TUBE CARE &
MAINTENANCE
VACUUM TUBE
WARRANTY
We
guarantee our tubes for ninety (90) days, which is the same
warranty the we receive from our supplier.
CARE, MAINTENANCE &
REPLACEMENT
1.
START
UP: For the sake of simplicity, the Steel Guitar
Black Box does not have a stand-by switch to allow the tube
to warm up before the high voltage is applied to it. This
should be considered with regards to tube life. The cold
start-up of a Black Box is best kept to a minimum. That
means if you are going to turn it on in a given day, you
may want to just leave it on and warm until you pack it up
for the evening. Frequent start-ups can contribute to
premature aging of the tube. Fortunately replacement tubes
are very inexpensive for the Black Box. You may want to
purchase a back-up to keep on hand. This really goes for
any tube gear.
Both the Revelation Tube Preamp and the Tonic Tube Preamp
has a stand-by switch. You should leave this switch in the
down position when you turn on the power switch. Once power
is on, wait about 15 seconds, and then turn on the Stand-By
switch. The tube will be warmed by then and will not be
stressed by the high voltage being applied.
2. REPLACEMENT:
When the tubes begin to exhibit symptoms that suggest the
need for replacement, the procedure is simple for any
qualified person who understands the nature of a high
voltage tube device. ONLY qualified personnel should
attempt replacing the tubes. It must be done with the unit
unplugged from the AC power source. Leave the Stand-By
switch "up" and wait at least one minute. Then the lid is
carefully removed by the Phillips screws on the top of the
lid as well as the one on the faceplate. The tubes are then
easily accessed by hand. The location of the tube type is
clearly marked on the circuit board near the tube socket.
Feel free to experiment with other brands of tubes as long
as they are the same type.
3.
TYPES:
STEEL GUITAR BLACK BOX - 1 tube
(1) 12AX7 (ECC83, 7025, 5751, ECC803 or similar)
REVELATION TUBE PREAMP - 3 tubes
(3) 12AX7 (ECC83, 7025, 5751, ECC803 or similar)
TONIC TUBE PREAMP - 2 tubes
(2) 12AX7 (ECC83, 7025, 5751, ECC803 or similar)
REPLACEMENT TUBE UPDATE
& ORDERING
As
a manufacturer we strive to find the most reliable source
of quality, newly manufactured tubes that we can. However,
from season to season various tube brands seem to come and
go due to inconsistent quality and reliability issues, thus
requiring us to use different brands of tubes in our gear
over the past few years. Put simply, they don't make them
like they used to.
Most recently,
we were again finding quality issues with a good share of
our JJ 12AU7's and 12AX7's batches. After extensive
research and consultation with other amp manufacturers and
audiophile nuts, the path has led us to a recent generation
tube manufactured by Shuguang in China.
I must admit, that for
years I avoided these tubes because of my general bias
against goods manufactured there. But I've since learned
that this factory has not only been making good, solid
preamp tubes since the '80s, but is now on the 9th
generation of refinements. High end amp makers such as
VHT/Fryette, Fuchs, Boogie, and many others have found
these to be the most consistently reliable preamp tubes
available today, far surpassing European tubes in many
respects. Much to my surprise, these are proving to not
only sound excellent in the clean circuits we manufacture,
but are also reliable, low-noise, low in microphonics, and
happen to be about the only new tube that truly holds up to
certain critical voltage spec's as defined decades ago for
these dual-triode types.
To further insure quality control, I've found that I
currently like the service and consistency of the TAD -
Tube Amp Doctor versions. TAD is a German company that
deals directly thru MOJO here in the US. TAD only
sells the premium selected versions of this tube,
pre-tested for low noise and low microphonics.
For those who need to replace the 12AU7's
in their older Black Boxes
and Revelations and Tonics, I'd recommend these
HERE,
their premium 12AU7. The price is good and Mojo gives a 30
day guarantee on it.
For 12AX7
replacement
in the Revelations, Tonics,
SMS Classic preamps, and newer Black Boxes, I'd recommend
either of these:
TAD
12AX7A-C Vacuum Tube or TAD
7025 Highgrade Vacuum Tube
Since I have a limited ability to keep a large stock of
replacement tubes, I'd encourage people to contact MOJO
at www.mojotone.com
for affordable replacement
tubes in their SMS gear. But if someone wants to spend some
extra money, I'd surely recommend that people explore some
of the various tube dealers and consider some new-old-stock
premium brands that are tested for low-microphonics. Some
brands to consider are: Telefunken, Brimar,
Mullard, Tung-Sol, GE, RCA, Sylvania, and more. And as
always, should you have any questions or concerns at all,
please do not hesitate to contact us directly.