Updated 11/22/14
Guitar Amplifier Blueprinting - Tube Data Sheets
& Guitar Amp Prints
Below I will have continually updated vacuum tube data sheets listed and guitar amplifier prints.  There are also links to some
website with prints on the first page of this website.   In the area of guitar amp schematics on the front page are also links to
speaker manufacturers where there are detailed specs on many speakers.
It is important to keep in mind that all tubes of the "same type" may not share characteristics.  As a few examples, the 6L6 tube
types can range from the mid 20 watts to 30 watts of max dissipation.  The EL-34 is generally a 25 watt tube while the E34LS is a
30 watter.  The KT66 is thought of as a 25 watt tube but also carried a 30 watt "maximum" rating on some sheets.  The 6550s
ran from 35 or so watts to 42 or so.  The KT88 is stronger than a 6550 and ran from the 32 or so watt versions to 50 watts with
the KT88S and 42+ watts with the KT88SV.  Refer to the data sheets above for exact figures.

The 12AX7, 7025 and ECC83 carry the same specifications but may sound very different, especially in the first gain stage of your
amp.  Swapping different tubes of the same type is a fast and easy way to get different tone or response from your amp.  V1 or
V2 in some amps such as the Vibrato channel in Fender black face and silver face amps (the first gain stage) has more impact than
the changing of any other tube for the most part.  

12AT7, 12AY7, 5751, etc., will all react differently depending on brand, construction (due to changes in materials and
construction), etc.
As a bit of side info - Some people think that Groove Tubes "re-brands" other factories tubes.  They do sell a number of tubes
from other factories which go through GT's own selection and testing process in some cases but they also have a number of
tubes specific to GT which are of their own design and done on their own tooling - exclusive to GT.   Some of these are:

GT-E34LS (the only 30 watt EL-34 tube with additional plate mass and is NOT the same as the JJ E34L.  If you look at the JJ and
GT side by side at the plates you will see a physical difference.

GT-KT88SV - also an exclusive tube off GT and Penta tooling out of the JJ factory from a long standing relationship with JJ and
formerly Tesla.

GT-6CA7GE - the reproduction of the General Electric 6CA7 which is an electrical replacement for the EL-34 tube but has a harder
vacuum and an active beam forming element not found in an EL-34.

GT-6L6GE - the reproduction of the General Electric 6L6GE clear top using the original micas and materials.  This tube is stock
issue in Fender's custom shop series amplifiers.

GT-KT66HP - a proprietary KT66 which can handle over 525 volts on the plates.

12AX7M - a reproduction of the Mullard 12AX7.  
The list of current GT preamp tubes is here:
http://www.groovetubes.com/tubes_list.cfm?ObjectGroup_ID=107

The list of current GT output tubes is here:
http://www.groovetubes.com/tubes_list.cfm?ObjectGroup_ID=108

The list of fun things and things like bias tools is here:
http://www.groovetubes.com/groovetoys.cfm?Category_ID=30
If anybody orders directly off the GT website from the above links there is a comment section for online orders.  If you put some
comment in there such as "show this order to Myles" I will hand trace the output tubes.   If you want to discuss ratings for output
tubes or application ideas feel free to email me at GT by
clicking here.   This hand tracing offer is only for folks that come from my
website here as this is normally an additional charge to hand select and trace tubes for very specific applications and is what my
SAG group does at GT.  This is one of the building blocks used when I blueprint an amp for clients.
Guitar Amplifier Prints and JCM 2000 bias instructions plus some manuals etc.
Actual test results on current production tubes


One reason I will be doing this, is that all current tube makers show the specs for their tubes by just copying the specs of the past
that are the standards. Unfortunately ... everybody falls way short of the standards and the range of specs in any given run is +/-
50% typically, and typically on the minus side. There is very little consistency today.

I am in the process of building datasheets for all the GT proprietary tubes and I am working with Aspen to get him to allow me to
publish ACTUAL data and curves, not just replicate spec. I want to do this on EVERYBODY'S current production tubes and publish
this. Doing things this way will there be a bit better chance of keeping the tube makers honest and have them improve or utilize
better QA processes. I spent almost ten years at United Technologies doing QA so it is a bit hard to let go of some of those
methods. That is one reason the GT-12AX7M has gone through at least ten design and tooling changes, and many material
changes. I get samples, I find problems, I shut down production if I can.

If, as an example, the GT 12AX7M has specs that are not as good as they should be, they will be published just like everybody
else's as an example.  The same set of standards will apply to everybody.  Hopefully some day we can once again have tubes that
are the same in their specs and the only decision for the player will be to pick what tonal characteristics they prefer. Right now
most people cannot even compare two tubes tonally as they generally differ way too much to make it an accurate comparison.
Output Tube Actual Specs

GT-EL34M - JJ KT77 - GT-6CA7GE - GT-5881C -
GT-6L6 CHP Black Plate - GT-6L6GE - GT-E34LS -
GT-KT66HP - GT-KT88SV - xxx - xxx