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Struggle replacing Old AVR - tried RZ50, 4800h, and Cinema 70 - what now?

voodooless

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I know, for example, a power cube measurement of a Marantz amplifier and it strongly indicates a sound image that is being cut off.
The cube only tells you what happens at the extremes. If you run your amp at those levels, you need a bigger one anyway. Now sure, there will be model to model variations on what those extremes are for different loads. So it can give you some useful selection criteria.

But @DonR is talking about operations within normal parameters. And there al these amps will be virtually indistinguishable. They are all AB designs with plenty of low output impedance and proper feedback implementation. They are all highly load independent and have plenty of bandwidth.
 

pogo

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But @DonR is talking about operations within normal parameters. And there al these amps will be virtually indistinguishable. They are all AB designs with plenty of low output impedance and proper feedback implementation. They are all highly load independent and have plenty of bandwidth.
And that's exactly what I doubt in the real world. What you hear must also be measurable. Are there any meaningful measurements at different operating points for the aspects you listed? Preferably for the AVRs mentioned here.
What are the operations within normal parameters?
 

voodooless

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And that's exactly what I doubt in the real world. What you hear must also be measurable. Are there any meaningful measurements at different operating points for the aspects you listed? Preferably for the AVRs mentioned here.
What are the operations within normal parameters?
There are plenty of AVR reviews at ASR. Power vs THD should tell you want you need to know. Normal parameters: not clipping.
 

pogo

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There are plenty of AVR reviews at ASR. Power vs THD should tell you want you need to know. Normal parameters: not clipping.
Measured only on a purely ohmic load and only for a short period of time!
However, it is not possible to derive other operating points from this, such as how the amplifier behaves at a load with 3.2ohms including a phase shift (real speakers), ....
 

HarmonicTHD

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And that's exactly what I doubt in the real world. What you hear must also be measurable. Are there any meaningful measurements at different operating points for the aspects you listed? Preferably for the AVRs mentioned here.
What are the operations within normal parameters?
Things you hear can be measured 100 times over. Audio is not a difficult signal to measure compared to modern technology. Perception is a bit trickier as it involves psycho acoustics here level matched double blind test can reliably tell what the individual perceives or not. Or with a larger test group what the „average“ listener can perceive. There have been plenty of studies.
 

voodooless

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However, it is not possible to derive other operating points from this, such as how the amplifier behaves at a load with 3.2ohms including a phase shift (real speakers), ....
No, we don't have those, but also little indication that we really need these metrics in the first place.
 

pogo

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but also little indication that we really need these metrics in the first place
I see that differently and even more so when I look at the power cube diagram of a Marantz on page 52: Link
An standard Marantz AVR will certainly not perform any better, especially when multiple channels are active.
 

voodooless

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I see that differently and even more so when I look at the power cube diagram of a Marantz on page 52: Link
An standard Marantz AVR will certainly not perform any better, especially when multiple channels are active.
None of that means it will be audible differently from the other amps though. It only means its limits are lower in certain cases. Again, this may be relevant if you have speakers with certain loads, but as long as you keep within operating limits, it will not matter.
 

pogo

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We currently have a good example here in a German forum with Klipsch RP-8000F on a Denon x4800h. The deficits of the built-in power amplifiers can be reduced by bi-amping on the AVR, i.e. the distortion behaviour of the lower part has less influence on the higher part through bi-amping.
 

voodooless

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the distortion behaviour of the lower part has less influence on the higher part through bi-amping.
Once you're at this point, you just need a higher-power amp, the low end will still distort.
 

voodooless

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Once you're at this point, you just need a higher-power amp, the low end will still distort.
And let's not forget that these AVRs are crammed with relatively crappy AB amp boards, probably costing below $10 per channel to produce. It's amazing that they even get the performance out of them that they deliver. Quite a few interatoin of optimizations (cost vs performance) have gone into these over the years.
 

HarmonicTHD

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We currently have a good example here in a German forum with Klipsch RP-8000F on a Denon x4800h. The deficits of the built-in power amplifiers can be reduced by bi-amping on the AVR, i.e. the distortion behaviour of the lower part has less influence on the higher part through bi-amping.
How was that quantified?

As @voodooless said, any load dependent frequency response change might only come out at the „edge“ cases and not necessarily during „normal“ listening levels. Therefore it is important not to generalize but to look at each case individually with SPL required, Speaker sensitivity and Impedance curve and Amp Power FR curve.

Plus the question of audibility still remains. In one of these threads it was claimed that ca 1dB SPL difference at ca 8KHZ and being pretty narrow resulting from load dependence of a 50USD Fosi amp into LS50 is clearly audibly.

I didn’t test that myself. It might just be audible with a test tone but with music increasingly difficult. Only a level matched blind test could tell for sure.

In most cases the amps and speakers are just fine and people claim differences based on flawed listening tests.
 

pogo

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Therefore it is important not to generalize but to look at each case individually with SPL required, Speaker sensitivity and Impedance curve and Amp Power FR curve.
I'm with you there, if you add the phase shift and the program material:

 

Times

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How was that quantified?

Not at all. Here's the link to the thread (it's in German, though):
Denon x4800h Bi-Amping + Klipsch RP-8000f Erfahrung @ www.hifi-forum.de

The OP has absolutely no clue what he does and what he talks about. I tried to translate some of it and from the other thread the same OP started:

After adjusting the frequency crossover via the XTZ's gain control, I no longer recognize my speakers!
The sound has increased so much that it brings tears to my eyes.
Thanks to the frequency crossover adjustment, Audyssey measures in a much more balanced way. In single-wire mode I have EQ adjustments that are 15db apart. However, after I adjust the frequency transition in bi-amp mode using the gain control, I have EQ adjustments that are only 5dB apart and produce phenomenally audiophile sound.

I explain this "dimensional leap" by bypassing the passive crossover and allocating the output voltage of the audio signal more effectively from the receiver.
I think this realization is a thorn in the side of the hi-fi industry.

I suspect the internal mono power amp blocks have a noticeable effect.
The tweeter in bi-amp mode is driven more extensively. I only knew such a tweeter operating mode from power amplifiers with +300W at 8 ohms per channel.
The XTZ A3 300 (150W/8 ohms) and A3-400 (200W8 ohms) could not drive the tweeter so powerfully.
In my opinion, bi-amping stereo operation with the Denon x4800h is an outstanding additional gain.
How can that be? Is the crossover of the RP-8000f perhaps responsible for this?

I now have a groundbreaking sound improvement thanks to a trick:
I operate the Denon and an XTZ power amplifier in bi-amp mode.

Now I have used the gain control of the XTZ to tune the frequency crossover of the 2-way Klipsch so that the EQ curve of Audyssey miraculously corrects itself by a maximum of 2 db.
Without this frequency crossover tuning (single wire), I get strongly deviating 15db EQ adjustments.
The sound has increased indescribably with my Klipsch!
The sound feels projected and room filling, similar to the 8D headphone sound. I can only explain this phenomenon by the fact that the Klipsch have been adapted and work almost like active loudspeakers.
I no longer recognize the otherwise already good RP8000F. Everything sounds much more real.

I don't know how it's even possible to come to this conclusion after reading that thread...

We currently have a good example here in a German forum...
 

voodooless

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Also note that when bi-amping, if one channel clips, the other one isn’t far behind. The trick here is that these amps will be mostly current limited. Due to the high impedance low frequency bit of the tweeter crossover, it will be able to deliver a stable voltage for longer than the bass section.
 

HarmonicTHD

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I'm with you there, if you add the phase shift and the program material:

Impedence Curve contains both, Magnitude and Phase.

Program Material is irrelevant for the FR tests and a sweep is sufficient, but of course program material might influence power requirements (crest factor).
 

HarmonicTHD

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Not at all. Here's the link to the thread (it's in German, though):
Denon x4800h Bi-Amping + Klipsch RP-8000f Erfahrung @ www.hifi-forum.de

The OP has absolutely no clue what he does and what he talks about. I tried to translate some of it and from the other thread the same OP started:







I don't know how it's even possible to come to this conclusion after reading that thread...
Thanks for the link.

You are right. Utter nonsense and clearly falls into the category „flawed listening“ test and no facts whatsoever - snake oil.

@pogo you are creating a big strawmen here and you are fishing for evidence based on a flawed test. Try a different approach.
 
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pogo

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What is wrong with the perceptions in the first post in the other forum?
Don't pay attention to the restructured sequence of Times!
 

HarmonicTHD

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What is wrong with the perceptions in the first post in the other forum?
Don't pay attention to the restructured sequence of Times!
Now I am even more surprised that you even have to ask that question as you have been here long enough.

A) Non controlled listening test (we see claims like that every day here. None has been proven in the last years).

B) No facts like I mentioned above (SPL, Power FR curve, Impedence curve, etc) which would indeed indicate at least the possibility of a FR change. Nada Zilch Nothing. Pure speculation.

Just the usual BS we see here. Not wasting my time on this. See my post above: „In most cases amp and speakers are fine“
 
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