View Full Version : bi-amp a 4312A ?

10-24-2004, 07:47 AM
Hi, 1st, sorry for my english

I have a pair of 4312A.
If the 2213H is not filtered by the crossover, why not drive directly the 2213
with a dedicated amp, and use another amp to drive
the high/med group ?
This will be done easily, by the addition of a second terminaisons board…

What do you think about that?


Tom Loizeaux
10-24-2004, 08:06 AM
I suppose you coud improve the 4312A slightly with bi-amping, but bi-amping helps the most, I believe, by bypassing the inductor on the woofer...something you don't have in the 4312s design! You would only bypass the capacitors between the mid and woofer. I don't think that would be very noticable.


Alex Lancaster
10-24-2004, 08:11 AM
As Tom says it would be slightly better, but too much work and expense for the improvement.

10-24-2004, 12:21 PM
Hello Frenchie

I not sure it's worth it. You couldn't even try an active as you would screw up the driver balance. If you have the extra amp around it would be an easy thing to try. You have preamp outs/ins on an HT rig?? You could use the rear channels as the tops and have a built in level control provided you could switch off the delays. Give it a try tell us what you think.


John W
10-25-2004, 08:24 AM
Check out this link, where there is a great article on the subject.

I http://sound.westhost.com/bi-amp.htm

I think you will need an active crossover on the low end to get any real benefit.

I have a similar question, though, for my pair of L-65s.
The 122A is crossed over at 1000hz. If I wanted to by-amp these speakers would I need to set up an active low and high crossover at 1000Hz and bypass the inductor on the woofer. If so, what would be the best crossover slope for this speaker be?

Or what if I did a low pass at 1100Hz, a high pass at 900hz and basically used the existing crossover? Would the exsting crossover work as it currently does, with just more added punch in the bass, and clarity in the high end?

10-25-2004, 04:04 PM
I have used 122A's in a biamp set-up with my XPL's. I used a JBL M552 which is a active crossover with 24db L/R with symetrical slopes. I did it at 300 hz but could walk it up too. Figure as long as both drivers have a reasonable overlap you should be able to do it. Chances are you could bring the crossover down a bit with the steeper slopes. As far as what the best would be????


10-25-2004, 05:49 PM
The objective for my opinion, is to use the opportunity to bi-amp "plug & play" a speaker whithout active crossover (this will respect the originals specifications) and simply with the help of a second stereo amp (and a second terminaisons board on the 4312).

It is rare to find a speaker system so advanced with a such rustic crossover, with a woofer who run free.

Gains will be multiple and classic in multi-amp: no big courant needed for the med/tweeter and possibility to use a very high quality amp of some watts.


Alex Lancaster
10-25-2004, 07:49 PM

IMO, You are killing flies with a .50 Mag Desert Eagle; It would be better if You traded up to at least 4333´s, and then BiAmp.

10-26-2004, 04:33 AM
Originally posted by Alex Lancaster
IMO, You are killing flies with a .50 Mag Desert EagleAnd that's a problem!? :rotfl:

11-12-2004, 06:53 AM
By reading this excellent link (given here by John W) :


i have undertood why 4312A can take "only" 100w.

The 2213H nomimal power is 75W. And it is not filtered and his coil absorb all the frequency range in a 4312A.

• Frequences combined simultaneously (Low+med+high) increase the voltage and the power.
• Power increases as the square of voltage, so twice the voltage is four times the power.

(wit music, a crossover at 350 hz = 50% of power for bass
50% for med&high.
Crossover at 1200hz = 65% for bass…)

So it seem that have a low-pass filter, even passive,
can really increase the output of a woofer.
(the coil get hot only wtih power that can be rights movements.)

so 75 W max. of musical message in a 2213h without filter
= 37,5 W at 350 hz or 48,75W at 1.200 hz, etc…
and no more.

Night and day wit a thrue 75 W in a limited range
like 25hz - 800 hz , for exemple…

The benefit of filtering (active or passive) the 2213h must be great

Alex Lancaster
11-12-2004, 07:23 AM
:) Frenchie:

The 2213 is driven full range, but it has a rising impedance/frequency, which the designers put to good use, it does not burn off all the mids and highs, it kind of rejects them.

I think I posted before, that You will be better off to trade for better speakers, if You bi or tri amp them, You are restricted to the same low and high freq restraints, it will sound better, but i do not think the cost is worth it.