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Originally Posted by obender /img/forum/go_quote.gif
I want to buy my first set of electrostatic headphones and decided for either Stax 3050 or 2050 (cheapest Stax headphone + amp combos). pricejapan.com delivers both of these only for 100V but I live in Europe and electricity here is 230V.
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I've ordered a 2050 set from PriceJapan and am waiting for delivery. But I'm not worrying about the little wallwart. As far as I can see in photographs and brochure, it is a cheap, commonplace, off the shelf voltage converter. You can replace it with any other wallwart that fits your local socket and doesn't diss Colonel Ohm. 4W divided by 12V is 333mA, so any 12V 400mA or better wallwart will do. I have, just looking around my study at what lies loose and isn't in use, not even opening boxes because my family is already in bed, a Lloydtron multi-voltage wallwart, bought at the local pound shop for 1.99, that does 12V and a third of watt, a variable Lego power supply, two Panasonic 12V 500mA wireless phone units, a spare ethernet router power supply 12V 1A, and a vast array of similar or better that are plugged in and possibly in use or perhaps just sitting there waiting for the associated equipment to be brought back in use but that may be liberated if I decide my sound is more important than powering up a Newton I haven't used for years.
Quote:
Originally Posted by obender /img/forum/go_quote.gif
I noticed that the amplifier in the Stax 2050 combo (SRM-252) is powered at 12V via an external adapter. I was wondering if it is possible to replace the adapter supplied by Stax with a regular 12V adapter. Does anyone know if there is anything special about the adapter Stax provides apart from the polarity? Does it have to be regulated or does the amplifier have a regulator inside?
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On the pictures the supplied wallwart is clearly too small to have anything special about it; in fact it looks cheap and minimal, probably ordered in by Stax on price out of someone's catalogue. Replace it with something stiffer in the current but the same 12V, as in my list above (I will choose the 1A unit from the router). Choosing the bigger current capability cannot harm your amp because it will draw only as much current as it needs. But it will make the delivery of that current smoother by dragging the voltage down less.
I'll inspect the inside of the 252 amp when I have it in hand to see if there is further smoothing inside (more than possible) and decide on hand of the quality of sound whether it is worth building a better power supply. There's a firm in Germany that advertises on German Ebay which makes alterations to the 212 power supply (in German "netzteil") and also to the amplifier itself; I assume people spend another third (by the time carriage is added for sending boards back and forth) of the cost of their basic Stax kit with this firm for a good reason.
The problem with a better power supply is that the cost can soon mount up substantially to a third or a quarter of what we paid for the 2050 kit at PriceJapan. On the other hand, if the set is the actual value charged by the cheapest European suppliers, 800 Euro, then an improved powersupply, if necessary, may be justified.
There is another problem with upgrading power supplies in a heavyhanded manner. Just stepping back a moment, the power power supply, and in particular its capacitors, are often the most expensive components next to the case and transformers (and upmarket tubes, if any) in any amp design manufactured for commercial distribution; energy storage is an obvious place for cost accountants to make big impact. (In the Stax line, it seems very likely on general consideration of the size of the Stax operation and its likely design staff numbers that the 300 and 3x3 amps are just 212/252 amps, with at most very small signal section differences, but with dedicated, power supplies -- but check the price difference a good power supply makes!) So, in general, if you buy a commercial amp and it dinna work too well, you beef up the power supply in the first instance by adding energy storage, and suddenly you have better bass extension. The usual obsessives we find in among the audiophiles (and some designers too) then conclude that if a little is good, plenty has to be better. But the truth is that nothing fails like excess, and in current storage in sound reproduction the first cause of nasty, overhanging bass skewing the entire sound spectrum is usually the wrong amount of capacitance in the power supply. That might be even more particularly true in earspeakers, where the quality of the bass is very obvious, very forward on your attention. I know for a fact that it is especially true in floorstanding electrostatic speakers like the Quad ESL-63 and even more so in its predecessor the ESL (sometimes called -57); building amps to drive big stats directly, or trying to match them to woofers is a pain in the posterior because the quality of their bass matches the exceptional quality of their midrange.
The optimum amount of power supply capacitance is determined by the limitations of the sound reproducer, the output device, in this case the earspeaker. It may be that when the amp and speaker arrive, the two are matched to perfection and that no power supply upgrading is necessary. (The stiffer wallwart isn't upgrading in that sense, it is just a mild sort of tweak.)
HTH.
Andre Jute
Visit Jute on Amps at
http://members.lycos.co.uk/fiultra/
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