This tube is based upon a tube which is considered something of an icon to EL34 users in both the audio world and guitar amp world; the Mullard EL34 xf2,
There were a number of variants of the original tube and GT picked the classic XF2 dual getter version to reproduce. The original was a classic and this tube is on it's way to developing it's own great track record just as the GT-6L6GE, E34LS, and KT88SV proprietary tubes. This tube is now available in matched quads and duets.
In Marshall DSL/TSL bias at 74-78mA for the 100 watt amps using the Marshall test points and bias method that sums two of the tubes. For 50 watters bias at 36-38mA. In Mesa Stiettos use a #6 or #7 rating to get perfect bias setting with the fixed Mesa bias design.
Many feel this is the finest 6L6 tube currently made. This tube with it's majority of USA components is made on the original General Electric machines, the original tools, dies, materials and processing formulas as acquired from the liquidation for the last American tube factory in Owensboro Kentucky. Stunning clarity, and tone that is reminiscent of Carl Perkins through Jimi Hendrix... both of which mostly recorded through Fender amps in a period when they only used this tube. The most expensive (because of the the high US content)
John 5 is one of today's high energy guitarists.
He has has been the guitarist for Marilyn Manson, Rob Zombie and has worked with
many other bands and artists.
Fender recently released their John 5 signature model
guitar and the video here shows a lot more on this particular event.
If you click on the small artist spotlight photo here
you will download a larger one which can be used as a screen saver.
There is a lot of info on John 5 on his official website
at www.john-5.com
The SAG-MHG kit has been quite popular for people looking for that extra edge and increased gain in their amplifiers. It may be called the "Marshall High Gain" kit but it has been popular in Mesa, Bogner, Soldano, Rivera, and even Fender's current amps as well as the black and silver face era amps where the 12AX7MPI phase inverter will make these amps more agressive over their 12AT7 original configuration. Adam Day (Slash) and John 5 are just two of many that swear by these.
For those of you that already have these kits and want to order additional kits to "fine tune" you amp, let us know the numbers on the labels on the V1 and V2 tubes. Then, let us know if you would like more gain or less gain. We will attempt to build a kit with higher or lower gain than your current kit or come as close as possible to the characteristics of your current tubes.
Regarding the number on the label. Some tube vendors will "rate" preamp tubes and try to equate "gain" by using transconductance. This is not possible. True gain is circuit dependant and takes many factors into account such as transconductance, plate resistance and more. There are tube testers out there such as the VTV tester that has a scale marked "gain" which is not true gain at all. It is a generic number of some sort. A tube can have very high transconductance but if the plate resistance is low the gain will be very low even though the tube looks great on a TC tester. Conversely, a tube such as a long smooth plate Ei might have a very low transconductance reading but due to high plate resistance be a very high gain tube. This is one reason the Ei (and it's original design tube the long smooth plate Telefunken) were prone to physical microphonics unless well tested.
The number on the box is something of a code that takes into account the transconductance, current output, plate resistance, curve traces for the tube's constant current curves over the entire operating range of the tube in circuit under load with signal, and TRUE gain. These measurements require custom built equipment that is quite sophisticated and costly. Producing these kits takes time so there may be a wait after your order of a few days. In some cases when we have a range of average tubes there may not be any in a particular run that will yield any that pass the criteria for the MHG kit and there may be a longer delay.
An adapter which allows class A/B amplifiers
such as Marshall and Fender, to replace their output tubes with the EL-84 tube,
and operate in class A. This reduces the power of the amplifier. In the case
of a 100 watt amp, the output will be about 40 watts. In a typical 50 watt amp,
the power will be about 20-25 watts. This will also turn your class A/B grid biased amp into a cathode biased amp with the feel and response of a cathode biased amp; think Vox AC-30 or AC-15 as a simple example.
These are used in pairs or quads, not
individually. These are NOT for use in Class A amplifiers. For Class A
amplifiers, please use the 928, not this 928-PR.
Understanding the GT Tube Performance Rating System
Many folks who buy our tubes know that we use a special process to categorically rate our tubes so that players can select the tubes that best fit their preferred tones and styles. However, we get a lot of questions about our rating system, and what the numbers actually mean.
Here is a brief description.
RATING 1 to 3: Offers an early and wide range of distortion and a softer attack. These tubes are great for Rock and Blues solos.
RATING 4 to 7: Our normal performance tube rating. It's the best all around rating for all types of playing.
RATING 8 to 10: GT's most dynamic, most clean power rating. These tubes are good for power players, Jazz, and bass amps.
IMPORTANT BIAS NOTE: If you're replacing a tube with the SAME TYPE of Groove Tube (tube model and rating), you should have no problems with your amp's bias. In any other case, you should always have a qualified amp tech reset your amp’s bias whenever changing your tube type or rating number. Contact Groove Tubes if you have questions about which tube will work for your amplifier, or whether re-biasing is required.
Click on the chart at the right for a much more detailed explanation.
GrooveTubes now has a Myspace page. Feel free to send us a friend add request.
Once you are on our friends list you will have one more place to ask us questions. You can still send your questions to the sales or techsupport email addresses below.
On the GT myspace page you can post comments with graphics, videos, your show schedule or record release information or just say
hello.
Just click on the GT logo or go to you own myspace page and type in the username "gtelectronics"
