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Reality not hype. A Great Valve, A Great Price
on February 6, 2013
EEC83s (12AX7s) are the most common valve made. Some of the ones being made today match, or out-perform American and British versions made in the 1960s. The Svetlana (Sovtek) 12AX7LPS is THE best buy in hi-fi land since the AR turntable or the Advent Speaker. It's also cheap. The Sovtek 12AX7 LPS, consistantly out performs all other version I have tested. The bottle glass is thick, oversized and the microphonics are therefore low. They are long plates, so you probably do NOT want these for your guitar amp. These are for hi-fi preamps, voltage preamps or phase spitters. Even if your heater voltage is DC, ALL converted DC has some AC rements (which cause your hum along with ground loops). The spiral filiments often help, although, if you have built a good preamp, they should not make any difference. My Mcintosh C20 gives me 65db S/N in the phono sections with the Sovtek 12AX7LPS. My collection of 20 or 30 NOS Mullard and Telefunken don't do better than about 62 db. And they sure as heck don't sound any better! Electrons cannot tell brands.
As far as as the vague descriptions like "soundstage", "presence", "airy feeling", I cannot give you any of that hokus pokus. But the 12AX7LPS has better signal to noise, higher mu, lower distortion, better periodic harmonics, less microphonics, lower distortion (of all types) than my mint condition original Telefunkens and Mullards made in the early 1960s. BTW: original NOS of Mullard and Telefunken are usually the a great disapointment. After 50+ years being knocked around, they are usually noisy and often gasseous. Sure they are valuable today, but for 30-40 years they were junk and probably thrown about a garage. Neither gass or microphonics will show up on the common tube checker transconductance and plate ma tests. As for those magical hi-fi nut descriptions from people with magic ears but no brains, you can go by those, or you can go with science good test gear and knowledge.
Most of the long plate 12AX7s now being made in Europe -and even some in China, are excellent. Most complaints come from people who don't know enough about electronics nor have the tools to maintain and repair their old or even new gear. Many of the NEW preamps and amps are horrid. They look cool -real works of art, but are NOT good gear. Why? -Read some books! Try the ARRL Handbook -1st 4 chapters for a start. If you want valve hi-fi then you had better learn your stuff because otherwise you are going to be ripped-off silly.
GET SOME TOOLS, READ SOME BASIC BOOKS AND LEARN HOW TO WORK ON YOUR OWN GEAR. YOU WILL ENJOY IT MUCH MORE KNOWING THAT YOU ARE HEARING WHAT YOU SHOULD BE AND YOU WON'T GET RIPPED OFF SO MUCH -LIKE PAYING $$$ FOR WORTHLESS "SPEAKER INTERCONNECTS". You see, the world has moved on to high current FET and class D Hi-Fi. These are FAR better technologies. But I am old and so is my gear. Plus, my records are old and they sound better on my nice old McIntosh, Dyna or handmade gear. Of course, all my gear has been rebuilt and updated with modern components and improved circuit fixes. "Bumble Bee" or Kimber caps will NOT sound any better that the dirt cheap Xicon or Solen. -Do a double-blind fold test and see.
So get your speaker cable at the hardware store. Pay no more than 20 cents/foot. 14-18 gauge is fine. Just watch the aamp's phase. Solder your own RCA patch cords with Switchcraft plugs and good cheap cable. Gold plated ANYTHING is a scam. Gold is not even as good of a conductor as copper! Plus, it is thin, and wears off in a week. Copper, silver plated, or high nickel content steel or nickel-plated copper (e.g. Switchcraft) is the best. And unless it is for a MM or MC cartridge, or you are mastering records with computer gear (high RF and EMF), it matters not.
Learn Ohm's law and you will save a lot of money. Learn Hertz, Maxwell, and everything RCA did in the 1920s and 1930s , and you can build a damn nice Hi-Fi. Mr. Williamson was not writing anything new in 1947. It was new only to Mr. Williamson and his readers. The RCA Victor engineers had Hi-Fi in 1930. Push-Pull (class B) has been around since 1923 and 300Bs and 2A3s are directly heated (They have no independent cathode) and will HUM like a bee while delivering low power and naddaladda bass. If you want you Hi-Fi to sound like a 1930's movie house, use 300Bs or 2A3s. Or use 811s or 572Bs for a fraction of the price and get many times the class A wattage.