JBL Open Baffle & Horn speaker OKOB

Well :)
Lets start with a picture.

JBL OKOB.jpg
 
Parts:
The two bottom woofers are JBL 2226H.
The one at the top is JBL 2220H.

Horn is JBL 2360 with JBL 2446H driver.
The driver has the standard ribbed titanium diaphragm.

Tweeter is JBL 2404H.

All is crossed by passive filter so it can be used with only one amplifier.

JBL OKOB Crossover.jpg
 
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Crossover:
The 2226`s are crossed under dipole peak, just filling in to the 2220.

The 2220 has no high pass filter, just playing down as low as it can.
It crosses at about 700 to the 2360/2446.

2360/2446 plays from 700-7k where the tweeter 2404 take over.
 
Amplifiers:
Since the OB & Horn speaker is quite efficient these speakers can be run with low wattage amplifiers.

Preamp is an Musical Innovation MI16.

I have two power amps.
Musical Innovation MI10 2x15w class A Push Pull. This is built into vintage Electrocompaniet enclosure.

The other is an choke zen like amplifier. This is built into an FW look alike enclosure I bought in ebay. Don`t know if it is piracy, if so I am really sorry to mr.Pass.
Did not think of it when I bought it.
The inside is not similar to FW, it is as my passive filter, a rats nest......
 

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Here is schematic of mye diy amplifier.

It is quite inefficient. I have to use an 8ohm resistor on the speaker output to get it sound good with my speakers.

I think this will bring about 2w to each speaker.....
It is enough for normal listening :)
Gain is also quite low.

Afraid of blue LED`s? I use 1Mohm in series with the blue LED`s and it`s quite ok.

The goal of the amp was building something that need very few parts.
The chokes cost some money though....cheaper to build FW F2.


On the positive side the chokes bring down the temperature.
 

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Thnx argotic & Zen :)


Well...why not active....?
I wanted to learn passive, so it got passive all the way.
And I have learned a lot!
And I do only need one amp :)

For full active I need four amps.
If going for DSP I want the Groundsound DCN 28.
Ground Sound
This is quite expensive.

for the time I play with passive. Got the parts used and cheap.
And I`m quite happy with it.

The thing I miss the most not having DSP is delay.
The horn driver is long way back compared to the bass and tweeter.

Also the crossover between 2220 and 2360 could hav been a little nicer done active.
The 2360 horn has som impedanses around 7-800 that is esaier to deal with in an active system.




Best
oks
 
The speakers is original a JBL 4675C from a cinema.
I bought three of these speakers for about 1,5 year ago.

The result is what is today.

In the beginning I ran as is, biamping using miniDSP 2x4.
The bassreflex enclosures from the original system is not good, quite resonant.

The Open Baffle idea is based on some other speakers in Norway.
I built the baffles almost one year ago, and used 3x2226 in the beginning.

If using three 2226`s only need to remove 10ohm resistor that is on the JBL 2220.

The 2220 sounds better than the 2226 in the 200-700 region so thats why I use it.
 
The 2360 is a CD horn (Constant Directicity)
This means that it spread the sound in more constant direction vertical and horisontal.

It starts beaming about 10khz.

In the lower region it has som impedanses.
This brings some growl that can sound cool.

I have tried the BMS 4590 coax driver into it, from 400hz and all the way up.
It is an ok way to go if want only one horn.
But using the 2446 from 700-> and add a tweeter is better.

Have also tested JBL 2410 small format driver in the 2360.
2410 sounds very nice from 2k-10k.
I crossed it at about 1500.
But using small format 1" driver it needs adapter.
This adds length to the already long throat and causes some issues.

I have tested aquaplas diaphragm in the 2446. If using the driver high, aquaplas dampens the ringing and resonanses above 7k.
When using tweeter I didnt find the aquaplas to bring any advantage over the standard ribbed ti diaphragm, so I sold the aquas.

Could test the alu diaphragms (2441), but I am quite happy with the standard diaphragms.