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REVIEW: Ray Samuels Audio Dark Star solid state headphone amplifier - Page 17

post #241 of 372
Quote:
Originally Posted by WarriorAnt View Post

Actually I do know something about class A amps I just don't think the limit your talking about is significant or that it happens long enough to say the amps are dropping out of class A action.  I mean its just theoretical right.  Whats the time duration?  Is it long enough to say the amps are really not in Class A or working in Class A?


Here’s a article might help explain, Leaving Class A by Nelson Pass

 

post #242 of 372
Quote:
Originally Posted by WarriorAnt View Post


I've had KSA 80. KMA 160's  KSA 150, KSA 250.  They were full on class A amps.  This is the first I've ever heard that they went into Class AB or B at any time.   Are you saying that at some point during their operation they move into class AB or B from class A?  

 



Not exactly.  I own a ksa250, and you can look up the stereophile article on it. Into 8 ohms its actually only 32 watts of class A.

The kas300 is different, its sliding bias class A, it looks at the input signal and sets the output stage current to meed the class A

requirements, up till the thing starts to overheat at which point the cpu dials back the power. 4 different bias points.

The fpb series amplifier do the same thing, but have much more bias points (i think 32). Same thing with the master reference

amp which has a minimum bias of 100 watts into 8 ohms.

post #243 of 372
Quote:
Originally Posted by cooperpwc View Post

Quote:


He did not say that. Read the quotation again as it is very carefully worded. He says that the DS is "running in" Class A. He says that it "will not switch or cross to class B due to it's capability". He then defends the validity of Class AB as a good compromise for amplifiers. (On this last point, it is not a direct concession that the DS is Class AB but the implication seems to be there.) He does not however say that the DS is Class A topology.

 


Actually the defense of the class AB part is lifted directly out of wikipedia without a reference/credit. Hence my plagiarism comment. Here is the relevant section from wikipedia:

 

"Class B and AB

Class-B or -AB push–pull circuits are the most common design type found in audio power amplifiers. Class AB is widely considered a good compromise for audio amplifiers, since much of the time the music is quiet enough that the signal stays in the "class A" region, where it is amplified with good fidelity, and by definition if passing out of this region, is large enough that the distortion products typical of class B are relatively small. The crossover distortion can be reduced further by using negative feedback. Class-B and -AB amplifiers are sometimes used for RF linear amplifiers as well. Class-B amplifiers are also favored in battery-operated devices, such as transistor radios."

 

Link to the whole article here


 

 

post #244 of 372

bcg27, no disagreement here (although I am not too concerned about the purported plagiarism aspect. Wikipedia is the closest thing to a universal resource that exists these days.)

 

The salient question is: why did he cite it? 


Edited by cooperpwc - 2/6/12 at 7:26am
post #245 of 372

Why does it matter?

post #246 of 372
Quote:
Originally Posted by TheWuss View Post

Why does it matter?

While I love the sound of the Darkstar I too would prefer the maker of many multi-thousand dollar amps to have (or at least explain better, if he does) an understanding of these technical details. Copying a wiki is kind of an eyebrow raiser.

If an amp designer doesn't know all the details, his/her amp could sound great under normal conditions, but a certain set of conditions could align and damage your headphones or your hearing in irreparable ways.
Edited by Maxvla - 2/6/12 at 7:47pm
post #247 of 372
Quote:
Originally Posted by TheWuss View Post

Why does it matter?

 

 

Exactly. I don't see how it's possible for this to be a class A amp and I'm a little disappointed in Ray's explanation. But this topic has been blown way out of proportion. And a lot of the comments are coming from beta 22 owners which kind of sums it up for me. The two things most important in an amp imo are it's built quality and sound quality. And those are two things are simply outstanding and among the best I've seen or heard. So no it's probably not class A, but what's the point really. And yes I'm still scratching my head over the claims of it either being or "running" in class A. But it ultimately come down to how well it's built and how good it sounds, and in both categories, it deserves the highest of marks. This thread is getting way out of control.


Edited by moodyrn - 2/6/12 at 7:50pm
post #248 of 372
Quote:
Originally Posted by Maxvla View Post

Copying a wiki is kind of an eyebrow raiser.


well, unless i'm mistaken, english is not Ray's first language.

i for one would use wikipedia if i were trying to compose my thoughts in a second language.

after all, if it's already been written succinctly and correctly, why go to the trouble?

 


 

 

post #249 of 372

He probably quoted the wiki because he sees it as a consensus authority, and agrees with it.

post #250 of 372
True points I suppose.
post #251 of 372
Quote:
Originally Posted by moodyrn View Post

 

 

Exactly. I don't see how it's possible for this to be a class A amp and I'm a little disappointed in Ray's explanation. But this topic has been blown way out of proportion. And a lot of the comments are coming from beta 22 owners which kind of sums it up for me. The two things most important in an amp imo are it's built quality and sound quality. And those are two things are simply outstanding and among the best I've seen or heard. So no it's probably not class A, but what's the point really. And yes I'm still scratching my head over the claims of it either being or "running" in class A. But it ultimately come down to how well it's built and how good it sounds, and in both categories, it deserves the highest of marks. This thread is getting way out of control.


Totally agree with you. I sold my RP010B MkII for the DS and could not be happier plus the service Ray provides is top notch. Sometime ago I bought a two months old Apache that got the umbilical cord connector in the amplification unit damage. I did not realized that happened and use it for a few days. The damage in the connector caused a short circuit and partially damage one channel. I sent it to Ray. He repaired it at no charge other than shipping. What else can you ask for service?

 

 

 

post #252 of 372

I have been reading this thread enough times and would like to add the different between a Class A vs AB topology and advantages.

 

Class A amplifiers often consist of a driven voltage or current device such as a power transistor or tube
connected from output to positive power supply and a constant
current components connected from output to negative power
supply. The signal to the driven component modulates the
output voltage and the output current. With no input signal,
the constant bias current flows directly from the positive
supply to the negative supply, resulting in no output current,
yet lots of power consumed. More sophisticated Class A amps
are driven (in a push-pull fashion).


The basic premise of a Class-A amp is that the output device(s) shall conduct all the time (through 360 degrees of the signal waveform). This means that in the simplest form, the power devices must conduct a continuous current which exceeds the maximum peak load (loudspeaker) current. If we use a power level of 20 Watts (hardly a powerhouse) for all further calculations, we can see the whole picture.

 

In contrast, a typical Class-AB power amplifier's output devices only conduct for about 182 degrees (at full power), which means that for much of the signal's duration, only one or the other device is conducting. The other is turned off. The "crossover distortion" so often referred to is nothing to do with the frequency divider in the speaker system, but is created as the signal "crosses over" the 0 Volt point.

Figure 1

Briefly, Class A amps sound the best, cost the most, and are the
least practical. They waste power and return very clean signals.
Class AB amps dominate the market and rival the best Class A
amps in sound quality. They use less power than Class A, and
can be cheaper, smaller, cooler, and lighter.

 

The Class A amp is much more linear and is always turned on 360 degrees in its peak to peak RMS value were the Class AB amp is only using half value.

 

As a long time audio hobbyist and Electrical Engineer; I quite frankly can understand why a equipment manufacture would choose a more simple design as long the results are satisfy to the ear and that is all should count.

 

Enjoy music!


Edited by Audiogalore - 2/11/12 at 10:10pm
post #253 of 372

 

Quote:
Originally Posted by Audiogalore View Post

As a long time audio hobbyist and Electrical Engineer; I quite frankly can understand why a equipment manufacture would choose a more simple design as long the results are satisfy to the ear and that is all should count.

 

 

I agree, although headphone amps use considerably less power unlike high powered speaker applications when class A is prohibitive then class AB makes sense.

post #254 of 372
Quote:
Originally Posted by johnwmclean View Post

 

 

I agree, although headphone amps use considerably less power unlike high powered speaker applications when class A is prohibitive then class AB makes sense.


Correct and that is why I use as follow for my headphone listening:

 

1) Class "A" 300B SET WOO WA5 for my tube listening.

 

2) Class "A" Pass Lab First Watt F1 for my solid state listening.

 

Both are fantastic with the HE6 and K1000, but has cost me a great deal more to have achieve such detail and linear sound. Even though I personally have not heard the Class AB designed Ray Samuel DS; I am speculating reading the thread the ones that have purchased are enjoying the sound targeting the HE6 and other high impedance phones. That is why everything in the hobby only is relevant/objective to what satisfies us and not others.

 

Enjoy music!

 


Edited by Audiogalore - 2/12/12 at 7:21am
post #255 of 372

Hi

Well here I am with nothing else to do(pouring with rain outside)so have just read this thread.

Like so many of the threads on Head-Fi,they get hijacked (a little discipline needs to be had?)Take away the totally inane comments and you end up with a couple of pages of useful information.

I once made the comment that so many of threads didn't actually make any reference to 'sound quality'(of the original performance).A reply told me I was on the wrong Site! Surely,when reviewing any HiFi equipment ,reference must be made to the one thing it's suppose to do?? Would you do a review of a Vehicle without stating how it drove?

 

I must however,express my thanks to Skylab and warp08 for their reviews of The Dark Star.Both have given their thoughts on what really matters-music!!(not only equipment).

However,in reading warp08's review I got totally lost in opulence of anything 'high end'.Let me explain.One of my other interests is Wine.I know all the best wines.If I haven't drunk them,I've read about them.I know what they are,which to buy and which to sell(for uplift).What's more difficult to find (and evaluate) is those well made 'everyday' wines which are a fraction of the price but are undeniably, quality! I just got the feeling that everything that was recommended came from a list of 'what cost most'? I know a Rolls-Royce is a great Motor Car but is it good to take the Kids to School in or Shopping or to go Fishing???

 

Quite rightly reference was made to the break down of the percentage  costs of the 'system',giving 40% to the 'source' units.However,no mention of the 'real' source-the music itself.

The most demanding of 'sources' is Classical!! With the variety of Instruments, either solo or group(Orchestral or Chamber)voice(Opera)with truly 'Professional' musicians and recordings made in the best of acoustical locations with the best recording Engineers etc etc(and do you want to Judge 'soundstage'??).warp08  states " outside of classical music" but then doesn't refer to it!

 

Surely there must be somebody else out there who uses Headphones for something other than the reproduction of poorly recorded head banging music at high listening levels??(or Gaming!!)

 

Having said that,I think I'll stick with my B-52,thanks RS!

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