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Open Baffle Epiphany!

Poultrygeist said:
I'm tempted to get these Maggie's specially designed for Wurlizer. They look to be in great shape.

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Someone please try the versions made for organs. I gotta think speakers made for very expensive tube organs were held to a higher standard than home console speakers.

Many tube guys believe that organ tubes offer superior sonics compared to regular tubes.
 
I finally obtained a second 4 ohm 49cz Zenith to complete a pair.
I replaced the Magnavox 12's in the baffle with these.
I'm also using an open back paper Maggie 4" tweeter with them. I wired them in series for an 8 ohm load.
They are a big improvement over the Mag. 12's. The Mid's are outstanding. I have not soloed them without the high-end help yet, but they sound pretty darn good this way.
I did try them without the Alpha's and they were rather thin on the low end.
 

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essNeff said:
I finally obtained a second 4 ohm 49cz Zenith to complete a pair.
I replaced the Magnavox 12's in the baffle with these.
I'm also using an open back paper Maggie 4" tweeter with them. I wired them in series for an 8 ohm load.
They are a big improvement over the Mag. 12's. The Mid's are outstanding. I have not soloed them without the high-end help yet, but they sound pretty darn good this way.
I did try them without the Alpha's and they were rather thin on the low end.
Click to expand...


To my ears the Zeniths sound good without the Alphas probably because I primarily listen to small group acoustic jazz where the lows rarely reach the low 40's.
 
I was playing the Zenith's with a Mag. Tube amp that rolls off on the bottom end so that could be part of it
The baffle is kind of narrow as well.
 
Poultrygeist said:
Someone please try the versions made for organs. I gotta think speakers made for very expensive tube organs were held to a higher standard than home console speakers.

Many tube guys believe that organ tubes offer superior sonics compared to regular tubes.
Click to expand...

I'm pretty sure I just bought these exact "Magnavox for Wurlitzer" speakers. I've got to slow down, my wife will kill me when she finds out. :)

The magnavox's thick ribbed cones appear similar to the zeniths (though they seem to be much thicker than the ribs on my Zeniths) Maybe the ribs will prove to be something we should look for when searching out vintage full rangers for open baffle use. Should be a fun and interesting shootout.
 
The highly sought after Mitsubishi Diatones were inspired by the ribbed cone alnico Zeniths. They only came in smaller sizes and these are 6 inches.

diatone-p-610ma_2.jpg
 
jelly_bean said:
I'm pretty sure I just bought these exact "Magnavox for Wurlitzer" speakers. I've got to slow down, my wife will kill me when she finds out. :)

The magnavox's thick ribbed cones appear similar to the zeniths (though they seem to be much thicker than the ribs on my Zeniths) Maybe the ribs will prove to be something we should look for when searching out vintage full rangers for open baffle use. Should be a fun and interesting shootout.
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The advantages of buying raw drivers vs complete speakers is they cost less and take up less space which makes them easier to hide. :D
 
G'day all,

am planning first OB self-build.

Any opinions on the material or panel thickness of your beloved OBs? Don't think MJK references to this.

FB
 
Poultrygeist said:
The advantages of buying raw drivers vs complete speakers is they cost less and take up less space which makes them easier to hide. :D
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So true! I'm building a shelf in the garage to stash all my drivers that are not in service. Keeps them out of the way, and keeps them safe. It buys me at least a few weeks before anyone finds out I've added to my stash. :)

Doing my research on those Maggie (Rola, cleveland, jensen, etc) organ speakers, I found that some of them came in pairs with a ribbed cone for lower frequency and a smooth cone for mid/high frequency. Then, I also found that some of the ribbed cones did service as a full ranger. I guess we will find out. But those ribbed cones sure look a lot like those good Zeniths...

fordiebianco said:
G'day all,

Any opinions on the material or panel thickness of your beloved OBs? Don't think MJK references to this.

FB
Click to expand...

I'm no expert, But I've found that 3/4 worked best for me. Easy to source, easy to work with, and cheap. I spent hours researching and realized I was just trying to find a better way to make a flat board with a hole in it. Grab a flat board cut a hole in it and see if you like it. if you do, and I hope you do, then you can source a nice piece of birch ply, and build something that looks more presentable. The great thing about OB, is you can be up and running in a matter of hours. I built the JE labs baffles with some crappy scrap plywood lying the back yard, 10" RCA alnico drivers from 1957 and lived with them for about a year because I couldn't stand turning them off. They can be THAT good.

I'm now running H frame open baffles. I'm starting to experiment with bracing my h frames to help remove the resonance from the woofers being transferred to the top baffle. I'm also planning to make a sand top filled baffle as well. You can take these as far you'd like. Its probably at the point of diminishing returns now. But to me, tweaking and playing with them is almost as fun as listening to them.

Feel free to PM me if you have any more questions, I'll help where I can. Poultrygeist is also a great source of info around here and is one of our resident OB preachers, and in my experience, is happy to help. :)
 
I've had good luck with both plywood and MDF in 3/4" thickness. A full sheet of either would be 4 ft X 8 ft which stores like Lowes or HD will cut down for you if you buy from there.

I can buy a full sheet of MDF for around $25 but the same size sheet of good plywood would cost at least twice as much. I haven't heard any resonance with either but I never play at extreme levels.

Small group acoustic jazz does not require high volumes which could excite the baffles so complex bracing and exotic sandwiched thick layers aren't necessary in my case.

Plywood advantages: easy to finish, looks good, and no toxic dust
Plywood disadvantages: costly, subject to voids in the plies, less dense

MDF advantages: low cost, more dense, no voids
MDF disadvantages: toxic dust requires a mask when cutting, difficult to finish or paint ( it's why I wall paper mine )
 
OpenBaffle-02.jpg
I believe that drivers need to be firmly held in place. (No, I have not hard data to prove the point.) Thus I used 3/4" plywood for the baffle, braced with 2x4's and plywood partial sides. This build was based on MJK's small, passive XO project; drivers are FF85k and Alpha 15a.
 
That's my thinking as well. Reducing vibration in speaker cabinets is a good thing. Should be the same with a baffle. maybe it makes a smaller difference since there is no box, but there is no harm in making things as sturdy as possible. I'm going to be making a few baffles that can take various sized drivers (8",10",12") and will be attempting to make them as rigid as possible. I don't listen loud, but I can always feel the subwoofer vibrations on the top baffle of my h frames.
 
Something interesting I've found while looking for different vintage drivers is the similarity in design between all the manufacturers.

The cones and front surround of the Magnavox for Wurlitzer drivers I just purchased look quite similar to the Zenith 49cz852,802,703 etc.

Did they copy each other? I don't necessarily think they traded designs (did they?) but it's hard to not see how similar most of those drivers are from the 50s and 60s.

Anyway, can't wait to try them out. :)IMG_2048.PNG
 
I had a similar thought. The Mag woofers I bought have a near identical cone to the 49CZ's. They do not have Alnico magnets however.
The CZ49's are very musical for so large a cone. I would guess that the paper material helps with the smoothness they display.
Not bad for 50+ year old!
 
I'm completely and totally baffled now.

I have a quad receiver and have constructed 4 small open baffle speakers with 8" Heppner speakers removed from some vintage electric organs. Space constraints limit the room I have. I use a Polk subwoofer to provide bass for my system.

I have A/B'd these speakers with some production speakers and these sound better to me.

Thanks to all posters who have introduced me to open baffle speakers.

Below are some pics... one showing the rear speakers behind my listening chair, and the other showing the fronts.
IMG_20170627_155800948.jpg IMG_20170627_155828916.jpg IMG_20170627_155920201.jpg
 
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