Photonis ECHO versus 4G 

yea, basically they produce a tube, test it and depending on it's performance it gets a classification as echo, echo+, 4g, etc.

US ECHO is what ECHO plus in EURO. So all the ECHO in the US is one grade higher

​@@offffofof That's incorrect. Europe retains the best tubes from Photonis. I know, because I work there.

@@andyakarudolfhessiansack7936 Interesting. How do you explains that rest of the world get all blemmish and low FOM tube for echos

@@offffofof They don't. The commercial echo, echo plus go all over the world. Echo/plus are all fallout from the 4g/4g+ line. They are NOT nerfed, they just fell out, due to not meeting mil-spec. However, all the very best 4g+ go to European forces first. We are taking the tip of the spear here, they get the amazing foms, amazing gains (19,999) the Foms (2800) ebis (0.1).

@@andyakarudolfhessiansack7936 Interesting. but for echo grade do they ship lower grade to euro? ECHO from ACT always have a blem on zone 1 or 2 while the US one are always clean

Yeah everything seems to be bigger in the USA

I've got a 2337 FOM 33.86 SNR and it rocks. There is only a very small amount of noise in the darkest of conditions, I love it.

No. Like computer chips, every unit is slightly different. The imperfections of the manufacturing process are what causes the different specs of the tubes.

@@Mr_Glenn there's no in the middle for gain though. WP echo is usually 9000 and 4G is 11000. Gain is something that's programmable. Sure, sort them by SNR, EBI, and non metric quality, but screwing down the gain channel for differentiation is not kind. I suppose an echo with 11k gain would be too attractive.

​@@Tattlebotmy Echo+ has 9988 gain, it's not bad at all. The gain is all over the place, but 10k for an echo is certainly not unheard of. Echos are just fallout tubes.

@@Mr_Glenn I think they degain the echos to improve the lifespan judging by the higher lifespan rating. Gen 2 requires a higher mcp voltage to get enough gain. This results in higher energy electrons bombarding the phosphor, bleaching it. Caveat: high gain tubes may use an additional stage

​@@Tattlebot As much as that could be true, I've always heard that echos are fallouts of their mil spec tube line.