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Topic: Speakers vs amps and cd players (Read 76778 times) previous topic - next topic
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Speakers vs amps and cd players

Reply #150 –
Quote from: Green Marker on
Quote from: Arnold B. Krueger on
The time domain and frequency domain are perfectly related to each other by a number of different mathematical means, the most common of which is Fourier analysis.  If an artifact exists in the time domain then it also exists in the frequency domain.

Thanks, but I know this. I am familiar with the use of Fourier transforms and the equivalence of the frequency and time domains - my own DSP-based audio system uses it extensively. But I also know that a room's contribution is not simply an indiscriminate "phase shift" regardless of whether the signal is a steady tone or a transient. Therefore it does not follow that it will automatically mask phase distortion in the speaker system.


It is a time delay that manifests itself as a phase shift.  Sometimes it is easier to look at it as a time delay, and sometimes it is easier to look as a phase shift. If the phase shift is < 180 degrees over a wide range then looking at it as a phase shift is usually the more helpful approach.

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This is different from a speaker that has a flat frequency response, but arbitrary phase distortion.


How?

Because the 'equation' between the original recording and what reaches the listener's ears is broken. The room didn't break it, because the delays, phase shifts and amplitude variations it introduced are all linked consistently.


Not so much. Consistently wrong and unhelpful is still wrong and unhelpful.

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You may say "We can't possibly hear the difference. Let's do a scientific experiment to show it". But I'd rather just use technology (DSP) to bypass the question all together and have zero phase shift contributed by the speakers (or as close as possible).


Zeroing out phase shift is a well known fool's journey. Not because it is inaudible, but because it is an impossible goal.  Moderation in all things!

Speakers vs amps and cd players

Reply #151 –
Quote from: xnor on
Quote from: Arnold B. Krueger on
(3) Avoid using accepted technology for designing the enclosure, picking drivers and designing the crossover.

That's the point I really don't get. There is free software for this. Data for a basic simulation is entered quickly.
If the simulation already comes up with dubious results then continue with that design and if the implementation is even worse, then continue and sell the product with the justification that "speaker design is art after all"?

... if there is a simulation at all.

Or do they blindly trust simplistic simulations without ever measuring the implementation?


IME there is nothing like getting 4 or 5 figures for a 2 or 3 figure loudspeaker to convince someone that they are doing everything right. ;-)

The Eggleston looks to me like a legacy design where the driver manufacturer moved on and left his builders behind, but they were getting a nice cash flow and didn't want to mess up a good thing.

Speakers vs amps and cd players

Reply #152 –
Quote from: Arnold B. Krueger on
I sense that you aren't trying, and are back trying to bully me into doing your bidding.


Perhaps I don't understand the meaning of your posts back when you posted and require clarification. Is it so difficult to ask you to be more clear about this particular topic? I asked you some clear questions hoping you would lay my fears to rest. Why you would ask me to grovel at your feet, I don't know.

Speakers vs amps and cd players

Reply #153 –
Quote from: Arnold B. Krueger on
Both THD and IM can be caused by the same basic nonlinearity.


Sure, but there can be port nonlinearity, doppler effects, and other nonlinearities that only show up with multiple frequencies.

What I'm trying to say is that you probably never need to worry about amplifier IMD (either), if the amp is not broken.
"I hear it when I see it."

Speakers vs amps and cd players

Reply #154 –
Quote from: Rich B on
Quote from: xnor on
Back to distortion, look at this Focal bookshelf.

In the best case THD is down probably -50 to -60 dB. That's over 0.3% to 0.1%. In the bass it's more like 1% to 2%.


A random floorstanding speaker, same story. (93 dB)
A €25,000 floorstanding speaker, worse in the midrange. (91 dB)
A much cheaper floorstanding, cleaner. (96 dB according to manufacturer)

As you can see, these speakers don't need much power to reach high SPL and high distortion. Less than 20W @ 4ohm for 100 dB SPL.


Keep in mind that this is just harmonic distortion. As soon as you play real music you will get loads of intermodultion products.


Please forgive me, but can you explain how I am supposed to read the graphs you provided? These are distortion graphs, or frequency response graphs?


The 25000 speaker is the KEF Blade. So what exactly am I looking at with that graph? You say the distortion is worse in the mid-range? What about the frequency response and low-frequency dynamics? Is it not any good?

Normally when you look at a speaker line, you think the cheapest speaker within that line offers the most basic performance. That a more expensive speaker within the same line offers better performance until you reach the flagship. Is it possible that a lesser speaker in the same line offers improved measured performance?

Speakers vs amps and cd players

Reply #155 –
Quote from: xnor on
Quote from: Arnold B. Krueger on
Both THD and IM can be caused by the same basic nonlinearity.


Sure, but there can be port nonlinearity, doppler effects, and other nonlinearities that only show up with multiple frequencies.


AFAIK port nonlinearity shows up as THD as well as IM.  IME it is easy enough to hear with a single tone.

Doppler is not a traditional nonlinearity (motor, suspension) and it is different enough from them that it deserves a discussion of its own. Yes. strictly speaking it is IM. But it is not a consequence of traditional nonlinearities.

The perception of Doppler is also different. For example, masking usually doesn't explain when it is audible and when it is not.


BTW I allowed for Doppler when I said: "Both THD and IM can be caused by the same basic nonlinearity."

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What I'm trying to say is that you probably never need to worry about amplifier IMD (either), if the amp is not broken.


...or clipping! ;-)

Speakers vs amps and cd players

Reply #156 –
Quote from: Arnold B. Krueger on
Zeroing out phase shift is a well known fool's journey. Not because it is inaudible, but because it is an impossible goal.  Moderation in all things!

Oh well, I'll dial some phase distortion back in, then! After all the science, it comes down to the old audio saying: "Now don' ee be getting ideerzz in yurr 'ed about that there 'liminayding phase dizz'torshon. The old ways is best, an' allus shall bee."

Speakers vs amps and cd players

Reply #157 –
Quote from: Rich B on
Please forgive me, but can you explain how I am supposed to read the graphs you provided? These are distortion graphs, or frequency response graphs?

The 25000 speaker is the KEF Blade. So what exactly am I looking at with that graph? You say the distortion is worse in the mid-range? What about the frequency response and low-frequency dynamics? Is it not any good?


The sore thumb is the red line at the bottom of the page that peaks at 75 dB at about 700 Hz.

Looks to me like the tweeter is being over stressed, probably by a tweeter crossover with too gentle of a slope at its low end.

I think that AJ may have even alluded to this in his comments about the Q family because the Blade seems to be yet another Q-family member. 

The Q family has another problem due to the flare of the waveguide for the tweeter being the woofer cone which is potentially moving fast and far enough to cause trouble.  Another example of why subwoofers are a good idea.

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Normally when you look at a speaker line, you think the cheapest speaker within that line offers the most basic performance. That a more expensive speaker within the same line offers better performance until you reach the flagship. Is it possible that a lesser speaker in the same line offers improved measured performance?


All things are possible, but your basic idea is a reasonable expectation.

One of the reasons for testing is to make sure that something unreasonable is not going on, because unreasonable stuff still happens.

Speakers vs amps and cd players

Reply #159 –
Quote from: Green Marker on
We could follow scientific procedure to attempt to define what is funny. It might be interesting, and maybe not worthless knowledge, but it wouldn't be science.


Luckily we are interested in whether audio gear produces audible artifacts, not whether it is funny.
 

Speakers vs amps and cd players

Reply #160 –
Quote from: Rich B on
A speaker that I thought sounded very nice to me was the KEF LS50. Please review the technical measurements and tell me if this is considered to be a good performer on the bench.

http://www.soundstagenetwork.com/index.php...&Itemid=153



Yet another KEF Q-series device, but very pricey.  Given your previous comments about your goals for SPL. not a bad choice.  Needs a subwoofer.

Speakers vs amps and cd players

Reply #161 –
Quote from: Arnold B. Krueger on
Quote from: Rich B on
A speaker that I thought sounded very nice to me was the KEF LS50. Please review the technical measurements and tell me if this is considered to be a good performer on the bench.

http://www.soundstagenetwork.com/index.php...&Itemid=153



Yet another KEF Q-series device, but very pricey.  Given your previous comments about your goals for SPL. not a bad choice.  Needs a subwoofer.


I own Paradigm Studio 20 v5 bookshelves in one of my rooms. I do use a subwoofer to augment the low-end. I don't know how well they perform on the bench or if you guys would consider it to be a high fidelity speaker.

Speakers vs amps and cd players

Reply #164 –
Quote from: Rich B on
I own Paradigm Studio 20 v5 bookshelves in one of my rooms. I do use a subwoofer to augment the low-end. I don't know how well they perform on the bench or if you guys would consider it to be a high fidelity speaker.


http://www.soundstagemagazine.com/measurem...gm_studio20_v3/

As has been said here before in the past week or so, significant performance differences between submodels are generally pretty small, often just cosmetic.

We could take this as clear evidence that some people think that 10 seconds worth of Googling is beneath their dignity.

Speakers vs amps and cd players

Reply #165 –
Quote from: Rich B on
These are my speakers :

http://www.stereophile.com/content/paradig...-v5-loudspeaker


Street price seems to run from $600 to 900 each.

Begs comparison with:

http://www.stereophile.com/content/infinit...er-measurements

Which I've paid as little as $100 each for.

Please compare and contrast. I'll give you that the Paradigms are prettier looking.


Speakers vs amps and cd players

Reply #166 –
@LS50: Well, you can't expect undistorted low frequency output at high SPL with a small woofer in a small box and there's the problem that Arnold mentioned before (but I doubt the little woofer is moving much).
Almost all of the LF comes from the rear port.

With that in mind, the performance seems to be pretty good.
"I hear it when I see it."

Speakers vs amps and cd players

Reply #167 –
Quote from: xnor on
@LS50: Well, you can't expect undistorted low frequency output at high SPL with a small woofer in a small box and there's the problem that Arnold mentioned before (but I doubt the little woofer is moving much).
Almost all of the LF comes from the rear port.

With that in mind, the performance seems to be pretty good.


How do my speakers fare (Paradigm Studio 20 v5)?

Speakers vs amps and cd players

Reply #170 –
Quote from: Arnold B. Krueger on
Quote from: Rich B on
A speaker that I thought sounded very nice to me was the KEF LS50. Please review the technical measurements and tell me if this is considered to be a good performer on the bench.

http://www.soundstagenetwork.com/index.php...&Itemid=153



Yet another KEF Q-series device, but very pricey.  Given your previous comments about your goals for SPL. not a bad choice.  Needs a subwoofer.

Lower than average sensitivity, though. From Stereophile, "85dB/2.83V/m."

KEF do an active speaker with what looks like similar drivers - the X300A - which is cheaper.

Speakers vs amps and cd players

Reply #171 –
It was said earlier that when amps clip they run out of voltage. But what about current? I thought voltage x current = power and an amp that runs out of power begins to clip.

Another thing I wanted to know is what do manufactures mean when they specify an amp at a minimum recommended impedance. Like they'll say minimum 6 ohm or 6 ohm compatible. What does that mean? Or is that just a guideline? Does it matter when playing music?

Speakers vs amps and cd players

Reply #172 –
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It was said earlier that when amps clip they run out of voltage. But what about current? I thought voltage x current = power and an amp that runs out of power begins to clip.
The relationship between voltage, current, and impedance is defined by Ohm's Law.  If your amp can't supply the current, the voltage will also drop.  i.e. An oscilloscope measures voltage, and you'll see the voltage clipping if your amplifier clips due to lack of current.

Amplifiers are considered "constant voltage" devices.  Obviously, the voltage isn't truly constant because normal audio is a constantly-varying signal that depends on the program material and the volume setting.    In this context, "constant voltage", means that the output voltage does not depend on impedance (or current).  That is, you'll get the same voltage with 4-Ohm speakers, 8-Ohm speakers, or no speakers (infinite impedance), as long as the amplifier is operating properly within it's specified limits, etc.


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Another thing I wanted to know is what do manufactures mean when they specify an amp at a minimum recommended impedance. Like they'll say minimum 6 ohm or 6 ohm compatible. What does that mean? Or is that just a guideline? Does it matter when playing music?
It's possible to damage an amplifier (by drawing too much power & current) if the impedance is too low.  Or, you might just get distortion (clipping) at lower than rated power.


In accordance with Ohm's law, current is inversely proportional to impedance.  If you cut the impedance in half (with the same voltage) you'll get twice the current and twice the power.  In fact, you'll find that many amplifiers are rated at twice the power with 4 Ohm speakers.    If an amplifier isn't getting twice the power at 4-Ohms, it's being current-limited (at 4 Ohms).  Or, it might be thermally limited with thermal protection kicking-in if you "pull" too much power with lower impedance. 

BTW - If you double the voltage you also double the current (assuming constant impedance), which means doubling the voltage gives you 4 times the power.


If you wire a pair of speakers in parallel, you cut the impedance in half and double the power (if the amp can provide the current).  For example, say you have a speaker connected and it's getting 100W.  If you connect a 2nd speaker with the same impedance, it will also get 100W.   

This is similar to plugging-in a 2nd light bulb to the wall socket...  You get twice the current and consume twice the power.  If you try to get too much current the breaker will "blow".  And, you might get a slight voltage drop if you "pull" a lot of power from the socket.

High power car stereo amplifiers are sometimes rated down to 1 or 2 Ohms so you can connect two or more 4 Ohm woofers.

Speakers vs amps and cd players

Reply #173 –
Quote from: Rich B on
It was said earlier that when amps clip they run out of voltage.


Not at all. Trying to help some people seems to be like diving into a sewer because they incessantly misrepresent what you say. Are they merely incapable of remembering what was said 5 minutes ago, or are they being malevolent?

Here's what I actually said:

Quote from: Arnold B. Krueger on
The most common source of clipping in actual use is that the amp is being called on to provide more energy at any particular moment than it is capable of providing without clipping.  The reasons for that vary with the situation, but in general clipping is caused by the limited  ability of the amplifier to produce the required current and voltage. The most commonly exceeded limit relates to voltage.


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But what about current?


Just stated in clear English:

"...in general clipping is caused by the limited  ability of the amplifier to produce the required current and voltage.

Translation from clear English to hopefully clearer English:

It is possible that the amplifier is clipping due to its limited ability to produce the required current or voltage or both.

I tried to be helpful by adding

"The most commonly exceeded limit relates to voltage"

which means that the limit could be due to a lack of voltage or current or both, but the most likely is a lacking in voltage.

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Another thing I wanted to know is what do manufactures mean when they specify an amp at a minimum recommended impedance. Like they'll say minimum 6 ohm or 6 ohm compatible. What does that mean? Or is that just a guideline? Does it matter when playing music?


It is clearly a guideline. In general it does not matter when playing music for 2 reasons:

(1) The crest factor of music is high, and power amp ratings are based on signals with low crest factor.  High crest factor signals are easy on amps.

(2) Most people's preferences (like apparently you!) for music are for less than 105 dB SPL peaks.

Speakers vs amps and cd players

Reply #174 –
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Just stated in clear English:

"...in general clipping is caused by the limited ability of the amplifier to produce the required current and voltage.

Translation from clear English to hopefully clearer English:

It is possible that the amplifier is clipping due to its limited ability to produce the required current or voltage or both.

I tried to be helpful by adding

"The most commonly exceeded limit relates to voltage"

which means that the limit could be due to a lack of voltage or current or both, but the most likely is a lacking in voltage.


Yes, but the emphasis was placed on voltage. I was trying to understand why you placed emphasis on voltage, as opposed to current. Like you say that clipping is most likely when the amp is lacking in voltage, so now why is that? As opposed to a lack of current?