Using PA Speakers In A Home "Audiophile" Application!

My concern would be breakups in the drivers, which cause distortion and harshness. PA stuff mostly does not care about that sort of thing since sound pressure is the main goal. But its a big deal with home audio speakers, where such things can shoot the product down.

@atmasphere , Thanks for the input... I am leaning more towards this 3 way design for reasons mentioned above. It isn’t all that cheap, however...$3000 - 3500 a piece ($6000 - 7000$ for a pair). Nevertheless, since this is 106 db sensitive/possibly running at fractions of a watt for home listening levels...what type of "audiophile grade" home audio amplifier might you recommend?

Other thoughts: I did some searches and found some notes on Benchmark’s website...may be a good fit?

"The Benchmark AHB2 is the only high-powered amplifier that is designed to be noiseless when driving very high-efficiency speakers. The A-weighted signal to noise ratio is 132 dB in stereo mode (135 dB in mono mode). This is 17 to 30 dB quieter than the best competing amplifiers. More importantly, the A-weighted output noise of the AHB2 is -112 dB relative to 2.83 volts. Since speaker voltage sensitivity is measured at 2.83 volts, we can use the sensitivity to calculate the acoustic noise produced by the amplifier-speaker combination. If we select the worst case, an extremely sensitive 110 dB speaker, the acoustic noise will be -2 dB SPL at 1 meter from the speaker. This means that the acoustic noise is 2 dB lower than the threshold of normal hearing. This indicates that the noise produced by the AHB2 should be inaudible in this worst-case example.

In contrast, most high-quality amplifiers produce a noise voltage that is 17 to 30 dB higher than that of the AHB2. When these competing amplifiers are connected to 110 dB speakers the acoustic noise will be 15 dB to 28 dB above the threshold of hearing! The AHB2 may be the only power amplifier that is capable of noise-free operation when driving extremely sensitive speakers."

Small amounts of crossover distortion produced by push-pull transitions in the output stage may translate into audible defects. This is especially true when driving high-sensitivity speakers. High-sensitivity speakers can reveal the shortcomings of traditional class-AB amplifiers. It is not surprising that many people do not like the way high-sensitivity speakers sound when driven from a class-AB amplifier.Benchmark AHB2 1W Distortion Level.

The AHB2 uses a patented feed-forward error correction system to eliminate crossover distortion. This system provides 1st-watt performance that exceeds that of a class-A amplifier"

Might you have any other amplifier suggestions for this "PA experiment", $5000-ish & under?

I suppose my Klipsch “Jubilees” (535 bass bin/402 horn) from their Pro Cinema catalog might be stretched to call a PA speaker. Although designed for active application I run mine with passive crossovers and Faital compression drivers on the 402 horn. Yes, they can and will run you out of the room but yes again, at 105 db sensitivity they can be remarkably tame and sublime with flea watt amps. If you’re looking for immersive, direct, front soundstage experience look no further. Top to bottom horn loaded bass is something to behold. Are they living room acceptable, no. But with all this I am thoroughly enjoying my relatively new Coheret Audio coaxial 12 GR. A wonderful change of pace - 

With regards to the Benchmark amps, I use two as monoblocks with the Jubilees. They are extremely quiet through these big horns. But honestly no more so than any of the First Watt amps I use - 

@deep_333 You will need a low noise amp for that and also one that has low gain, otherwise the noise floor of the amp won't be much help. The Benchmark, while excellent, as over 30dB which means you'll notice noise from your front end.

Our class D amp is quiet (but not that quiet) but it only has 22dB of gain.

I think you'll have to try things out and see what works. High efficiency speakers are often a challenge that way.

SET amps often have only 15 dB of gain, sometime even less. But their noise floors are not as good as our amp but that doesn't mean they won't work. But you would be looking for low noise tubes...

I don't think an SET is a good idea with this speaker since its designed with the idea that the amp can behave as a voltage source. SETs can't do that so you'd have a tonal coloration due to frequency response errors.

@atmasphere wrote:

My concern would be breakups in the drivers, which cause distortion and harshness. PA stuff mostly does not care about that sort of thing since sound pressure is the main goal. But its a big deal with home audio speakers, where such things can shoot the product down.

I don't know the specific product referred to by poster @deep_333, but as a claim aimed at pro drivers in general your statement is incorrect. If there are breakup modes prevalent here it's most likely due to a driver section being used outside it's recommended frequency range, and not because the drivers are more prone to breakups as such than "home audio" variants or very expensive, boutique equivalents - unless we're speaking beryllium diaphragms in the MF/HF drivers, which extend more cleanly into the upper octaves for a given diaphragm diameter. Motorforce is a factor as well, but hardly applicable as a significant contributor in this context.

Moreover, as a design intended for active configuration there are obvious advantages using steeper filter slopes, and thus avoid severe driver overlapping as you would with passive designs. This not least is a factor with horn-loading. Modern pro drivers (and even ones decades old) are extremely well designed, and used within their design parameters - not least actively - will yield no effective problems with breakup modes. 

@deep_333 wrote:

Nevertheless, since this is 106 db sensitive/possibly running at fractions of a watt for home listening levels...what type of "audiophile grade" home audio amplifier might you recommend?

I can say for certain pictured PA speakers above aren't 106dB sensitive overall. The direct radiating woofers are in the 96-99dB sensitivity range, although the horns above are +100dB sensitive. If they were passively configured then the system sensitivity would be dictated by the least efficient driver section (with the horns above dialed down to match LF), which are the woofers here. Since these are intended for active config. a staggered sensitivity rating for each drivers section should be stated.

With regard to amp matching, Ralph is the meastro here in giving advice. Noise can be an issue though with +100dB sensitive drivers coupled directly to amps without any passive filters in between, which can be partly alleviated with higher impedance drivers of 16 ohms, or simply a fitting resistor size in series over the MF/HF section.