Everything special about this JJ E83CC amplifier tube is under the hood. It looks like the JJ ECC83S vacuum tube and if it wasn’t for the screening you couldn’t tell them apart. So why a different model number? Back in the day many companies switched the order of numbers to indicate that this vacuum tube was better than the standard model. JJ has continued that tradition and produced a tube that recreates a vintage Tesla tube with the same model number.
What the two tubes share is the short box plates and frame grid. I have read that this same design was pioneered by Amperex. The short plates can be easily seen and they’re standard issue on many JJ tubes. The frame grid is the special sauce. Normally the grid wire is wound around two vertical support rods on opposite sides of the cathode. The frame grid tube has a rigid frame that almost looks like a ladder and the wire is wrapped around that. This improves the quality and consistency of the grid winding and reduces vibrations that could cause microphonics. The tube sounds very good and it’s extremely quiet. Spiral filament winding does seem to have an effect.
The noise floor is better than the standard ECC83S / 12AX7 tube. Frequency response is excellent. In the lower register of guitar it produces a nice thump. Great for palm muting, drop tunings and percussive rhythm. Mids are upfront but not honkey and there’s no issue with highs. When I slammed the front end of my amp with a boost pedal the overdrive was quite musical and focused. I didn’t get heavy mush. I also ran a pair of these tubes in my phono stage with good results. I’d have no problem recommending for use in studio rack gear or other audio applications.