I have some 12au and 12ax that are branded Hammond and are made in GB. Also have several GE and Sylvania made in GB 6bm8. You are right. Pay attention to details!
Sylvania JAN 6189 is a fantastic tube for little money. In my DAC, I prefer it over the famous Mullard boxplate M8136 (another 12AU7 equivalent).
Mine was from 1966 or so. Sounded nothing like my MC30's, sadly. I thought it would 'cause everyone told me it would. Everyone wuz wrong.. :^) The guy who bought it wanted it for one reason. I told him the McIntosh 240 had more of that holographic tone but he didn't care. The 275 was bigger. Simple as that.
I never owned a 12AU7 equipped tube amp, but that 5963 plate curves are superior to the 12AU7 unless you run those 12AU7s at maximum current and the 5963 still looks better at medium to maximum current.
Om top of the 12at7 preamp tubes I'm using, I didnt know the 6cg7 can actually change the sound too. I found a nice NOS stash in my cabinet.
Here comes that age old question that truly cannot be answered honestly, suggesting 1 over the other Preamp tubes and what is "best". In the 50 years I have been selling servicing building and modifying audio gear, Fact is the same factor of relative sound quality or "tone" from 1 person to another. BUT! all human's ears are not the same, So, fact is 1 XXXXX tube in "center slot" may be great for your ear/style/tastes, But It may be totally Wrong for the person you just recommended to change tubes, sadly you can't audibly audition tubes in the store, But I would definitely recommend "road testing" many types of the Industrial dual triodes out there. Prices are great TBH since you guys all made the others $$$$$$. The truth is the 5814A tube was designed as an Industrial valve with higher quality construction ( ie) heavier filaments, plates even thicker glass envelopes to meet Military, Industry and had closer adherence to quality. All 4 numeric digit tubes are there for better quality overall. Yes these factors effect "tone" that 4-letter word I've grown to hate. Just One man's beer is another's champagne. My favorite is the 5814A's in my SVTs front end, and again every tube is different even among brands, (Older RCA's verses new runs etc.) I Built a hot swap preamp substitution box that extended the driver tube socket out to a 6-position switch with 6, 9 pin sockets and a separate heater transformer, The sound is easily compared with the twist of a knob. "My guitar player still has it strapped to his Marshall for our Pink Floyd Tribute band, there are 6 different tubes and 6 different sounds, \ As always Keep on experimenting with things. Try an old worn-out tube with half its life gone, It may be the sweetest thing your amp needed to cure its distorted bite in mellower genres, Wolf Out!
Perhaps a dumb question: On a integrated amplifier that uses a pair of 12au7 tubes (or alternatives) on the preamp section (Rogue Sphinx, for example) what is best option: a) to have an unmached unbalanced pair of NOS tubes b) to have of matched balanced pair of modern tubes c) to have balanced 12au7 tubes no matter if they are matching Once asked JJ why they didn’t offer matched 12au7 type of tubes and the answer was the it is irrelevant for the kind of use they are intended in audio circuitry. Is this right? My question only makes sense when forced to keep tube-rolling costs down (or tube substitution when the stock ones fail) because the obvious and better choice is matched NOS, like those from Amperex or Mullard.
Timely of this to pop back up, have 12ax7’s in my integrated, designer suggested I try some 12au7’s. Anyone using valvo’s? Have one in my phono stage but wasn’t the easiest to get at the time.
I’ve found that if the circuit design using a pair of preamp tubes for input gain (12AU7, 12AX7, etc..) that finding a pair that has decently matching gains on the first triode (if that is how the tube is implemented) is a good way to go. If the tube is in the phase inverter section, balanced triodes are favorable. Amplitrex and some other testers out there can show the gain numbers per triode.
If you need GE 5814's, this dude is selling for cheap.. A US GE 12AU7A ECC82 5814A TUBES IN ORIGINAL BOX. Ring Getter Rib Plate | eBay
I agree with this 100% I have a few pair of Amperex Bugle Boy 7316's and nothing I have tried is better period. I do have some extra's to sell if interested..
Looks like those are actually 12AU7s, but this guy is listing some "equivalent" numbers too, while not realizing that 5814s are not actually identical to 12AU7s. Still it's a great price!
There’s something to be said about tube rectification as both the MC30s and MC60s were the best sounding tube amps McIntosh ever made. Restored, they still compete with the best amps out there!
The picture makes these look pretty good. But that tell me nothing about their electrical performance. The strength number 56 which was mentioned is the minimum value which the TV-7 tester manual specifies is still good for a 12AU7. This is just a relative number as the TV-7 lacks scale which is calibrated to read in micro-Mhos.
Wow! I stumbled upon a little stash of those at a surplus place once. They were Tektronix branded and the numbers were barely visible. Stunningly good 12au7 variants.
Maybe, BUT they do not sound as 'musical" according to many who have used them. I actually have a lot of 10 used pulls that test new I bought for 15.00 several years ago. Have not actually tried any myself, but I will someday.
