tubes on top. S/S on the bottom.
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Contrary to widespread belief, passive bi-amping (which I assume is what you are envisioning) will not give you significantly more power, and in fact may give you no power increase at all. See the following thread:
If you use different amplifier models for the lows and the mid/hi's, you may also have a problem keeping the gains matched, as was stated. And you may degrade the sonics, at least slightly, if the two amps have differing sonic characters.
My suggestion is that you consider simply replacing the VTL's with something more powerful.
I've got 60w dynaco mkiiis running the tops of my VR4s (89db), and a 170w power amp running the bottoms. The power amp has potentiometers for each channel, which I turn down to a little less than half and keep them there. (You can accomplish the same thing by other means). I've used a passive pre to good effect, but currently have them running through a Juicy Music Peach II. It sounds great, and I love the tube/ss combination. I change the flavor of things by switching out the power tubes in the monoblocs from time to time. No way I'd sell those VTLs.
Sy, you're welcome!
Stewie, I don't doubt that you have an excellent sounding configuration. And I see nothing wrong with Sy obtaining a second set of amps, or a stereo amp, and trying it in a biamp'd configuration, before deciding whether or not to sell the VTL's (provided that the gain-matching issue is addressed).
However, since his main concern is obtaining more power, my main point is that he should NOT choose the power rating of the new amp(s) based on the expectation that bi-amping will provide a significant power increase. Because it will not, as explained in the other thread that I linked to.
He should choose the new amp(s) such that it has sufficient power to satisfy his requirements while operating alone. I note that the C7 manual recommends amps of up to 350 watts.
Also, the fact that his speakers are rated as being only slightly less efficient than yours says little about the amount of power he needs. The dynamic range of the music you and he listen to may be quite different, the room size and listening distance may be different, and the sensitivity ratings of the speakers may be defined differently and/or be inaccurate.
Two basic points should be kept in mind:
1)Passively bi-amping two pairs of 125W monoblocks will not result in the equivalent of a 250W amp (which is only a 3db increase anyway), and will probably result in the equivalent of very little more than a 125W amp.
2)Passively bi-amping 125W monoblocks on top and a 350W amp on the bottom will also result in the equivalent of very little more than a 125W amp, because since the top and bottom amps will have the same input signals (assuming gains are matched) and the same output voltage swings, maximum power delivery will be limited by the clipping point of the lower powered amp. That clipping point may be slightly higher in the biamp'd configuration, due to increases in its internal voltages resulting from reduced current demand (since it would be supplying current essentially just to the mid/hi drivers, and not to the woofers), but in terms of audible volume that increase will be negligible or close to it.
Sorry Al and Kal
I bought a CJ MF 2500A in 2002 to replace my CJ MF 2100. A year later I bought bi-wireable speakers. First I bi-wired and then I bi-amped horizontally. Both times there was a significant improvement in sound quality. I had the advantage of amps with identical gain,input impedance and sensitivity.
Econotweaks -- Nothing I said was meant to negate the possibility that bi-amping can produce a significant improvement in sound quality, if done right. In fact my post in the other thread that I linked to above specifically pointed out, among other things, that the sound quality of the amps may benefit from the reduction in the current demand on each amp that biamping results in.
The issue here is not sound quality -- it is how to obtain a significant increase in power.
Thanks for your congenial posts. But I thought the issue wasn't more power per se (that is, I didn't hear him say, I need more power, should I bi-amp?) but rather, I want to bi-amp, so should I worry about keeping things balanced between bottom and top in terms of watts, or should I supply the bass speakers (since they demand more power) with a more powerful amp, say a ss? Anyway, the OP seems to have abandoned the idea, so. . . .
I biamp with 4 150 watt monoblocks.When I first decided to go that way I didn't really know what to expect with respect to volume levels etc. What I found was that volume levels remain about the same. However, the sound is much better. There seems to be more of it and less strain on peaks. My speakers are about 90db sensitive and an easy load to drive. Bi amping makes them sound better all round but the volume levels remain the same. You may need more power all round. I like solid state for power amps matched with a hybrid preamp and phono stage but you may like something else.
I see nobody has mentioned active biamping yet, so let me throw it in.
Sy: a way that might accomplish what you seemed to be intending in your original post is to include an active crossover between the preamp and the amps: the full bandwidth signal goes from the pre to the crossover, where it's separated into mids/trebble and bass. From the crossover you get a set of cables carrying mids/trebble going to the VTL and another set of cables carrying the bass going to a solid state amp. Then from the VTL to the mids/tweeter and from the SS to the woofer/s.
With this configuration now your VTL needs to reproduce only part of the bandwidth. At around 350 Hz crossover point you get 50% of the energy to the mids/trebble and 50% to the bass. Then you do effectively increase the power of your system. A lot more info at sound.westhost.com/bi-amp.htm.
The downside of this configuration: now you need a SS power amp, a crossover, 2 extra power cords, 2 extra ICs, and the rack space required by these. Are you better off by spending all this and the time it will take to tune this setup, or by simply buying a larger amp that can play your speakers better? Also, at the website I listed it clearly says you should remove the passive crossover of the speakers for this to work, although some users haven't done so and report huge benefits anyway.
Me? I don't know! I've been toying with this idea too. I cannot remove the passive x/o in my speakers withou damaging them (so no way), and I'm torn with the extra expense vs. living happily ignorant thereafter :)
I hope this helps.
If you want a biamped system why do it in a piecemeal fashion where you have to ensure that the gains are correct and either insert your own filters or feed full range signals to the speaker inputs. Instead, buy an active speaker where the gain is set, there is an appropriate power availability for each driver, the signal is properly bandlimited at the amplifier, and the system was designed as an integrated whole. Then you will end up with the full benefits of separate amplifiers. Otherwise you either have to invest an enormous amount of time designing and testing the system to arrive at system in which you will have any assurance of accurate performance.
after all , i have decided to bi-amp, with the same amps that i have. i will wait for another pair of vtl 125 to come on for sale.. i underdstand that there may not be an increase in volume, but , if the sound quality is better, than its worth it!!!
if nayone know about a pair of 125 for sale , not to expensive, i would be interested