Two pairs of the speakers in the same room - is it a problem?

[SlowCar]

I have not seen it in the one you linked, please post the link if it is a different one you are now referring to.

This is the exact fragment I am refering to. Question is - the same rules applies to preamp->amp.

20X ratio stated for loudspeakers would correlate more to 10X ratio for power amps, but personally I would double that and go for 40X minimum (some would argue 200X or even 1000X but that would be just being silly..) for loudspeakers and 20X for amps, the higher the better, to a point. There is always a point of diminishing return.

So as far as I understand - using Denon preouts to both mentioned speakers may be problematic?
If so - what are exact problems that can occur? Is it only less energy? Or as in speakers (because speakers doesn't have flat impedance across frequency range) it will create audible differences? If only less energy is problem - will not there be problem with volume mismatch when using eg. focal's fronts with completely different center/surrounds?

 

[Vladimir Filevski]

So as far as I understand - using Denon preouts to both mentioned speakers may be problematic?

No, see my post #57.

If so - what are exact problems that can occur? Is it only less energy?

Yes, only less than 1 dB voltage drop across whole frequency spectrum, i.e. frequency response stay flat as before.

Or as in speakers (because speakers doesn't have flat impedance across frequency range) it will create audible differences?

Because loudspeaker impedance varies with frequency, high output impedance of the power amplifier will react with the loudspeaker impedance, producing not flat frequency response. Hence the 20x rule. Or 200x rule.
But input impedance of the power amplifier is ruler flat (pure resistor), so the frequency response stay flat, irrespective of the output impedance of the pre-out. Hence the 10x rule.

If only less energy is problem - will not there be problem with volume mismatch when using eg. focal's fronts with completely different center/surrounds?

No problem, any volume mismatch is easily adressed with the AVR/processor management system.

 

[peng]

This is the exact fragment I am refering to. Question is - the same rules applies to preamp->amp.


So as far as I understand - using Denon preouts to both mentioned speakers may be problematic?
If so - what are exact problems that can occur? Is it only less energy? Or as in speakers (because speakers doesn't have flat impedance across frequency range) it will create audible differences? If only less energy is problem - will not there be problem with volume mismatch when using eg. focal's fronts with completely different center/surrounds?

If you are using the Denon pre outs, no it won't be problematic because the Denon pre out will be driving your power amp. You need to know your power amp's output impedance to determine if it is too high for your speakers. For example, the Hypex NCore amps do have very low output impedance so even 4 ohm speaker will be fine is you use the right size/length cables. Volume "mismatch" when using different front and surround speakers won't be an issue either unless the difference in sensitivity between those speakers are huge, otherwise when you run autosetup/Audyssey, they will get level matched, to eliminate such "mismatch".

 

[SlowCar]

Ok, great. One issue resolved. Thank You guys.
2 more to go - hdmi can be bypassed by a proper tv. Last one is - does measurments with DSP turned on are the same as in review?

 

[peng]

@SlowCar , to be clear, if you have good reasons to go with an AVP, go for it. However, you seem concerned about even a minor factor such as output impedance of the pre out, so you should probably pick an AVP but make sure that it actually measured better than the X3700H.

As Vlcadimir explained, the "fairly high" output impedance of the Denon would result in some voltage drop when pair with power amps that have low input impedance such as the Focal trio6 Be's amp but that won't affect sound quality. The pre out will see the Focal speaker (that an active speaker) a power amp, not a speaker lol..

 

[SlowCar]

The pre out will see the Focal speaker (that an active speaker) a power amp, not a speaker lol..

I am aware of that

AVP is not an option because of price...

 

[DanielT]

Speaker crossovers are designed for a specific baffle width (this is called baffle step compensation if you care to search). Above a frequency that depends on the baffle width, the speaker radiates into half space, and below that frequency into full space. This cases a gradual 6dB rise above that frequency.

Two speakers next to each other would have a wider effective baffle than one speaker, changing that transition frequency. A flat speaker will no longer be flat. This would likely be EQable.

In addition, diffraction occurs at the baffle edges. The crossover would be designed to take this into account to some degree. With speakers next to each other, diffraction effects will be different than what was anticipated in the design.

Of course, the same effects occur when you place a speaker next to anything.

But literally bookshelf loudspeaker, which is placed in a bookcase. How to look at it?

A bit extreme, maybe, the speakers in the picture. Stuffed in like that, but maybe it has its advantages..... and disadvantages.