What is this Mesa SPAX7???

[MesaDCLP]

I just got a few of them from Mesa, and none would fit my Mark IV without trimming off the rubber. Looking closer, ... black medium plates with gold pins?

What is this re-branded tube? EH Gold = Russian 2 with gold pins, aka new SPAX7???

 

[fdesalvo]

From what I understand, it's a standard mesa 12ax7 that has very low noise and microphony characteristics.

 

[joseph_68]

This tube is a 12AX7 that has been tested and highly-graded by Mesa for low microphonics and stable operation. It is supposedly good to use in the V1 slot to help stabilize your amp's performance and minimize hum.

However, it is my experience that while this tube does in fact help quiet down hum and/or buzz creeping through the circuit - this comes at a cost. There is a slight, but noticeable loss of presence and higher frequencies in the tone of the clean channel on my Nomad 55. The gain channels seem to be unaffected by this, but the effect on the clean tones was no doubt enough for me to pass on this tube. Perhaps the SPAX7 will do more in your Mark IV, however the rubber wrap is supposed to be part of the gimmick - um I mean "performance enhancement". :twisted:

All jokes aside, these are probably just simply standard Mesa 12AX7 tubes that have been through even more thorough testing. I am guessing that the SPAX7 versions would be the "best of the batch" at any rate!

 

[Rocky]

I just got a few of them from Mesa, and none would fit my Mark IV without trimming off the rubber. Looking closer, ... black medium plates with gold pins?

What is this re-branded tube? EH Gold = Russian 2 with gold pins, aka new SPAX7???

the tube in that photo doesnt have gold pins.

 

[212Mavguy]

Yep, it is a Russian build fo sho. Has some nice anti microphonic construction features. The heat shrink tubing wrapped around the extra fat bottle side may cause a tight fit inside a tube shield, but try running the tube naked with the shrink wrap intact...I put two layers of heat shrink on slightly microphonic 12__7 tubes in my vintage collection to help damp bottle vibrations. The longer the tube runs, the hotter and more rubbery the wrap becomes, helping make the tube less microphonic operating in the tube killing hell of a combo amp.

 

[trackerdan]

My Studio Caliber DC 2 came with an SPAX7 with no shrink wrap on it. The glass case is labeled SPAX7.

 

[HipKitty]

The tubing was originally used to reduce "glass ring"/microphonics. I know that some current production 12ax7's are being made with a thicker envelope (glass) to reduce noise problems that included the microphonic glass (think Tung Sol).

I haven't ordered a spax7 in years now so I can't really say if their new stock is comes "under wrap"....however, the tube pictured is Russian and not Chinese as all of the spax7's that I've seen in the past were.