The arrows point out the position of the getters, which in these tubes, are also round getters. The one with the circular getter at top is often referred to has a "halo" getter, for obvious reasons. Give your New Old Stock (NOS) tubes plenty of burn-in. Usually, you can tell when the tube has sufficient burn-in by how quickly the bias settles. The getters need time to burn off the gas molecules that have infiltrated the tubes while sitting unused for the last several decades.

Selecting and Buying Millett Tubes -
In selecting/buying tubes, one thing to remember is the great variation that exists in NOS tubes. They are not like opamps, transistors or other semiconductors. With few exceptions, silicon-based active devices are consistent to a certain level of performance. While tubes were similarly rated - even new, they were nowhere near as consistent in their performance. The meaning of the acronym "NOS" also means that great differences are likely to exist. The sound of your MiniMAX can depend almost exclusively on the tubes. While the buffer and different transistors have a great effect, they can only provide current to the signal that the tube has already provided.

What does this mean to the MiniMAX builder and owner? Quite simply, buy more tubes and try more tubes. You may be shocked to find how different they can be. The brand differences range from slight to great, but can be wildly inconsistent. I used to offer opinions on brands (found on other MAX websites), but as mentioned below, you will almost find a particular tube construction stamped/marked by any of the manufacturers.

So Who Made What?
Despite a plethora of different brand Millett MiniMAX tubes, only 4 mfrs actually made the tubes (from most reports) - GE, RCA, Sylvania, and Tung-Sol, for sure. Further, each company may have only made two or three types, but bought others from their competitors and re-branded them. I suspect that this also went on during stock shortages, as well. The re-branding became ubiquitous. Moreover, many of the mfrs shared common plates.

Tracing the true manufacturer becomes very difficult. The RCA tubes generally have a flattened octagon label with the tube designation, while GE etched small dots on the tube glass. Sylvania's are usually distintinguished with the box at the top of the plates and above the top mica spacer, while RCA seems to be the only ones to use the horseshoe side-getter (but they used other types, too). GE's seem to use the ring getter more often, but this is not consistent. While they all have shared some of the plate designs at one point or other, GE seems to be the only one with stamped "J" plates for the lower gain tubes. Others trimmed their plates, and they were not stamped in one piece. The 12AE6's are consistent in having mostly whole plates. One imgagines that the tube design was often the same, and a manufacturer simply trimmed part of the plate to cut down on gain for a different model tube. Obviously, this is only anectodal and your mileage may vary. There are exceptions and you may find RCA octagons and GE-etched dots on the same tube! So, it seems prudent to match plate construction and perhaps getter construction, as well - the getter does seem to determine a particular series, period of manufacture, or both.