or the cheapest one.
From my experience nobody can tell the difference between the cheapest and most expensive 12ax7 in any of the circuits I have designed and built. In fact, the tendency is to choose the cheapest tube as the best when compared in 'bind shoot-outs'.
Maybe I am doing something wrong. Oh well...
I once had an old Fisher 400 amp which I got for free off the street outside an 'audiophile' shop. I stripped the original Telefunken 12ax7 tubes from it (all 8 or 9 of them) and sold them for a tidy profit online. Then I restored it and used the cheapest China 12ax7's I could scrounge. Sounded exactly the same. I then sold it....
Those were the days.
Those were the days.
if u cant tell a difference, youre on the wrong thread. delete them posts.
I can definitely tell significant enough differences between 12ax7s, even in well designed clean tube circuits. It's subtle in many cases, but there. When in non-linear land (as in an overdriven guitar preamp) the differences become more pronounced - and this is circuit dependent, so eg an inexpensive chinese new production tube might sound the best in a particular use case.
I will say it's fun rolling 12ax7s in the overdrive section of my Frenzel. In that amp, it's designed and built well enough that swapping in (say) a RCA black plate in place of (again, say) a Raytheon is immediately apparent. The dynamic response differences in the upper end of the frequency range are easy for me to hear. But again that's just me, ymmv and so forth. This stuff is subjective, but me and a bunch of other people saying the same thing aren't exactly nobody.
I will say it's fun rolling 12ax7s in the overdrive section of my Frenzel. In that amp, it's designed and built well enough that swapping in (say) a RCA black plate in place of (again, say) a Raytheon is immediately apparent. The dynamic response differences in the upper end of the frequency range are easy for me to hear. But again that's just me, ymmv and so forth. This stuff is subjective, but me and a bunch of other people saying the same thing aren't exactly nobody.
Well, I'm not a moderator so there is little chance of that happening. 😉
I will tell you where I believe the perceived difference in 12ax7's comes from. It's the internal (plate) resistance when run at low anode voltage. At low anode voltages there can be a lot of variation in the internal resistance between 12ax7's. I know because I took the time to actually make measurements with many samples I had on hand. China, Russia, Japan (toshiba), Philips (NL and USA), Mullard (UK), RCA (USA), Telefunken, Siemens, etc...
If you run 12ax7 at higher anode voltages then you don't have that problem (so much) and the internal resistance tends to drops to around 70k Ohm (even for the cheap ones). Certain older (and maybe much loved) designs run 12ax7 at as low as 85v on the plate (crazy!) which may work with certain older 12ax7's but then, won't with others... For these older circuits you will very likely notice at significant difference between a cheaper china or russian 12ax7 and a vintage RCA flat plate from the 1960's.
So when I design for 12ax7 I try to avoid such low plate voltages. Since doing this, every 12ax7 performs pretty much like a Telefunken Flat plate (or Mullard CV4004, etc.) - whatever your favorite is. 12ax7's are all very linear and have a lot of gain. The plate can handle serious voltage and they work exceptionally well with a decent load (at least 3x the internal resistance). Don't run them with too high current though. That will reduce their lifespan.
Of course everyone knows they are horrible drivers. Their signal response gets rolled off with significant input capacitance of the following stage too. But take these things into account and you will likely find they are quite underrated and useful devices. Even the cheap ones.
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Anyway, the JJ E83CC looks like a decent price for a new 12ax7. Competitively priced, so if the quality is there then that's nice to hear.
If you are using ECC83/12ax7 for phono, matching them is a serious chore. I had a very nice lot of sovtek 12ax7a's but am starting to run low now, and I really don't want to buy more russian tubes anyway. The price of them has gone up as well.
If you are using ECC83/12ax7 for phono, matching them is a serious chore. I had a very nice lot of sovtek 12ax7a's but am starting to run low now, and I really don't want to buy more russian tubes anyway. The price of them has gone up as well.
I'd imagine so, seeing that Phillips owned Valvo for most of the last century. But I asked because ceylon.mooney seems to know exactly what they are.
looks like phjilips holland, but id need many more pics for positive ID. most likely phiips holland. @patrickblue i dont know exactly what they are, but philips holland is most likely, as most of the valvo-branded tubes that aint valvo are philips holland. sometimes theyre other manufactures.
I believe I did say on P2 of this thread:
"They are clearly labeled Valvo. May have started life in the Philips Heerlen factory but emerged as Valvo tubes."
"They are clearly labeled Valvo. May have started life in the Philips Heerlen factory but emerged as Valvo tubes."
@Magz, tubes are identified by manufacture not by label. most ECC83 labelled valvo are not valvo. as ive clearly informed you, yours are definintely not valvo.
the reason that tubes are identified by manufacture and not label is because they are commonly rebranded by the first buyer; sometimes these buyers are wholesalers, retailers and often times these buyers are other manufacturers.
here are some examples:
notice that this tube says "marshall" on it. well, theres no such thing as marshall tubes, yet it says marshall.
it is, in fact, an EI yugoslavia ECC83 (aka 12AX7) nickel plate. marshall bought it and wrote their name on it. for those who are unable to indetify these tubes by sight, most european small signal tubes have the manufacture codes etched in the glass or stamped/painted on the bas between the pins, tho the stamping rubs off.
here we have 2 tubes braded "amperex 7308" with "made in usa." it is neither.
these are neither amperex, nor are they made in the USA. these are soviet 6n23p or 6n23p-EB, cousins of the 7308. see this getter construction? this is called "UFO getter" or "upsde-down UFO getter." exactly 0 usa or amperex tubes used this construction. moreso, it is exclusively soviet/russian.
heres is valvo ecc83
notice the getter construction and manufacture D-codes in the second line
very early philips 12AX7 also had tilted getter, and so do some matsushitas, so manufacture codes can be very helpful.
the reason that tubes are identified by manufacture and not label is because they are commonly rebranded by the first buyer; sometimes these buyers are wholesalers, retailers and often times these buyers are other manufacturers.
here are some examples:
notice that this tube says "marshall" on it. well, theres no such thing as marshall tubes, yet it says marshall.
it is, in fact, an EI yugoslavia ECC83 (aka 12AX7) nickel plate. marshall bought it and wrote their name on it. for those who are unable to indetify these tubes by sight, most european small signal tubes have the manufacture codes etched in the glass or stamped/painted on the bas between the pins, tho the stamping rubs off.
here we have 2 tubes braded "amperex 7308" with "made in usa." it is neither.
these are neither amperex, nor are they made in the USA. these are soviet 6n23p or 6n23p-EB, cousins of the 7308. see this getter construction? this is called "UFO getter" or "upsde-down UFO getter." exactly 0 usa or amperex tubes used this construction. moreso, it is exclusively soviet/russian.
heres is valvo ecc83
notice the getter construction and manufacture D-codes in the second line
very early philips 12AX7 also had tilted getter, and so do some matsushitas, so manufacture codes can be very helpful.
My point was that I pointed out the Philips link 2 pages ago. I don't need a first grade tube lecture.
I'm very very much removed from "first grade" and knew some of what @ceylon.mooney posted, but not all of it. I'm constantly learning, as should we all.
im here to learn and to participate. im grateful for comin across something new to me, and if i can offer something im happy to.
Yup. When you operate them in the linear region there aren't any issues. It's funny, how a circuit can be designed bad enough to sonically react to a swap in tubes of the same type and be considered an excellent piece of gear for that reason.
Aw, don't take it so hard - I complimented you in post 20 and lots of other folk have chipped in too. I have passed your recommendation on to others, though I will apologise now for not following through - though I think the 12AX7 family is very useful, I don't often use it and, if I was going to, I'd plunder my stash of NOS 20EZ7s (the stash of 6EU7s went to my brother for his guitar amps).