How to equalize a bi-amplification setup?


Greetings!

Any one experienced in bi-amplification setups with different amplifiers, where output must be equalized?

In my bi-amp setup I use one pre-amplifier connected two different amplifiers, via balanced and unbalanced connection, feeding a pair of 2-ways loudspeakers (Pass Aleph P, Pass Aleph 3 on tweeter and Pass Aleph 0s on woofer).

Problem is the Aleph 0s results in a final higher sound volume (at least +3dB). Theorically I think this should not happen as manual gain of both amplifiers indicate a +20dB gain, altough the Aleph 0s outputs much more current.

How can I "calm down" the bass amp without comprimising the sound quality and without opening the loudspeaker to introduce one attenuation circuit?
sony
Why dont you try to drive the EQ unit with a preamp/ crossover output then feed the poweramp directly from the eq unit.
This will keep the EQ out of the high range amp and all the signal degrade to the less critical Lows.
I did this set up with the crown EQ-2 Equilizer unit with very good results driving krell amps and 801#3's. I dont know if your eq will drive the poweramp directly or not try and listen...
All you need is in-line attenuators (potentiometer or fixed resistors) in the IC to the Aleph 0s. All this is lot of bother, I think.

Kal
You stated "via balanced and unbalanced connection"

If you are using the Aleph 0 in balanced mode and the Aleph 3 in unbalanced, that is your problem. The Aleph P has 15 dB of gain using the balanced output, but only 9 dB using the unbalanced.

The only way I see to avoid using an attenuator is to use a splitter and drive both amps via their unbalanced inputs.
I BI-Amp the lows with a different amp and use a behringer parametric Eq to adjust the input sensitivity and equalize two room resonances. I realize I am putting another device between the preamp and bass amp, however the ability to have relatively flat in room bass responce far outways the negatives. (At least for me)Pipe organ is a joy without that 40Hz room resonance I used to have and I don't have to mess with the mids and treble.
I don't remember your gear...it's been a while. Can you switch inputs on the amps so that the extra gain from using balanced is on the upper freq's and not the bass. 3db is not a lot and may be able to be smoothed out a little from speaker placement with a pick-up of 1-2db in the bass freq's through room gain.

I usually don't post on gear I'm no longer up on but did use this type of approach at one time in a past setup...sounded much more in step so if no use with your problem...may help someone else latter.

Dave

Dave
I don't remember your gear...it's been a while. Can you switch inputs on the amps so that the extra gain from using balanced is on the upper freq's and not the bass. 3db is not a lot and may be able to be smoothed out a little from speaker placement with a pick-up of 1-2db in the bass freq's through room gain.

I usually don't post on gear I'm no longer up on but did use this type of approach at one time in a past setup...sounded much more in step so if no use with your problem...may help someone else latter.

Dave
Herman, you're right! I've confirmed the "problem" is the pre-amplifier. According to Pass Aleph P manual, Gain: 15dB balanced out; 9dB unbalanced out.

So, we're talking about a 6dB difference!

Cadet1, what's the model/price of the behringer parametric Eq?
Behringer PEQ 2200 Ultra-Q 5 band parametric. On sale at parts express for $69.99. These are mono so you would need 2. very good for the money. In case you are wondering, my syster is proceed electronics and revel M-20 speakers with DIY subs which are equalized. I hope to soon get revel studio's and passively bi-amp and eq the woofer section below 200 Hz. Parts express has a return policy so you can't go wrong.
An easier solution:

Whatever interconnects you are using, contact the company and they can make you a balanced Y splitter so that the output of the amps will be the same. Feeding both amps balanced will probably also give you better sound.

Richard
The Aleph 3 doesn't have balanced inputs
Herman, that's right - only the Aleph 0s has balanced inputs.

Drrdiamond, could I extract the signal of the balanced output of the preamplifier and split it into a balanced and unbalanced connection? (one XLR to one XLR and one RCA)

Another reason for doing so is that I will have more power in the end than attenuating the signal to the bass amplifier.

Cadet1, I must say that my bass section is not a sub-bass one (200Hz), since it will be handling frequencies up to 2.5KHz, so there's a lot of midrange there. Couldn't the eq spoil it a bit?
sony,
Personally, I'd be uneasy about going up that high. In my present system the signal is only EQ'd below 100Hz.Something like EVS attenuators would probably work better for this application,I used to have a pair of these and they work extremely well. Only one series resistor in the signal path and one shunting to ground.
Sony,

Unfortunately, no.

Sorry
From Nelson Pass I received an excellent tip that applies to this or other setup:

Connecting preamplifier balanced output to the amplifiers unbalanced inputs: pin 3 for Amp1, pin 2 for Amp2; both share pin 1 ground; phase of amp1 inverted at the speaker output.

If Amp1 has more gain than amp2, put pin 3 into a 10K pot.

Voila! Simple and brilliant.
Have you look into an active crossover? Multi-amp system really need an active crossover to be done correctly.