Omni 15TB Woofer only with a Jensen C15K

[mange656]

I just completed an Omni 15TB bass only bin. The paint is drying as I type. I used a Jensen C15K woofer (new version from Italy). Before the squeals start about using the wrong driver, I am a bass player converting over to Hammond organ. I have a motion sound Pro 3T for the Leslie high frequencies and now I have the O15TB bass cab for my bottom end. The O15TB rocks on the bottom end. The mids to the 800 hz crossover between the O15TB and the Motion Sound Pro 3T sound much better than my 12" floor monitors, the bass is solid even on the pedals. Overall the O15TB and Pro 3T blend in a very musical way.

I chose the Jensen C15K because of the frequency response and overall sound coloration that it has. I looked Leslie speakers used with Hammond organs and wagged that the O15TB would load the woofer in a manner similar to that cabinet. Basically the Leslie fires the woofer downward into a rotating drum (simulated by the Pro 3T), the rotating drum is enclosed in a lower compartment that outputs the sound through louvers. The Leslie bass reflex port also fires into this lower compartment. The O15TB loads the front and back of the woofer cone in a similar manner. The Pro 3T sits nicely on top of the O15TB.

I really liked the way the O15TB and Pro 3T sounded when I worked through some Hammond material. Solid in the low end, great mids. All notes were very defined. I even checked out the EPs and other sounds on my XK-1. With the Pro 3T stopped for EPs the whole setup sounded great. With that in mind the O15TB will stay as a bass only unit and if I have any great loss in the 500 hz to 800 hz range (difference between the O15 full range xover and the bass only version to the Pro 3T) I can live with that. I suspect that with the right driver the O15TB 15" driver will extend to 800 hz just fine sorta like the OmniTop 15. For those who play keyboards the note definition is outstanding (organ can really muddy up the sound when you play down low). The bark when percussion is turned on was really solid and forced me to reduce the setting slightly for several of my patches.

I will post some pictures in a day or two when I have the whole stack setup again.

Thanks Bill for designing these speakers.

[LelandCrooks]

Award for most unique usage.

Very interesting.

[mange656]

Award for most unique usage.

Very interesting.

Thanks for not trashing me, though I do have a pair of 3015s that I will plant in O15TB's now that I have heard what this cab can do. The Jensen has specs that would probably make Bill cringe but I was going for a "the speaker flaws / response" is part of the whole tone package.

I know what the Jensen sounded like in a 4.5 cu ft ported box but wow I did not expect to get the low frequency range extension I am getting out of the O15TB. It makes a world of difference. Like any one who plays bass I know that the sound I get when practicing usually won't cut it when playing live. Kinda the same with the Hammond. The extension is very tight and well defined. No mush at all.

I was actually pleasantly surprised that it works as well as it does. The horn / hybrid O15TB loads woofers so the 73 - 74 hz (per Jensen) fs is pulled down in this enclosure. I did have a nasty buzz when I first leaned on the system but I traced that to one of the swivel casters fixed by the "ah yes the match book under the wobly vibrating caster trick". After that the only buzzing was change and objects on the desk, the window, tightened down the lamp shades...

If the sound had sucked with the EPs, Clavs and synth then I would have added mid and hf components to the O15TB. But the O15TB + Pro 3T sound great. Even ran it against a live mix from earlier in the year and if mixed well.

Thanks Leland

[Randall Dibble]

Hey, I'm very interested in your post.

I have six Hammonds in my home.

MY wife wants them moved.

What Hammond are you playing with ? more information on the setup.

Drawbar settings?
Do you use the pedals?
What amp are drive it with?

To many questions!

[Mikey]

Along the same lines, but quite different ... what would be the result if a driver were used in an O15 which has 35hz fs and .85 qts?

[mange656]

Hey, I'm very interested in your post.

I have six Hammonds in my home.

MY wife wants them moved.

What Hammond are you playing with ? more information on the setup.

Drawbar settings?
Do you use the pedals?
What amp are drive it with?

To many questions!

I am playing a Hammond XK-1 Clone wheel as some call it but real Hammond to me, and a Hofner early 60's model 182 bass.

Drawbar settings are varied from the 888000000 to 888888888 depends on what I am playing my normal staring point is 858000000 on my lower manual (Korg K61P because the keys are the same width as the XK1) and 888000000 on the upper manual. If I am playing two or three note chords on the upper manual I will add additional drawbars to the lower manual (I am normally chopping bass lines with my left hand on the lower manual) to fill in the right hand work. I am still learning on the Hammond man am I learning (played bass since 16, bit of rhythm guitar here and there, never any lead work) and now I have been putting on the Hammond for about 1 year. The tonal variations from a Hammond are really awesome but man oh man what a steep learning curve. I have also added a set of Solton / Ketron 13 note bass pedals to the mix as anyone who plays a Hammond knows if your covering bass and you need to change drawbar settings, chorus / vibrato, Leslie speed, percussion settings, adjust distortion and other parameters you need three or more hands (feet can substitute for a hand with bass pedals).

For amps, well the Motion Sound Pro 3T has a built in 40 watt amp for the treble driver covering 800 hz and up. The Pro 3T allows you to contour the high frequency to match a Leslie 147 (rolls off the highs above about 4 khz). For the Omni 15TB bass cab with Jensen (from Italy ie new Jensen classic ceramic speakers) I used a Behringer PMH 2000 bridged for the initial tests. For real use that will change to a Crest VS 450 (150W RMS @ 8 ohms vice 500W PMO @ 8 ohms for the Behringer).

As I said I had a purpose when I built this combo up and that was to emulate a Leslie to my ear anyway. The Jensen C15K suffers from a poor Xmax and probably a too high fs. That said I have not been able to locate good Thiel Small data on the Jensen P15LL woofer that is "THE LESLIE" woofer. Weber speakers have one that has that data (Tonewheel General Hospital) with a freq chart and TS data but I believe it is really an Eminence custom built by Weber. They cost about the same. The tone (coloration of the speaker) was the issue for me. The eminence Delta 15 and Kappa Lite 3015 did not have the mid bite I was looking for even in the O15TB. So the Jensen it was.

Thanks for the comments and I hope my rambling helps

[Randall Dibble]

I see your plan is clear. Please keep/us informed as to progress.

Your results will help me and others.

Question; Have you thought of using a T39 for a sub with the Bass pedals?

Keep up the good work!

[mange656]

I see your plan is clear. Please keep/us informed as to progress.

Your results will help me and others.

Question; Have you thought of using a T39 for a sub with the Bass pedals?

Keep up the good work!

I did think of using a horn sub but... I evaluated pack space, number of items to load in and load out as well as complexity of the setup. I had the Jensen on hand and given the range of the woofer only section of the O15TB I wagged that I could get extension up to the 800 hz crossover point of the Pro 3T. The O15TB has a really good sound on the pedals as well as the lower manual when I assign the pedals to the 25 lower keys (the XK-1 will play both the lower manual note and the pedal note so chords down low in this configuration get real muddy fast).

The Jensen only has about 20 hours on it so it still needs to break in. I do not expect a huge improvement in the bottom end after break in. However, when I play the pedal part on the pedals or push all the draw bars in for the lower manual the sound is tight and it sits in the mix where I would place a bass guitar part. When I pull the 2' through 1' draw bars out a bass boost on the Hammond XK-1 from 0 to 2 (range is 0 - 9) allows the bass to keep up with the highs.

When I turned it up tonight and played I discovered another buzz. I isolated that to the wood rails on the bottom of the Pro 3T sitting on the O15TB. 4 little weather strip squares fixed that so I will get 4 rubber feet for the Pro 3T wood rails.

I activated the XK-1 demo songs so I could walk about the house and hear the sound at a distance and the bass is solid in the other rooms. That said I can't say enough good things about the o15TB enclosure. The demo includes pedal work with both manuals in full operation so the full up Hammond sound is demonstrated. All kinds of stuff in the house was vibrating on some of the notes.

There is no farting out or other issues at the volumes I intend to play this rig at just solid clear sound unless I dirty up the signal. Even at volumes louder than I would typically play at the low notes including the pedal low C were defined and powerful. Not dub or overwhelming. The real beauty is in the mids and how they project. The mids are crisp, clear and defined. Best way I can describe it is a bass with c**ppy pickups on a muddy amp boy those notes just blend but they don't lend well to fast playing because the notes blur into one. Change to a premium pickup and an amp with solid note definition and every note and mistake can be heard. Well that is how this sounds. Stand back far enough for the bass waves to develop and they are right there. Up close (on stage) if your get that really low end bass sound the whole mix will sound muddy and the bass will lose a bunch of definition if it doesn't overwhelm the rest of the band. Good bass tone in the bedroom vs tone on stage vs FOH sound and in this case pedal and left hand bass on the organ.

Here is a photo of the setup.

O15TB with Motion Sound Pro 3T

[WB]

I had the Jensen on hand and given the range of the woofer only section of the O15TB I wagged that I could get extension up to the 800 hz crossover point of the Pro 3T.

You should be fine with an 800 Hz crossover. I measured my O15TB sub (3015LF) and the 500 to 800 Hz range was still good. It did drop sharply after 800 Hz.

[mange656]

I had the Jensen on hand and given the range of the woofer only section of the O15TB I wagged that I could get extension up to the 800 hz crossover point of the Pro 3T.

You should be fine with an 800 Hz crossover. I measured my O15TB sub (3015LF) and the 500 to 800 Hz range was still good. It did drop sharply after 800 Hz.

Thank you for the test results. My ears said OK but... it is always great to have validation via measurements.

I did have it up to war volume this weekend (wife and kids went school shopping). Wow, what a difference over direct radiators. This rig really puts out the pedal bass when pushed and the amp is just putting along going is this all you need me to do.

Thanks again for the test results

Andy

[mange656]

One Jam at war volume... well just a good volume. Spinning air really makes a difference. Plenty of bottom end. I actually ended up reducing the bass tone control as this cab really puts out the low end. I also ordered and have installed a Selenium D250-X phenolic horn driver in the Motion Sound Pro 3T due to the "Ice Pick" highs the default titanium driver puts out. I just couldn't tame the highs. For the songs I didn't play keys on I used my Hofner 182 with flats. Boy the other players were smiling. The drummer really liked the tone and punch.

Sooo for a driver not recommended it works out very nice. Hammond Organ playing really works a system. I really like the note definition at all volumes. Clear. I will never go back to a direct radiator.

Thank you very much Bill. Keep up the good work.

[crackbass]

good luck with the d250-x, i use one in some home-brew bass cabs. they actually go quite low for a horn (especially at this price point). i have found they still have good clack without over bearing super highs.

[mange656]

good luck with the d250-x, i use one in some home-brew bass cabs. they actually go quite low for a horn (especially at this price point). i have found they still have good clack without over bearing super highs.

The d250-x is crossed over at 800hz by the Motion Sound Pro 3T. Works quite well. I used a small mixer to mix down the organ, piano and bass. I stop the Pro 3T when I play piano or bass because they sound really funny with the Leslie effect. Best of all, no more ice pick highs. The response is starting to fall at 5K perfect for organ.

Thanks for the input this board is great.