fEarful question

[Execut1ve]

I was just browsing through greenboy's fEarful enclosures. I noticed under the advantages of the fEarful enclosures is listed "lower box tuning via shelf extension." I read about that here, but I am not clear on what exactly the shelf extension does. Anyone able to explain?

Thanks!

[BurningSkies]

It makes the port 'deeper'. Thus giving more volume to the port and making the cab extend to lower frequency range. On my fEarful 15/6 port shelf is the full depth rather than splitting it into the shelf, plus extension. I knew I'd want deeper anyway.

[Execut1ve]

Is there any known, quantifiable relationship between the shelf extension and how much lower you'd like to go? Say, how much would the shelf need to be extended to better play certain lower notes

[Petebass]

Originally Posted by Execut1ve

Is there any known, quantifiable relationship between the shelf extension and how much lower you'd like to go? Say, how much would the shelf need to be extended to better play certain lower notes

First off, don't fall into the trap of thinking longer ports automatically equals more lows. Lengthening the port does indeed lower the tuning frequency. But lowering the tuning frequency does 2 things to the frequency response, it introduces more sound in the lower end of the cabs frequency capability but it also can create a situation where the low frequencies start to roll off sooner. In other words you might gain 3dB at 40 Hz but you might also move the -3dB point from 60Hz up to 90Hz, resulting in a cab that sounds less full overall.

I wouldn't mess with the porting too much.

[mulchor]

Just like most things, there's a lot of research detailing and quantifying loudspeaker design elements.

A good university library will have plenty of info.

On this topic, just like most things, there's precious little on-line that's worth its carbon footprint.

[Execut1ve]

Originally Posted by Petebass

In other words you might gain 3dB at 40 Hz but you might also move the -3dB point from 60Hz up to 90Hz, resulting in a cab that sounds less full overall.

Couldn't this be corrected in the EQ though? Whereas the lowest frequency capability of a cab couldn't?

[billfitzmaurice]

Originally Posted by Execut1ve

Couldn't this be corrected in the EQ though? Whereas the lowest frequency capability of a cab couldn't?

EQ can correct it, but at the cost of power. A mere 3dB of boost at 60 Hz can nearly double the power draw from the amp. And there's the matter of cone excursion, and that demand in the upper bass region will also increase if the tuning of the cab is lowered. As to the lowest frequency capability of the cab, most users are off by at least a half octave between what they think they need and what they really need. Or, in the case of a cab they have, what they think it's doing and what it's really doing.

[Execut1ve]

Originally Posted by billfitzmaurice

As to the lowest frequency capability of the cab, most users are off by at least a half octave between what they think they need and what they really need. Or, in the case of a cab they have, what they think it's doing and what it's really doing.

All right Bill, you seem to know what you're talking about. I'm playing a 5 string tuned to low A, using an Ampeg BA115 to hear myself onstage. What do I need/what am I getting?

[Mr. Foxen]

Sort of tone you are after is more important than your tuning. Plenty of metal bassists tune really low, but have a clanky sound without any real bottom, that is still happy through a sealed 8x10.

[4Mal]

Originally Posted by Petebass

First off, don't fall into the trap of thinking longer ports automatically equals more lows. Lengthening the port does indeed lower the tuning frequency. But lowering the tuning frequency does 2 things to the frequency response, it introduces more sound in the lower end of the cabs frequency capability but it also can create a situation where the low frequencies start to roll off sooner. In other words you might gain 3dB at 40 Hz but you might also move the -3dB point from 60Hz up to 90Hz, resulting in a cab that sounds less full overall.

of course in the case of the fEarful cab - the port extension was actually part of the design... which renders the above as probably accurate in a generic sense but maybe not in this specific scenario...

I wouldn't mess with the porting too much.

dead on the money there!

I run the fEarful 12.6 w/o the port extension as I'm mostly a 4 stringer. I have played 5 through it though and I really don't think the extension is necessary. Part of the eqution for me is that I also built a 12 Sub which is tuned a bit lower to begin with so If I feel the need, I can drag that along for the ride as well... If I were playing moslty dub - I might have been more inclined to try the port extension.

If you really want authority down low and clarity everywhere else, you might consider doing the 15.6 using the upgraded mid driver. I don't need that kind of volume so for me the 12.6 is a better bet. It easily hangs with the 2 guitarists using 40 watt tube amps, key's and a mic'ed kick drum in 'loud' band. We run Mackie 450's out front for that band.

If you're realky lighting it up volume wise, the 15.6 has the same voice but is capable of going much louder. It is also more efficient. I'm transportation limited in that I carry a bunch of PA and bass rig, sometimes guitar rig in my Subaru... the 12.6 fit's the 15.6 won't ...

[Execut1ve]

I'm not really looking for huge volume so much... this would be used for my own personal sound onstage, so it really only has to compete with the monitors.

[Mr. Foxen]

If it is just onstage sound, you probably don't need to worry about the bottom so much, concentrate on clear mids, since that is what you'll pic up most of the notes you are playing from. If you are running all the out front sound through the PA, apparently lots of bottom on stage is detrimental. Although I've never had a sound man actually complain about it harming the out front sound, only that my rig made his desk vibrate too much to comfortably operate the sliders.

[Execut1ve]

maybe I'm being ambiguous here... I don't need a LOT of bottom end, but I would like to hear my lowest notes reproduced well. I don't think those are necessarily the same thing. I guess I"m talking more about extension than overall volume?

[rpsands]

I've tuned my 5-er to A with the stock fEarful port and I think it's fine.

[billfitzmaurice]

Originally Posted by Execut1ve

All right Bill, you seem to know what you're talking about. I'm playing a 5 string tuned to low A, using an Ampeg BA115 to hear myself onstage. What do I need/what am I getting?

With a 5 string tuned to low A you don't need an F3 lower than 40Hz. You'd have to check the fEarful threads to see which of the versions would meet that requirement. I doubt the BA115 F3 is less than 70Hz, and it will have a big response hump around 100 Hz, so while it goes fairly loud it can't go low. You definitely need a lot more than 100 watts to deliver a fat bottom, even at monitoring levels. Don't even think about using the BA115 and fEarful together.

[Execut1ve]

Originally Posted by billfitzmaurice

Don't even think about using the BA115 and fEarful together.

don't worry, I wasn't the BA115 would probably come home to be used for my own practice

[Execut1ve]

not to be a pain... I'm legitimately curious here why does the F3 have to be only 40Hz to reproduce a note with frequency 27.5Hz? again, just curious

[Passinwind]

Originally Posted by Execut1ve

not to be a pain... I'm legitimately curious here why does the F3 have to be only 40Hz to reproduce a note with frequency 27.5Hz? again, just curious

Read this thread from the Amps FAQ.

[Petebass]

Originally Posted by Execut1ve

I'm not really looking for huge volume so much... this would be used for my own personal sound onstage, so it really only has to compete with the monitors.

Be careful here! How loud are the monitors? Most people underestimate their SPL requirements in this scenario.

It may only be a personal monitor but it's not uncommon to measure at typical rock/pop gigs an average ambient stage volume of 112dB plus peaks hitting 116dB. Sometimes louder. That's loud!

[Execut1ve]

well, the drums are electronic, so that cuts down the ambient stage noise a lot