Originally Posted by Pappucho
In defense of aftermarket amplifier, such as Ray's amplifiers, and your typical cmoy, there are several reasons why these higher end amplifiers should sound better. For starters, the precision resistors he uses have a 0.1% tolerance meaning that if he uses a 10K resistor it's within 0.1% of that stated value. These are much more expensive than the typical resistors used in a Cmoy which are usually 5% to 10% tolerance.
It is well known by the engineering community that tolerance as low as .1% rating is not a true rating, but it is underrated. Thus is the reason why CMOY diy kits, and any diy kits recommend at maximum, 1% thin film transistor is recommended for my CMOY(Jlabs). Also, for CMOY, 5% to 10% resistors doesn't have to be used(Jlabs recommends 1%), its user's choice what tolerance they want to put in. Also, resistors are very cheap, even the very low tolerance ones. Go to mouser and check.
What this translates to in sound is that each channel will more likely match each other and give you greater stereo separation. He also uses thin film resistors which to my ears sound better than cheaper thick film smd resistor,
not true, 1% thin film transistor are recommended for CMOY for the Jlabs version. And you can put .1% one if you belive that they are .1 or you can actually hear the sound improvements.
again these are much more expensive than what someone would typically use when building a Cmoy. Then theres the power supply. I don't know specifically what he uses but I am pretty certain it's regulated and will hold a steady voltage during driving of headphones. If your cmoy uses a typical resistor voltage divider for your vitual ground, the basic power supply section of a typical cmoy, then you're not getting a good power souce for your amplifier circuit.
portable amps are bias by a battery, DC source of power, no serious regulation is required for DC, since power is constant(no fluctuations like AC). If the source is AC its a different story. what regulators do you speak of for a DC supply? Here is a link to wikipedia article on regulators,
Even if you add in an IC driven virtual ground you might not be getting a clean power source as what's typically used in these higher end amplifiers. This means that your amplifier circuit is straining to drive your headphones and clipping and distortions are probably occurring muddying up the sound. Then there's the question if you're Cmoy is a simple opamp design without buffers. Another sign that you're potentially not getting enough current to your headphones and potentially underdriving them.
I'll say again, the power source is DC and you are comparing how clean the power is?? Please explain how 9v or 18v or 24v powered CMOY may be clipping or under driving phones, but not RSA's 3v. Swing limit?? I have not had any clipping issues( I've heard a RSA amp clip), I would suspect 3 to 4v RSA would clip before a 9V CMOY would.
I don't know Ray's amplifier design but based on how well his amps are received I believe he's taken this into consideration and building a circuit that will not fall short on driving your headphones. Now, for that military grade circuit, it's just not the circuit board itself to take into consideration, it's the design of the board too. From reading on his website, he separated signal traces and power traces from each other by placing all of each on a single side of the board.
In other words, the power lines are all on one side and the signal traces are on the other. What this means, in theory, that you should get less noise leaking into the signal from the power line traces. Also, each side has a full ground plane further reducing channel crosstalk and potential noise interferance. A dual side board such as this is more expensive than a single sided one. I don't think the typical Cmoy has this advantage.
Thats pretty much standard with any circuit layout, not just RSA. Any circuit layout is designed reduce noise, RSA is not the only circuit does that. If you are saying a portable amp design inside single casing has complete noise isolation on an integrated on a PCB without using separate casing, thats far from the truth. Also, where do you think noise comes from?
Knowing how a Cmoy is built, in it's simplest form, there are headphone driving limitations that will result in inferior sound when compared to more complicated designs.
Its an overstatement to say simplicity equate to inferior sound, without any proper reasoning. It is not always the case, CMOY is an example of that.
Now, all this is moot if you're happy with what you're hearing. But from a design point of view, I can see where the money goes and why a higher end amplifier should sound better.
I am happy with it, I built it with $15 budget and if it can drive my HD650, it can drive any IEMs without causing any distortions and I'll say again, I cannot differentiate SQ with RSA's amps.