je ressort le topic, parce que j'ai trouvé quelque chose de très intéressant!
jugez plutôt (c'est long mais très instructif!):
ECC83,12AX7 Test Report from Watford Valves in the U.K.
OBJECT OF THE TEST
To establish the best sounding ECC83/12AX7 of both New Old Stock and current production variety.
EQUIPMENT USED
The amplifiers used were: 70 's Fender twin reverb fitted with J.B.L's. A 70's Fender twin reverb fitted with
original Fender blue back speakers. A Mesa/Boogie mark 4 combo. Marshall 100 super lead into 4 x 12 cab.
Fender Princeton reverb 2. Vox AC10 with Elac speakers. Guitars used where a 1973 Fender Stratocaster,
1980 Yamaha SA 2000S semi acoustic and a 1980 Gibson Les Paul Standard.
Audio tests were carried out using a Croft Micro Audiophile pre amp. A Leak stereo 20 power amp trough
Tannoy 15' super reds. The source was Thorens TD150 Grace & Supex & A.R. Legend, Linn arm & Denon
Cartridge.
The tests were carried out to provide in real working and playing situations how the valves performed. The
test rig use to select the valves prior to evaluation was our own custom designed unit click here for picture.
Valves were selected for low microphony, low noise and gain rated Click for more info
Mullard ECC83 & Mullard M8137 Box anode, R.C.A 7025 & Telefunken ECC83 Where used as the
reference.
The test reports have been updated on 1st September 2000. We used the same equipment with the
addition of a Fender pro junior and the same reference valves for evaluation. All the valves tested where
selected to the same specification as our original test samples. The new valves tested where, The French
Mazda 12AX7 military grey plates, The French Mazda 12AX7 military silver plates, The Tesla N.O.S
E83CC/ECC803S Telefunken replica new old stock valves. The only new current production item being the
Sovtek 12AX7LPS.
ECC83/12AX7LPS SOVTEK
The new Sovtek 12AX7LPS valve is now in full scale production in Russia. The valve is of medium to high
gain and has a special spiral filament. This filament greatly reduces hum when operated in amplifiers with
AC heaters. This is certainly the best 12AX7 that Sovtek have come up with. On the plus side in audio you
get more detail in the treble register. The valve is open and has very balanced presentation and importantly
the valve has life and sparkle not muddy like the WA or WB. Over long periods the valve was easy on the
ear again unlike the other Sovteks we have listened too. Bass response was fine, not as deep or thundering
as the Mullard , Brimar or JJ/tesla but one could easily pick out the bass line. The minus points were on
vocals as they were not as refined as the new old stock tubes.
In Guitar amps we noticed that the level of microphonics were higher than the WB, This would be also be
consistent with the higher gain of the tube. The valve gave a bright and clean sound but not as sharpe as
the G.E. When the valve distorted it retained it's control and sounded sweet. Overall this is a very good
sounding valve that provided a good choice for audio or guitar.
ECC83/12AX7 MAZDA GREY PLATE
A French military valve that is noted for it's Mullard Tone. In audio application these valves were detailed ,
lively and very balanced. Plenty of bass slam in these babies. In guitar amps these rocked. The valves are
very high gain, yes more gain than the famous Mullard ECC83. The distorted tone was rich and fat . Treble
response was clear even when really distorted. The valves were supremely quiet, however due to the
immense gain special selected version would be needed if your amp has a cascading gain pre amp section.
ECC83/12AX7 MAZDA SILVER ANODE
A French military valve with special silver plates made for special application military use.
In audio amps the valve displayed a slight treble forwardness. This gave the impression of less bottom end
thump when compared to the Mazda grey plates. A Fantastic detailed performer the sound stage was big .
The valve was again very quiet which shows how well made they are. The gain on these valves are
somewhat less than the grey plates but still in the medium to high gain bracket.
This valve was amazing in Fenders. That sweet rich out of phase sound with a strat just jumped out of the
speakers. The valve was more percussive than the siemens E83CC and with a sweet alnico speaker the
guitar sung. It's compression was quite late giving bags of clean headroom. For that sweet Fender tone
these have no equal.
ECC83/E83CC/ECC803S TESLA
This valve was the Czech replica of the famous Telefunken ECC803S. The valve has the large "A" frame
getter and thick grade glass which eliminates microphony. The valve also retains the gold pins and plate
structure of the Telefunken. This valve is not the same as the new JJ/Tesla E83CC. The first thing that
strikes you is that it is very quiet and the valve displayed no microphonics whatsoever. Beautiful on female
vocal as it has a super midband, very fast and dynamic. We dug out our private stash of real Telefunken
ECC803S and noticed that these were identical in every way including the sound ( except for the diamond
mark). The valve is not as high gain as the Mazda Grey or the RFT. Sonically this was excellent. Rich bottom
end silky smooth treble and nice balanced.
In Guitar amps the sound stage was big, no rings, no pops just your guitar. This valve seemed very neutral
not colouring the sound in any way. When pushed into distortion the valve sounded rich with super late
compression. This valve is super it just does what it is supposed to do nothing more nothing less.
ECC83/12AX7WA SOVTEK
Low to medium gain double triode with the same sound quality and less gain than the WB. When distorted
did not have the detail or balance of n.o.s valves. The valve seemed to be pushing everything through the
mid band. When pushed hard the sound compressed very early. Good for general repairs.
ECC83/12AX7WB SOVTEK
Low to medium gain double triode with low microphonics. Clear bright sound earlier distortion than WA. The
valve lacked clarity and definition of new old stock valves. Same sound as WA however far better than the
Chinese 12AX7. No snap crackle and pop.
ECC83/12AX7WB SILVER ANODE SOVTEK
This is the early silver anode WB as used by Groove tubes. Many of our customers tell us these have a
better sound than the current production type. We found that they sounded identical to the current WB but
we found generally that they had higher gain than the modern item. This resulted in the distortion happening
a little earlier, therefore we found these to be a good choice for guitarist on a budget.
ECC83/12AX7 Sylvania
Classic American valve which was fitted by all the great 60's amplifier companies such as Ampeg, Fender &
Gibson. This valve produces a rich warm sound with excellent balance. When distorted produces a fat
sound with plenty of drive without loss in top end clarity. In the Fender amps the valve produced a clean
bright response which was great for finger picking. Single coils sounded full with no harshness and plenty of
detail. In the Boogie a sweet clean sound was easily attained which was crisp and clear. Once you rocked
the Boogie the Sylvania valves produced a classic rock sound with a little mid forwardness which I liked. In
the Boogie we found that due to the high gain nature of the amp low microphony selected valves produced
the best results. Early 1960's production ideal choice for all vintage Fenders.
ECC83/12AX7WA Philips-JAN
American military low noise valve made in the famous Sylvania plant in emporium. It retains the classic warm
solid sound of the early Sylvania but has less drive. This proved useful in the Boogie as the lower gain of
the valve gave less microphonics. Mid range was very musical with all the clarity of the Sylvania.the bottom
end was superb and in comparison to the Sylvania sounded a little tighter and better defined which was
welcomed in the Marshall amps. The bass was not as deep as the Mullard but the Philips did have that
instant British style tone. In the Fender amps all the tone that you would expect was there. This is a superb
valve and an instant upgrade for all modern amps.
ECC83/12AX7WA G.E-JAN
This is a rugged American military spec valve of immense quality. This is the same valve that was standard
in 70's Fenders. The G.E valve is famous for it's big crisp sound stage and bright top end response which
breathes life into Fenders. This valve really supplied that authentic Fender twang. The valve was brighter
than the other American valves and also worked really well in the vox by giving it a clearer top end
response. When the valve distorts it has a rich harmonic feel and chime. Even under heavy Boogie
distortion the bass and mid range detail was also superb. Thoroughly recommended.
ECC83/Mullard
The legendary British valve which is the most sought after ECC83/12ax7 type of all time. The key is the way
the valve distorts. It reproduces exactly what is driven into it with great musicality. It combines smooth drive
with balanced low microphonics. The Mullard reproduces every subtle detail with a rich sound stage. When
overdriven the valve had a 3 d effect which made the valve really sing. This sounded amazing in the Boogie.
The noise level even at full saturation were very low. The bass response has great kick without loss of
definition. We came to the conclusion that this was going to be a hard act to follow.
ECC83/M8137 Mullard BOX ANODE
The special military grade Mullard is one of the lowest noise and distortion types ever built with a superb box
style anode plate. Raved about by vacuum tube valley and quite rightly so. The sound stage is detailed and
relaxed and it handles complex music with ease. If you want the best audio valve then this is it as it has less
distortion than the standard ECC83 Mullard. The mid band is superb with vocal rich and clear. Now very rare
and sought after. For audio, stamps on the Telefunken ECC83 and leaves it for dead.
ECC83/E83CC Siemens
Original German valve with extra mica support at the top of the valve and ribbed anode plate. Well balanced
with large sound stage with low distortion. Relaxed and very detailed. The valve had a real percussive ability
which was great for Fender style picking. Bass & treble where in correct proportion. The valve also had a
superb mid band response which was not as detailed as the Mullard but crisper than the U.S valves. Superb
in audio applications on acoustic or Spanish guitar as this gave the impression that the guitar was being
played in the same room. Super in the noise department and was as quiet as the box anode Mullard. This
valve can be highly recommended for audio or guitar.
ECC83/TELEFUNKEN
The classic German low noise ECC83 which provided a superb rich sound stage. The valve was electrically
well balanced but did not have mid range honk or bite of the Mullard ECC83. The midrange detail of the
m8137 also left the tele in the shade when we used it in an audio test. The valve shares all the Siemens
strong points and does everything exceptionally well. Clarity is perfect with no fuzz or bass distortion. This is
an all-time classic valve and has a very high regard in audio circles.
ECC83/R.F.T
German valve that I have seen also branded Brimar, Siemens & Telefunken. This tube was also used for a
long period by Marshall. The valve has a rich bass response with great drive. Very low in microphonics due
to thick glass envelope. The valve also distorts earlier than the U.S.A types. The valve does show less treble
response than the U.S.A types which lends the valve to be used in a more rock style set up. The rich
harmonic distortion make this a great valve in Marshall. Boogie and Vox amps. It showed rich sustain with
plenty of bass crunch. Mid range was clear and detailed. Defiantly for the rockers and blues players.
ECC83/CV4004 Brimar
British military spec with half flange anode. Instant British rock sound. Exceptional balance and sound
staging with great drive. Has not good the rich harmonic distortion or the unique 3d effect of the Mullard and
under full distortion does not appear to have the same bite. The presentation is relaxed and musical which
all the new ECC83 types do not match. It does everything it should do excellently.
ECC83/TUNGSRAM
Hungarian valve which is identical in construction to the Mullard. It has additional internal supports which
greatly reduces microphonics. Good balance with clean top end response. The valve sounded vibrant in the
Fenders and was low in noise. This is very important in old Marshall if you want to make the amp cut through
by increasing the presence control setting without all that hiss. The Tungstram does need around 48 hours
run in to get the best out of it. The valve had more headroom than the R.F.T. and was as quiet as the
Mullards.
ECC83/12AX7 CHINESE
This valve tended to be fitted by all the major amp manufactures when it was in production. On the plus side
the valves have good gain and low microphonics, which suited the Boogie and the Marshall amps . The
drawback is its complete lack of tone. This gave the wasp in a jam jar trade mark sounds. The treble was
fizzy and the bass response gave a hazy distortion. The music sounded like a vale was placed in front of the
speaker. The valves also after small amounts of gigging tended to sound harsh and brittle. Therefore we do
not recommend this type. (The latest Chinese 12AX7C made on new tooling is currently under test and has
shown some positive results at Westwood Music.)
ECC83/E.I YUGOSLAVIA
This valve closely resembles the Telefunken ECC83 due to its' smooth anode plate design. This , however
is where the comparison ends as the valve sounds nothing like the tele. The valve is far too microphonic for
use in guitar amps. We have even tried so called selected versions from other dealers and even Boogie
branded items all of which are in our opinion unusable except as phase splitters. The valve does have
plenty of gain and have a rich rock sound. The downside is that even ones which are low in microphonics
seem to go microphonic within a few months. Therefore we don't recommend its' use in guitar amplifiers.
ECC83/E83CC JJ TESLA
We re-evaluated this valve as early production items seemed to produce excessive hum which rendered
them useless. The valves gain characteristics place it in the medium to high gain range. The bottom end
response is clean and clear. The valve has a solid structure which makes it free from adverse microphonics.
Tonally these are great. The mid range has a slight blurring which seems to increase the harder you push it.
Great for rock sounds but not ideal for clean. The top end is sweet clear and has nice sustain.
ECC83/5751 G.E.-JAN
This is a low gain valve which produced all the classic G.E sound stage and performance as described with
the 12AX7WA. The valve was very low in distortion and very difficult to clip. This is an excellent valve for use
in Fenders or any clean stage application. The sound was bright and vibrant with plenty of detail. The valve
was very well balanced indeed it was very easy to get identically matched valves. This valve is far better
than any currently produced valve for clean pure Fender style twang.
ECC83,12AX7 Test Conclusion
The first thing I will say is that under these tests the unanimous conclusion was that the new old stock valves
offer better sound quality than the current production types. The second thing is that tonality is in the ears
of the listener and you may find that a current production item has exactly what you are looking for. So try as
many valves as you can until you find the sound you are looking for.
Guitar valves
The Mullard ECC83 was the clear winner as its own superb character shone through. Detail, sustain and
perfect balance where second to none but what won the day was its' superb 3 d distortion character which
not even the Mazda grey plate could match.
The runner up was a very close race. The RFT had a great rock tone and Mullard style gain. The valve
could be made to distort very easily and was really at home in the Marshall and Boogie amps. This is ideal
for the rock player as bass crunch is there in abundance. The Tungstram was also close. This valve had
detail, balance and large sound staging. this was a good all round valve with less balls than the Mullard or
the R.F.T. The R.F.T & Tungstram are exceptional valves and will work well in any situation.
The Siemens E83CC was the runner up in our last test report up by virtue of its percussive nature in the top
register. Some people thought this was due to its treble forwardness. The silver anode Mazda was definitely
better for finger picking as it seemed to jump out of the Fender amp and demand attention. The Siemens
still retains that position as it was a better balanced valve for audio use.
The Tesla E83CC/ECC803S was the best all rounder as it is very well made and it will let the music sing
through with no additions. The valve had detail, balance and finesse. The valve is are rare as the
Telefunken and for use in valve microphones is a dream as super low noise.
The Mazda 12AX7 grey plate are Mullards on hyper drive. Mass gain, this is the most powerful valve in terms
of output we have ever measured. It is a great rock valve but just does not have the Mullards unique
distortion character or freedom from microphonics. Superb in vintage amps were you need a little more bite.
The G.E where considered to the most American sounding due to its bright nature. I love the sound stage
and crisp distortion of this valve and it is certainly a great all round valve with low microphony.
The Sylvania and Philips valves all showed a similar sound quality. The Sylvania valves where of higher gain
and higher drive than the Philips. This would led to if the valves where unselected to microphony in critical
driver positions. The Philips seemed to be tighter in the bass area but retains the classic mid band warmth.
This I love and I must say it really sounds good in Fender amp.
The Brimar CV4004 is a classic British sounding valve. Refined and well balanced and does every thing it
should very well. The valve is not aggressive as the Mullard, G.E. or the R.F.T.
The current production items in terms or pure sound quality the Tesla JJ and the New Sovtek 12AX7 LPS
are top of the bunch. The E.I valves also sound good but are just so appalling in the microphony department
that in our opinion it is unusable in guitar amp. Many dealers advertise these as tested and low noise. They
may be low noise compared to each other but I have never found any that are true low noise low microphony
when compared to a Mullard, Siemens, Telefunken & Brimar.
The current Tesla JJ valves are higher gain than the early production years and are used heavily by Groove
tubes & Mesa Boogie. The valve generally has a good rich sound with a forward presentation. When pushed
really hard the valve can sound a little rough around the edges. The valve has less top end sparkle than
some of the new old stock tubes but has plenty of bite. The audio boys may look for a brighter top but this is
the best sounding current production ECC83/12AX7 for rock guitar around.
The Sovtek valves are certainly low on microphonics. This is why they are used by more o.e.m than any
other valve. The WB and LPS are the best for guitar. The LPS seems to be cleaner and sharper than the
other Sovteks. What you lose in low microphonics you get back double in terms of gain. This provides more
crunch , more dive and more musical than any other Sovtek before.
The Sovteks do tend to suffer from a little mid range fuzz when pushed and lack the mid range detail of
N.O.S valves. The LPS goes a long way to redress the balance. They offer exception valve for money and
are available in quantity.
Audio valves
Here we are looking for the ultimate detail, fast dynamics and musical involvement. One valve has it all.
The winner is the Mullard M8137 box anode. This simply sounded more involving and musical than the
Telefunken or the Siemens. The Mullard ECC83 was also close and is a testament to how well made the
Mullards are.
The Mullard just had the most detailed mid band with close mic work easily heard through the speakers. The
German valves were all very neutral as was the Tesla E83CC/ECC803S New old stock. The R.F.T just
lacking the top end richness and sharpness and bottom end clarity of its' West German cousins. The M8137
showed less distortion than The Mullard ECC83. Both these valves had that bit more detail in the midrange
which makes them stand out from the pack.
Two dark horses both of which made late claims to get into the ratings.
The G.E 5751 is simply a superb valve which showed all the G.E character but with lower distortion levels
than the G.E 12AX7.
This I feel is next audio valve which a few years from now will get more and more sought after and more
expensive. The valve was specially balanced for identical triode section and has a lower amplification factor
(70 mu) when compared to a ECC83/12AX7 (100 mu). The valve had a musical and pleasing sound.
The Mazda grey anode and silver anode are fantastic sounding audio valves. The silver plate is a more
musical more detailed G.E type sound. It also seems to handle any music with authority. The grey plate is
The Mullard ECC83 before they came of age. Not Quite the Mullard but very close.
The Tungstram is a superbly rich and musical valve . The valve is low noise and has a very sweet treble.
Which is full of depth and definition.
The simple rule to remember is that all the valves do sound different and it may the least expensive valve
that meets your needs. Once you have found your preference always get some spares because in life three
things are certain, death, taxes and N.O.S valves will dry up.
