OB bass with JBL horn?

NYCOne · 3rd September 2011, 08:12 AM

I've been running a Martin King OB designed speaker set of an FF85Ks over an Eminence Alpha 15s using a passive XO.

I've recently gotten interested in horns and bought a BMS 4590 and JBL 2397. They sound great, but I need a bass unit to fill in the bottom end. I've built a homemade MOX style Sallen Key active XO and I wondered if I could use an OB H baffle for the bass. When I asked the question on Lansing Heritage, there was a suggestion the combination wouldn't work due to dead spots formed by interference waves.

Has anyone tried a CD over an OB?

Thoughts?

jerome69 · 3rd September 2011, 08:33 AM

I never use a CD over an OB. But I can say :
The crossover frequency of the BMS is 300Hz. I will not use a H Frame till 300Hz, but under 150Hz. A simple OB can work great.

NYCOne · 3rd September 2011, 04:23 PM

Quote:

Originally Posted by jerome69

I never use a CD over an OB. But I can say :
The crossover frequency of the BMS is 300Hz. I will not use a H Frame till 300Hz, but under 150Hz. A simple OB can work great.

I guess I'm looking for a solution for 35-700Hz. Most of what I find is more like 50-1000 or 35-150Hz. What are most folks using for CD bass in DIY?

badman · 3rd September 2011, 04:42 PM

If you want 35, from minimalist (most CD) OB bass, you should accept the 150Hz top end. Since it requires a lot of EQ and excursion to get the 35, you don't want the same transducer trying to do 750, as it'll be a very poor quality 750 when the bass is really bumpin'.

jerome69 · 3rd September 2011, 04:54 PM

Most folks use a 8",10",12",15" PA bass driver in a box.

35-700Hz OB ? Not so easy.

1.
3 ways active/passive ? H frame 35-150, 8" 150-700 and BMS.

2.
I have done it with passive equalization, (35-500) 2x12" (SLS315) (16" width) but 82dB sensitivity.

3.
Very large panel (at least 40") with some 12". You can earn 6dB.

4. The easiest way, simple active OB with 12", 10" and equalization, . Try to find drivers with Fs < 30Hz. Use a parametric crossover, mini dsp, Behringer etc. is easier.

Pano · 3rd September 2011, 05:54 PM

I ran Altec 811 horns over 15" Selenium woofers on OB for awhile. It worked OK. The crossover takes some work, tho.

mayhem13 · 4th September 2011, 06:52 AM

OB bass array towers.......4 Eminence Kappalight 15LF's per side and DSP. EXPENSIVE option but get's it done....all done. Takes the floor and the ceiling right outta the picture. With the incredible sensitivity per side even after active processing you're still left with hefty output capability for not much wattage.

NYCOne · 4th September 2011, 07:57 AM

I finished my MOX style SK Active XOs, so active is certain, (I'll use a passive for the BMS top).

I'd looked at a JBL 2235 or 2245 in a vented box. It looks like it covers 35-1000Hz when I model it in BassBox, but I'm hesitant to build something without knowing anyone running something similar.

3rd September 2011, 08:12 AM	#1
NYCOne diyAudio Member Join Date: Jul 2010 Blog Entries: 1	OB bass with JBL horn? I've been running a Martin King OB designed speaker set of an FF85Ks over an Eminence Alpha 15s using a passive XO. I've recently gotten interested in horns and bought a BMS 4590 and JBL 2397. They sound great, but I need a bass unit to fill in the bottom end. I've built a homemade MOX style Sallen Key active XO and I wondered if I could use an OB H baffle for the bass. When I asked the question on Lansing Heritage, there was a suggestion the combination wouldn't work due to dead spots formed by interference waves. Has anyone tried a CD over an OB? Thoughts?

3rd September 2011, 04:42 PM	#4
badman Custom Title diyAudio Member Join Date: Sep 2003 Location: Sunny Tustin, SoCal	If you want 35, from minimalist (most CD) OB bass, you should accept the 150Hz top end. Since it requires a lot of EQ and excursion to get the 35, you don't want the same transducer trying to do 750, as it'll be a very poor quality 750 when the bass is really bumpin'. __________________ I write for www.enjoythemusic.com in the DIY section. You may find yourself getting a preview of a project in-progress. Be warned!

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3rd September 2011, 08:33 AM	#2
jerome69 diyAudio Member Join Date: Feb 2008 Location: Lyon	I never use a CD over an OB. But I can say : The crossover frequency of the BMS is 300Hz. I will not use a H Frame till 300Hz, but under 150Hz. A simple OB can work great.

3rd September 2011, 04:54 PM	#5
jerome69 diyAudio Member Join Date: Feb 2008 Location: Lyon	Most folks use a 8",10",12",15" PA bass driver in a box. 35-700Hz OB ? Not so easy. 1. 3 ways active/passive ? H frame 35-150, 8" 150-700 and BMS. 2. I have done it with passive equalization, (35-500) 2x12" (SLS315) (16" width) but 82dB sensitivity. 3. Very large panel (at least 40") with some 12". You can earn 6dB. 4. The easiest way, simple active OB with 12", 10" and equalization, . Try to find drivers with Fs < 30Hz. Use a parametric crossover, mini dsp, Behringer etc. is easier.

3rd September 2011, 05:54 PM	#6
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	I ran Altec 811 horns over 15" Selenium woofers on OB for awhile. It worked OK. The crossover takes some work, tho.

4th September 2011, 06:52 AM	#7
mayhem13 diyAudio Member Join Date: Sep 2008	OB bass array towers.......4 Eminence Kappalight 15LF's per side and DSP. EXPENSIVE option but get's it done....all done. Takes the floor and the ceiling right outta the picture. With the incredible sensitivity per side even after active processing you're still left with hefty output capability for not much wattage.

4th September 2011, 07:57 AM	#8
NYCOne diyAudio Member Join Date: Jul 2010 Blog Entries: 1	I finished my MOX style SK Active XOs, so active is certain, (I'll use a passive for the BMS top). I'd looked at a JBL 2235 or 2245 in a vented box. It looks like it covers 35-1000Hz when I model it in BassBox, but I'm hesitant to build something without knowing anyone running something similar.

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