Amp merry-go-round (B-12)

[drbassman]

Yeah, we're lucky here on Rochester.  John's a good tech, even custom builds and sells his own line of tube amps and cabs.  He called the other day and the B-12 head is fine.  He didn't find anything wrong with it!  Maybe something was loose, I'm not sure.  I'll pick her up today and see what's up with that.

[drbassman]

Got the amp back and all is well.  We found a broken fuse that was still functional.  The lack of output was me using the wrong speaker jack, we think.  She sounds really sweet with my new Ampeg 15" cab and the original cab isn't bad either.  It's gonna be a great practice amp.  There's some rust and a faint musty smell, I suspect she sat in someone's basement for some time.  We'll clean it up a little and it should be fine.

I wanted to date the amp, but can't find a serial number.  I've had it apart twice and can't find anything.  The schematic glued into the bottom of the tray says B-12NC and B-15NC.  No other labels or sets of numbers.  Any ideas?






Here's the original cab.  Cute little thing, isn't it?  In pretty good shape, the grill cloth needs some restretching.

[dadagoboi]

NICE!

The serial number on mine is in 2 places: stamped on the chassis below the power cord and on a paper label inside the cabinet.

My serial # is 0039xx, schematic has "165" printed in the bottom LH corner.

[drbassman]

The label on mine has fallen off.  Just glue residue left.  I'll look closer with a flashlight on the chassis. Thanks.

[stiles72]

Some Portaflex heads won't have a serial # (my '63 B15 doesn't) but you can look at the pot codes to get a rough idea of when your amp was made.  The amp should have CTS pots, and they should have a seven digit # starting with 137.  The middle two digits are the year, the last two digits are the week the pot was made.  You could then estimate that the amp itself was probably built 4-8 weeks after the pots were made, since Ampeg was turning them out pretty quickly back then.

Example:   #1376302 (137 = CTS pot, 63 = 1963,  02 = second week of )

[drbassman]

Great idea, I'll try that.

[Psycho Bass Guy]

Or maybe it's big brother - a B15S from 72  - 60 watts,  7027A tubes ,  actually powerful enough for small gigs  but weighs a ton..... 

As a heads up on 7027A's, they're just 6L6GC's. RCA made them for the hifi market and gave them extra suppressor grid connections and sold them to Ampeg cheaper than 6L6GC's as part of their marketing plan. Other than the extra connection at the base, which no Ampeg uses, they are literally just 6L6GC's.

[drbassman]

Finally had a minute to open up the B-15 head and the CTS pots are 1376341 and 33.  So it looks like it's probably a 1963 model or 64 at the latest.  Very cool!

If you look closely, you can see my old B-15 in the lower left corner.  Sure was a fine little amp.  It's nice to have another, even with the 12" speaker.  This picture would have been right around 1964.

[slinkp]

Hey you with the long hair!  Are you a girl??

Seriously though...  Great photo.  That is very cool.  What did the band sound like?

[stiles72]

Finally had a minute to open up the B-155 head and the CTS pots are 1376341 and 33.  So it looks like it's probably a 1963 model or 64 at the latest.  Very cool!

If you look closely, you can see my old B-15 in the lower left corner.  Sure was a fine little amp.  It's nice to have another, even with the 12" speaker.  This picture would have been right around 1964.

Yep - probably a '64, since the pots are late in the year, the tray schematic says "B15NC",  and the amp has a rectifier tube. Very desirable amp!   Most  '63's were labled B15NA (cabs were marked NB) and they had a solid state rectifier.

Nice photo too btw!

[drbassman]

Hey you with the long hair!  Are you a girl??

Seriously though...  Great photo.  That is very cool.  What did the band sound like?

Geez, I haven't heard that in a long time!  Sure wish I had more hair now!!!  The band was pretty good actually.  We played a lot of Beatles, Animals, Rascals, Yardbirds, John Mayall, Stones, etc.  Those were great times!  We started out in 6th or 7th. grade as a surfer band in south western Ohio, no less!  The closest waves were on the local Miami River, usually around 6 inches on windy days.

When the Beatles hit the US, we were transformed immediately and the music fit us perfectly.  I'm happy a few of those photos survived all of the moving I did as a kid and young adult.

[drbassman]

Yep - probably a '64, since the pots are late in the year, the tray schematic says "B15NC",  and the amp has a rectifier tube. Very desirable amp!   Most  '63's were labled B15NA (cabs were marked NB) and they had a solid state rectifier.

Nice photo too btw!

Cool, I was wondering about the rectifier as I was reading about those over the weekend.  I'm just as happy that I don't have one.  So, 1964 it is.  A good year as I recall: freshman in high school and a great band to play in.  Those were the days!

[Pilgrim]

.... So, 1964 it is.  A good year as I recall: freshman in high school and a great band to play in.  Those were the days!

Dang, Bill, that was my freshman year in High School too! 

No band though, orchestra, wrasslin' an upright bass.

[rahock]

Damn, you're making me feel young. I graduated in 1970. Thanks guys, I needed that .
Rick

[dadagoboi]

This will make you fell even younger.  I graduated HS in '64...do have all my hair, though.