The different of "OO" and "O" STR 415 tube

[NightSwan]

I am looking for the mesa STR 415 tubes.
And I find there are two type of STR 415 TUBES. One has two rings inside the top of the tube called top "OO" and another is only one ring inside the top of the tube called top "O"
Anyone know the different of them? Be sure both are MESA logo.

Thanks

 

[woodbutcher65]

Those are the getters. Single getter and double getter. The difference is that with a double getter, the larger deposited layer of beryllium (the silvering on the top of the tube) can absorb more stray gases (especially oxygen) inside the tube and increase tube lifespan.

They don't directly affect the operating parameters of the tubes, just their potential lifespan.

I've never seen a single getter 415. STR 387s introduced the double getter design and the STR 415 carried it on and made other improvements to the 387's design. Some early 387s were made with single getters.

The STR 387 is identical to the 7581A military tube type.

 

[s-fresh]

Sadly you can't even see the getters in this shot, but I seem to remember these 415s only having one getter each. Also the plates inside are darker colored and the little mounting flats are lighter colored than normal 415s.

 

[woodbutcher65]

No, those are dual getter. It's easy to tell by the shape of the silvering.

Dual getters create a "v shaped" silvered pattern on the top of the tube.


Here's an example, and a fine one at that. Dual getters, and note that the silvering pattern is closely related to the position of the getters.

Single getter tubes look like this:

Yours are definitely dual getter tubes.

The color of the mica spacers may be indicative of some coating applied during their manufacture. I don't really know.

 

[s-fresh]

Thanks for that, some good information! This was a local amp I was considering trading for and only got a look once in the dark. I got these pictures later and the tubes always looked funky compared to my own stash of 415s/416s. I thought I saw a single getter but it must have been another amp online around the same time.

 

[woodbutcher65]

Glad to help!

What kind of amp is that there? I can tell it's pretty dirty and it has seem some road use based on the clamp ring rust.

The way I clean up an amp is to take the chassis out of the cabinet, lay down a lot of newspapers on a table, pull the tubes out, put the chassis over the newspapers, and spray the whole amp down with a spray cleanser followed by a rinse delivered by water in a spray bottle. I try to avoid getting it directly on the pots but anywhere else gets the cleaner. 409 works. Windex works. Lots of cleaners work, but be sure to rinse well afterwards. A soft brush that allows you to work into the corners and between parts is very useful.

It's nothing to worry about. Most electronics and circuit boards go through a full solvent bath at the factory after soldering. Electronics can handle some pretty harsh chemicals, as long as they're rinsed off well and dried afterwards.

 

[s-fresh]

It's an M180.

 

[woodbutcher65]

That's a close relative of the D180, and I just got done refurbishing a D180. It has incredible clean headroom. Sounds very good, too!

 

[NightSwan]

There is really one getter STR-415, I have seen twice on Ebay.
I don't how to post the pictures, so I copy the link. That's why I am thing what is the different.

https://www.ebay.com/itm/Mesa-Boogie-Engineering-Single-Halo-6L6-Vacuum-Power-tube-Strong-no-reserve-/323320595962?_trksid=p2047675.l2557&ssPageName=STRK%3AMEBIDX%3AIT&nma=true&si=4DBrR61Qiwe3f3f%252FRFFAkXBQusI%253D&orig_cvip=true&rt=nc

 

[s-fresh]

 

[Boogiebabies]

I have single getter STR-387 Labeled Mesa STR-415 and dual getter STR-415 labeled Mesa 415. It really boils down to supply and not wanting to change the screening paint STR-415's. The 7581A is a copy of the 415, but 35 watts. Too much headroom to me for a guitar amp , but bass it should be fine.