Sylvania 6550 tubes...information

[Butterbone]

Hey guys it's me again.

I finally got that big monstrosity from the other pictures into the garage. I'll be starting another thread on that thing once I get it out of the box and I can take more pictures of it.

This thread is about a pair of vacuum tubes I found.

Sylvania 6550 MJ / ABB. You'll see in the pictures that the MJ is inside a box and ABB is printed underneath the box.

I can't find information or even pictures of this specific tube.

They are in a tube. They may be recent. I haven't found any other markings or lettering on them other than what is in the pictures.

Can someone post a link to testing the tubes with a multimeter?

I've also added some pictures of a pair of vintage microphones. An Electro-voice model 926 crystal mic and ann Aiwa m23 crystal bullet mic.
Just for fun.

Thanks

[Butterbone]

Forgot the mic's. hehehe.

[Butterbone]

One more thing.

I also picked up at the same time as these tubes another pair of amps.

One is an Epiphone Pacemaker.
It's cool, but someone had put a new speaker in it. The speaker is obviously from the late 80's based on the font and advertising value of the full print decal covering the speaker magnet.
How badly does it affect the value of one of these old tube amps if someone added new components?

The other amp just says, LA 25 Solid State with some odd logo on the far lefthand side.

Any ideas???

[Stevem]

Those tubes are in a tube that to me means they are pulls and in the tube that new tubes came in.
A 6550 may not cut it in some high power amps that where designed for use with the far better 6550A model tube.

There is no way to test a any tube with a multi meter other than proving out that the filament is not open and or a short from the heater to plate and or heater to screen has taken place.
I use to have 2 of those Eipi pacemakers and I sould have held on to one of them, oh well!
The LA in the model number of that stereo tells me that it is liklely a mid 60s to mid 70s Lafayette brand amp.
These where made in Japan and do not sound all too bad for what they where.
If it still works ( no blown output stage) than it likely needs main power supply filters if it had not been in constant use and on some of the Lafayette models it can be a bear to change them out!

[Butterbone]

What makes you think they aren't the new tubes in the packaging?

They don't look like air has gotten to them and the estate they came from has...tonnage of music gear and electronics.

So the 6550 tubes were replaced by more powerful 6550A tube design.

Who would want the 6550's and for what purpose do you think?

I think the one amp is a Sears and Roebuck store model amplifier. I'll have to take the back off to find components and look them up.

I'll post some pictures when I can.

[Firestorm]

Sylvania never packaged tubes like that, so Stevem is very likely right that someone pulled them and saved them. Unfortunately, that doesn't always mean they're still good, but if they are, they could be very good indeed.

[eniam rognab]

yeah, tubes in boxes and old paper smell, mmmmmmm

not plastic, for sure

i came across an old microphone too and traded it pretty decently with someone who plays blues harmonica through old mics and amps, so maybe research if these might be good harmonica mics

[Invertiguy]

It's also entirely possible that the tubes are NOS even if not in the original packaging. Not all tubes came in boxes, especially those sold to OEMs or large repair shops, who got their tubes in bulk packaging. It's also possible that the boxes the tubes came in simply fell apart with age and someone repackaged them with what they had on hand. Just because a tube is NOS doesn't mean it hasn't been stored in a barn with a leaky roof and rats for 30+ years, and boxes are only paper, after all. But without any visible indications of use, there's no way to tell without testing them. It's still one hell of a find!

[rp]

Sylvania never packaged tubes like that, so Stevem is very likely right that someone pulled them and saved them. Unfortunately, that doesn't always mean they're still good, but if they are, they could be very good indeed.

Groove Tubes used to package tubes like that. Maybe they still do? Long ago but I don't remember any labeling on the clear plastic tube, but the tubes would have Groove Tubes written on them. Was like 30 years ago. How time flies.

[Butterbone]

Aren't tubes supposed to have more information on them.

Aren't manufacturer and year codes supposed to be printed or stamped on it somewhere?
Cause I can't find any other numbers on them. It just seems oddly generic considering all the information you guys have put forth and what I have been finding on my own.

[Reeltarded]

Pardon me, but everything seems oddly generic to you. It wont if you hang around this junk for 40 years.

That tube is the GT packaging from the late 80s and those tubes are not NOS. They are the pulls from the amp the GTs went in. Bet a life on it. My own.

[Butterbone]

Those two tubes seem oddly generic to me.

That's why I said "It just seems oddly generic considering all the information you guys have put forth and what I have been finding on my own."

[Firestorm]

What do you want to know about them? They're Sylvanias from the '70s (or very early '80s) 'cause that's when Sylvania was making them. The "MJ AAB" is a date code, but I don't think there's anyone who can decipher it anymore. It's EXCEPTIONALLY unlikely that they are unused, but Sylvania 6550s have a reputation for longevity, so they may be perfectly functional. You have to test them.

For what it's worth, the difference between 6550 and 6550A may be mostly the shape of the glass. The first 6550 was made by Tung Sol in a type ST16 envelope (coke bottle) and rated for 600 plate volts and 35W dissipation using the Design Center system. Later Tung Sol data sheets still have the 6550 in the coke bottle, but switch to the Design Maximum system giving it a rating of 660V and 42W. Same tube, different rating systems.

Sylvania and GE later made their versions in the straight-sided T12 glass rated 660V/42W using the Design Maximum system. It's possible GE later physically tweaked the screens to improve their numbers, but I'd guess the differences in datasheets are just conversions between the two systems.

Good used 6550s are worth money. Again, have them tested.

[rp]

Very hard to tell from the pics but the getter looks good. People changed tubes for many reasons, buy new used amp change tubes to make it and yourself happier, maybe the guy believed the hype about groove tubes, maybe he just had to try 10s. Maybe the store who sold him the amp or tech who serviced it larded the profit w/ some GTs. Pretty good chance those tubes are fine, go build yourself a bass amp around them.

[Butterbone]

Firestorm, RP, thank you.

That is exactly the information I am looking for.

I have too many amplifiers sitting around as it is. I'm trying to flip this stuff without better history I don't know who to point it at.

Sadly I have called every music shop and tv repair shop in my area and no one has the ability to test tubes anymore.

There is a guy 50 miles away but he charges $20 a tube to test them. I have no indication that they are worth $20 a tube if tested out.


Maybe you guys could look at this post: http://ampgarage.com/forum/viewtopic.php?t=24858

Second page I just updated with info and pictures.

Thanks again.