baffle in the exact middle of the cube. The inverted T which rests atop the H-frame is 24 inches high and the width of the H-frame. I used that height as I had a half sheet of MDF on hand. My Beta 12LTA's center is mounted 15 inches from the bottom and 7.5 inches from the side. If I build it again I'll drop it down from 15 to 14 inches.

The tweeter center is 4.5 inches from the corner. I plan to replace the in-baffle super horn tweeter with the B&G Neo 3 planar tweeter which currently sits above the Beta on a lollipop stick mount.

I still use the 2a3 Bottlehead mono block SET to drive the Betas but now use two 300 watt class D plate amps to drive the Alphas ( Yung SD300 on sale at PE for $99 ). The 300 watt plates are way more than I need so the Yung SD200 would work fine.

Plate amps if you don't know are replacement sub amps. I cut a 4 inch pine board in sections to make the frames they rest in and added binding posts on the rear which connect to the H-frames via speaker cables. I show some pictures of them over at AK under the modern gear section.

The Neo 3 tweets are being driven by a Topping T-amp but I plan to try them with a Miniwatt SET to see how they sound.

A major improvement came from moving to an active crossover. I now use a Behringer CX2310 two way to handle the crossover for the Neo tweets and the Beta mids. I discovered that by depressing the 2310's frequency x10 button I went from high to low to high to mid range. The Alphas use the plate amp crossovers which is a better choice. I tried a Behringer 3 way but couldn't get it to sound right so I returned it. The cheaper CX2310 is transparent in my system.

I've received several PM's from very happy AK members who have built this OB. The general comment seems to be "they sound so much more open and alive compared to box speakers". One guy at AK said the "Alphas in the H-frames are the best reproducers of natural sounding bass he's ever heard" and he's heard a lot.

Another great advantage of OBs is the ease in which they can be built. If Poultry, who has never built a birdhouse, can do it anyone can.

The straight cuts can all be done at Home Depot so the only thing left is the driver holes which can be done with a drill and a jig saw but better still with a router and Jasper circle guide.

[Poultrygeist]

I guess there's no reason to post pictures or anything else here anymore.