BFM PA Cab : Active or Passive

[TOMSKY]

hello to all, (sorry for my english ... i'am French )

i would like to build one of BFM pair of cabs for PA use (don't know which one yet ).

So i wondering if, in BFM conception, the amplifier is in the cab (active) or not (passive) or if the two solutions are possible.

What are the advantages and the inconveniences of each configuration ?

You'll be cool if you use simple language for answer me ... thanks

Thomas

[Jon Barnhardt]

All of the cabs are passive.

Some people have made them active by adding small amplifiers to the cabs, but most of us run them as passive cabs.

[Rune Bivrin]

Passive is generally better.

With active speakers you'll wind up running two cables to each speaker. One for the power and one for the signal. And since the signal is low-level it's much more sensitive to interference.

[Frederic Gelinas]

De façon générale, les enceintes passives sont une meilleure alternative. Pas seulement avec les design de M. Fitzmaurice. Tu ne gagnes pratiquement rien à intégrer l'amplificateur à l'enceinte. C'est possible de le faire, mais ça n'est pas recommandé, pour de multiples raisons. Cette option n'est d'ailleurs pas dans les plans: tu devrais faire la modification à tes risques.

[Bas Gooiker]

Passive is generally better.

With active speakers you'll wind up running two cables to each speaker. One for the power and one for the signal. And since the signal is low-level it's much more sensitive to interference.

You could use the Powersoft Digimod modules to make your speakers active, and the built in dsp combined with the completely digital signal chain through cat5 will give you endless options and control.

But being here, asking this question makes me inclined to think your best option would be a passive set with separate amps and DSP!

[TOMSKY]

Thanks for the aswers American mates ... merci pour ta réponse cousin Canadien

This is true, my PA knowledge are very ligth.

- Assume that I want to amplified 2 Cabs Passive fullrange (no matter how powerful for instance).
In this case i need 1 amplifier 2 chanels
I plug right cab on chanel 1 and left cab on chanel 2.
What is the interest to have the possybility to adust the volume of each Cab indenpently ?

- Now if I add a subwoofer to my two fullrange cabs, can I plug 2 Cabs on chanel 1 and Sub on Chanel 2 or I need a 4 chanels amplifier or better an other one 2 chanels dedicated for the sub only. Does I need to add crossover to route good frequencies in good Cab and Sub.

Thanks.

[Frederic Gelinas]

Most (all the ones I know) power amps have separate input gain (volume) controls for each channel. Setting different levels for the channel is easy. Even easier, is to set the volume at your source (mixer?).

You can run 2 cabs on one channel if the power amp is rated to run at 4 ohms. Again, most of them do today. A lot can even run 2 ohms loads (or 4 cabs). You can get away with only 2 amp channels to drive 2 tops and 2 subs.

If you add a subwoofer, you will need a crossover and a limiter. This is mandatory. You probably need an equalizer too. A DBX Driverack does all of this (and more) in a single box (Behringer DCX2496 is another popular alternative).

[Bas Gooiker]

Cheapest version for an all in one loudspeaker management in France would be T.racks DS 2/4

It might be good for you to check out some of the "post it" marked threads on http://hornplans.free.fr/forum.html. Its a French forum about horn loudspeakers with also a lot of background info about amplification, crossovers etc. which might be a little easyer to understand in your native language.

You wrote that you want to build a PA but you havent decided which cabs to build. Maybe you could tell us what your plans are with them so we can advise you... Are you a Dj, or do you want to do live music?

[Rune Bivrin]

Cheapest version for an all in one loudspeaker management in France would be T.racks DS 2/4

It's cheap, but it works excellently if all you need is cross-over and limiting.

[TOMSKY]

Thanks for links.

I am a bass player in a Funk/Soul band.
I also play drums, trombone and I have a turntable for scratching at home.

My intention was to make a versatile PA system, could be used at low volume in house and at high volume for our little gigs (less than 100 pers).
So the main PA system would be composed by two fullrange cabs, but with the possibility to add sub when the audience are more importante or for outdoor gigs.
The resonnement is it correct ???

The band is composed as follow :
- 1 singer with 1 mic
- 1 tenor sax player with 1 mic
- 1 trumpet player with 1 mic
- 1 electric guitare player sometimes in PA by DI (I think it's not necessary most of time)
- 1 electric bass player (4 strings) sometimes in PA by DI (I think it's not necessary most of time)
- 1 drummer with 1 mic for snare and 1 mic for bass drum (I think it's not necessary most of time)

So in your opinion, what's BFM Cabs are indicated for my utility considering these two configuratons ?
- PA for 3 mics only (singer, sax, trumpet)
- PA for 5 mics (singer, sax, trumpet, drum), E Guit, E Bass (I think this configaration is too much for our gigs but ...)

Of course cheaper and more portable is it, better it will

[Bas Gooiker]

If you want a fullrange option there are eighter the omni's or the Jacks.

For maxiumum portability, cheap driver + option to add additional cabs i'd go for the Jack 12.