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Old 31st May 2002, 07:04 PM   #1
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Default DIY JBL 4 Way Sound Reinforcement

I have been looking at the posts in the loudspeaker forums, some very interesting projects and clever people out there.
Currently halfway through a large speaker project for my self, personally not so into home audio addictions but prefer something for a few more people to hear.
If anyone wants to know about this project and problems and good parts could they offer advice? If it is a turn off I will understand!

Thank you

Dave
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Old 31st May 2002, 07:13 PM   #2
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Default Group Addictions ?

Ummm, need more details before we can make that decision.

Regards, Eric.

PS - There are pro-sound guys here.
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Old 31st May 2002, 07:15 PM   #3
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PPS - Not all clever people are 'out there'.
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Old 31st May 2002, 10:33 PM   #4
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Default JBL Sound Reinforcement more info.

4 of JBL 2226j low/sub bass vented enclosures

2 of JBL 2206h in top cab design, a pair of these cabs, also containing ( or loaded! don't you hate that pro audio term?) with 2380a horns (90x40 nominal coverage).

Attached to horns jbl 2446j 2 inch throat compression driver.

Very high frequency 2404h bi radial 100x100 coverage.

I am using crown K2 on bass. (2500w 4 ohms)
I am seaching for suitable mid amp. (1200w per side into 4 ohms needed).
Qsc ex 1250 on compression drivers. (300 a side 8 ohm).
H and H mx 250 on 2404 bi radials. (80 a side into * ohms).

This system will be stereo, currently testing with dreaded behringer cx 2300 in mono. Botom cabs have been made in mdf as a temporay test four seperate enclosures tuned to 40hz.

Top cabs are being made in birch ply by cabinet maker,should be going to see them tommorow. Details of bracing and port sizes not finalised. Calculations done on win isd.

I have a few concerns about the sound quality I could end up with, I have tried to steer clear of cheap and nasty bits.

Is this of any Interest?
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Old 31st May 2002, 10:37 PM   #5
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Default JBL Sound reinforcement

ps.

Thanks Mr Feedback

You're on the other side of the world, nothing like local help!

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Old 31st May 2002, 11:27 PM   #6
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Dave,

This is a breif on-the-run type post, which I'll add to later tonight. I'm very familiar with the 2226 and 2445/2446/2380A series' (I have 6 pairs of these).
How low and loud do you want this thing to go?

In the meantime, have you seen these?
http://www.audioheritage.org/html/pe...ues/system.htm
http://www.audioheritage.org/html/pe...audiophile.htm (home system but interesting)
http://www.geocities.com/loudspeakerguru/ ( a LOT here in multiple pages. Jeff knows his stuff)

Tap Eric's brain, he's very experienced and knowledgable. But do it now as he's getting a bit old and senile. Reasonably nice too for a sandgroper.

hehehe
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Old 1st June 2002, 12:00 AM   #7
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Default JBL sound Reinforcement

Thanks Brett

That audio heritage site is so large, I hadn't found these articles!

Dave
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Old 1st June 2002, 12:44 AM   #8
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Default JBL Sound Reinforcement

How Loud and Low?

In a small to medium sized bar or club this ain't enough bass, will have to do on current budget.

I have used these bass cabs for a party once, here is a quote from a unknown guest.

Guest: How much 'k' have you got.
Lee (party helper): Well that amp is 2.5k (crown with ioc flashing)
Guest: Sounds more like 1.8
Lee

Have had stern words with 'experts' who think these drivers are poor, of course low frequencys will be at the expense of volume to some degree, would like to lower fb and increase number of drivers in the future.

Wn isd gives 134db for four of these at one metre but that does not take into account power compresion, port losses and driver excursion. In fact that last statment might be total bs I have no measuring equipment bar a multimeter!

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Old 1st June 2002, 03:29 AM   #9
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"In a small to medium sized bar or club this ain't enough bass, will have to do on current budget. "

Hmmm, that sort of setup ought to cut it good enough and loud enough - it used to in the late eighties for pub rocknroll.
There is no real sustitute for lots of drivers and amplifiers if really high power lows is what is needed - only it gets costly.
Maybe hire some extra lows cabs for a show and see if this is the soloution.

IME to get the most and cleanest for all the audio bands is to use 4 wire power extension lead wired as star-quad, ala Canare loudspeaker cable.
This will help to get that extra dB or two clean, reduces driver dissipation, and reliability.
Be sure that all cables are wired in the same direction.
RC networks across the driver voicecoils will clean things up, allow amps to deliver more power, improve reliablity, and improve sonics overall.

Regards, Eric.

BTW - who is this Brett character ?
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Old 1st June 2002, 09:01 AM   #10
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Typo - "This will help to get that extra dB or two clean, reduces driver dissipation, and INCREASES reliability."
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