Bi-Amping

You can hate me.......it won't hurt my feelings! Some of my ex-coworkers will tell you that I made a career of getting people (mainly bosses) to hate me. Ah......the good ol' days.

Anyway.

Seriously, if you are going to try that many drivers, with that combo of crossovers, you MUST use some fancy measuring stuff to know that it is done right. In which case, you would know for certain what the problem is.

I'm not saying that multiple drivers, etc. won't work. I am saying that you can't guess what works and what doesn't. I think it is a safe guess that you do not presently have the gear to do such. Ergo, you don't know why you have a gain problem.

OK, back to your problem.

8 V out of a preamp is enough to melt any amp. Most amps have 26 dB of gain. A few dB either side, maybe.

As for drive, it should be able to drive 2 amps. Most amps are at least 10K input Z. That is not likely to be the problem. 5k is not that hard of a load to drive, which is probably a safe guess for worst case. A mismatch in gain more likely is.

As for your setup............you may want to try 4th order Linkwitz-Riley. That many drivers, with crossover points so close together, can be a nightmare. Not only do you have to take into account the phase of the crossover, but also that of the drivers. Heh, heh.....

One of my famous audio designer buddies had a very expensive multiple driver systen, made by a very well-known designer. I showed him how it had a nasty comb filter effect, depending on whether you were a short guy like me sitting down, or a really tall guy like him standing up. And everything in between.

He very quietly put them up for sale 2 weeks later.

But I do not understand why the pre-amp needs to be cranked all the way up just to get nearly the same sound (dB) I had previously

Your ears are fine, and yr setup seems correctly done. What's happening is you're losing energy in the pre->2amp connection. That's because you have halved the input impedance of the amps by putting them in parallel -- i.e. the "combined" load the pre sees is now very difficult and it is struggling to provide the appropriate amount of energy (and isn't making it). The two amps together are sucking up the pre. Remember, when you halve the voltage, the wattage drops to 1/4th.
The rest (room, you need a shrink, 3way xover, etc) don't apply;^) Cheers!

Heh, thanks Gregm, yout thoughts (final ones are noted) :)

I agree, the pre is my problem and I have confirmed this by using another preamp. I have sent an email to B&K but I havent recieved any return responce as of yet. Possibly a phone call on mMonday would be a better idea.

The only options I believe I have are to either use a different pre, or, an electronic cross-over.

As for my cross over points, each driver has it's own independent crossover network which is terminated to it's appropriate power input. With exception given to the subs, they use the internal 80hz low pass x-over via the B&K.

Since I do not have the working knowledge of how the output from the B&K is provided (independently, or summed), I can not say what amount of voltage is present under a given load (the amplifiers draw at various output levels).

I appreciate your help guys, I really do, while I do not agree with all that has been written it is food for thought.

Thank you

Oh and BTW, (sorry I missed this comment) here are the specs according to the Proton manual:

Rated power output 20Hz to 20khz 110 wpc

Dynamic Power at 8 Ohms/4 Ohms/2 Ohms

20ms - 540/1000/1500 wpc

Dynamic Headroom @ 8 Ohms/4 Ohms/2 Ohms: 7.3dB

I.M.D @ rated power: 0.02%

Damping Factor: 150

Freq. Responce 20-20kHz: +/-.02dB

Power Bandwidth @T.H.D 0.1%: 10 - 40kHz

Input resistance / capacitance: 1V

Channel Crosstalk: 85dB

S/N ratio 120dB

Hope this helps (I guess)

This one makes no sense:

"Input resistance / capacitance: 1V"

Check that one, and let us know...........

The one about "dynamic power" is just marketing nonsense, written to impress you. The idea is that the peak power, at the top of the waveform, is calculated to be such-and-such watts. In the real world, it is a useless figure.

The one about head room is more revealing. That tells me it probably has a smallish power supply, and that the rail voltage will sag a great deal under a constant load. Problem is, they give one figure for all 3 impedance levels, and that can't be right. I bet it is a lot less than 7 dB @ 8 ohms. At least I would hope so.

So much for believing specs.