About Table-1: The "#1," "#2," etc. designations in the tube manufacturer/type headings indicates that several tubes were tested within each type. Each triode section was first evaluated in a tube tester, the resulting “readings” (in bold) are relevant only to the “/ the minimal reading” (not bold) as per Notes 1 & 2. Triode-1 of each tube was then evaluated for Lo Gain and Hi Gain in a preamp circuit that emulates a conservative mic preamp and a more aggressive guitar preamp, respectively. With the exception of GT 12AX7M #2, all measured tube distortion is primarily second order (octaves). The GE, RCA, Mullard and Telefunken tubes were added to provide a reference, but here again tubes can vary-even within the same brand/type. For tubes of same type but different manufacture, the tester readings do not seem to correspond with the gain measurements. A future test will determine whether there is relationship between each triode's gain, within the same tube, and the respective tester reading.

NOTES:
1. tube tester reading / minimum tester reading (For Triode-1: Plate = pin-1, Grid = pin-2, Cathode = pin-3)
2. tube tester reading / minimum tester reading (For Triode-2: Plate = pin-6, Grid = pin-7, Cathode = pin-8)
3. Triode-1 gain with no cathode bypass cap
4. Triode-1 gain with a cathode bypass cap
5. Measured % distortion of Triode-1 at approximately +16dBu (lower for non-12AX7 types)
6. Measured % distortion of Triode-1 at approximately +23dBu (lower for non-12AX7 types)
7. This is the only tube that exhibited a significant third-harmonic component.
8. Distortion Range Notes: The nominal levels chosen for the Lo-Gain/Hi-Gain measurements are 12dB to 18dB down from +35dBu. Using the GT ECC83 as reference, this is the level just before an obvious asymmetrical flattening of the waveform occurred.
A.) @ +35 Hi-gain dist. = 10 % w/bypass cap
B.) @ +29 Lo-gain dist. = 2 % w/o bypass cap
C.) @ +35 Lo-gain dist. = 5 % w/o bypass cap but at same level as A.

Mix Books

Modern Recording and Mixing

This 2-DVD set will show you how the best in the music industry set up a studio to make world-class records. Regardless of what gear you are using, the information you'll find here will allow you to take advantage of decades of expert knowledge. Order now $39.95

Mastering Cubase 4

Electronic Musician magazine and Thomson Course Technology PTR have joined forces again to create the second volume in their Personal Studio Series, Mastering Steinberg's Cubase(tm). Edited and produced by the staff of Electronic Musician, this special issue is not only a must-read for users of Cubase(tm) software, but it also delivers essential information for anyone recording/producing music in a personal-studio. Order now $12.95

Newsletters

MixLine

Delivered straight to your inbox every other week, MixLine takes you straight into the studio, with new product announcements, industry news, upcoming events, recent recording/post projects and much more. Click here to read the latest edition; sign up here.

MixLine Live

Delivered straight to your inbox every other week, MixLine Live takes you on the road with today's hottest tours, new sound reinforcement professional products, recent installs, industry news and much more. Click here to read the latest edition; sign up here.