Dating Fender Tube Amps by Serial Number, Part 3
by Greg Gagliano

Copyright 1999, 20th Century Guitar Magazine.

I know, I know. It’s been over a year since Part 2 of this series was printed, but that’s because I’ve been busy collecting data. For those readers who may have joined us recently, I am doing some Fender amp research along with Devin Riebe and Greg Huntington. Our research efforts are now in their fourth year (will it ever end?). Part 1 and Part 2 of this series can be found in the March 1997 and November 1997 issues of TCG, respectively.

Again, I would like to thank everyone who responded to our request for data as outlined in Parts 1 and 2.

The main focus of this article will be speakers found in Fender amps, but before we get into that topic let's go over a few other areas first.

Early silver face amps: Part 2 went into this topic in some detail, but since that article was printed, I have been asked a lot of questions about this subject. There still seems to be some confusion about how to distinguish between a silverface Fender amp that has the desirable AB763 circuit and one that has the less-desirable AB568/AC568 circuit. Part of the confusion stems from the lack of any AB568 or AC568 tube charts. Fender never printed any since there were plenty of leftover AB763 tube charts available and these were used well into 1969.

Although the cosmetics changed, the circuits remained unaltered from the blackface circuits on the earliest silverface amps. The date of the change from the blackface circuit to the CBS silverface circuit was dependent on the model, but most of the amps that were modified received the circuit change by mid-year of 1968.

The cosmetics of the silverface amps during the transition between circuits was also in transition making it difficult to determine circuit type on cosmetics alone. The amps during this period could have the earliest style silverface grill cloth or the more familiar silverface grill cloth. All of the amps would have the aluminum grill trim and they may or may not have the thin black vertical lines on the control panel. One clue that can be used is the ink stamped chassis date code that is usually located in the chassis, but is sometimes found on the underside of the chassis behind the tubes. These read something like T020366 or F034267 where the "66" and "67" denote the year and the "03" and "42" denote week of the year.

Of course, the most foolproof way is to pull the chassis and look at the layout. In fact, on the 40-watt and 80-watt amps you can simply pull the chassis out about 2 inches and look for the big honking ceramic power resistors that are connected to ground from the cathode (pin 8) of the power tubes. If those resistors are there, the amp has the dreaded CBS silverface circuit. I am also confident that the serial number can be used as a rough guide for determining the circuit, but again, pulling the chassis is the only way to confirm.

Transitional circuits: I've been getting quite a few reports from amp geeks about circuits that don't completely match the schematic for a particular model. Leo Fender was notorious for tweaking circuits and the results of some of his tinkering can be found on late examples of an amp prior to the switch to a new circuit. Also, the different component values could be due to a necessary substitution on the production line when a particular value was out of stock. Ran out of 100K ohm resistors? Stick a 90K in there: no one will notice or care (at least not until the mid to late 1990s).

These changes have been observed on tweed, brown/blonde, and blackface models. Often the differences are minor such as small changes in resistor or capacitor values. I had a '63 Concert with the 6G12-A circuit but had a completely different (factory stock) bias supply circuit than shown on the schematic.

Perhaps the most surprising transitional circuit that has been reported to me (thanks Brian!) is for the early 1968 silverface Showman. Two examples are known to exist; one from the February-March period and one from the March-April period. These amps have AB763 tube charts and normally any silverface amp made prior to May 1968 will have the AB763 (a.k.a. blackface) circuit. After April 1968, most of the big Fender amps received the AC568 circuit, which is a semi-cathode biased design. However, these two Showman amps have a fully cathode biased design that is factory stock!!! There is also an unconfirmed report of an early '68 Twin Reverb with the cathode bias circuit. If you see one of these cathode biased amps, please let me know!

These amps do not have a bias trim pot. The wire from the two 220K ohm bias resistors is connected to the brass control panel ground plate. The only thing connected to the bias cap/diode is the tremolo circuit. The cathodes are tied together and connected to a single 165-ohm resistor and 80 mfd 150V bypass capacitor which are both grounded at the other end. This cathode set up is similar to, but simpler than, the AC568 circuit. Every other part of the circuit (power and preamp) is identical to the blackface AB763 schematic.

Perhaps these two Showman amps were field prototypes, experimental units, transitional between the AB763 and AC563 circuit, or just a plain bad idea. Bad because cathode biased amps run very hot especially those with four power tubes (witness the Vox AC-30). In addition, a cathode biased Showman would produce something around 50 watts of power instead of the 80-plus watts from a fixed (grid) bias Showman. According to the owner of one of the cathode biased amps, it runs very hot; so hot that the tolex melted under the chassis mounting strap near the power tubes! Also, the amp eats power tubes, does not have much headroom and breaks up early.

Oddities: One of Leo's experiments or "one off" custom amps surfaced recently. It's a circa 1955 tweed Tremolux (5E9) that has two factory stock Jensen Hi-Frequency tweeters with a passive crossover between the Jensen P12R and the tweeters. I wonder if Leo was influenced by Magnatone's use of tweeters?

A few export model brown/blonde amps have surfaced that have a 6-way voltage selector switch located in the chassis, instead of on the back of the chassis. This necessitates removing the chassis from the cab to change the voltage setting (which would only be a problem if you hopping from country to country with the amp). Interestingly, these amps have Triad power transformers while concurrently produced domestic models had Schumacher units.

CBS era quality control: We've previously discussed the "OA" and "OB" date codes mistakenly stamped on the tube charts of January 1966 and February 1966 amps, respectively. As well, we've discussed misspelling "Division of Colombia Records Division" instead of "Division of Columbia Records Division" on the rear chassis panel on some amps from late 1965 and early 1966.

These mistakes were merely cosmetic. There were quality lapses in the circuits themselves during the CBS years, some of which had serious consequences. Examples of these include ceramic caps used in parallel to achieve the correct value instead of a single cap, change to often inferior sounding "chocolate drop" caps, and incorrectly wired circuits.

A friend brought me a '66 Princeton Reverb that was humming badly. I recognized the 60 cycle hum and thought perhaps the filter caps were shot, but it turned out the two 100-ohm ground resistors for the tube filaments were never installed at the factory!!! I’m surprised the Fender dealer didn't send the amp back and even more surprised that somebody bought it with the way it was humming!

I also worked on a late '67 silverface Deluxe Reverb (with the blackface circuit) with an inoperable tremolo. Boy, was I surprised to see that the tremolo circuit was wired incorrectly by the factory!!! Either the factory worker was asleep at the wheel that day or there was a new hire that was still learning how to assemble amplifier circuit boards. I tend to believe that the latter idea has some merit since Fender practically doubled its size after the CBS takeover. Bigger facilities meant more workers with little or no experience.

Speakers: Like many people, I was a bit disappointed that Teagle and Sprung's Fender amp book did not have much info on speakers. So, I have compiled a list of speakers used in Fender amps and took some photos of some of them as well. The list, presented below, is based on our actual observations, but is not comprehensive. If you have a Fender amp with a factory stock speaker other than one shown here, please let us know and we'll add it to the list!

JBL: JBL speakers were optional (at additional cost) for nearly all models from 1960 to about 1980. JBL D-series speakers had orange baskets and Fender by JBL labels in the 1970s. JBL D-series speakers can generally handle upwards of 60 watts each. A pair of JBL D-120Fs in a Twin Reverb are only seeing about 40-watts each (no sweat), but remember that no speaker likes to see square waveforms. So, driving the Twin with any amount of distortion lowers the power handling capacity of the speaker, which makes any speaker more susceptible to damage; even a high-wattage type like the JBL.

Jensen: Jensen was the prevalent stock speaker in Fender amps from 1946 through about 1961. As the story goes, Leo Fender wanted Jensen to make some changes to speakers and either the speaker couldn't (price constraints?) or wouldn't do so. That's when ol' Leo switched over to Oxford as the standard speaker (though Jensens were still used from time to time). Just conjecture, but the lack of orders from Fender from 1962 - 65 must have hurt Jensen's pocketbook so they hit up the new owners of Fender (CBS) for some business. These Jensens wear brown and gold Fender by Jensen label and were put into Fender amps beginning in late 1965 through about mid-1967. Some amp geeks don't like the way these Fender label Jensens sound, but let your ears be your guide. I think they sound just spiffy.

Jensen Vibranto LI and MI series speakers (alnico magnets) and Jensen EM-series speakers (ceramic magnets), while excellent, were not used by Fender. I have included them here because I get a lot of questions about them. They are were often sold as replacements for blown speakers which is probably one reason why the ended up in more than a few Fenders. The Vibranto LI series speakers had a lifetime warranty and it seems that Jensen went out of the musical instrument speaker business just in time to avoid the claims. All speakers can and will fail eventually (just like the hard disk on your computer); remember that.

Jensen speaker models denote their approximate power handling capacity and magnet type. The actual power ratings have been published in several books so I'll discuss them in general terms here.

The R, S, and T suffixes denote a low power rating: good for Princetons and Champs, but the R is barely able to handle the power of a Deluxe. The Q and P suffixes denote a medium power rating. These are especially good for multi-speaker amps up to 40-watts since multiple speakers divide the amp's total output power between them. For this reason, the P10Q is the speaker to have in the 5F6-A Bassman. Note that it does not appear that Fender used the "P" rated speakers very often. The N and LL suffixes denote a high power rating, with "high power" being a relative term. The P12N, on a good day, can handle 20 watts. It's no wonder that 80-watt Twins easily shredded a pair of them. Note that Fender did not use the "L" rated speakers (but Ampeg and Leslie did).

Oxford: Oxford speakers codes work in a similar fashion, but it is the letter that denotes power handling. The higher the letter, the higher the power rating. I found an Oxford ad in a 1960s trade magazine with the peak power ratings of some speakers: K = 25 watts, L = 30 watts, M = 40 watts, and T = 45 watts (12" speaker) or 60 watts (15" speaker). It is important to note that these are peak power ratings, not RMS power. The RMS rating is more realistic and is usually about half of the peak rating so use that as a rough guide.

The "J" rated speakers are usually found on 12-watt Princetons. The "K" rated speakers are found in reverb and non-reverb Deluxes and in multi-speaker amps up to 40-watts such as the Tremolux and Concert. The "L" rated speakers are found in reverb and non-reverb Deluxes, some Tremolux amps, and multi-speaker amps like the blackface Concert, Super Reverb and Vibrolux Reverb. The "M" rated speakers had good service life in the piggyback Bassman and Bandmaster amps, but were easily blown in blonde Twins. The "T" rated speakers were standard in Twin Reverbs, but like the Jensen C12Ns, they often had a short service life.

Many amp geeks don't like Oxford speakers found in Fender amps from 1965 through the 1970s. The gap distance was increased in the Oxfords that Fender used later in the decade and this reduced their efficiency (and they were cheaper to make this way). Again, I say let your ears be your guide. I've heard many great sounding Fender amps with Oxfords. I will admit that I prefer Jensens, but I've never let an Oxford speaker sway my decision from owning a Fender amp. Additionally, the Oxfords from early '60s generally sound very good. According to noted vintage amp specialist Gregg Hopkins, these early Oxfords were constructed similarly to Jensens from that period with respect to materials and voice coil gap. That could explain why they sound good.

CTS: CTS (Chicago Telephone Supply!) speakers were used occasionally in Fender amps until the mid-1960s. These are good quality speakers that tonally lie between Jensens and Oxfords. The alnico 10-inch CTS speaker was the most prevalent speaker in Super Reverbs from the mid-1960s through the 1970s.

Utah: Fender didn't use Utah speakers very much until the 1970s. The Utah speakers from the '50s sound very good and I've heard a killer '66 Super Reverb that was equipped with factory original Utahs. Generally, the Utah speakers of the '70s weren't as great sounding as their predecessors, but again let your ears be your guide. If you like the way your '75 Twin Reverb sounds with its Utah speakers, just leave it alone and go right on playing. Utah went on to become Pyle of Radio Shack and car audio fame.

Eminence: Eminence has its roots in CTS (Mr. Gault left CTS to found Eminence) and many of the early Eminence designs are similar or identical to CTS speakers (good examples of the similarities can be found in mid-1970s Ampegs). Fender began using Eminence speakers as standard in nearly all of its tube amps beginning in the early 1980s. These are generally made to Fender's specifications and in some cases, such as the reissue '65 Twin Reverb, the speakers were designed to emulate the Jensen C12N speakers which were often found in the original '65 Twin.

Rola: Yet another speaker that Fender used in the mid to late 1970s was Rola.

So in technical terms, why don't the non-Jensen speakers from the mid-1960s through the 1970s sound as good as Jensen speakers? Speaker guru Ted Weber explains:

"Utah, CTS, Oxford, etc. simply copied the Jensen designs and started competing for Fender's business. As a result of the price wars, they had figure out how to make the speakers produceable with a very low reject rate as well as use less expensive parts, i.e. smaller magnets. So, they widened the gaps to make them easier to throw together on a fast assembly line. This lowered the energy, so the voice coils were shortened to compensate. The companies also needed to produce speakers with long term reliability, so they doped the surrounds. The end result is that with some of these speakers you get a relatively sensitive driver that sounds great at lower volumes, but falls apart when you push it -- flabby on the low end and/or harsh on the high end."

Replacement speakers: It is very common to find non-original speakers in Fender amps made up through about 1980. Because reconing wasn't a common option until the 1970s, players simply replaced the speakers if they blew up. In some cases, such as Altec and JBL, the factory would recone a speaker. Today, reconing is a very popular option for players to keep their amp's speakers original. Reconing must be done correctly and with the right parts so stick with a reputable reconing service that offers a warranty. In most cases, the reconed speaker will sound nearly as good or as good as the original. In some cases, the speaker will sound even better. The reconed Oxford 12K5 in my Deluxe Reverb sounds better than any original cone 12K5 I've heard.

There is a strong market for used speakers. Many times a player can find an original speaker to replace the non-original speaker. Another option is to install vintage style speakers. Jensen has reissued the C10Q, P10R and P12N and WeberVST makes many models of Jensen-style alnico and ceramic speakers.

One final note before you scope out the speaker chart -- there are exceptions to every rule and this especially applies to Fender! So, if you see a factory stock P12P in a tweed Deluxe, don't be overly surprised.
 

A New Internet Resource: Over the last 12 months or so, I've had several people ask me to put together some sort of Fender amp guide on my web site. A great idea, but I simply didn't (and still don't) have time for such a venture. However, Mark Ware thought it was a good idea, too, and he put together a very informative Fender Amp Field Guide.  The site is nicely done and includes descriptions, pictures, and schematics for Fender tube amps as well as other Fendercentric information.

Dating by Serial Number Update: The good news is that good progress is being made, but I am in fact, still desperate (if you could only see the pitiful look on my face right now) for more info, especially for tweed, brown, blonde and silverface amps. I have practically no information for some models like the Bassman 100 and other "non-popular" silverface amps. And keep those blackface amp data coming! Also, I need more information from reissue '63 Vibroverb amps and Custom Vibrolux Reverb amps.

I'm still trying to make sense of the "mysterious" production numbers and this is one area where I don't have a lot of info: mainly because production numbers were not written on a lot of the tube charts. However, the next article in this series (Part 4) will discuss some preliminary production trends (oh boy!). Were 1,000 or 10,000 or 100,000 Super Reverbs made? Stay tuned.

Reminder: We are still in need of information about any and all Fender tube amps. Everything is confidential, we don't make record of who owns what amp in the database. What we need is the following:

1) Model name

2) Model number on the tube chart

3) Date code letters on the tube chart

4) Production number on the tube chart

5) Speaker codes and model (if speaker is original)

6) Transformer codes (if the amp doesn't have date codes on the tube chart)

7) Cosmetic features (flat/raised logo, tweed/tolex, blackface/silverface, rough/

smooth blond tolex, white/skirted knobs, TV-front/wide-panel, etc.)

So please... send your amp data to the author c/o TCG Magazine. Thanks for your support and stay tuned for Part 4 of this series!

Special thanks to Gregg Hopkins at Vintage Amp Restoration, St. Louis, Missouri for allowing me to photograph the speakers from his inventory.

The author and his partners would like to thank those people who have sent us Fender amp information (and you know who you are dahlings).  Also thanks to the many dealers that we visit for allowing us to make notes about the amps in their shops and at their guitar show booths.

DATING FENDER AMPS BY SERIAL NUMBER, PART IV
by Greg Gagliano

Copyright 2001, 20^th Century Guitar Magazine
 

Yes, I know it's been exactly two years since the last installment in this series. Before we get into the amp info, let me give you an update on what's been going on since I've been getting a lot of e-mail asking when the results of the research is going to be available.

First, we (Devin Riebe, Greg Huntington and myself) must collect enough information to be able to date amps by serial and determine production totals. "Enough" means an adequate amount of information to identify trends with reasonable certainty. Sadly, the majority of information we gather does not have any details about possible date of manufacture (pot dates, transformer dates, tube chart date codes, etc.) and without this important info, the research takes longer.

Second, we are very dependent on information sharing. Devin, Greg and I do collect data on our own, but the research goes much more quickly when we receive information from other sources, i.e. other people. And it's not always easy to collect data ourselves. Some stores and dealers at guitar shows are very happy to let use inspect their amps while others go ballistic and show us the door. Some collectors send information, others, upon first contact, run away to their secret underground amp lairs never to be heard from again. But we persevere through thick and thin.

This brings us to another topic which I will briefly mention. Many, many nice people from the United States, Canada, South America, Europe, Australia, New Zealand, and Japan have contributed information to our research and we are extremely grateful to all of you (and you know who you are dah'lings). I try my best to answer each and every e-mail that I receive that either requests information or that submits info for our research. Sometimes my answers are very short, but that's usually because I have a lot of other e-mail to read and answer. It's not because I'm trying to brush any one aside.

Occasionally, we have to deal with mean people who do not wish to contribute data as they feel our research is a one-way street. Honestly, I don't understand why they the bother writing if they don't want to contribute. Just don't contact us, it's that easy, sheesh. I find their rhetoric tiresome, but as the authors of the Ampeg book and I discovered during our Ampeg research, mean people are just part of the game. Ironically, it's the mean people who most often ask to see our results: a one-way street, their way! Thankfully, the nice people far outnumber the mean people and I again want to thank all the nice people for their support and encouragement as well as for the information they provide.

Third, this is hard work. I could probably earn a Ph.D. from this project. Sometimes we need to take a break and taking a break means not making any progress. We don't get paid for this and we all have day jobs. This is a hobby for us and a labor of love, or insanity, take your pick.

Lastly, during the course of our studies we've come across several complicating factors that have slowed things up. We're are more frequently encountering "parts amps". As with vintage Fender guitars, Fender amps (which have lots of bolt-on parts) are being modified to make a less desirable amp (silverface) into s more desirable one (blackface). Most of this are really easy to spot, but we still have to weed through this "parts amps" to figure out what they are or aren't (be careful out there!). As mentioned in previous installments in this series, the majority of Fender amps are serialized by model and/or chassis type. Many of these serialization schemes changed within a given model. Also, there is some duplication of serial numbers for a given model. I will go into the details of the serial number systems in the next article, but needless to say, it makes thing much more difficult for us.

If you would like to contribute information to our research you can do so by e-mail (tcguitar@tcguitar.com). All the info is entered anonymously and we don't keep records of who sent what info.

Also please note, thanks to Mr. Gearhead (see below), we are no longer collecting data for any Fender tube amp made after 1984, except Reissue models (we still want info for those!). Solid state amps were, and still remain, excluded from our research. That means we don't need info for models such as The Twin, Pro Jr., Blues Deluxe, Sedan deVille, etc. But we do want info for the '59 Bassman, '63 Vibroverb, '65 Twin Reverb, '65 Deluxe Reverb, '63 Reverb Unit, Custom Vibrolux Reverb (not a true reissue, but what the heck, we dig it) and the newly released '65 Super Reverb. Call us vintage snobs, but we gotta draw the line somewhere.

For those of you with "modern" Fender amps (tube or solid state made after 1989) or Fender reissue amps, you can go to FMIC's "Mr. Gearhead" web site (www.mrgearhead.net) which now explains how to date these amps based on codes and serial numbers. We cracked the reissue amp code here first (kudos to us, see TCG Nov. 1997), but the Mr. Gearhead site is very convenient.

Now that we're up to date, let me pass along some interesting tidbits of info that have surfaced in the last year or so.

There are some silverface Twin Reverbs from circa 1970 and Vibro Champs from circa 1973 without an "A" prefix in the serial number (I hate when that happens). Several Twin Reverbs from late 1971 (specifically October) have been observed with master volume chassis holes, but with conventional faceplates. This would indicate that FMI was already thinking about the change to the master volume circuit in Fall 1971 and probably even earlier.

Regarding model numbers, the model number for the Super Six Reverb is CFA7106 and the model number for the Quad Reverb is CFA7104. It appears that the last digit refers to the number of speakers. Since these model numbers are for the master volume models which shared the same chassis and circuit as the master volume Twin Reverb, I have to wonder if the model number for the master volume Twin (2x12) would be CFA7102 and the Vibrosonic Reverb (1x15) would be CFA7101. I haven't yet found the model numbers for these amps with the ultralinear circuit. The "D" suffix in the model numbers for the Dual Showman Reverb (TFL5000D) and Bandmaster Reverb (TFL5005D) denotes an amp for Domestic sale. Those with an "X" suffix, such as TFL5005X, were for eXport sale.

And speaking of export amps, I have several reports from Sweden that Fender export models from that country do not have the usual multitap power transformer with selector switch on the back of the chassis. Rather they are hardwired for 220V to meet the Swedish equivalent of U.L. approval. Another interesting tidbit is that Fender amps may have been distributed in Sweden by Hagstrom.

One frequently asked question I receive is "What is the difference between the AA763 and AB763 circuit for a Super Reverb (or Twin Reverb or Deluxe Reverb)?" For those without access to schematics, here are the differences:
 

The most important difference is the addition of the grid stoppers (safety first!). The only major difference in tone between the two circuits would be attributable to the different tone caps (.033 vs. .047). The .033 cap would yield slightly more midrange, but I don't think it would be very noticeable.

For some models like the blackface Concert, there was no change in phase-inverter resistor values, and no changes in tone stack cap values (fascinating!). And for other models, the tone stack did not change from .033 to .047 uf, but rather from .033 to .022 uf. The Bandmasters also saw no change in tone stack cap values between the AA763 and AB763 circuits. The "universal" changes do seem to be the oscillator circuit, cathode resistor change from 56K to 100K, and the addition of the 1500-ohm grid stopper resistors.

Did you know that early blackface amps (1963) do not have white silk screening around the bright switches? It's not certain when Fender added the white rectangle around the bright switches, but they are there by early 1964. Whether this was added before the end of 1963 is not known (yet). This feature would have been phased-in at slightly different times for the different amps as faceplates were ordered and used in somewhat different amounts and at somewhat different rates for each model.

Some general information about cabinet construction: solid pine, finger-joined cabinet construction from 1946 to circa 1972. An interesting feature on the tweed-style cabinets is the use of a dowel reinforcement in the top on either side of chassis. You can't see the dowels unless the tweed covering is removed, but this reinforcement prevented the wood from splitting due to the weight of the chassis.

Baffle boards were made of plywood from 1946 to 1962. Particle board (some call it MDF - medium density fiberboard) baffles debuted in 1963 and were used through the early 1980s. The baffle board was removable on amps made from 1948 to about 1972 and glued-in thereafter.

From circa 1972 to the early 1980s, the cabinets were no longer made from solid pine boards, but cheaper laminated, multi-piece pine boards. Each side of the cabinet was made from several pieces about three or four inches wide, glued side-to-side, to make up a plank the depth of the cabinet. These laminated cabs were not finger joined, but rabbet joined. The baffle board on these rabbet joined cabinets was mortised into the sides and bottom (i.e. not removable) to hold the whole thing together. That's why these post-1972 cabinets have the grill cloth stretched across a frame that is attached by a velcro-like system to the baffle. CBS almost certainly went to this construction method to save money, though at the expense of overall quality.

And with Fender, there are always exceptions to the rule. I have received reports of some pre-CBS blackface amps with one or more sides made from a multi-piece board. As well, I have received reports of some particle board bottoms used in master volume-era silverface amps.

I'm often asked if the marking on the inside of the cabinets are date codes. Sometimes date codes are ink stamped on the inside of the cabinet (mainly blackface and silverface amps including the piggyback speaker cabs), but those handwritten numbers you see in wax pencil or lumber crayon are actually matching marks. As a worker would through a run of cabinets and fit baffles to each one, he would mark the cab and baffle so they could be "married up" again after the baffle was grilled. The cabs were probably numbered sequentially within the production run. The number did not have any relationship to a particular employee though Sam Hutton is known to have marked the cabinets he assembled (usually in yellow lumber crayon) with an "S" superimposed over an "H" which looks like a $ with two strikes instead of one.

We've received some interesting reports about some oddball amps. The first was a 1960 brown Super Amp. The latest date code on it indicated 30th week of 1960 and the circuit and layout were neither 6G4 nor 6G4-A. This must have been one of those "Leo messed with it" amps that Forrest White speaks of in his book. This circuit is unique and transitional - part 6G4 in places, part 6G4-A in places, part "unique experimentation" in places.

An October 1963 Deluxe Reverb was reported with transformers (all Schumacher) all dated to mid-1963, except the reverb drive transformer which dated to December 62! The tube chart indicated the AA763 circuit, but there were some very strange original resistor values inside. Specifically, the reverb drive tube's cathode bias resistor was a 1K, 1-watt, instead of the normal 2.2K, ½-watt. The tail resistor in the phase inverter was 6.8K, the plate load resistors in the phase inverter were 47K and 56K instead of the normal (for AA763) 100K. The bias feed resistors were 68K instead of the normal 220K, and there was a disc ceramic cap on the board connected between the phase inverter plates. The ceramic cap is more commonly found on brown and blonde amps to prevent parasitic oscillation.

Some amp techs have observed examples of blonde and blackface amps with power transformers without center-tapped filament windings. These amps are usually the ones that have "hum" problems if they don't have 100-filament resistors added. Somewhere along the line Fender went to a center-tapped filament winding and no 100-ohm filament resistors. These amps could be modified simply by lifting the center tap, and installing the 100-ohm resistors in the usual place on the power lamp socket. If a filament in a tube shorts (happens most often in power tubes) it is a lot cheaper to replace a 10-cent resistor or two, than an $100 power transformer.

Fender's sudden transition from cloth wire to thick PVC wire (in pastel greens, white & yellows) is well documented by anyone who has ever pulled a chassis. Sometime in late 1968, the cloth covered wire went away. However, several amps from the late '60s (non-reverb Princeton, Vibrolux Reverb, Bandmaster Reverb, and possibly a Deluxe Reverb) with oddball wire have been reported. The Princeton Amp was an early-mid 1969 model entirely wired (factory original & stock) with thinwall, 22awg irradiated PVC (IPVC) wiring. IPVC wiring is usually found in electronics like computers, not lo-fi amps. Keep your eyes peeled for wire with very thin, cream to yellow insulation. It's likely IPVC.

Scanning a few internet discussion pages, I've noticed quite a bit of misinformation going around regarding Fender tube amps mainly from people who haven't studied the available published literature on Fender amps, i.e. they haven't been reading these articles in TCG. The good thing is that the misinformation is often corrected by someone who is knowledgeable. One of the most common topics that falls into this category is early silverface amps. Here's a very quick summary that may be helpful: the earliest silverface amps were made in 1967 not 1968, not all "drip edge" silverface amps are from 1968 or 1969 (they could be from 1967), not all "black line" drip edge silverface amps have the blackface circuit except for Vibrolux Reverbs, Deluxe Reverbs, Princetons, Princeton Reverbs, Champs, Vibro Champs, and Broncos.

I'll leave you with a bit of juicy info, namely, some preliminary production estimates for several random amp models. This info will be further refined and presented in a future article (and y' all can hardly wait, I know).

Bassman (blonde) 12,000 units

Princeton Reverb (blackface) 19,000 units

Tremolux (blackface) 8,000 units

Vibrolux Reverb (blackface) 10,000 units

Vibroverb (reissue) 6,000 units

Special thanks to amp tech guru and fellow Jersey Boy, Mark Norwine at Carlson Amplification Inc., and Gregg "Portaflex" Hopkins at Vintage Amp Restoration for contributing interesting and fun facts to this series.

DATING FENDER AMPS BY SERIAL NUMBER, PART V
by Greg Gagliano

Copyright 2002, 20th Century Guitar Magazine
 

They said it couldn't be done!
                    Over 6 years in the making!
                                        Finally, what everyone has been waiting for!
                                                            How to date Fender amps by serial number!!

Okay, I know you're all just dying to skip ahead to the serial number tables but try to contain your excitement and read through the article first.  I promise the tables will still be there after you finish reading.  Besides, no article in the Dating Fender Amps by Serial Number series would be complete without some interesting information, n'est ce pas?

FUN FACTS
Oddlings - Yet another printing error has surfaced, this time from the FEI (pre-CBS) days.  A 1957 tweed Vibrolux was reported with a tube chart printed with circuit "5E3" (tweed Deluxe)  instead of the correct 5F11 (see photo).  Clearly Fender wasn't afraid to use incorrect parts when they were in a bind.  We also received a report of a tweed 5G12 Concert.  The 5G12 Concert is the earliest version from very late 1959 and early 1960 so the existence of a tweed example, while extremely rare, is certainly plausible since Fender was making lots of tweed amps during the same time period.  It’s unknown if the tweed covering was a mistake ("Oops, I thought this was a 4x10 Bassman cabinet that I was covering") or intentional, perhaps as a special order.

Non-Schumacher transformers - It's been universally accepted that Fender only used Schumacher transformers on amps made in the 1960s and 1970s.  These are marked with EIA code "606" which is the company number for Schumacher.  Well, this universal "truth" was debunked when we found a bunch of amps with transformers made by the Better Coil and Transformers company.  These are marked with EIA code "831" and are most prevalent during the 1966-68 time period.  Some examples include a '66 Princeton Reverb and '6 Pro Reverb with Better Coil output transformer, a '66 Deluxe Reverb and '67 Twin Reverb with Better Coil reverb transformer, and a 1968 Vibro Champ with Better Coil trannies.  These units look, and apparently sound, just like the Schumacher-made units so it's easy to overlook that "831" code.

Working at FMI - I was able to interview a fellow (who wishes to remain anonymous) who worked at Fender in 1972-73 in the amp department.  Although his job was somewhat limited, his recollections provided some really fascinating insights to how the amps were built.  For instance, he confirmed our assumption that the amp chassis were put into stock after being stamped with serial numbers and that the chassis were pulled from the stock bins randomly (just as with Fender guitar neck plates).  He recalled, "We just went to a big bin every morning and loaded our wheeled rack with a batch of whatever chassis we were working on that day.  The boss came around and said what we'd be building.  The chassis weren't used chronologically.  Probably the same as the pots and transformers that we just dug out of the boxes.  I think in the corners of the boxes were older pots remaining from earlier dates... leftovers."

Regarding production he recounted the following information:  "I think I remember being 'pushed' to come up with 30 of the simpler chassis (Super Reverb?) per day.  I think the better, older hands did 35 a day.  Like I said, there were 5 or 6 of us at the benches every day.  But it wasn't always 'cool guitar' amps, sometimes I was making Fender Rhodes Satellite amps on bent aluminum, sometimes only Champs.  I remember two 'suits' from upstairs standing behind me occasionally doing time studies.  They actually held clipboards and stopwatches to measure how long it took for me to attach various parts.  Of course I tended to hurry more when they were
there, and I would fumble more, too."

Another really interesting fact was that he recalled that the eyelet boards were loaded/wired/soldered in Mexico!  "I remember the circuit boards were pre-made, from Mexico, easy to screw into the chassis.  Same with the little rectifier boards.  When we had filled our cart we'd wheel it over to the Chicano chicks.  They were something to behold, all chatting away while soldering so quickly, it didn't hardly seem like they were looking at the amps. After that the foreman would add the tubes, turn 'em on and set the bias."

Export models - We've confirmed that Fender amps were distributed by Hagström in Sweden.  Not only that, but to meet Swedish safety codes, Hagström removed the external voltage selector switch (fitted to all blackface and silverface export models) and hardwired it internally (see photos).  Notice that the original Fender back panel was removed and replaced with a Hagström panel.  One has to wonder where all those factory original export back panels are!  Maybe they'll show up on eBay.  Another interesting tidbit is that a lot of Fenders were imported into Australia in the late 1950s and early 1960s that were stock 110-volt (domestic US) units.  The Australian Fender Distributor then installed 240V - 110V stepdown transformers in the bottom of the cabinets.

Mid-1968 Super Reverb export model modified by Hagström for the Swedish market.  Note the removal of the voltage selector switch and hard-wiring.  Also note the vertical black lines on the control panel (found on earliest silverface amps) and the large ceramic power resistors coming off the power tube sockets which indicates the AB568 circuit.

I Didn't Know That! Some Fender amp expert I turned out to be.  I just discovered that the silverface Bandmaster speaker cabinet (the big, tall one without tilt-back legs) is ported (see photo).  I thought they were completely sealed units.  I guess this is what the 1969 catalog refers to as "large, individual specially designed baffles."  And all along I thought the big n' tall silverface cabs were just a macho thing to compete against the awesome looks of a Marshall half stack or full stack.  But really, these cabs were large because they were of a "special design" that “greatly improves tone and volume without distortion, and permits optimum performance of the speakers.  At least that's the reason according to the '69 catalog.

Also, another thing I've never seen before is a what appears to be a shipping tag of some sort (see photo).  Note the check boxes for DOM (domestic US model), EXP (export model), CSA (Canada model), STD (standard) and SPEC (special).  I have to wonder how often Fender used the SPEC check box and what features a "special" amp or cabinet would have?!  Since the new owner would have likely removed this tag immediately upon arriving home, I’m amazed that the one in the photo has remained intact since mid-1968!

PRODUCTION
Along with dating amps by serial numbers, we were interested in determining production totals, if possible.  There is some debate about how to interpret the production code information on late '50s to mid-1967 tube charts and Greg Huntington is still working with those.  One thing we know for sure is that production codes can help date an amp to a particular month within a given model run.  Greg and I also disagree about determining production from serial numbers.  I will present my hypothesis here and let Greg present his side of the story in a future article.

Unlike serial numbers used for most Fender guitars and basses, we know that serial number sequences are unique to a particular model or a family of models of amplifiers.  This is similar to the early '50s Telecaster and Precision Bass having their own unique serial number system.  Because the serial numbers are for a particular model and that chassis were stamped sequentially, is reasonable to assume that the serial number infers the Nth unit manufactured.  Some caution is advised since it is likely that not all chassis were used due to defects or that duplicate serial numbers may have been stamped.  Since these two scenarios are probably a very small percentage (or fraction of a percent) of total production, I’ve chosen to ignore them.

Another caveat is that it's impossible to determine the production totals for "family" models, that is, models that share a common chassis.  These "families" are:  the Vibrasonic (6G13) and blonde Showman (6G14); the narrow panel tweed Super, Bandmaster, and Pro; the brown Vibrolux (6G11) and blonde Tremolux (6G9); the blackface Vibrolux (AB763) and blackface Tremolux (AB763); the brown Super, Pro, Concert and blonde Bandmaster (6G7); the silverface Super Reverb and Bandmaster Reverb; the blackface Pro, Concert and Bandmaster; the Vibro Champ and Bronco; the non-master volume Twin Reverb and Dual Showman Reverb; and the master volume Twin Reverb, Quad Reverb, Super Six Reverb, Dual Showman Reverb, and Vibrosonic Reverb.  There is no way to separate out production for these models, but with enough data, we might be able to do some frequency distribution and such to determine a rough estimate.

For the uniquely serialized models, the production estimates using my hypothesis, can be determined from the serial number tables.  This info may make some vintage dealers cringe when they find out how common some of these amps really are, but that's just tough noogies.  For example, the serial numbers for 5F6 and 5F6-A Bassman amps run from BM00001 to BM04600 therefore we can conclude that there were about 4,600 units made.  How about those rarebird Vibroverbs?  Well, the serial numbers for the brown Vibroverb run from 00100 to 00600  indicating a total production of around 500 units, and the serial numbers for the blackface Vibroverb run from A00100 to A05300 indicating a total production of around 5,200 units.  The brown Deluxe is less common at about 4,800 units made (serial numbers run from D00100 to D04900).  Anyway, you get the idea.

Just remember that if you're interested in production from a "family" model listed above, you cannot use this method.   For instance, the serial numbers for tweed Bandmaster (3x10) run from S00001 to S03700.  At first glance you'd think there were about 3,700 Bandmasters made, but you'd be wrong.  Remember, this model shares a chassis with the narrow panel tweed Pro and Super.  Therefore, the only thing we can infer is that there were 3,700 tweed Bandmasters, Pros, and Supers made in total.   Sure, you could assume that if production was equal between models that there may have been 1,233 units of each model made, but currently we don't have the data to support this kind of inference.

DATING
The tables are pretty much self-explanatory, but here are some guidelines to keep in mind when using the tables to date your amp.  First, the tables should be used as a guide only.  You'll still need to look at various features and date codes to absolutely confirm a year of manufacture.  Large overlaps in years may be due to lack of sufficient data (late 1940s to mid 1960s) or simply that the stamped chassis were used way out sequence (mid 1960s to early 1970s).  Some, but not all, export models don't fit exactly into the sequence given and are usually from a year or two later than the serial number would otherwise indicate.  Silverface amps without the "A" prefix are generally from the 1970-71 time period and the dating tables can be used to date them if you add an "A" prefix.

Please note (this is very important) that there are many exceptions to the "rules" I have outlined here.  Though rare, there are some amps with bizarro serial number letter-prefixes and/or missing expected prefixes that don't fit the tables.  Thankfully, these aberrations are pretty rare.  Just as with Fender guitars, you'll find serial numbers that should fall in a certain year, but don't.  Example:  Vibrolux Reverb with serial number A756254 should be a ’77, but the latest date-coded parts date it to 1978.  Some serial numbers have a letter prefix plus 4-digits instead of the usual 5- or 6-digits.  Likewise there are some serial numbers with an extra digit (usually a zero) after the letter prefix.  Again, these are rare and exceptions to the norm.

Finally, if you don't see a particular model or year listed, it is because 1) there wasn't enough data to generate a dating table or 2) it falls under the “universal” scheme for A6-, A7-, A8-, A9-, B-, or F-series serial numbers.  In the case of early tweed amps, there simply isn't enough info available at this time to accurately date these by serial number, though some rough guidance is provided.  Same goes for Princetons made after 1966.

Don't get all bent out of shape if you see a model that wasn't "supposed" to be made in a certain year.  Case in point; we have documented two factory-original non-reverb blackface Deluxe Amps from January 1967.  The model was supposedly discontinued in 1966.  Remember, FMI didn't like to waste anything (witness the Custom and Swinger guitars) so using up the remaining AB763 Deluxe chassis wouldn't be a surprise.

DATING TABLES
For mid to late '70s silverface amps and early '80s "blackface" models, the serial numbers are date encoded much the same way as Fender guitars from the late '70s:

A6 + 5-digits - 1976
A7 + 5-digits - 1977
A8 + 5-digits - 1978
A9 + 5-digits - 1979

B + 5-digits - 1975, 1976

F0 + 5-digits - 1980
F1 + 5-digits - 1981
F2 + 5-digits - 1982
F3 + 5-digits - 1983
F4 + 5-digits - 1984
F9 + 5-digits - 1979, 1980

Examples:  Vibrolux Reverb with serial number A756154 (A7 = 1977), Princeton Reverb II with serial number F077698 (F0 = 1980), and Super Reverb with serial number B10753 (B = 1975 or 1976).   Note, there is enough data for B-series Twin Reverbs (and variants) to differentiate between 1975 and 1976.  These are listed in the dating table.  Unfortunately, there isn't enough data for other B-series models to identify the '75s from the '76s, but with your help, hopefully we'll collect enough info to do this for a future article.

Bandmaster 5C7, 5D7 (tweed)
 0001 to 0800 - 1953
 5000 to 5500 - 1954

Bandmaster 5E7 (tweed)
 S00001 to S00350 - 1955
 S00350 to S01200 - 1956
 S01100 to S01800 - 1957
 S01700 to S02500 - 1958
 S02500 to S03700 - 1959

Bandmaster 5G7, 6G7 (brown)
00001 to 01000 - 1960

Bandmaster 6G7, 6G7-A (blonde)
00001 to 02400 - 1960
02300 to 05100 - 1961
49000 to 58000 - 1962
58000 to 59200 - 1963

Bandmaster AA763, AB763 (blackface)
 A00001 to A01700 - 1963
 A01400 to A08000 - 1964
 A07700 to A17000 - 1965
 A16000 to A22000 - 1966
 A20000 to A27000 - 1967

Bandmaster AB763, AC568 (silverface)
 A26000 to A29000 - 1967
 A28000 to A34000 - 1968
 A33000 to A34000 - 1969
 A34000 to A45000 - 1970-72

Bandmaster Reverb AA768, AA1069, AA270, TFL5005 (silverface)
 A31000 to A35000 - 1968
 A35000 to A45000 - 1969
 A45000 to A49000 - 1970
 A48000 to A54000 - 1971
 A54000 to A59000 - 1972
 A59000 to A66000 - 1973
 A66000 to A77000 - 1974
 A75000 to A78000 - 1975
 A78000 to A80000 - 1976

Bassman 5B6 (tweed)
 0001 to 0300 - 1951
 0300 to 0400 - 1952
 0400 to 0600 - 1953

Bassman 5D6, 5D6-A (tweed)
 0600 to 0900 - 1954

Bassman 5E6, 5E6-A (tweed)
 0100 to 0200 - 1955

 BM00001 to BM00550 - 1955
 BM00550 to BM01200 - 1956
 BM01200 to BM01600 - 1957

Bassman 5F6, 5F6-A (tweed)
 BM00001 to BM00400 - 1957
 BM00400 to BM01500 - 1958
 BM01500 to BM03100 - 1959
 BM03100 to BM04600 - 1960

Bassman 6G6, 6G6-A, 6G6-B (blonde)
 BP00100 to BP01100 - 1961
 BP01100 to BP05000 - 1962
 BP05000 to BP08400 - 1963
 BP08400 to BP12000 - 1964

Bassman AA864, AA165, AB165 (blackface)
 A00100 to A03800 - 1964
 A03800 to A15000 - 1965
 A15000 to A25000 - 1966
 A24000 to A33000 - 1967

Bassman AB165, AC568, AA270, AA371 (silverface)
 A32000 to A40000 - 1967
 A39000 to A49000 - 1968
 A48000 to A58000 - 1969
 A58000 to A60000 - 1970

Bronco AB764 (silverface)
 A19000 to A21000 - 1967
 A20000 to A26000 - 1968
 A25000 to A28000 - 1969
 A28000 to A29000 - 1970
 A29000 to A32000 - 1971
 A32000 to A35000 - 1972
 A33000 to A39000 - 1973
 A39000 to A42000 - 1974
 A42000 to A51000 - 1975

Champion 800 (tweed)
 01 to 1000 - 1948-49

Champion 600 5B1 (tweed)
 01 to 1300 - 1948-49
 1300 to 1700 - 1950
1700 to 5000 - 1951-52
5000 to 5500 - 1953

Champ 5C1, 5D1 (tweed)
 5500 to 6600 - 1953
 6600 to 8000 - 1954
 8000 to 9999 - 1955

Champ 5E1, 5F1 (tweed)
 C00001 to C00800 - 1955
 C00800 to C03100 - 1956
 C03100 to C06000 - 1957
 C06000 to C08800 - 1958
 C08800 to C12500 - 1959
 C12500 to C15500 - 1960
 C15500 to C16800 - 1961
 C17000 to C19000 - 1962
 C19000 to C21000 - 1963
 C21000 to C23000 - 1964

Champ AA764 (blackface)
 A00100 to A02000 - 1964
 A01900 to A05200 - 1965
 A05200 to A12000 - 1966
 A12000 to A12200 - 1967

Champ AA764 (silverface)
 A12200 to A13900 - 1968
 A13900 to A18000 - 1969
 A18000 to A30500 - 1970
 A30500 to A32000 - 1971
 A32000 to A35000 - 1972
 A32000 to A42000 - 1973
 A42000 to A50000 - 1974
 A50000 to A63000 - 1975
 A63000 to A85000 - 1976

Concert 5G12, 6G12, 6G12-A (brown)
00001 to 02400 - 1960
02300 to 05100 - 1961
49000 to 58000 - 1962
58000 to 59200 - 1963

Concert AA763, AB763 (blackface)
 A00001 to A01700 - 1963
 A01400 to A08000 - 1964
 A07700 to A08800 - 1965

Model 26 Deluxe (woodie)
 100 to 1500 - 1946-48

Deluxe 5A3, 5B3 (tweed)
 001 to 800 - 1948
 800 to 1900 - 1949
 1900 to 3000 - 1950
 3000 to 5400 - 1951
 5400 to 6800 - 1952
 6800 to 7300 - 1953

Deluxe 5C3, 5D3 (tweed)
 0001 to 1500 - 1953
 1500 to 3600 - 1954
 3600 to 5300 - 1955

Deluxe 5E3 (tweed)
 D00001 to D01400 - 1955
 D01400 to D03000 - 1956
 D03000 to D05000 - 1957
 D05000 to D06800 - 1958
 D06800 to D09000 - 1959
 D09000 to D10000 - 1960
 D10000 to D11000 - 1961

Deluxe 6G3, 6G3-A (brown)
 D00100 to D00900 - 1961
 D00800 to D03800 - 1962
 D03800 to D04900 - 1963

Deluxe AA763, AB763 (blackface)
 A00100 to A00500 - 1963
 A00500 to A02800 - 1964
 A02800 to A05600 - 1965
 A05600 to A06100 - 1966
 A06100 to A06500 - 1967

Deluxe Reverb AA763, AB763 (blackface)
 A00100 to A00300 - 1963
 A00300 to A03900 - 1964
 A03900 to A13000 - 1965
 A12000 to A19000 - 1966
 A19000 to A24000 - 1967

Deluxe Reverb AB763, AB868 (silverface)
 A24000 to A26000 - 1967
 A26000 to A28500 - 1968
 A28500 to A33000 - 1969
 A31000 to A33000 - 1970
 A33000 to A34500 - 1971
 A34500 to A37000 - 1972
 A37000 to A39000 - 1973
 A39000 to A42000 - 1974
 A42000 to A43000 - 1975
 A43000 to A45000 - 1976

Dual Showman AA763, AB763 (blackface)
 A00100 to A01400 - 1963
 A01400 to A01700 - 1964
 A01700 to A04300 - 1965
 A04300 to A08000 - 1966
 A07800 to A12000 - 1967

Dual Showman AB763, AC568 (silverface)
 A12000 to A12500 - 1967
 A12500 to A15000 - 1968

Dual Showman Reverb AA768, AA769, AA270, TFL5000 (silverface)
 A13900 to A16500 - 1968
 A16500 to A22400 - 1969
 A21700 to A25600 - 1970
 A25600 to A37000 - 1971
 A37000 to A50500 - 1972
 A50500 to A68000 - 1973
 A68000 to A99999 - 1974
 A81000 to A99999 - 1975

 B01000 to B15000 - 1975
 B15000 to B68000 - 1976

Harvard 5F10 (tweed)
 H00100 to H00500 - 1956
 H00500 to H01400 - 1957
 H01400 to H02000 - 1958
 H02000 to H02600 - 1959
 H02600 to H03400 - 1960
 H03400 to H03500 - 1961

Musicmaster Bass CFA-7010 (silverface)
 A00100 to A04100 - 1972
 A04100 to A07900 - 1973
 A07900 to A09500 - 1974
 A09500 to A09800 - 1975
 A09800 to A10500 - 1976

Princeton 5B2, 5C2, 5D2 (tweed)
 2500 to 3600 - 1953
 3600 to 4400 - 1954
 4400 to 4700 - 1955

Princeton 5F2, 5F2-A (tweed)
 P0001 to P00350 - 1955
 P0001 to P01100 - 1956
 P01100 to P02400 - 1957
 P02400 to P03000 - 1958
 P03000 to P04300 - 1959
 P04300 to P07000 - 1960

Princeton 6G2, 6G2-A (brown)
 P00100 to P01000 - 1961
 P01000 to P05100 - 1962
 P05100 to P07200 - 1963
 P07100 to P09900 - 1964

Princeton AA964 (blackface)
 A00100 to A02500 - 1964
 A02500 to A07000 - 1965
 A05000 to A10400 - 1966

Princeton AA964 (silverface)
 A10000 to A11000 - 1967-68
 A11000 to A15000 - 1969-70

Princeton Reverb AA1164 (blackface)
 A00100 to A02100 - 1964
 A02100 to A07500 - 1965
 A05500 to A14500 - 1966
 A14000 to A18700 - 1967

Princeton Reverb AA1164, B1270 (silverface)
 A18500 to A19500 - 1967
 A18900 to A21500 - 1968
 A21500 to A25500 - 1969
 A24000 to A25000 - 1970
 A25000 to A26000 - 1971
 A26000 to A27500 - 1972
 A27500 to A30000 - 1973
 A30000 to A32500 - 1974
 A32500 to A34500 - 1975
 A34500 to A36000 - 1976

Pro 5A5, 5B5, 5C5, 5D5 (tweed)
 01 to 600 - 1948
 600 to 1100 - 1949
 1100 to 1700 - 1950
 1700 to 2500 - 1951
 2500 to 3500 - 1952
 3500 to 4800 - 1953
 4500 to 6000 - 1954

Pro 5E5, 5E5-A, 5E5-B (tweed)
 S00100 to S00800 - 1955
 S00800 to S01200 - 1956
 S01200 to S01800 - 1957
 S01700 to S02500 - 1958
 S02500 to S03700 - 1959

Pro 5G5, 6G5, 6G5-A (brown)
00001 to 02400 - 1960
02300 to 05100 - 1961
49000 to 58000 - 1962
58000 to 59200 - 1963

Pro AA763, AB763 (blackface)
 A00001 to A01700 - 1963
 A01400 to A08000 - 1964

Pro Reverb AA165 (blackface)
 A00100 to A02700 - 1965
 A02700 to A09200 - 1966
 A07000 to A10200 - 1967

Pro Reverb AA1265, AB668, AA1069, AA270 (silverface)
 A10000 to A10500 - 1967
 A10500 to A12000 - 1968
 A12000 to A13300 - 1969
 A13400 to A14500 - 1970
 A14500 to A15000 - 1971
 A15000 to A15600 - 1972
 A15600 to A17200 - 1973
 A17200 to A19700 - 1974
 A19700 to A20000 - 1975
 A20000 to A21500 - 1976

Quad Reverb CFA7104 (silverface)
 A33000 to A37000 - 1971
 A37000 to A50500 - 1972
 A50500 to A68000 - 1973
 A68000 to A99999 - 1974
 A81000 to A99999 - 1975

 B01000 to B15000 - 1975
 B15000 to B68000 - 1976

Reverb Unit 6G15 (brown, blonde, blackface)
 R00100 to R00900 - 1961
 R00900 to R02600 - 1962
 R02600 to R04800 - 1963
 R04800 to R07400 - 1964
 R07400 to R09800 - 1965
 R09800 to R11000 - 1966

Showman 6G14, 6G14-A (blonde)
 00001 to 00350 - 1960
 00200 to 00800 - 1961
 00800 to 01500 - 1962
 01500 to 01800 - 1963

Showman AA763, AB763 (blackface)
 A00100 to A01400 - 1963
 A01400 to A01700 - 1964
 A01700 to A04300 - 1965
 A04300 to A08000 - 1966
 A07800 to A12000 - 1967

Showman AB763 (silverface)
 A12000 to A12500 - 1967
 A12500 to A15000 - 1968

Super incl. Dual Professional (tweed)
 01 to 400 - 1946-47
 500 to 1200 - 1949-51
 2000 to 4300 - 1952-53
 4500 to 5500 - 1954
 5500 to 6100 - 1955

Super 5E4, 5F4 (tweed)
 S00100 to S00800 - 1955
 S00800 to S01200 - 1956
 S01200 to S01800 - 1957
 S01700 to S02500 - 1958
 S02500 to S03700 - 1959

Super 5G4, 6G4, 6G4-A (brown)
00001 to 02400 - 1960
02300 to 05100 - 1961
49000 to 58000 - 1962
58000 to 59200 - 1963

Super Reverb AA763, AB763 (blackface)
 A00100 to A00600 - 1963
 A00600 to A06000 - 1964
 A05900 to A13000 - 1965
 A11000 to A20000 - 1966
 A20000 to A27000 - 1967

Super Reverb AB763, AB568, AA1069, AA270 (silverface)
 A26000 to A29000 - 1967
 A27000 to A35000 - 1968
 A35000 to A45000 - 1969
 A45000 to A49000 - 1970
 A48000 to A54000 - 1971
 A54000 to A59000 - 1972
 A59000 to A66000 - 1973
 A66000 to A77000 - 1974
 A75000 to A78000 - 1975
 A78000 to A80000 - 1976

Super Six Reverb CFA7106 (silverface)
 A33000 to A37000 - 1971
 A37000 to A50500 - 1972
 A50500 to A68000 - 1973
 A68000 to A99999 - 1974
 A81000 to A99999 - 1975

 B01000 to B15000 - 1975
 B15000 to B68000 - 1976

Tremolux 5E9, 5E9-A (tweed)
 0001 to 00650 - 1955
 00650 to 01000 - 1956
 01000 to 01300 - 1957
 01300 to 01700 - 1958
 01700 to 02700 - 1959
 02600 to 03300 - 1960

Tremolux 6G9, 6G9-A, 6G9-B (blonde)
 00100 to 01000 - 1961
 00900 to 04200 - 1962
 04200 to 05900 - 1963

Tremolux AA763, AB763 (blackface)
 A00100 to A00500 - 1963
 A00500 to A03700 - 1964
 A03200 to A05700 - 1965
 A05200 to A08000 - 1966

Twin 5C8, 5D8, 5D8-A, 5E8, 5E8-A (tweed)
 001 to 500 - 1953-55

 A00200 to A00725 - 1956-57

Twin 5F8, 5F8-A (tweed)
 A00010 to A00725 - 1957-59

Twin 6G8, 6G8-A (blonde)
 00001 to 00100 - 1960
 00100 to 00225 - 1961
 00225 to 00400 - 1962
 00400 to 00525 - 1963

Twin Reverb AA763, AB763 (blackface)
 A00100 to A01200 - 1964
 A01200 to A04300 - 1965
 A04300 to A07000 - 1966
 A07000 to A10400 - 1967

Twin Reverb AB763, AC568, AA769, AA270 (silverface)
 A10500 to A11300 - 1967
 A10500 to A16500 - 1968
 A16500 to A21400 - 1969
 A21400 to A25600 - 1970
 A25600 to A37000 - 1971
 A37000 to A50500 - 1972
 A50500 to A68000 - 1973
 A68000 to A99999 - 1974
 A81000 to A99999 - 1975

 B01000 to B15000 - 1975
 B15000 to B68000 - 1976

0100 to 3400 - 1970

Vibrasonic 6G13, 6G13-A (brown)
 00001 to 00350 - 1960
 00200 to 00800 - 1961
 00800 to 01500 - 1962
 01500 to 01800 - 1963

Vibro Champ AA764 (blackface)
 A00100 to A02000 - 1964
 A01200 to A08100 - 1965
 A08100 to A16000 - 1966
 A16000 to A20500 - 1967

Vibro Champ AA764 (silverface)
 A19000 to A21000 - 1967
 A20000 to A26000 - 1968
 A25000 to A28000 - 1969
 A28000 to A29000 - 1970
 A29000 to A32000 - 1971
 A32000 to A35000 - 1972
 A33000 to A39000 - 1973
 A39000 to A42000 - 1974
 A42000 to A51000 - 1975
 A51000 to A53000 - 1976

Vibrolux 5F11 (tweed)
 F00001 to F00300 - 1956
 F00300 to F00900 - 1957
 F00900 to F01500 - 1958
 F01500 to F02800 - 1959
 F02800 to F04000 - 1960
 F04100 to F04400 - 1961

Vibrolux 6G11, 6G11-A (brown)
 00100 to 00700 - 1961
 00700 to 03700 - 1962
 03400 to 05500 - 1963

Vibrolux AA763 (blackface)
 A00100 to A01300 - 1964

Vibrolux Reverb AA864 (blackface)
 A00100 to A00800 - 1964
 A00800 to A03600 - 1965
 A03600 to A08300 - 1966
 A08300 to A10700 - 1967

Vibrolux Reverb AA864, AA964, AB568, AA270 (silverface)
 A10700 to A11000 - 1967
 A11000 to A12000 - 1968
 A12000 to A13700 - 1969
 A13700 to A23400 - 1970
 A23400 to A24500 - 1971
 A24500 to A25000 - 1972
 A25000 to A27000 - 1973
 A27000 to A31500 - 1974
 A31500 to A33000 - 1975
 A33000 to A34000 - 1976

Vibrosonic Reverb (silverface)
 A44000 to A50500 - 1972
 A50500 to A68000 - 1973
 A68000 to A99999 - 1974
 A81000 to A99999 - 1975

 B01000 to B15000 - 1975
 B15000 to B68000 - 1976

Vibroverb 6G16 (brown)
 00100 to 00600 - 1963

Vibroverb AA763, AB763 (blackface)
 A00100 to A05300 - 1964

YOU CAN STILL HELP!
Sadly, these tables do not mean that our research is finished.  We still need more data to fine tune existing dating schemes (including the overlap in the "universal" A+6 digit and F series) and to provide dating tables for missing models and/or years.  Also, we're still researching the "mystery of the production number" on the tube charts of late '50s through mid-1967 amps.  Please continue to send submit info to us via e-mail.

Thanks again to everyone who contributed information to make these dating tables possible.  We hope you find them useful!!

Special thanks to Sixten Forsén at EDGAR Audio in Sweden for the information and photos, to Sam Hartley for the information and photos, to Greg at Retro Sound in Australia and Paul Mastradone for the excellent info.

Extra special thanks to my co-researchers, Devin "The Tweed King" Riebe and Greg Huntington, for their invaluable assistance with collecting data and information about Fender amps.

About the author:  Greg Gagliano is going on vacation.  You can try to contact him by e-mail, but don't be surprised if you get a pre-recorded message.