Hi Scott, It is kind of rare to find factory installed JBL 120F's in a twin but not unheard of. Supposedly, if they are original to that amp, they would have an ink stamp on them that matches the stamp on the tube chart inside the cabinet.or a stamp that would be a code like AA2565.25th week of 1965.

For further information on suspending speakers contact JBL and request Technical Note Volume 1, Number 14 – “Basic Principles for Suspending Loudspeaker Systems”. Stand mounting Some SR-X models (SR4702X, SR4722X) include a receptacle cup to facilitate mounting on tripod stands.

Unfortunately these stamps are not always on the speakers and are sometimes on the cabinet, or on the inside or outside of the chassis. Another clue on a later 60's speaker might be a tiny F punched into the foil label.

In the end, only your ears matter. JBL's are universally considered 'hi-fi'.very clean, good bass but perhaps a bit harsh on the treble side.brittle maybe? I had a factory JBL equipped twin for a very short time. It was a late 68 production with gray framed JBL D120F's in it and the factory JBL badge on the grille cloth. Absolutely mint. I sold it because, for me, it did not sound good.

It was a kind of sterile amp. For some sounds it was a perfect, like stepping back through time to a Memphis recording studio.

Clean, clean clean. Good with a tele for country. If you prefer your sound a bit dirtier, or perhaps, looser, the premium price of a JBL equipped black twin might not be worth it. Thank you – great response and much appreciated! This Twin does not have a stamp on the tube chart that would match the pattern you listed. There are two stamps on the tube chart: Production “58” and “PG” stamped near the bottom right. Unfortunately I only have pics of the amp to go on for a few more days. Batik mega mendung vector background.

The pics I have are, however, very high resolution and cover almost all of the speakers + cab in the back. The speakers and do NOT show an “F” imprinted on the foil label of the speakers. I have the serial numbers on the speakers and, from what I’ve been able to gather, they look to be from around the same time as the amp (1965). Unfortunately the pics do not really include the cone (so I can’t see any stamp on the cone). The frames are gray with yellow JBL on the driver.

Serials are 117xx and 120xx (where “xx” is a number). They say “signature speaker” across the top (but not “Jim Lansing signature speaker” like the ‘61s apparently). And I’m with you on the “ears” bit – I won’t hesitate swapping these out if they aren’t what I want. I’ll just carefully pack them up and, if I ever sell it, they’ll go with it and make it a premium cost J I have a pair of Tone Tubbies in my 73 Twin that are amazing – maybe they’ll be great in a ’65 too. I hope to find out! I appreciate your time on this, Kevin – thank you for any insights!

Scott kevin 13/1/2010, 20:28 น. It is highly likely the chassis was made in '65 and the amp assembled in '66.however, with it being JULY of '66, this scenario becomes a bit less likely. Ask the seller if there is a PG inkstamped somewhere inside or outside the chassis.Ask the seller for all the #'s off the transformers.IE: they should all be 606-6xx.or 606-6-xx.the X's represent the week of the year. They should all be starting with that 6 for 1966 after the 606 which stands for Schumacher. Also, does it say Fender Electric Instruments or Fender musical Instruments under the Twin Reverb Amp logo.post 1966 it would say 'Musical' not 'Electric'.

I ended up not buying it. I found another ’65 that is three serial numbers away from the one I was looking at and the date stamp showed September ’65. Given the serial numbers, that makes sense – the chassis was probably built in Aug/Sep 65 and then put into the cab immediately. I have a tough time believing that Fender “lost” this chassis for almost a year.

And it says “Fender Musical Instruments” on the stamp although, to be fair, I’ve seen Greg G’s saying that this was put in place in early-to-middle ’65 inconsistently but in ’66 consistently. In the end I thought it was too hazy (as you put it) and, since he wanted a premium price for a ’65, I bailed.