High efficiency 2 way - JBL 2445J CD on a 2380A Bi-Radial

Mazza

Member
2013-07-18 2:55 pm
Dear all,
I was lucky enough to recently pick up a pair each of some nice JBL 2445J CD's on JBL 2380A Bi-Radial horns in very good condition.


I want to build some nice high efficiency 2 ways with a 15" woofer. Something like the Calpamos from Humble Homemade Hifi that uses the P-Audio knock off of this JBL horn .

The Faital Pro 15PR400 woofer used in that design is available locally at $370 AUD in Aus.

However I have a line on a pair of unused Faital Pro 15HP1020 for $250 AUD each . My concern with these are:
1: These have an FS of 40hz - but I like lots of bass! and
2: there's that dip in the manufacturers measured response around 350hz - am I correct to say that is going to be an audible issue for these drivers if used in a 2-way?

Faital Pro 15HP1020 frequency response:

818534d1582208650-efficiency-2-jbl-2445j-cd-2380a-bi-radial-15hp1020_response_8-gif




The other locally available option is the Dayton Audio DC380-8 15" Classic Woofer that can be had for $220 AUD. The 1/12 smoothed response looks really pleasing to my eye and the 18hz fs should mean great bass response.

My next questions are will I hear the difference between these woofers here? Here's both modelled in a target 150 liters of cabinet volume:

818538d1582209749-efficiency-2-jbl-2445j-cd-2380a-bi-radial-woof-png




Perhaps I'm over thinking this and should just jump on the Faital Pro 15HP1020? Or should I go for the bass extension of the Dayton's?

I do like to listen to two channel music with full range deep digging bass.

I also will use these for main channel HT duties in front left and right position.

Thanks for any help here.

:cheers:
 

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Looking through the specs again. I believe the Faitalpro is actually the better one for your application compared to the Dayton. You are looking for a midwoofer and Faitalpro extends to 4kHz compared to 2kHz for the Dayton. The reason the Dayton can go so low for the Fs is because the cone is almost twice as heavy as the Faitalpro at almost 200gm. So I would believe that in terms of midrange clarity, the Faitalpro would be better. The dayton I believe is something more for bass work only. Faitalpro also has twice the xmax of the Dayton at 9mm.

You have a really good price for the Faitalpro. Normally Faitalpro speakers are not cheap.

Oon
 

Mazza

Member
2013-07-18 2:55 pm
Gents,
Thanks for the comments.

Hi Oon,
I'd not thought about the baffle step, but what you say makes great sense of course.
These 2" CD's on these horns are supposed good to as low as 500hz but I've also read that >800hz is better which is where I'll like aim for, this should also help for a smooth directivity hand off from the 15" to horn?

Hi Rob,
I just really like full range mains for music - sans subs. Don't get me wrong, I like subs....

attachment.php


Hi pelanj,
I'm an passive crossover kind-a-guy so I'll just use CD compensation Wayne Parham Pi Pad style. With efficiency to burn on this 2" CD I'm certain they'll play flat or my preferred voicing of a gently rolled off top end to well beyond where my old ears can resolve.

Any other thoughts, suggestions are very welcome.

Thank you!

:cheers:
 

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pelanj

Member
Paid Member
2008-07-17 8:47 am
Hořovice
Yes, that should work. Here is my own measurement of a 2445 on a 2380 clone - I think I should revisit trying to EQ the 2445. I tried that and failed, but I did it wrongly as I see it now. There is some information on a crossover that should work here: 2445J/2380 + 2404H passive xo help I never got to trying out that one, but I think I should try to mimic this with my active XO.
 

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Mazza

Member
2013-07-18 2:55 pm
That is encouraging to hear pelanj!

I picked up the Faital Pro 15HP1020's yesterday. They look nice with their custom turned Tasmanian Oak phase plugs. The gent I picked these up from doesn't like dust caps.

They appear brand new. No scapes or scratches in the mounting holes are to be seen....


:cheers:
 

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pelanj

Member
Paid Member
2008-07-17 8:47 am
Hořovice
I played a bit more with the EQ and moved the crossover to 800 Hz. If attenuated ca 10 - 12 dB, they can play with a slight roll off up to 20 kHz. For more "air", I would still need a tweeter for the top octave. And they definitely deserve a fine woofer like you have, mine is an old Peavey low end, since that is what I have im a box right now.
 

Mazza

Member
2013-07-18 2:55 pm
Dear all,
Very much hoping for some thoughts on my enclosure design. Slot ported to a tune of 37hz.

Outside dimensions (cms) are:

W 50
D 45
H 94.8

Interior dimensions (cms) are:

W 45.2
D 40.2
H 90

Vol gross 163.53 liter. Timber will be ply of 24mm thickness.

Will be window braced above and below woofer with a combination of acoustic poly and glass batts lining walls and window braces.

Looking forward to cutting ply this weekend.

Advice, suggestions appreciated!

:cheers:
 

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Mazza

Member
2013-07-18 2:55 pm
Thanks for the input puppet.

While I have the capability to DSP this system I'll mostly drive these from a nice old 90's Yamaha AX integrated for simplicity.

I'm hopeful that this low tune will benefit from some room boundary gain to help give a little free transform lift.

I'm also keen to know what people think of my first port resonance - my thinking is that this won't be a problem as I'll be crossing at around 800hz. I'd gladly be corrected before I cut any timber!

Cheers.
 

Brett

Member
2002-01-07 6:02 pm
The 2445 will play OK to about 8k, then the factory Ti phram will oil can; you can't EQ this out. The 2380 will be OK to 800Hz with a steep HPF, it's too small for much lower and will lose pattern control at 10k or so because of the driver exit diameter.
Been there, done that.
 

Mazza

Member
2013-07-18 2:55 pm
First measurements - set up

Dear all,
Here's my first attempt and measuring one of these JBL 2445J & 2380A.

I measure with Omnimic with 4.5ms gating about 80cm from the center of the horn mouth. Horn & driver combo driven from DATS V2.

I have a home made turntable graduated in 10 degree sections for 0-90 degree off axis measurements. I have a large acoustic treatment filled with Bradford Sound Screen on the side that I placed on the side of the that I rotated the driver towards.

I measured in my lounge at the end of my work desk. The top of turntable is about 80cm from the carpeted floor. :)
 

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Mazza

Member
2013-07-18 2:55 pm
First measurements - results

Too many images to post! Measurements follow here.

First up is on axis - no smoothing:

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0-50 degrees off axis horizontal 1/12th smoothing:

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Polar 0-90 degree horizontal 1/12th smoothing:

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Now for the vertical 0-30 degrees 1/24th smoothing:

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Here is the polar 0-90 degree vertical 1/24th smoothing:

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Impedance sweep (PDF also attached):

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Mazza

Member
2013-07-18 2:55 pm
First try HP crossover

So I wanted to verify the ULF potential of the JBL 2445J & 2380A and if I could get some CD compensation working effectively.

Here's my first try crossover:

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Here's the simulated XSim response without any smoothing:

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XSim .dxo attached for completeness which includes the impedance data.

Thoughts and suggestions very much appreciated.

Now I just need to get a wriggle on and build some enclosures!

:cheers:
 

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Mazza

Member
2013-07-18 2:55 pm
Diaphrams

Hi Pelanj,
I'd be guessing I have original JBL smooth Ti diaphragms that these shipped with??

I dented the foam in the back chamber with a thumb, it isn't springing back...

:xfingers:
 

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pelanj

Member
Paid Member
2008-07-17 8:47 am
Hořovice
So I think I have the same type - but they could be also some no-name replacement. Maybe it is just the scaling, but it seems mine are like 5 db down in the HF compared to yours. I will try your crossover with my measurements and maybe do some new ones:)

The foam was totally rotten and half fallen off on mine. I removed it and installed polyfil without any measurable difference.