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

[Mart68]

I'm amazed that some people here think all amplifiers will perform optimally into any impedance load.

IME this is a common problem with many modern loudspeakers where impedance dips low. The effect on sound quality is very obvious,

I'd also suggest it is the reason why some people argue over the sound quality of a given budget amplifier, some saying it is good, others saying they found it poor. This is not cognitive bias. It's entirely dependant on the load presented by the loudspeaker to the amplifier and so entirely dependant on the loudspeaker(s) the amplifier was used with when the opinion was formed.

Also just having lots of watts on tap is not necessarily the solution. The amplifier must be able to maintain power into a low impedance load and it must be able to do that instantaneously. If it cannot then this will be a problem at any volume level.

 

[Willem]

This was linked to in another thread: https://archimago.blogspot.com/2021/08/summer-musings-no-not-all-amplifiers.html?m=1

 

[mononoaware]

I'm amazed that some people here think all amplifiers will perform optimally into any impedance load.

IME this is a common problem with many modern loudspeakers where impedance dips low. The effect on sound quality is very obvious,

I'd also suggest it is the reason why some people argue over the sound quality of a given budget amplifier, some saying it is good, others saying they found it poor. This is not cognitive bias. It's entirely dependant on the load presented by the loudspeaker to the amplifier and so entirely dependant on the loudspeaker(s) the amplifier was used with when the opinion was formed.

Also just having lots of watts on tap is not necessarily the solution. The amplifier must be able to maintain power into a low impedance load and it must be able to do that instantaneously. If it cannot then this will be a problem at any volume level.

Hi I have a question, would you say:

Speakers that have large negative dips in impedance are flawed in their design?

Or

Amplifiers which are unable to deal with these large dips in impedance are flawed in design?

Reason I ask is the low cost speaker I have been using recently (Fostex FE103NV in back-loaded horn) has a nominal impedance of 8 ohms, and looking at the measurements it never drops below 8 ohms and has a positive spike to around 64ohms @ 90hz.

The KEF LS50 which is much more expensive speaker also has a nominal impedance of 8 ohms, but according to its measurements it has 3 peaks and 3 dips down to around 4ohms @ 200hz, 55hz and 20hz.

I actually recall reading somewhere about how many manufacturers “cheat” with their nominal impedance ratings, and their rated impedance is not indicative of their actual impedance.

Edit: I noticed now KEF US does actually have “minimum impedance: 3 ohms” as a specification.

 

[Willem]

I would say that speakers with deep dips in the impedance curve are a bad design, and I would say that amplifiers with a high output impedance are also bad designs.

 

[escksu]

Hi I have a question, would you say:

Speakers that have large negative dips in impedance are flawed in their design?

Or

Amplifiers which are unable to deal with these large dips in impedance are flawed in design?

Reason I ask is the low cost speaker I have been using recently (Fostex FE103NV in back-loaded horn) has a nominal impedance of 8 ohms, and looking at the measurements it never drops below 8 ohms and has a positive spike to around 64ohms @ 90hz.

The KEF LS50 which is much more expensive speaker also has a nominal impedance of 8 ohms, but according to its measurements it has 3 peaks and dips down to around 4ohms @ 200hz, 55hz and 20hz.

I actually recall reading somewhere about how many manufacturers “cheat” with their nominal impedance ratings, and their rated impedance is not indicative of their actual impedance.

Edit: I noticed now KEF US does actually have “minimum impedance: 3 ohms” as a specification.

I wouldnt call those amps flawed in design. I would rather say by choice due to budget. If you want to design an amp that cost $500, you will have to cut corners compared to one that cost $5000.

 

[FeddyLost]

Yes, we can. Most of us migrated here to avoid wooly thinking and purple prose.

So, we just need to have good oscilloscope with FFT for test bench to measure amp output at speaker's terminals and avoid any emotionally colored terms like "heresy" until we clearly know what is going on.

Speakers that have large negative dips in impedance are flawed in their design?
Or
Amplifiers which are unable to deal with these large dips in impedance are flawed in design?

I'd say that any tool usually made on purpose and customer must know that no manufacturer really interested in solving his problems.
So, either you buy "sinergetic solution" from one seller and hope he is competent and didn't cheat on you too much, either speaker+amp compatibility is totally yours PITA with all possible issues (i.e. underpowered Denon for Wilsons or Krell for widebander).

 

[Jim Matthews]

So, we just need to have good oscilloscope with FFT for test bench to measure amp output at speaker's terminals and avoid any emotionally colored terms like "heresy" until we clearly know what is going on.

Quoting the OP :

"With CXA80's, the speakers popped into existence, the sound felt like it was hitting me, bass felt boomy and the mid and highs, especially vocals felt into my face. With the Denon 600ne, the sound felt like they were coming from the speakers, the voicing was back, and I didn't feel they emmersive feeling."

These are typical of phishing expeditions, where the OP either hasn't read the myriad similar threads discussing damping factors, power supplies or headroom and announces their "discovery".

Clothing it in circa 1990's advertising language is no longer tolerable.

The least used feature of any mature forum is SEARCH followed by FAQ.

 

[ahofer]

Here is a detailed comparison of two very different amps, with measurements of their in-system performance:

http://archimago.blogspot.com/2021/08/summer-musings-no-not-all-amplifiers.html

 

[Jim Matthews]

I'm amazed that some people here think all amplifiers will perform optimally into any impedance load.

You're absolutely right.

It's also well documented and common knowledge at this point.

 

[FeddyLost]

The least used feature of any mature forum is SEARCH followed by FAQ

I think such experience of OP don't give a lot of correct search keywords.

 

[ahofer]

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 assume you saw my many comments on what might be going on in that Harbeth video? The meter is likely measuring apparent power not real power, and probably vastly overstating the power delivered. This is due to a pedal tone in the music right at the toughest phase angle and impedance low of the M40 (and meters that measure apparent power).

https://www.audiosciencereview.com/...-dynamic-range-music.23100/page-2#post-775277

 

[Jim Matthews]

I think such experience of OP don't give a lot of correct search keywords.

Quite right. I'm still realizing how little I actually know about the hobby.

What I do know is that the reviews section here covers most of the topics raised by the OP, and provides background into the basics of sound reproduction with electronic means.

 

[weasels]

i feel like these sorts of comments can unintentionally get people defensive/hostile/upset etc.

I think it’s ok to examine the reasons for someone’s experience but no one should deny its reality.

I think this is well intentioned but potentially misguided. Perceived experience is not the same as reality - we don't get to have our own facts.

 

[Mart68]

Hi I have a question, would you say:

Speakers that have large negative dips in impedance are flawed in their design?

Or

Amplifiers which are unable to deal with these large dips in impedance are flawed in design?

Reason I ask is the low cost speaker I have been using recently (Fostex FE103NV in back-loaded horn) has a nominal impedance of 8 ohms, and looking at the measurements it never drops below 8 ohms and has a positive spike to around 64ohms @ 90hz.

I don't know but I suspect that for loudspeakers some ease of drive is sacrificed to get the sensitivity figure up. Sensitivity figure for any speaker is fairly easy for a buyer to find, an impedance trace for the speaker - not so easy.

Added to which the tendency to exaggerate the sensitivity figure or to publish a 'best case' figure seems to be commonplace. So speaker manufacturers do seem to think that higher sensitivity equals more sales.

sure the speaker may not sound so good when you get it home and hook it up to your amp which isn't up to the job, but that may be why it seems to be customary now to advise fifty hours (or even more) of 'break-in' for speakers, which as we know is nonsense.

By the time you've discovered that they don't improve it's a lot harder to go back and say 'I don't want them'. Or you go on a forum and get told 'You need a better amplifier.'

As regards amplifiers as someone already said, an amp that will drive any load will not be cheap to make so will not be cheap to buy. In the old days you'd go to a dealer and he would present to you amp/speaker pairings that he knew worked and you'd go home happy. Nowadays with everyone buying on line, a bit here, a bit there, it's easy to get it wrong if a) you don't take this into account and b) you don't do due diligence.

 

[mononoaware]

Thank you for your reply.

an amp that will drive any load will not be cheap to make so will not be cheap to buy.

I do not know what expensive would be exactly, but if said "amplifier" guaranteed compatibility and flexibility in driving various extreme speaker impedance loads there could be a market for it? (customers willing to pay a premium for a properly designed amplifier)

Nowadays with everyone buying on line, a bit here, a bit there, it's easy to get it wrong if a) you don't take this into account and b) you don't do due diligence.

And I think psychologically people want to believe the decision they made is correct (more so with expensive purchases), therefore they will hold onto the product even if initially it is a disappointing experience.
I agree buying online makes the possibility of purchasing a terribly performing product higher (due to aggressive marketing etc) for uninformed customers, especially when one does not do due diligence in research.

 

[PeteL]

I assume you saw my many comments on what might be going on in that Harbeth video? The meter is likely measuring apparent power not real power, and probably vastly overstating the power delivered. This is due to a pedal tone in the music right at the toughest phase angle and impedance low of the M40 (and meters that measure apparent power).

https://www.audiosciencereview.com/...-dynamic-range-music.23100/page-2#post-775277

Can you elaborate on this a bit. It's a peak meter, it monitors the peaks current value. Instantaneous values. I haven't dabbled with these notion much lately, maybe my question is ignorant, refresh me. but how could real power has meaning when monitoring instant values, RMS Power has no meaning in an instant measurement no? I mean a true RMS power meter only work with alternative current but on a amplified audio signal? What resistive reference would be appropriate to use? Yes I'm a bit shy to ask, you can laugh but I'm an electrical engineer working in audio and it may very well be some basics I don't remember, honest question.

 

[ahofer]

Can you elaborate on this a bit. It's a peak meter, it monitors the peaks current value. Instantaneous values. I haven't dabbled with these notion much lately, maybe my question is ignorant, refresh me. but how could real power has meaning when monitoring instant values, RMS Power has no meaning in an instant measurement no? I mean a true RMS power meter only work with alternative current but on a amplified audio signal? What resistive reference would be appropriate to use? Yes I'm a bit shy to ask, you can laugh but I'm an electrical engineer working in audio and it may very well be some basics I don't remember, honest question.

Well, you are more qualified to understand this than I, but my understanding is that these are peak power measurements taken by an instantaneous measurement of voltage and current, and at the low impedance/phase angle extreme you will see high peaks that do not correspond to actual power required - although they can cause thermal problems. Furthermore, as stated within that thread, known errors in voltage measurement are magnified at that frequency (by the wide open current measurement) to create large errors. Hope I’ve stated it correctly.

 

[PeteL]

Well, you are more qualified to understand this than I, but my understanding is that these are peak power measurements taken by an instantaneous measurement of voltage and current, and at the low impedance/phase angle extreme you will see high peaks that do not correspond to actual power required - although they can cause thermal problems. Furthermore, as stated within that thread, known errors in voltage measurement are magnified at that frequency (by the wide open current measurement) to create large errors. Hope I’ve stated it correctly.

I guess we could say it like that, it's a valid indicator, but it's not the real power "required". But again trying to find the "real" power, I'm not sure it could be done, it's either an integral, or convert it to "as it would be trough a resistor X" but we don't know X. I don't think it maters much it's a Peak Power meter, Peaks have no real meaning if we and to convert it to "RMS Power burst for a short time" That's really what you'd like to know but it involves a nominal reference, A "PPM" still tells you how much the amp is working at this time, just don't tell you in term of "consumption" We want to know how much it push, not really how much it uses but all that is just semantics, Instant power is hard to make sense of but it's still commonly used. That said, It's one understanding that may have some flaws in rigour. Happy if someone can vulgarize it better.

 

[ahofer]

I guess we could say it like that, it's a valid indicator, but it's not the real power "required". But again trying to find the "real" power, I'm not sure it could be done, it's either an integral, or convert it to "as it would be trough a resistor X" but we don't know X. I don't think it maters much it's a Peak Power meter, Peaks have no real meaning if we and to convert it to "RMS Power burst for a short time" That's really what you'd like to know but it involves a nominal reference, A "PPM" still tells you how much the amp is working at this time, just don't tell you in term of "consumption" We want to know how much it push, not really how much it uses but all that is just semantics, Instant power is hard to make sense of but it's still commonly used.

Right. But in the context of the video that Willem referred to it is used to suggest how much power the speakers require, yet it probably isn't a great measure.

 

[PeteL]

Right. But in the context of the video that Willem referred to it is used to suggest how much power the speakers require, yet it probably isn't a great measure.

Sure, but even a speaker "nominal impedance" is in the end quite useless. I agree with you we should not use shortcuts like that, an amp power is specified trough a resistive load and the relation is not direct. What we can tell tough, if we use the same peak measurments on many amps, and for the same load and same SPL we try a smaller amp and the peak shows lower, then we can say that this amp cannot supply the current. It's still the standard way to measure it trough a dynamic load so at least it's valid in term of comparison, but since load varies we are stuck with incomplete data.