Explain to me what I'm hearing from 45W to 80W

[Katji]

I do not understand what you are referring to. Do you take offense with my providing a visual example?

No, sorry [LOL] I realised later that it might be misunderstood. And it was.
Now it needs the reply you were replying to, to make it clearer. But here's yours, with what could've been emphasised:

If you want to see what that "impedance interaction" looks like: here is a measurement of my Clear hooked up to my soundcard vs my AVR (ignore everything beyond 1KHz, mic not accurate enough for that). Suffice it to say, the AVR did not sound good.

Maybe even use a huge font, and repeat three times.
>24 hours later, after we had eventually "established" that speaker impedance, minimum impedance not the "nominal impedance" spec is the most important factor, someone comes again with the same..."dogmatic[?]...whatever.

I might still be ready to be triggered into a rant about the "you..must..do..volume..matching, otherwise..." thing...

 

[Willem]

Power is king if you want realistic reproduction of dynamic music, and the Harbeth video posted earlier is very revealing. I have inefficient Quad 2805 speakers in a large room. I first used them with my existing 2x45 watt Quad 303 power amp, but it did sound a bit strained. So I replaced the amp with a refurbished 2x140 watt Quad 606-2. At moderate levels the new amp sounded the same, but with dynamic music at higher levels the difference was audible. More recently I have added a subwoofer for more bass power, and more recently again a high pass filter to relieve the main speakers and power amp of the heavy lifting to reproduce the lowest frequencies. This gave even more headroom. And indeed, adding an active subwoofer and preferably a high pass filter is another way to add more power.
As for beefy power amps, I think classs D (Hypex or Purifi) is now the way to go, if only because of their energy efficiency.

 

[Chrispy]

Yes, low power amps are perfectly fine. Most of us do not need 100-200w for personal listening. Also, most of the speakers in the market are 6-8ohms and sensitivity of 86-89db. This makes them easy to drive and do no need a high power amp. They at also mostly bookshelf speakers.

Threadstarter is using a q950 floor stander with 1 x 8" woofer cone and 2 x 8" passive... So, this speaker will definitely need more power than average bookshelf speakers to drive. It may be overkill for small room personal listening

The size of the drivers doesn't mean that particularly let alone the passive radiators. Some prefer more power for peak handling or simply higher spl. It depends on details of use. Bookshelf speakers are usually at a disadvantage simply due Hoffman's Iron Law....

 

[Spkrdctr]

Deleted due to my being late to the party.

 

[Spkrdctr]

See, a well thought out and good answer. Can everyone learn from this? Rather than immediately going to “member is retarded and need to do double blind testing and full scientific PhD level analysis before even beginning to think about basics nonsense”

Nonsense? Around here? No way!

 

[LTig]

Threadstarter is using a q950 floor stander with 1 x 8" woofer cone and 2 x 8" passive... So, this speaker will definitely need more power than average bookshelf speakers to drive. It may be overkill for small room personal listening

Haven't checked the sensitivity of the Q950 but in general it's just the opposite. The bigger the speaker (and the woofers) the higher its sensitiviy and the less power you need. The passive speakers do not need any power at all (hence the word 'passive') and work like a port.

 

[NiagaraPete]

I am being 100% genuine. I like lotsa power in my audio gear. Tri-amping and active crossover or better is my idea of a system.

My wife had a friend over and asked “what is that” her reply “his stereo” giving me the stink eye. Next question “why does he have 3 of the same”. No reply was needed, I played Acoustic Alchemy Papillon.

 

[escksu]

Power is king if you want realistic reproduction of dynamic music, and the Harbeth video posted earlier is very revealing. I have inefficient Quad 2805 speakers in a large room. I first used them with my existing 2x45 watt Quad 303 power amp, but it did sound a bit strained. So I replaced the amp with a refurbished 2x140 watt Quad 606-2. At moderate levels the new amp sounded the same, but with dynamic music at higher levels the difference was audible. More recently I have added a subwoofer for more bass power, and more recently again a high pass filter to relieve the main speakers and power amp of the heavy lifting to reproduce the lowest frequencies. This gave even more headroom. And indeed, adding an active subwoofer and preferably a high pass filter is another way to add more power.
As for beefy power amps, I think classs D (Hypex or Purifi) is now the way to go, if only because of their energy efficiency.

i do not have any experience with Class D amps. How do you think of them? I have read about the MBLs but they are ridiculously expensive.

 

[escksu]

Haven't checked the sensitivity of the Q950 but in general it's just the opposite. The bigger the speaker (and the woofers) the higher its sensitiviy and the less power you need. The passive speakers do not need any power at all (hence the word 'passive') and work like a port.

I see, thanks for pointing it out to me.

 

[Galliardist]

Haven't checked the sensitivity of the Q950 but in general it's just the opposite. The bigger the speaker (and the woofers) the higher its sensitiviy and the less power you need. The passive speakers do not need any power at all (hence the word 'passive') and work like a port.

You might want to tell that to owners of some very large and nominally sensitive speakers with big woofers, like the B&W800D, which measure as sensitive at 1kHz but have low impedances in other parts of the frequency range and hence high power requirements. In fact, the speakers under consideration here show some of that behaviour.

Also, passive radiators and ports don't work by magic, but are driven by the active drivers in the speakers. As a result they will have an effect on power requirements. You'll need someone more knowledgeable than I am to go beyond that basic observation though.

 

[PeteL]

simplywyn, you really should stop comparing how far the volume knob goes on each amplifier. That is a function of the input sensitivity of the amp.
The CXA80 has an input sensitivity of 0,78V, meaning that this is the amount of voltage required to drive it to full power. The Denon probably has an input sensitivity in the region of 0.2V, meaning less voltage is required to drive it to full power. In other words, the Denon gets to full power faster, i.e. with less motion of the volume knob.

I agree with statements made by other members that the CXA80 is more powerful, hence it does not clip / distort as often, hence the better sound that you perceive.

And yes, if you plug in a 200W @ 4Ω amp, the additional power reserve will prevent the amp from distorting / clipping even at really loud levels.

Well actually this can be key. no one seem to mention gain structure in this thread, but such obvious difference is not only the wattage difference.
@simplywyn what is the source? your mention "I can barely move the volume much before it was unbearable " This suggest a mismatch between the source output and your Denon input. Amp don't like to have to attenuate that much the input in order to not clip. It can create all sort of non-linearities. This is not common but something to consider. So what's plugged in it?

 

[escksu]

You might want to tell that to owners of some very large and nominally sensitive speakers with big woofers, like the B&W800D, which measure as sensitive at 1kHz but have low impedances in other parts of the frequency range and hence high power requirements. In fact, the speakers under consideration here show some of that behaviour.

Also, passive radiators and even ports don't work by magic, but are driven by the active drivers in the speakers. As a result they will have an effect on power requirements. You'll need someone more knowledgeable than I am to go beyond that basic observation though.

Oh ok, thanks. I too was wondering about the radiators. Although they do not require power, they still need energy to move and likely have inertia as well. Hence, the woofer has to move sufficient air within the cabinet to make these radiators move properly.

 

[Galliardist]

Well actually this can be key. no one seem to mention gain structure in this thread, but such obvious difference is not only the wattage difference.
@simplywyn what is the source? your mention "I can barely move the volume much before it was unbearable " This suggest a mismatch between the source output and your Denon input. Amp don't like to have to attenuate that much the input in order to not clip. It can create all sort of non-linearities. This is not common but something to consider. So what's plugged in it?

For my sins, I've been assuming that the OP is using the built-in DAC with the amps concerned, and so hadn't worried about gain. If an analogue input is being used from a source (or even power in from an external DAC/preamp) then gain may well be an issue.

On a practical point, the proposed Purifi power amps are just that, and will need a source device and volume control.
In that setup, the system will need sufficient gain to provide the required power to the speakers.

I don't see that the OP has mentioned source devices anywhere, or what source/volume control/preamp will be used with the Purifis. There's plenty of scope to introduce new problems - some forums are littered with reported problems due to gain.

 

[Aerith Gainsborough]

the Harbeth video posted earlier is very revealing

Frankly put: I found the video nonsensical.
They do not give a reference on how loud the SPL was, nor what their preferred listening distance is.

All the video showcased was that ineffective speakers use a lot of energy. Not exactly newsworthy.
Try dumping 600W into modern, efficient speakers... I don't think you will like the result.

 

[Chrispy]

Oh ok, thanks. I too was wondering about the radiators. Although they do not require power, they still need energy to move and likely have inertia as well. Hence, the woofer has to move sufficient air within the cabinet to make these radiators move properly.

Not a load on the amp particularly, tho. Just the driver that's amped. Passive radiators are related to porting/venting a speaker.

 

[LTig]

You might want to tell that to owners of some very large and nominally sensitive speakers with big woofers, like the B&W800D, which measure as sensitive at 1kHz but have low impedances in other parts of the frequency range and hence high power requirements. In fact, the speakers under consideration here show some of that behaviour.

Those dips in the impedance curve are a result of the crossover design. A woofer's minimum impedance is the resistance of the voice coil at DC (frequency = 0) and impedance can only get higher, typically with a peak at the woofer's resonance and rising to higher frequencies due to the inductivity of the voice coil.

Also, passive radiators and ports don't work by magic, but are driven by the active drivers in the speakers. As a result they will have an effect on power requirements. You'll need someone more knowledgeable than I am to go beyond that basic observation though.

The passive woofer's are driven by the energy emitted by the back side of the woofer into the box. Since in a closed box this energy is transformed into heat a closed box speaker is less efficient (at low frequencies) than one with passive woofer's (or a port).

 

[LTig]

Oh ok, thanks. I too was wondering about the radiators. Although they do not require power, they still need energy to move and likely have inertia as well. Hence, the woofer has to move sufficient air within the cabinet to make these radiators move properly.

See my posting above. Also the passive woofer and the air volume inside the box work as a resonance circuit. At its resonance frequency the passive woofer has its highest acoustic output while the excursion of driving active woofer is almost nil.

 

[simplywyn]

Impossible to tell w/o extended measurements.

It might be in your head, it might be that the amp misbehaves, it might be that it doesn't "like" the speakers.
From some of your descriptions, I would concur with other posters, that you run it at/beyond it's capacity.

A low volume, level matched (via voltmeter) test would be intriguing to take power and psychoacoustics out of the equation but I guess you don't have the equipment for that. Anyhow, if the Denon can't deliver the SPL you want in a clean enough manner to be enjoyable, then it's pointless to beat around the bush. You need more power.

If I pass ~100dB on my Yamaha AVR (similar power to yours) the sound gets flat, harsh and very unpleasant.
Thankfully I dislike loud noises so I don't need more power.

I just tried it at very low volume, the difference is less noticeable, but STILL lightly noticeable. Once you crank it to even regular listening volume, the differences are very obvious.

 

[Aerith Gainsborough]

I just tried it at very low volume, the difference is less noticeable, but STILL lightly noticeable. Once you crank it to even regular listening volume, the differences are very obvious.

Define "low volume", define "regular listening volume".
What SPL did you set it to? One persons' low is another persons loud.
E.G.: Most in this forum would laugh at me if they knew the SPL's I consider loud.

I guess it is possible, that even your low volume is too much for the smaller amp to handle.

The other option would be volume matching.
You'd be surprised how similar +-3 dB can feel in terms of volume if you need time to switch between the setups yet +3 dB will let the louder source sound clearer, more alive, punchier, wider ... more fun (if the signal is clean).

Sadly, us humans are pretty crappy when it comes to assessing auditory sensations and volumes. Especially our ability to recall and compare is beyond abysmal. On top of that, our other senses can play tricks on us. If one amp is butt ugly and the other super pretty, which one do you think will sound nicer? (Again: clean signal and level matched).

Bottom line: human perception is weird. That's why many in the scientific world go to such lengths to attempt to compensate for it. Naturally, that isn't feasible for many a hobbyist. We usually can't set up DBT environments, don't have measuring gear to level match to 0.01dB etc. So we always need to be aware that our simplified comparisons, our perceptions and ultimately the conclusions we draw will be flawed.

 

[solderdude]

I just tried it at very low volume, the difference is less noticeable, but STILL lightly noticeable. Once you crank it to even regular listening volume, the differences are very obvious.

Record it and folks can listen along.