LarsHP
Headphoneus Supremus
If I go for a target of the stated load (8 Ohm), then I will use a 10 Ohm resistor in parallel and the (50 Ohm) headphone will then get 2 Watt. This is actually enough, but a little more would probably be nice.
I also asked about the choke and he said that is a good idea. It can reduce noise and improve sound quality, probably a slight improvement but definitely not night-and-day. Raaf, he wondered where you put the choke? It could be on the power supply to the screen of the tube or to the anode and it could be useful to know which. The main problem should be to find a choke that is small enough to fit in the amplifier.
I don't know why expensive amps like these have such a cheep power supply.
(...) the CS-300 was shortly followed by an improved version CS-300 X (Limited), where some changes were introduced (photo nr. 7). The output terminals used were better, there was an additional choke in the power supply, some passive elements were exchanged to better ones, but most of all the output tubes were exchanged to rare Mullard NOS.
A choke in power section, in the anode circuitry, is a “holy grail”, and is used by many tube device manufacturers. But like any other element, it has its problems.
(...)
... the choke, which was one of the biggest changes to the Limited version, is also gone.
(...)
... the HD800 are high impedance headphones - 600Ω – and they are not so forgiving, any error, any noise or hum can be heard immediately – just like with high efficiency loudspeakers. And with them, this hum was annoying. Mr. Waszczyszyn, like any scientist, systematically searched for the reason, and found out, that there is no choke in my unit, but only resistors, what increases noise slightly, and that the hum is a result of the chosen topology, with one channel closer to the power supply than the other. So it cannot be helped without reworking the whole amplifier. And I did not want to do that, because we could maybe improve on this one aspect, while destroying everything else, because architecture of elements is a part of the “magic” coming from years of experience. And I am sure Mr. Hyodo knew what he was doing. Well – this was probably a part of the compromise. There is nothing we can do with the loudspeaker output, but with the headphone output it is a different story. It was enough to solder a few resistors to the headphone socket, and that was it. Their values must be chosen experimentally, as it will depend on the impedance and efficiency of our headphones. At first the values were chosen too big, and needed to be adjusted, but now I can tell, that there is no hum at all! And no noise. This is the reason I recommend this simple trick to everyone – it is cheap and effective.
BINGO!
Here is what I stumbled on when I searched the net (with added bold & italics to the interesting part):
Link: http://www.highfidelity.pl/@main-135&lang=en
In other words, the standard/original CS300 does not have a choke in the PSU, but the later/upgraded versions has! This is in other words an "official mod" by the manufacturer.
The noise I hear with LCD-2 is in fact mostly a humming, which most likely is caused by the trafo inside the amp.
Edit:
I need to add this from the above article: