I've been curious about the new 5751 from JJ
since I heard about it a few months ago.
As some of you may know, the 5751
is similar to the very common 12AX7 aka 7025 and ECC83 but with a bit
less gain. In this review, Iíve compared the new 5751 with the JJ ECC83S
(12AX7) which has been my standard workhorse guitar preamp tube for
A casual visual inspection would give the impression that itís the
same as the JJ ECC83S and some have even suggested that the factory may
have re-labeled the ECC83s tubes that measured a little less gain than
average. This is not the
case. A closer inspection
reveals that the new tubeís inner construction more closely resembles
their ECC81 (12AT7) but some of the materials are obviously different.
It is indeed a totally new tube.
In our test, we used a vintage Fender Vibrolux Reverb and installed
the tube in the V2 slot which is the first gain stage for the
tremolo/reverb channel of the amp and is critical for good tone and low
Tonally, the tube is smooth and balanced but lacks some of the
harmonic complexity of the ECC83S. It also produces just a bit less
shimmer and sparkle in the treble ranges. It is however a good sounding
tube with no harsh overtones, low noise and low microphonics.
It can be very useful for amps that need a little taming in the
treble and gain. Gain wise, it does make a noticeable difference,
allowing for at least another number on the volume control to reach
similar breakup of a 12AX7.
Does it give you more clean headroom? Well, maybe just a touch if you
have hot pickups but headroom in these amps is limited by the output
power and speaker efficiency.
It will however give you a wider range of adjustment within the
clean zone of your volume control setting. It will break up at about the
same actual sound pressure level as any other preamp tube but you might
find it easier to adjust your settings when playing at lower volume.
Overall, we like the new 5751 and we expect it to eventually find a
place in a lot of different amps. You can plug it into any tube socket
that calls for a 12AX7, 12AY7 and most 12AT7 applications.