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

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

 

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.

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

 

 

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

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

 

 

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

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?

 

 

 

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

True points I suppose.

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?

 

 

 

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).

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

 

 

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