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Topic: Speakers vs amps and cd players (Read 76736 times) previous topic - next topic
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Speakers vs amps and cd players

Reply #175 –
Quote from: Rich B on
Quote
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?

Using some simplifications in this explanation: transistors are current-operated devices and high-current versions are easily made and relatively cheap. However, the output transistors have to be rated to withstand the supply voltage of the output stage, which is what governs the absolute maximum voltage the amp can deliver. High-voltage transistors are expensive.

Plus, the power supply will need to be beefed up since higher voltage also means more current will be needed for a given impedance load (power goes up with the square of the voltage, given a fixed load impedance) so even more expense.

In other words, it's largely about money and compromise. Doubling the output voltage will quadruple the power and cost (maybe) six or more times as much.

Speakers vs amps and cd players

Reply #176 –
Of course, on the market price is no good indicator of either performance or power.

The Jeff Rowland Model 10 amp, for example, used a bunch of $6 ICs at its core for the amplification (150W into 8 ohms continuous). The retail price was close to $7,000. Same with the Concerta II.

I wonder if those reviews would have been so positive had the reviewers been told beforehand that the amplification is done by a bunch of LM3886's.
Random example:
Quote
Tremendous transparency. Excellent musicality.... vocals were ooh so natural. Dynamics, I wasn't expecting this but these amps were really dynamic. Transient response was top-class, the snap of percussion was as good as I've heard in my (any?) system.
"I hear it when I see it."

Speakers vs amps and cd players

Reply #177 –
Quote from: Rich B on
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?


As has been pointed out, it is the natural tendency of a SS amp to deliver massive amounts of current to a low impedance load to the point of rapidly (fractions of a second) destroying itself though excess internal heating of its output devices. In the early days SS amps didn't manage this properly and many of them failed. Shorted speaker leads could be  fatal. A rubbing voice coil could be fatal. Too many speakers in parallel could be fatal. This was quickly addressed by adding current limiting circuitry.  It was then discovered that current limiting circuitry often created problems of its own by activating unexpectedly and by the very nature of its operation.

Clipping due to an amp running out of power supply voltage tends to be pretty clean - it turns music into flat topped waves or waves that have only a low frequency wave riding on them from the power line. The output devices are at the time in a low impedance state with a low voltage being dropped across them, and the load simply sees a signal that stops increasing at some arbitrary point which it sees very frequently because that what musical signals do. The amp and the load recover pretty quickly (microseconds).

Clipping due to current limiting can be messy. The output devices are put into a high impedance state and an attempt is made to cut current to the load. If the load is inductive (all speakers are at least somewhat inductive over much of the audio range) then the load reacts by increasing the voltage across it by drawing energy from its collapsing magnetic field to maintain the current flow constant. This inductive kick can reach 100's of volts (the same principle is exploited in automotive ignition systems) and destroy many components in both the amplifier and the speaker itself. Fortunately most amplifiers are designed to limit this kick to the supply voltage of the output stage, but you can see how messy this can be. The recovery time may stretch into milliseconds and it can be disruptive to the music.

In the 80s and 90s some high end designers built amplifiers with literally dozens of big, shiny output transistors per channel and these amplifiers were nearly impossible to cause to activate their protective circuits. They looked very impressive and in fact they had fantastic current reserves, but with ordinary speakers the shiny metal output transistor and massive heat sink bling did nothing for sound quality. If you had a truly pathological speaker, they were just what you needed.

Therefore clipping due to current limiting is avoided where possible by choice of output devices, which has been increasingly more economical due to the continuing advances in SS technology. Current/voltage capabilities that used to require a goodly number of devices with heavy duty metal cases in series/parallel can now be handled by a single far smaller device encapsulated in plastic. A single Y2K plastic transistor can approximate the current capacity of maybe a half-dozen ca. 1970 output devices.

Speaker technology has also improved. In the 70s and 80s a number of speakers such as the Infinity IRS went to marketwith  wildly aggressive impedance curves. They either fried poorly protected amplifiers or activated their protection circuits at relatively low listening levels.  In the 90s a number of manufacturers such as NHT recognized that amplifier-friendly speakers were less likely to be returned which made everybody much happier.  Today most speaker designers know that low impedances and high reactance don't mix at the same frequency. Low impedance with modest reactance is not necessarily as troublesome as is high reactance and high impedance in combination.

Speakers vs amps and cd players

Reply #178 –
Quote from: xnor on
Of course, on the market price is no good indicator of either performance or power.

The Jeff Rowland Model 10 amp, for example, used a bunch of $6 ICs at its core for the amplification (150W into 8 ohms continuous). The retail price was close to $7,000. Same with the Concerta II.

I wonder if those reviews would have been so positive had the reviewers been told beforehand that the amplification is done by a bunch of LM3886's.
Random example:
Quote
Tremendous transparency. Excellent musicality.... vocals were ooh so natural. Dynamics, I wasn't expecting this but these amps were really dynamic. Transient response was top-class, the snap of percussion was as good as I've heard in my (any?) system.



In case anybody doubts this, here is a picture of the output circuit card of that amplifier:



Clearly shown are LM3886 amplifier chips.  I believe that there were 8 per channel which can yield a fairly powerful amp. I see it is rated at 150/275 wpc 8/4 ohms.

http://jeffrowlandgroup.com/Docs/M10Manual.pdf

However the spec sheet for this chip:

http://www.ti.com/lit/ds/symlink/lm3886.pdf
(page 11)

shows  THD > 0.1% and rapidly rising above 10 KHz, which would be an embarrassment to any number of conventionally designed "PA" amplifiers that high end audio eggspurts love to look down on.

I also find the apparent absence of heat sink attaching screws to be a little appalling. The device is available with an electrically isolated package that would make the mica insulators superfluous.  It seems to have mounting hardware it shouldn't need and lacks mounting hardware that it should need. Whatever!

Speakers vs amps and cd players

Reply #179 –
6 per channel. Basically a beefier Gainclone with fancy case.

The performance doesn't seem to be bad and I don't even want to comment on that. But the price...
"I hear it when I see it."

Speakers vs amps and cd players

Reply #180 –
Quote from: Arnold B. Krueger on
Therefore clipping due to current limiting is avoided where possible by choice of output devices, which has been increasingly more economical due to the continuing advances in SS technology.

Today most speaker designers know that low impedances and high reactance don't mix at the same frequency. Low impedance with modest reactance is not necessarily as troublesome as is high reactance and high impedance in combination.

A combination of the above two means that any modern day SS amp with 100 wpc and most modern speakers can happily coexist in a typical home listening room without having to lose sleep or obsessing over clipping. And up to a point, watts are cheap, one can even have a 150 wpc amp without spending silly money, which will comfortably drive most modern speakers that will fit in said room aesthetically and sonically.

Speakers vs amps and cd players

Reply #181 –
Quote from: Rich B on
Yes I am aware of Sean Olives work and not surprisingly, his speakers, endorsed by his company, were preferred the most.

Sean Olive tests the speakers in his own facility, using techniques best served to bring about a result that people prefer, and lo and behold, out of all the speakers tested, his speakers were preferred.
Nothing at all suspicious about that.

A speaker that I thought sounded very nice to me was the KEF LS50.

I own Paradigm Studio 20 v5 bookshelves in one of my rooms.

 
Pssst, hey Rich, just a little FYI to fill some ummm, small gaps in your knowledge.
The man whose character you impugn, actually worked at the NRC (under Toole IIRC) prior to working at the "preferred speaker company". Though less known, KEFs Eureka/Archimedes project on the other side of the pond found largely the same thing, independently.
Both speakers you like above, are cut from the exact same cloth, the one you own, literally from the SO book. 

Quote from: Rich B on
You're either just plain naive, or just in denial.

I have long remarked that I haven't seen any issue on audio boards that can't be explained by Dunning-Kruger. 
Party on Garth...

cheers,

AJ
Loudspeaker manufacturer

Speakers vs amps and cd players

Reply #182 –
Oh and you 3 bling fashion speakers you "pictured", all would fail that school, rather badly. 
Yes, I can tell from just the pictures.
Loudspeaker manufacturer

Speakers vs amps and cd players

Reply #184 –
Quote from: Green Marker on
Quote from: Arnold B. Krueger on
However the spec sheet for this chip shows  THD > 0.1% and rapidly rising above 10 KHz...

Which graph are we looking at..?


Good point.  Overlooked a leading zero. The THD graphs in

http://www.ti.com/lit/ds/symlink/lm3886.pdf  page 11, figure 16- 18 are just fine, but not exceptional.

The lesson there is that amp designers (both high end and otherwise) that make a big thing out of using all discrete power amps are sending up smoke signals.

Speakers vs amps and cd players

Reply #185 –
Quote from: Green Marker on
Basically, as soon as someone says "Phase is inaudible with music. End of."

Not sure who said that, but it's largely irrelevant.
You wouldn't know this, but it's a logical fallacy to (attempt to) prove a negative.
IOW, "proving" phase inaudibility absolutely, is a fools errand.
Rather, the onus falls squarely on you GM, to prove "phase" audibility, with whatever you think you are doing with you limited knowledge set....and mic pointed straight in front of your speaker at some distance.
Why don't you explain how you did it here:

Lets see what "phase" you are talking about, what "distortion" exists in passives and exactly how GM is "hearing" this. Your methods should provide some fascinating reading.
Oh and by all means, don't be ashamed to post a pic of the studiophiles room too. 

cheers,

AJ

Loudspeaker manufacturer

Speakers vs amps and cd players

Reply #186 –
^ Could definitely use some more screws on the front. 
"I hear it when I see it."

Speakers vs amps and cd players

Reply #188 –
Quote from: Green Marker on
Basically, as soon as someone says "Phase is inaudible with music. End of." my sceptical antennae twitch! Much more information is needed, and even then it cannot tell the whole story.


A statement like "Phase is inaudible" is an excluded middle statement. Phase is audible under some conditions, not others.

Phase shifts applied differently to different channels gets to be easy to hear in modest amounts.

Phase shifts applied identically the same to different channels gets to be hard  to hear even in seemingly huge amounts.

Since we generally don't listen to speakers with our ears pressed up against the speaker cones, there is always a lot of phase shift due to the distance, so we have to be careful about talking about phase shift versus group delay which takes the delay due to distance out of the discussion pretty well.

Then we need to distinguish between phase and polarity, given that they are often conflated and are really two different things.

Finally, phase shifts can be audible with certain pathological signals, while completely  slipping by when the sounds are the usual music and drama.

Oversimplified statements have this nasty tendency to be always wrong, so falsifying them is often a cheap shot.


Speakers vs amps and cd players

Reply #189 –
I'll tell my life a little, sorry for that.
when I started using EQ some years back , I soon realized I could somehow end up with changes in the "imaging", a guitar would move upfront a little simply because I played with the midrange or some stuff like that. not knowing what caused it, I looked for information about EQ and most people I talked to(pre-internet was a bitch) were bashing EQ about phase shift. not finding better and mostly not knowing anything, I spent some times thinking that phase shifts were the one cause of my changes in spatial cues. I still read that often, so I guess a lot of people listened to the same dudes ranting about how bad EQ was.

since I've learned a little more about psycho acoustic and human hearing in general, how high freqs are easy to pinpoint compared to lower ones, how the shape of our ears changes the frequency response as a way to know up from down and other funky tricks. I came to realize that as soon as the FR was changing it was bound to affect everything else in the way we perceive music. 
and that's where I stand now, not 100% sure about much, but clearly a lot less obsessed with phase.

just to say that when we don't know much, we tend to pick the first presented thing that remotely looks like a solution and cling onto it. it does seem like phase(and lately jitter) is one of those thing. it's here, it does unclear stuff, maybe. let me blame it for whatever I don't understand.

Speakers vs amps and cd players

Reply #190 –
Quote from: ajinfla on
Quote from: xnor on
^ Could definitely use some more screws on the front. 


They look tight. He's definitely no audiophile 


Oh, that's a keeper.  But it took me a minute to see that -- so just in case anyone else missed it on that busy page:

Quote
Loose screws? Sometime in the late 1980's I visited an audiophile in San Diego. When he opened the door he exclaimed, "Norm! I've made the most incredible discovery! A simple modification that really improves the sound— opens it up, sharpens the imaging, and deepens the soundstage. I've loosened the screws on all my chassis. You gotta hear it!" He learned this tweak from a friend of his who had made a small fortune with a "CD enhancer" spray called Finyl. At the time, the ads for Finyl claimed it would increase the number of bits of resolution. His system sounded terrible.

I'd heard rumors that some audiophiles had their screws loose, but I never took them literally until that evening.

Speakers vs amps and cd players

Reply #191 –
Quote from: castleofargh on
I'll tell my life a little, sorry for that.
when I started using EQ some years back , I soon realized I could somehow end up with changes in the "imaging", a guitar would move upfront a little simply because I played with the midrange or some stuff like that. not knowing what caused it, I looked for information about EQ and most people I talked to(pre-internet was a bitch) were bashing EQ about phase shift. not finding better and mostly not knowing anything, I spent some times thinking that phase shifts were the one cause of my changes in spatial cues. I still read that often, so I guess a lot of people listened to the same dudes ranting about how bad EQ was.

since I've learned a little more about psycho acoustic and human hearing in general, how high freqs are easy to pinpoint compared to lower ones, how the shape of our ears changes the frequency response as a way to know up from down and other funky tricks. I came to realize that as soon as the FR was changing it was bound to affect everything else in the way we perceive music. 
and that's where I stand now, not 100% sure about much, but clearly a lot less obsessed with phase.

just to say that when we don't know much, we tend to pick the first presented thing that remotely looks like a solution and cling onto it. it does seem like phase(and lately jitter) is one of those thing. it's here, it does unclear stuff, maybe. let me blame it for whatever I don't understand.

But if you have the opportunity to minimise phase distortion from your speakers..? Does it matter whether or not some research (funded by a passive speaker manufacturer maybe?) seems to shows that "phase isn't important (for timbre in mono)"? It is an arbitrary distortion of the signal that can be minimised with DSP. 

Are people really arguing that phase isn't important, or are is it that the very thought of using DSP is so abhorrent to them that passive speakers just have to be adequate?


('Hilarious' that people can't see past the aesthetics of a pair of prototype speakers!)
 

Speakers vs amps and cd players

Reply #192 –
Quote from: Green Marker on
But if you have the opportunity to minimise phase distortion from your speakers..? Does it matter whether or not some research (funded by a passive speaker manufacturer maybe?) seems to shows that "phase isn't important (for timbre in mono)"? It is an arbitrary distortion of the signal that can be minimised with DSP. 

Are people really arguing that phase isn't important, or are is it that the very thought of using DSP is so abhorrent to them that passive speakers just have to be adequate?

Hey, I'm arguing all the way for higher fidelity, even if we're past some audible thresholds (true high end). I think most here are interested in what we can achieve technologically.
But claims about the audibility of various things, including phase, are often grossly exaggerated.

You gotta keep all the things in perspective. If you can easily correct the phase response then please do it, but its effects will likely be minimal to inaudible if there are problems with much more important things: the recording, the speakers, positioning, the room ...
I wouldn't tell someone with such problems that he has to fix the phase response.
Similarly I wouldn't tell someone to buy a better amp to reduce distortion by 0.5% when the magnitude response is all over the place.


Quote from: Green Marker on
('Hilarious' that people can't see past the aesthetics of a pair of prototype speakers!)

Was that directed at me? I thought it was pretty clear that my comment was not serious.
"I hear it when I see it."

Speakers vs amps and cd players

Reply #193 –
Quote from: xnor on
Quote from: Green Marker on
('Hilarious' that people can't see past the aesthetics of a pair of prototype speakers!)

Was that directed at me? I thought it was pretty clear that my comment was not serious.

Sorry xnor. I had a sense of humour lapse.

I screwed the fronts on (to recycled old speaker enclosures) simply so I could experiment with different configurations. However, interestingly, I notice that some manufacturers of BBC monitor type speakers deliberately screw the rear panels on rather than gluing them, as part of the thin wall 'lossy' philosophy.

Speakers vs amps and cd players

Reply #194 –
Quote from: xnor on
Was that directed at me? I thought it was pretty clear that my comment was not serious.

Probably didn't like the phase of your response.

The "hilarious" part is GMs talk about "phase" when he can't define it and talk about "hearing" it, when he "fixed" that which "plagues passives", with his own active speakers.
If GM could show specifically what he did and how he determined it lifting veils and whatnot, it would seem more like a HA discussion than an AA one.
I think we both already know why he can't.
No books or internets. 
Perhaps he's an anarchist?

cheers,

AJ
Loudspeaker manufacturer

Speakers vs amps and cd players

Reply #195 –
Quote from: xnor on
Hey, I'm arguing all the way for higher fidelity, even if we're past some audible thresholds (true high end). I think most here are interested in what we can achieve technologically.

I am not an engineer, but isn't the pursuit of something in audio engineering that is beyond audible thresholds, "bad" engineering by an engineer's definition? What's the point of it?

Speakers vs amps and cd players

Reply #196 –
Quote from: KumarK on
I am not an engineer, but isn't the pursuit of something in audio engineering that is beyond audible thresholds, "bad" engineering by an engineer's definition? What's the point of it?


Because there is no fixed audible threshold, and you want to build in as much margin as possible?

Some engineering, if it's 'only software' can be free to implement, in which case it's not necessarily bad engineering to throw it in, anyway.

Speakers vs amps and cd players

Reply #197 –
Quote from: KumarK on
I am not an engineer, but isn't the pursuit of something in audio engineering that is beyond audible thresholds, "bad" engineering by an engineer's definition? What's the point of it?

Depends on the extra cost needed to achieve the improvements, if any, and the budget. If some design lets you realize optimizations cheaply and easily, you'd be a fool not to make use of it.
Consider improvements beyond the established thresholds as safety margin, headroom, and finally plain overkill (for bragging rights).

Also, technological advancements that may seem like total overkill can trickle down so they become affordable for ordinary mortals, to the point where you achieve much better performance for less money.
"I hear it when I see it."

Speakers vs amps and cd players

Reply #198 –
Anyway, I've clearly rubbed a couple of people up the wrong way, for which I apologise. It's always going to be tricky when being enthusiastic about one thing (in my case DSP and active speakers) is implicitly a criticism of someone else's enthusiasms.

Speakers vs amps and cd players

Reply #199 –
I'm wondering why audiophiles haven't long made the move to active speakers. Well, actually I'm not since they cling to all kinds of old stuff.

I guess the main problem is that they'd need 2 to 3 times the cables from their heavy aluminum blocks (amps) to the speakers, the interconnects, the digital cables ... considering the price of audiophile cables. That would probably cost more than their whole system does now.
"I hear it when I see it."