Neutral Cabs

[la bam]

29 minutes ago, Bill Fitzmaurice said:

The limitation is that to do this the board needs enough channels to devote two to the bass.

..... and band members will end up banging in to them and moving them etc

 

[LukeFRC]

7 hours ago, Bill Fitzmaurice said:

The good ones do. They'll take a DI for the lows, a mic for the mids and highs. The reason for the DI lows is to minimize stage rumble that a mic will pick up, and to get a better low frequency signal than the speakers can deliver. The limitation is that to do this the board needs enough channels to devote two to the bass.

I think you’ve said before that your bass rig is uses one of your own designed Jack cabs? If you were playing a big gig with a good sound tech would you expect/want your  cab to be Miced? 

Is the cab adding that much to the sound? 

[Bill Fitzmaurice]

This ain't FRFR:

[LukeFRC]

4 hours ago, Bill Fitzmaurice said:

This ain't FRFR:

But miced up it adds something over and above the DI feed? 

[Chienmortbb]

19 hours ago, itu said:

So is it a Greenboy, then?

I suspect that Stevie is talking about various cabs he has designed but currently the BC112 Mk2 as outlined in the thread below. It uses a 12" plus a compression driver/horn and  custom crossover and is substantially flat.

 

[Chienmortbb]

8 hours ago, Bill Fitzmaurice said:

This ain't FRFR:

Agreed Bill, and credit to you for having the balls to publish the response.

[Chienmortbb]

With regard to using PA cabs, are they not designed to give a good response on a pole? With the mids/top reduced to balance out the loss of bass. Then when you put them on the floor your FRFR response is changed. I am sure some have DSP setting for Pole Top and Stage Monitor but just to take a powered PA without DSP adjustment might mean you cannot get a good sound.

[itu]

9 hours ago, Bill Fitzmaurice said:

This ain't FRFR:

Certainly not. This looks like a big dipper, as expected. If I have time, I will cut out the areas, where -3 to +3 dB, or rather -6 to +6 dB is happening. Someone who is not into acoustics may then understand, why I am so hesitant to accept this FRFR rubbish.

I do have to say that there are lots of good sounding cabinets with character out there, but it would be funny to call them flat response or even full range cabs. A bass with those coil-magnet pickups is not a full range instrument, so there is no need to have a full range cabinet, either.

[Bill Fitzmaurice]

1 hour ago, Chienmortbb said:

Agreed Bill, and credit to you for having the balls to publish the response.

Why wouldn't I? Unless you think commercial cabs are somehow better. FWIW right around the same time I designed the Jack 12 I also designed an award winning, as in 'Speaker of the Year', 1x12/6 for a manufacturer. I took both prototypes out on a few gigs. The J12 design ended up on my website, the J12 prototype is still my main cab. The drivers used in the other prototype are on a shelf in my basement, the cab is fertilizing my garden as wood ashes.

[paul_c2]

My understanding was that while no cab is truly "neutral", its possible to place multiple speakers in a reasonably scientific way to minimise their interference with each other; and that the better cabs/setups would have a not-too-far-from-neutral response to start off. Then, the sound engineer would put a series of tones through the system and use a calibrated mic and db meter to determine the non-neutral response, then correct it using a (eg) 31-band graphic eq. Of course, there's a million other things which affect the sound, including the difference of an empty hall and one full of people, but the above is the rough idea.

When it comes to cone size, then accepting that the system isn't PERFECTLY neutral you'd see a fairly flat response but it would tail off at something like 60Hz for a decent 12" speaker; and a 15" speaker might start tailing off at (say) 40-50Hz. Of course, its a gradual thing, not a sharp cliff edge. So if those frequencies are important, then a bigger cone would obviously be the one to use (but at greater cost, weight etc). If it were a FOH PA system, then the main drivers would probably be supplemented by subs, so would not be expected to cope with the lows, so its not particularly relevant anyway. But with a bass guitar setup using FRFR it probably is a factor.

[itu]

If you believe that the speaker cone size determines the frequency response, I would simply say that you are in a wrong path. The box around the element has crucial effect on the response, efficiency, lowest possible reproducible frequency, and what else? What did I forget?

It is the system, that can produce the sound, not the element by itself, especially at that low end. Well, there is the dipole but let's not dive into that now.

Mr Thiele and Mr Small used quite some time to understand the behaviour of a speaker - so the system that consists of the speaker element, the box, the cross over, the damping material etc. Their groundbreaking work is worth reading, if you want to understand something about the mechanisms that make the speaker systems scream.

[stevie]

17 hours ago, Bill Fitzmaurice said:

This ain't FRFR:

And your design goals were?