This tweeter is super!

[Poultrygeist]

You older guys may remember this add on super horn tweeter from Radio Shack. It is said to be made by Fostex and based on it's quality construction I can believe it. It gives that nice top end ssssparkle and hi-hats have never sounded better with my open baffles. Posting pictures here is hit or miss for me so bear with me.



http://gallery.audioreview.com/data/audio/500/medium/PA210007.JPG

[Poultrygeist]

http://gallery.audioreview.com/data/audio/500/medium/PA210009.JPG

[Poultrygeist]

http://gallery.audioreview.com/data/audio/500/medium/PA210005.JPG

[Ajani]

Are you running the driver in the center "fullrange" and using some kind of crossover(s) on the supertweeter and bass driver?

I think that setup is the reason why some persons prefer the name "wideband" to "fullrange" for drivers... Cuz it does sound funny to augment bass with a 15 woofer and treble with a supertweeter, if the driver is "fullrange"... It took me awhile to understand what benefit such a setup could have over a typical threeway design... I am fascinated with the concept though and hope to assemble, or at least audition, such a system some day...

Also are you using the same amp to run the Supertweeter and the widebander?

[Poultrygeist]

Ajani,

Unlike 99% of the speakers discussed on this forum there are no passive crossovers in this system. The 15 inch full range bass drivers are powered by Dayton/Emo monoblocks which have active crossover controls that I set at 80hz. The middle Tang Bands are driven by Paramour 2a3 monoblocks and they run full range. The horn super tweeters have two small caps that filter out all but the very high fequencies and connected in parallel, share the Paramours with the TBs. What we have here is a 3 Way that is quad amp-ed ( 6 drivers driven by 2 pair of monoblocks ). I tried driving the tweets with a Topping t-amp which worked great but I didn't feel like tieing up the t-amp when at 98db the tweets take nothing away from the Tang Bands.

Passive crossover networks are the sound destroying, power sucking, bottle necks that prevents drivers ( wide band or not ) from operating full range. Getting rid of passive crossovers in a system makes all the difference in the world. Wide banders/full rangers like all other speakers are a compromise but they do produce a superior frequency range vs purpose built drivers.

We can achieve good bass from large full range box speakers but OB's are another story. Open baffle speakers are known for their "live dipole sound" but like planers they are bass shy. The large 15 inch bass drivers produce more realistic bass than I've ever heard from a sub.

To some on this forum these Open Baffle 3 ways may appear crude but I'd put them up against anything out there. I've never heard a commercial speaker at any price sound like these. My Zu's have been relegated to HT duty as the OB 3 ways now rule the 2 channel roost.

[Ajani]

Ajani,

Unlike 99% of the speakers discussed on this forum there are no passive crossovers in this system. The 15 inch full range bass drivers are powered by Dayton/Emo monoblocks which have active crossover controls that I set at 80db . The middle Tang Bands are driven by Paramour 2a3 monoblocks and they run full range. The horn super tweeters have two small caps that filter out all but the very high fequencies and connected in parallel, share the Paramours with the TBs. What we have here is a 3 Way that is quad amp-ed ( 6 drivers driven by 2 pair of monoblocks ). I tried driving the tweets with a Topping t-amp which worked great but I didn't feel like tieing up the t-amp when at 98db the tweets take nothing away from the Tang Bands.

Passive crossover networks are the sound destroying, power sucking, bottle necks that prevents drivers ( wide band or not ) from operating full range. Getting rid of passive crossovers in a system makes all the difference in the world. Wide banders/full rangers like all other speakers are a compromise but they do produce a superior frequency range vs purpose built drivers.

We can achieve good bass from large full range box speakers but OB's are another story. Open baffle speakers are known for their "live dipole sound" but like planers they are bass shy. The large 15 inch bass drivers produce more realistic bass than I've ever heard from a sub.

To some on this forum these Open Baffle 3 ways may appear crude but I'd put them up against anything out there. I've never heard a commercial speaker at any price sound like these. My Zu's have been relegated to HT duty as the OB 3 ways now rule the 2 channel roost.

It may look crude but considering that audio pioneers like Nelson Pass use similar designs, then there must be some real merit to the sound quality...

I love the idea that you can build such a pair of speakers in stages! Start with just the Tang Bands in an OB, then add the bass drivers and finally the supertweeter...

+ you always have the option of building a more attractive baffle with an exotic wood veneer later on... I've seen some really attractive looking OB designs on DIY sites (also seen some that look like true Frankenstein creations)...

Quick question what frequencies do the bass drivers and supertweeters kick in? I'm guessing somewhere outside of the range our ears are most sensitive to...

[Poultrygeist]

The tweets start at 5,000Hz but extend to 40,000Hz which is perfect for bats. The Alpha's most practical range is 46Hz -3.5kHz but I cut mine off at 80Hz. I listen to jazz 90% of the time and the lowest note on a bass violin is E ( which is very rarely played ) and it reaches down to 41 Hz but my Alphas cover it.

[salad 419]

Since I missed the rest of your build (and I'm probably too lazy to search), are there any design/engineering concerns when building the "stand/board" for the "mid-range"?

I saw the H design for the subs, but missed the TB build.

This may be a fun project for the future.

[Poultrygeist]

Not really sal. The upside down T or stand/board as you call them is nothing more than 3/4 plywood joined with pocket hole screws and glued. The Tang Bands are mounted slightly off center. I cut the round piece of ply, left over from their hole, in half and made shelves for the tweeters. The stand/board is not connected to the H-frames but rests on foot pads. I'll soon be building another pair of H-frames for my 4.5 Tektons and/or Frugal Horns and will see how H-frames sound stacked two high. Others have done so with excellent results but it makes for one hell-of-a-large speaker. The flexibility of this design allows one to try a huge variety of full ranger drivers in the stand/board. If I hadn't already bought the Tang Bands when they were less expensive ( now costs $500 a pair - ouch! ) I would have sprung for the Dayton 8 inch Point Source Neo Drivers which are currently on sale at PE for slightly under $100. On the AC OB board ( where more details of this build are posted ) I see where folks are replacing their prized German Visaton b200's with the Daytons.

Let me remind folks that I have little to no carpentry skills and taught myself to use a router just to cut driver holes but a jig saw works fine. I hate cutting plywood so I get the guys at Home Depot to make all my cuts before I take the stuff home. I believe a twelve year old could build these 3 Way OB's.

[salad 419]

Excellent. I'll check out the AC OB forum.

The reason I was asking is that I didn't know if there was a reason other than aesthetics for your offset drivers or if there was some magical formula for the shape of the T/stand/board (what is the technical term so I don't sound like such an idiot?). It seems like there is flexibility also in the design to show off woodworking skills or try to match a design element in a room. I have no creativity or skills, but some folks do.

If the Daytons are proving to be a winner with this design, it makes a build even more likely.

Thanks for the info.

[Poultrygeist]

The mid drivers I've seen in this design are always off set toward the inside and a little closer to the top than the bottom. My mid baffles measure 19"H X 18"W and the center of the Tang Band is 11" from the left side and 10" up from the bottom. I don't think these measurements are all that critical. I used black painted molding to cover the ugly plywood edges. With stained high grade baltic birch ply these could be quite handsome. Had I known how good they would sound I would have gone that route.

I would definitely try the Dayton 8 inch Point Source ( PS220 ). It's SPL is 95.6 at 1W/1M which is a little higher than the TBs but it's Qts is a little lower.

[Ajani]

I would definitely try the Dayton 8 inch Point Source ( PS220 ). It's SPL is 95.6 at 1W/1M which is a little higher than the TBs but it's Qts is a little lower.

The build quality of the Daytons looks really good... I like the spring clips... I've often wondered why more fullrange drivers don't have some type of proper binding posts on them... Being able to connect the speaker wire directly to the driver is especially useful in an OB design. Saves the need for another set of connections and wires between the drivers and the speaker binding posts...

Just out of curiosity do you have any experience with Behringer active crossovers? Specifically this model:

Behringer DCX2496 Ultradrive Pro Digital Crossover 248-669 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=248-669)

It caught my interested because it is used in several (not-cheap) OB designs by Emerald Physics:

CS2.7 (http://www.emeraldphysics.com/page21/page21.html)

[Poultrygeist]

Even with the Dayton's spring clips I'd still use regular binding posts as you don't want to hook and unhook wires that connect directly to the drivers.. just too fragile.

I have the Behringer CX2310 electronic crossover but I need to take a course in how to hook it up and use the settings. The 3 page manual that came with it is of little help.

[Poultrygeist]

Danny of GR Research ( over at AC ) says my tweeters are facing the wrong direction. I tried them facing backwards but cymbals go tink instead of ting :-) Y'all, OB guys operate is another dimension.

[harley .guy07]

I remember those tweeters. Radio shack sold them in the 80's and 90's as add ons to speakers with too warm a high end and if I remember looking at them they were real utilitarian looking and I think I even had a friend that had a set hooked up in parallel with his mach 1 speakers.

[Poultrygeist]

Actually they're pretty good with HE speakers and this simple cap upgrade.....I've seen them priced at over $100 a pair on ebay.

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

[Ajani]

I'm just curious about what the trade off would be if you had used a 4" fullrange driver instead of the Tang Band & the supertweeter... I've seen a number of OB designs with just a 4" Fostex fullrange and Eminence 15" bass...

EDIT: Looks like that design is an older Martin J King design as well:

http://www.quarter-wave.com/OBs/OB_Design.pdf

[Poultrygeist]

Mounting the Alphas in H-frames is a newer design than using them in the same flat baffle shared with a smaller driver. I think I'm the second person to do the Tang Bands over the H-frames and was flattered when speaker genius MJK asked me to post pictures in his quarter-wave gallery with a build narrative.

The Tang Band W8-1808 really doesn't need a tweeter but I just like that little bit of metallic sparkle especially with brushed cymbals. The 4.5 Fostex driver can go it alone in the upper frequencies and while they have wonderfully detailed point source imagery they can come off a little thin compared to the 8 inch Tang Bands ( and probably the 8 inch Daytons as well ). The TB's are the smoothest and easiest to listen to drivers I've heard. Their price, unfortunately has risen through the roof.

Providing separate amplification and avoiding passive XO's for all my drivers and being able to control them has not been easy. I take the optical out from my CDP and pass it to a volume controlled DAC then take the analog from the DAC and feed it to the Dayton/Emo mono-blocks which are daisy chained together and power the H-frames. The preamp gets the analog signal from the same CDP and feeds the Paramour mono-blocks which power each separate channel for the Tang Bands and tweets.
I have ordered two low pass XO's to try with my next set of H-frames so I can get some use of my old ss gear collecting dust in my attic. I don't think solid state bass suffers as much from the evils of a passive XO.

I would like to incorporate my TT in the mix but yet have not been able to come up with a solution. While my pre has two outputs it's down on gain when both are used. The CJ pre ( had to give it back ) had plenty of gain for both outputs but it allowed for limited control of the H-frames.

[Poultrygeist]

Yesterday I sold the Zu's. That should speak volumes as to how highly I regard these home brew OB's.

[E-Stat]

The horn super tweeters have two small caps that filter out all but the very high fequencies
What you describe is a passive crossover. The tweeter in my Advents also use two capacitors in its crossover network. Originally, there was one 13 uF electrolytic, but I replaced that with a new 12 uF electrolytic (to maintain the voicing) along with a 1 uF film cap to soften the top.

rw

[Poultrygeist]

In the strict sense of the word yes but my main drivers are unaffected and run full range. Do those Advent multi-drivers run range?

[E-Stat]

In the strict sense of the word yes but my main drivers are unaffected and run full range. Do those Advent multi-drivers run range?
Since it's a two way, there's only one more driver to speak of - the woofer. Since the 10" woofer operates up to 1.5 khz, there is little need to suppress its output beyond that frequency. Yes, there is an inductor in the circuit and a resistor to match disparate output levels.

I fully agree with you as to the value of what a true full range speaker can do - as that is exactly what the Sound Lab U-1s are. A single large diaphragm is used full range with uniform output from top to bottom. Unlike four or five inch cones, they are capable of solid response from 25 hz to over 20k. It is for that reason I have used full range electrostats for over thirty years. I highly value their coherency and transient response.

rw

[Ajani]

Yesterday I sold the Zu's. That should speak volumes as to how highly I regard these home brew OB's.

Now I'm really glad I never pulled the trigger on the Zu's, since both forum members who tried them have now sold them...

I've been investigating MJK OB designs and am convinced that this is the way to go for my 1st DIY:

http://www.quarter-wave.com/Project09/Two_Speakers.jpg
Project 9 : Eminence Alpha 15A Experimental Open Baffle Design (http://www.quarter-wave.com/Project09/Project09.html)

Not the modular design (yet) but the combination of FE-108E Sigma & Eminence Alpha 15A with an active crossover in a 20" wide by 38" tall OB speaker system.

I'll start with getting the Fostex and playing around with them in my existing Technics enclosures (they should fit where the 4" Technics midrange drivers are). Should be fun.

[Poultrygeist]

My Zu's were exceptional speakers but I could not justify ownership when these OB's IMO are clearly better in every respect.

Ajani,

If you bi-amp that combo and use active crossovers you will not want for a better system.

I'm thinking of buying this stand alone bass amp with built in active crossovers to power the Alpha 15A's while it's on sale.

Dayton Audio SA230 230W Subwoofer Amplifier 300-813 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-813&FTR=sa230%20230w%20subwoofer%20amplifier)

[Poultrygeist]

Check out these nice sounding OB's vs BL Horns on youtube

Open Baffle Speakers vs Back Loaded Horn - YouTube (http://www.youtube.com/watch?v=MHeyPJS00Fc)

[Ajani]

My Zu's were exceptional speakers but I could not justify ownership when these OB's IMO are clearly better in every respect.

Ajani,

If you bi-amp that combo and use active crossovers you will not want for a better system.

I'm thinking of buying this stand alone bass amp with built in active crossovers to power the Alpha 15A's while it's on sale.

Dayton Audio SA230 230W Subwoofer Amplifier 300-813 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-813&FTR=sa230%20230w%20subwoofer%20amplifier)

This project looks like a great way to use the Emotiva XPA-2 I have lying around - that 300 watt beast should be an ideal bass amp for the Alpha 15A's...

+

I've been undecided on whether to buy towers (which I prefer) or monitors (since I've tended to change country every few years and portability is key). The advantage of this build is that I could just take the drivers and dump the plywood if I move. So I'd get towers that are portable...

I'll definitely get the Fostex to try out and if I see some promise in the results, I'll go through with the whole build...

[Poultrygeist]

The Emo will do the but you will need a Behringer active or a two 80hz low pass XO for the Alpha's. Even though the low pass XO's for the Alpha's would be passive they will have no effect on the other drivers as they are driven separately.

Choose a Fostex with a high Qts. ( .5 or higher is desirable for optimum OB sound )

[Ajani]

I plan to get the Behringer DCX2496 Ultradrive Pro Digital Crossover. And my choices for Fostex are either the really cheap (and disposable) FE103En 4" Full Range (used in MJK's original design) or the FE108EZ 4" Full Range Sigma Series (MJK's current favourite for this design)...

I think my only concern right now is whether this system will have sufficient bass... I would love to see some designs with dual Alpha 15s, as the height of the speaker would not even need to be altered to accommodate the additional driver...

[Ajani]

Did a search for OB with dual Alpha 15's and found that the Emerald Physics CS2.3 (speaker I got the inspiration for the Behringer Crossover from) uses twin Alpha 15's. It has the following spec:

Frequency Response: 20Hz - 22kHz -3dB (with DSP correction)

CS2.3 Specs (http://www.emeraldphysics.com/page9/page17/page17.html)

So it seems really good bass is possible with dual Alpha 15's in an OB...

Also I would be using the same dual bass drivers and active crossover as in a $5K pair of speakers (I see why DIY folks get so excited about cost savings)... Of course the big difference in my build and their design is that I'd use a fullrange 4" Fostex while they use a Eminence Beta-12CX 12" Coaxial Driver with a Selenium D220Ti 1" Titanium Horn Driver.... + their Baffle is not made (exclusively anyway) of the kind of cheapy plywood I'd be using....

6moons audio reviews: Spatial/Emerald Physics System Review (http://www.6moons.com/audioreviews/emerald/2.html)

[Poultrygeist]

With two 15 inch full range bass drivers of 98db sensitivity you will have high quality and plentiful bass. And unlike most subs the Alpha's bass is very musical. Although I now have four Alpha's I haven't felt the need to try them all in the same system. But for kicks and giggles I may.

[Ajani]

Of interest is that I added up the total cost of drivers and active crossover (assuming dual Alpha 15's) and it is only $30 less than the cost of drivers and active crossover for the Emerald Physics CS2.3 (I mentioned earlier)... So in theory I could build my own version of the CS2.3... Though I'd rather stick with MJK design...

[Ajani]

With two 15 inch full range bass drivers of 98db sensitivity you will have high quality and plentiful bass. And unlike most subs the Alpha's bass is very musical. Although I now have four Alpha's I haven't felt the need to try them all in the same system. But for kicks and giggles I may.


Let me know how it turns out and whether it sounds better or worse than just using a pair of Alpha 15's...

[Poultrygeist]

I have no doubt my home spun OB's would go toe to toe with those Emerald Physics. My main drivers are better and the Alpha's are equal. They bi-amp that design while I quad-amp mine. Anyone who would pay that much for the Emeralds would probably need the four Alpha's for their banquet hall.

[Ajani]

I have no doubt my home spun OB's would go toe to toe with those Emerald Physics. My main drivers are better and the Alpha's are equal. They bi-amp that design while I quad-amp mine. Anyone who would pay that much for the Emeralds would probably need the four Alpha's for their banquet hall.

How is the bass on yours? I'm getting confused because some persons claim to have experienced very little bass response using the Alpha 15's in OB... Though I think most (if not all) of those persons used tube amps to drive the Alpha's, while SS is recommended by MJK...

If the bass is good with a single pair of 15's, I probably wouldn't bother with the dual pair (I like bass but I'm not obsessed with it and don't need to fill a huge room with sound)...

[Poultrygeist]

In one set up I drive two Alphas with solid state mono blocks of 150 wpc and I'm only using slightly over a quarter volume at normal listening levels

In the other set up I power two Alphas with a JVC RX-D205 AVR digital amp in two channel mode which makes 110 wpc and I can't go above half volume comfortably. I tried selling the JVC on CL for $75 but thank goodness no one was interested. It now has a useful purpose in life! Older AVRs are a good and cheap choice to drive the Alphas as their internal DAC allows use of the optical connection from a CD player while the analog outputs from the same CD player can be fed to the tube preamp or integrated amp.

The Alphas would sound anemic with my tube amps but tubes are divine for the main FR drivers. In my home office which is about 13 ft X 15 ft I could get by with only one Alpha.