BFM Jack Lite

[Rick James]

Just keep this in mind - if you find yourself boosting the bass to fill in the frequencies below what the horn is handling, you're largely giving up the advantages of having a horn loaded cab in the first place.

I run a Jack 12, and I don't have to boost the bass. Using my head I've compared it side by side with lots of 112s, I prefer it to all of them, including the fearful 12/6 and Baer ML112.

The Jack will behave like any old direct radiator cab in the bass frequencies,

It doesn't, because the ports load into the horn, so even in the lows its more efficient than a regular ported cab. You see that comparing the SPL charts to regular ported cabs. Its 2.5dB more efficient at 50 hz than the Simplexx 12, and the Simplexx 12 is more efficient than most 112s. The Jack 15 is 4dB more efficient than the Simplexx 15 at 45 hz, and the Simplexx 15 is more efficient than most 115s.

 

[CL400Peavey]

Probably? P-r-o-b-a-b-l-y? The Jack 15 would lord over any commercial 410.

Maybe in the mid range, but its response is very peaky, and very mid centered.

 

[hdracer]

Probably? P-r-o-b-a-b-l-y? The Jack 15 would lord over any commercial 410.

Really?
So two of them would be much louder than a 810? My 100 watts would love that.

 

[Rick James]

Really?
So two of them would be much louder than a 810? My 100 watts would love that.

Look at the Jack 15 to 810 comparison charts, add 6dB to the Jack 15 to see what two will do.

 

[CL400Peavey]

Look at the Jack 15 to 810 comparison charts, add 6dB to the Jack 15 to see what two will do.

Nope. Only add 3, as he is using a tube amp.

 

[hdracer]

Nope. Only add 3, as he is using a tube amp.

Why is that?

 

[Handyman]

Why is that?

Your tube head should be putting out roughly the same amount of power into either 4 or 8 ohms. You'll get about a 3db increase from putting the same amount of power into twice the speaker area.

A SS head would also get about a 3db bump from only being able to supply full power into a 4 ohm load.

 

[CL400Peavey]

Why is that?

You are gaining efficiency, but not an increase in potential power output.

 

[CL400Peavey]

Having run this rig, and having a/b'd my dually against an ampeg 810, I will tell you that the 215 is more efficient than the 810, and is more than enough with a ~100 watt tube amp to gig with.

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[hdracer]

You are gaining efficiency, but not an increase in potential power output.

But they should be louder than my TL-606's?

 

[Handyman]

Having run this rig, and having a/b'd my dually against an ampeg 810, I will tell you that the 215 is more efficient than the 810, and is more than enough with a ~100 watt tube amp to gig with.

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I love the subtly tasteful color scheme you chose on your Dually there.

 

[CL400Peavey]

But they should be louder than my TL-606's?

With the same drivers? Maybe a little depending on how your TL's are tuned in the low end. Through the mid range, you will with the horn, but your response will change, you will have a more peaky response.

 

[CL400Peavey]

I love the subtly tasteful color scheme you chose on your Dually there.

I used to play a burnt orange bass with it too!

 

[hdracer]

With the same drivers? Maybe a little depending on how your TL's are tuned in the low end. Through the mid range, you will with the horn, but your response will change, you will have a more peaky response.

Same 3015's or PR400's
I built the boxes to spec, no mods.

 

[Rick James]

Nope. Only add 3, as he is using a tube amp.

It makes no difference, efficiency is relative to voltage, not power. When you double the cab count with constant voltage efficiency goes up by 6dB.

But they should be louder than my TL-606's?

Much louder.

 

[rogypop]

With the same drivers? Maybe a little depending on how your TL's are tuned in the low end. Through the mid range, you will with the horn, but your response will change, you will have a more peaky response.

Response evens out considerably with second Jack added.

 

[CL400Peavey]

Same 3015's or PR400's
I built the boxes to spec, no mods.

Right, you will gain efficiency in the mids, but it is not a 1:1 increase across the response.

It makes no difference, efficiency is relative to voltage, not power. When you double the cab count with constant voltage efficiency goes up by 6dB.

You double cabs you get 3db.

 

[rogypop]

But they should be louder than my TL-606's?

They would make your TL's inaudible in comparison.

 

[SubNoizeRat3691]

Really?
So two of them would be much louder than a 810? My 100 watts would love that.

The graph posted is 1 Jack 15 vs an 810. Your 100w amp would rule everything with 2 Jack 15's! I know mine does!

Horn loaded cabs work better in groups, 2 jack 15s would have a much smoother response than a single cab. I can't imagine a gig I couldn't handle with an Ampeg V4B and 2 Jack 15's.

 

[cfsporn]

It makes no difference, efficiency is relative to voltage, not power. When you double the cab count with constant voltage efficiency goes up by 6dB.
Much louder.

Please help me out on this as it has been making my brain hurt. On a tube amp, the wattage is the same into 4 or 8 ohms. Using the formula for voltage of watts=(volts^2)/ohms, wouldn't the voltage be higher going into a higher impedance load?

My math:
100W=(V^2)/4
(V^2)=400
20V at 4 ohms

100W=(V^2)/8
(V^2)=800
28.28V at 8 ohms

Am I missing something?