Mono block bi-amp cascade

General
1

Is there a way to use 4 mono amps off a cascade to mono block bi-amp a pair of speakers?

Thank you

2

Hi Shad,

Just some things that occur to me off the top of my head…

There are a number of pre-amps available now which include a cross-over with separate outputs for high and low frequencies for each channel. Some also include a sub output too.

Although most speakers that can be bi-amped don’t require it, it’s best to not send the low frequencies to the mid/tweeter and to not send the high frequencies to the woofer. If you don’t use a cross-over you may find that some of the power is wasted.

Here is one pre-amp that does this, though there are others.

One of the advantages of bi-amping is that the amp for the mid/tweeteramplifer can be smaller than the one for the woofer. Here is an example of a mono-block amplifier made specifically for bi-amping. It provides the woofer with twice the power available to the mid/tweeter.

Also there is pro-audio equipment that will split a high-level signal(taking into account impedance, like a pre-amp does) into two or more signals, but they usually don’t act as a cross-over.

Although I don’t think it is a good idea, there are XLR Y splitter cables like:

https://www.bhphotovideo.com/c/product/252312-REG/Hosa_Technology_YXM_121_XLR_Female_to_2.html

Dan

3

There also exist such a thing as an “external crossover” that will separate the high and low frequencies of the line level output to feed into separate amps, feeding the different parts of the speakers. As mentioned above, the simplest form of this is splitting out the subwoofer output, and feeding low frequency signal to a more powerful amp to feed the large, low frequency, drivers, which need the most power. Then a smaller wattage amp (supposedly that sounds “better” but can’t run the low frequency well enough) can feed the mid and high frequency drivers, which require much less power to run appropriately.

And, doing this requires the ability to bypass the crossover in the speaker. For best results, one requires a speaker system specifically designed for this purpose.

4

Hello Shad,

The goal of a preamp has always been to take the established industry line level and boost it up with the use of several gain stages through the use of transistors or tubes, to full volume for the sole purpose of… turning it down again! The output of the ladder DACs is at full volume so we only need to attenuate down to the intended volume using a passive constant impedance passive resistor attenuator. We consider the output of the ladders to be the purest form of the signal. The goal is to have no transistors or any kind of semiconductor devices after the attenuator. The attenuator goes directly to the output jacks. The output impedance of the cascade is 75 ohms, so it is low and robust.

Having said that, even though a preamplifier is a duplication of gain, I do encourage people to try their preamplifiers into their amplifiers and just listen. They almost always prefer to use the volume attenuator in the MSB DAC.

Your question makes me assume that you will drive the inputs of two amplifiers with no frequency splitting, then your speakers will have upper and lower binding posts, and you will allow the speaker crossover to do the high/low frequencies splitting. Please let us know what amplifiers they are and what the input impedance is. Thank you..

5

Never mind, I answering the wrong question…

6

I’m not entirely sure what you are trying to accomplish but I have several methods for what you might be trying to do.

  1. If you want an identical signal from 2 amplifiers (per XLR jack), that are not MSB amplifiers, at Poor to Good quality, (which will heavily depend on the amplifiers themselves) you may use a Y cable (balanced only please with true balanced amplifier inputs only). This has the downside of interaction between the amplifiers. If they are well behaved then the quality can be quite good. If they misbehave then the output of all amplifiers suffers and the quality will be quite bad.

  2. If the amplifiers misbehave at all (IE all switching amplifiers misbehave) then a transformer based splitter is the ideal solution. This is often used in studio environments. It is usually sold as a “line level passive splitter”, such as the Radial Engineering LX-3 (you would require 2 of them). It has the advantage of largely isolating the amplifiers from each other and therefore giving the best possible output from each.

  3. Use a preamp with multiple outputs to split the signal. This is highly dependent on the quality of the preamp and is likely to be the least performant of these three solutions. It has the downsides of solution 1 with the additional problems that the preamp would likely bring to the table. The preamp would ideally have both perfect performance and transformer coupled outputs.

If you are trying to drive speakers of different frequency ranges, then you would ideally use an outboard line level crossover (either passive or active). My preference would be passive with transformer coupled outputs, but the best line level crossover is up to interpretation.

If you are trying to drive 2 MSB amplifiers we would probably have to make you a custom solution that preserved the constant impedance of the MSB system. This would likely take the form of a custom, dual transformer, splitter box with impedance matching networks.

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