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

[Mart68]

I think he is suggesting that Krell is cooking the FPB specifications. Like lowering the rated 8R power output to make the linearity to 2R look better than it really is at measured values.

I don't think it's any secret that Krell and others do this. The KSA50S is is rated at 50 wpc, into 8 ohm measures at 75wpc. The KSA100 (100 watts) measures close to double that. This doesn't change the fact that they will drive difficult loads without changing their sound, unlike an awful lot of amplifiers that have a lot more watts per channel into 8 ohm.

Amplifiers lack of ability to drive low impedance loads and/or lack of power resulting in clipping are, I think, the main two reasons why people are not happy with the sound of their systems.

Many/most amplifiers are lacking in this regard because it's the bit that costs proper money to do right. Much easier to skimp on the power supply and rely on Darko/Guttenberg style bullshit to sell the product.

 

[escksu]

My point is quite simple. No amp really doubles its measured 8 ohm power into 4 ohms. (Edited - somehow I wrote 2!) I get your point about rated spec, but really...

It has relevancy. A lot of published amp specs are wrong. There are quite a few manufacturers that measure the 4ohm output of their speakers, double it and publish the result as the 8ohm output.

I don't know if Krell did that with the FPB 600, but the published spec says 600 watts into 8 ohm and the actual measurement is effectively 50% higher. How much headroom do you need?

Ok, this one i can agreed with you. They measure 4ohms and simply put 1/2 the value for 8 ohms. However i prefer to use the word over-engineered. Just like how ridiculously overly-engineered rb26dett and 2jzgte.

 

[escksu]

I don't think it's any secret that Krell and others do this. The KSA50S is is rated at 50 wpc, into 8 ohm measures at 75wpc. The KSA100 (100 watts) measures close to double that. This doesn't change the fact that they will drive difficult loads without changing their sound, unlike an awful lot of amplifiers that have a lot more watts per channel into 8 ohm.

Amplifiers lack of ability to drive low impedance loads and/or lack of power resulting in clipping are, I think, the main two reasons why people are not happy with the sound of their systems.

Many/most amplifiers are lacking in this regard because it's the bit that costs proper money to do right. Much easier to skimp on the power supply and rely on Darko/Guttenberg style bullshit to sell the product.

One downside is that amps that have alot of power on the tap usually cost quite a lot more. IMHO, once you go above 100W, it gets alot more expensive.

 

[Katji]

Wow eye opening, this is most definitely what's going on with my amps.

Yeh, I just saw that video posted in a thread that came up in search results:
Amplifier Power: How much do you really need and your system’s dynamic range.

"So what's the plan, Stan?" Given that you want to use the CXA80 for something else...or just get another amp anyway, for the something else purpose or for these speakers... You probably have some ideas about what to do, what to get.

 

[Mart68]

One downside is that amps that have alot of power on the tap usually cost quite a lot more. IMHO, once you go above 100W, it gets alot more expensive.

True, if you like insensitive loudspeakers it gets pricier. I prefer to buy used and cut the cost that way, but I appreciate that's not for everyone.

 

[escksu]

True, if you like insensitive loudspeakers it gets pricier. I prefer to buy used and cut the cost that way, but I appreciate that's not for everyone.

I am not exactly a fan of speakers with low sensitivity. However i do like dynaudio speakers. They arent very sensitive and worse, they are mostly 4ohms. They also need alot of power to really shine. So, i feel they work very well with krell integrated amps.

However, i personally dont think krell amps are suitable for everyone. As you might read, they sounds somewhat "cold". This is very evident in the 300il/400xi/s300i amps. But i feel this makes the amp more neutral or natural since it does not add its own character to the sound.

Btw, i too buy mostly used stuffs!! I sometimes buy amps thats not working well and repair them myself. I am also into amp modding. Its fun to change some components and see if there is a difference or not!!

 

[ahofer]

Well, the difference is pretty noticeable… I honestly don’t like this attitude of immediately thinking the person is at fault.

I know, it sucks, don't take it personally, it's just Bayesian inference from experience. A lot like the tech support guy telling you to do a cold boot.

But it does make procedural sense to do some controlled testing if you want to know the cause for sure, and eliminate likely other possibilities. As an engineer, you can't fault such response from people you are asking for help. It doesn't make sense to ask everyone here to join you on a path that is often fruitless.

It seems the answer you want is that the Denon is lousy, the Cambridge is better, and maybe there is something even better out there that someone could recommend. Certainly it is possible the Denon is underpowered for your speakers. You can get a lot of clean power for very little money with a Purifi or nCore build (I have a 252, but you could get a nc502 and just stop worrying about clean power). I very much doubt, however, you would hear the difference in a proper blind test between the Cambridge and the nCore (or anything else at reasonable volumes) unless your speakers are a more difficult load than I am presuming)

On that topic, I didn't read the whole thread or see speaker measurements, but it's possible the resistance dip in your speaker is also at a difficult phase angle, causing real problems for a low powered amp.

But all these conclusions properly come after level-matched testing. Sorry. We have only the scales on our eyes to lose.

PS - are they similar to the Q900? Not terrible - Phase angle extreme is rising from prior extreme at the impedance low, but it could be 70-120Hz where the Denon just can't deal with the apparent load.

https://www.stereophile.com/content/kef-q900-loudspeaker-measurements

 

[escksu]

I don't think it's any secret that Krell and others do this. The KSA50S is is rated at 50 wpc, into 8 ohm measures at 75wpc. The KSA100 (100 watts) measures close to double that. This doesn't change the fact that they will drive difficult loads without changing their sound, unlike an awful lot of amplifiers that have a lot more watts per channel into 8 ohm.

Amplifiers lack of ability to drive low impedance loads and/or lack of power resulting in clipping are, I think, the main two reasons why people are not happy with the sound of their systems.

Many/most amplifiers are lacking in this regard because it's the bit that costs proper money to do right. Much easier to skimp on the power supply and rely on Darko/Guttenberg style bullshit to sell the product.

Just to say, i dont think the ksa-50 will have any problem driving the Q950 even though its rated at 50wpc.

 

[escksu]

I went googling for the cxa-80. Its a really nicely built amp. The toroid transformer in the center. The heatsinks acting as a shield. I saw a pair of bipolar transistors for each channel. No idea what they are buy i think they are rated for 150w or more. Likely high current ones (est. 15-30A).

From the design, i am not surprise why it can drive the Q950 pretty well.

 

[Pennyless Audiophile]

The difference is night and day, but I guess I’m just fooling myself…

The wattage plays nothing here? 400W amp vs a 15W amp makes no difference?

No, you are not fooling yourself. Amplifications do sound differently in real life, they become indistinguishable only during blind testing, in strictly controlled conditions. That is, blind testing takes away all the subtle clues that let you appreciate the different sensations that they can give. So, it so not something I would suggest doing outside a research lab.
I am not saying that magic is involved, there must be an explanation obviously, but as far as you should be concerned, don't worry, just keep the one you like best.
You may be interested to learn that Andrew Robinson had a similar impression with the Denon.

 

[weasels]

Compared both in loud and soft…


Whatever I hear what I hear… you’re just pissed off. Get off your high horse. I’m an engineer by trade. The other guy offered a much better reasoning. I’m hoping he can give me some more info on how to really beef up the speakers.

That's pretty much the definition of subjectivity - "I hear what I hear" and only agree with comments that support my initial bias. The only rude person I've seen on this thread was the OP.

 

[Aerith Gainsborough]

“All amps sound the same and we are biased and stupid”… I literally just plugged in 3 different headphone apps to my d90, and all three sounded different high and day

Lets just say that all competently designed amps sound the same if they drive a load at a demanded SPL that they are designed for.
An important part of that is a low output impedance, so you you do get as little interaction with speaker impedance as possible.
That's especially important in headphone amplifiers, as you already found out but it also applies to speaker amps.

It basically acts as a built in EQ and colors the signal, in case of headphones often in a very noticeable way. Sometimes the result is pleasant, sometimes not. That is why many audiophile headphone listeners hunt for "matching" gear that produces the signature they like.
Sales naturally takes advantage of that, instead of familiarizing the average Joe with EQ and it's use because there is money to be made.
Yup, most of the audio industry is neither nice nor honest. They are after your wallet and they gladly sell you something you don't actually need.

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. Fun for movies though.

Second part would be to be audibly transparent in the distortion domain. Thankfully, barring clipping due to incompatible loads/demands that one is easy nowadays.

Naturally, another part is having enough power.
Big room, difficult to drive speaker and demanding content? Better have a beefy amp even for volumes we deem "moderate".

 

[simplywyn]

Yeh, I just saw that video posted in a thread that came up in search results:
Amplifier Power: How much do you really need and your system’s dynamic range.

"So what's the plan, Stan?" Given that you want to use the CXA80 for something else...or just get another amp anyway, for the something else purpose or for these speakers... You probably have some ideas about what to do, what to get.

I put my denon for sale and looking to buy two purifi mono blocks

 

[Katji]

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 you should spell it out, maybe bold for emphasis.

 

[Aerith Gainsborough]

Maybe you should spell it out, maybe bold for emphasis.

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

 

[Cbdb2]

It was pretty obvious, with denon I have to keep the clause under 40% otherwise it was annoyingly loud, with the Cambridge, I can go all the way to 80% and it'll just get more wide and detailed

Going from 45w to 70w is only 3db, not much change in loudness. The difference your hearing is in the volume pots.

 

[Cbdb2]

So the entire amp review industry is a lie? If every amp sounded the same, why does this site exist? I’m completely confused now.

Far as I'm concerned the whole audio review industry (key word meaning payday) is a lie, an obvious one.

Good amps are hard to tell apart, until they misbehave. The audible differences occur durring : clipping (happens more than most realize) recovery, instability/ringing(hard loads), ground loops, protection (over current, over heating)

 

[simplywyn]

Going from 45w to 70w is only 3db, not much change in loudness. The difference your hearing is in the volume pots.

I don't agree - here's what I heard (several scenes from sucide squad):

Suicide Squad:
Walking - the footsteps don't feel as sharp, and the landing doesn't feel as full bodied very flat
Bullets - CXA80, the bullets REALLY come at you, and I tried to even increase volume in Denon to compensate but never got that emmense sound pressure feeling of a bullet coming at you. Also with CXA80, it felt very directional, like you could hear the bullet coming, but with Denon, it felt very flat, closer to the TV.
Fighting - overall punches feel beefier on the CXA80, feels like there is wide soundstage, Denon feels like punches are coming from the speaker
Explosions - loud and wide on the CXA80, but just loud on the Denon, hurting my ears as well

Ferrari vs Ford:
Engine rumble: Deep and gnarly on CXA80 and sometimes in your face, on Denon, plain but loud, missing that deep pounding sound

I even gave the Denon more volume (from what my ears told me, it was louder) but definitely didn't get the same feeling. I think it's definitely the woofers not getting enough power.

 

[simplywyn]

Far as I'm concerned the whole audio review industry (key word meaning payday) is a lie, an obvious one.

Good amps are hard to tell apart, until they misbehave. The audible differences occur durring : clipping (happens more than most realize) recovery, instability/ringing(hard loads), ground loops, protection (over current, over heating)

See, good amps - I think the misnomer here is if you're comparing a 45W fabulous amp that doubles all the way down to 2R vs a 70W amp that does exactly the same, then maybe that's the case.

But I get the feeling that the 45W amp isn't doing the same stuff as the 70W amp. And numbers are all that people read.

 

[Aerith Gainsborough]

But I get the feeling that the 45W amp isn't doing the same stuff as the 70W amp.

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.