Dating a Wurlitzer

[Rob A]

You can take a look at the EIA code on  the power transformer to get a very general idea. I have 2 later 200A's with the Wurlitzer logo's on the back, one transformer stamped 9th week of '81, the other is stamped 29th week of '79.   Of course Wurlitzer probably used whatever stock they had lying around, so while it is not a very accurate way to date, at least you can determine that it was produced after a certain week/year. 

Also same idea with the EIA code the back of the Vib pot.   

http://www.triodeel.com/eiacode.htm

[DocWurly]

[I update this post as I get improved information.  Latest update is Jan 21, 2020. --SE]

Threads on this topic:

http://ep-forum.com/smf/index.php?topic=9303.msg50803#msg50803

http://ep-forum.com/smf/index.php?topic=9359.0

It is now clear that for all Wurlitzers from mid-1962 on, there are coded 8- or 5- digit date stamps on the wood of various parts of the Wurlitzer.  These may pre-date the assembly date of the instrument, but they are generally the latest and most accurate dates on the instrument.

The most reliably available and easiest-to-access coded date stamp is on the rear treble side of the main rail assembly, upside down, behind the damper arm rods.  You  will see a part number of "A-60-5" or, in many/all of the 1962-early 1968 examples, "A-60-2." The 8-digit stamp will be in the vicinity of that part number.

The other place an 8-digit stamp appears is on the keys themselves, usually repeated a couple of times on the far bass or far treble keys.  (There may also be part numbers or other stamps....you need to find the specific one that follows this format.)  This date may be chronologically very close to the other one, or it might differ by days, weeks, or even close to a year, so it is most accurate to check both stamps.  There is no consistency to which stamp has the latest date.  The dates seem to have something to do with when those respective parts were manufactured or inspected, as opposed to when the instrument was finally assembled.

The code is YMMDDxxx.  (The last three digits are a serial number that rolls over to "000" after every 1000 parts produced; combined with the date, it gives a unique number to each assembly).  Sometimes a 5 digit code is found on the keybed, usually under the treble and or bass keys.  These numbers may not match each other, and they mean YMMDD.

We are used to seeing 2 or 4 digit codes for years, which perhaps why this code escaped detection for so long.  The "Y" is a single digit, meaning it does not tell you the decade in which the instrument was made.  A May 13, 1972 instrument will read 20513xxx, but so will one produced in 1982 on the same date.  So you need to know the general range of years your instrument was produced.  But as no instrument was made for more than a decade, this isn't really a problem.

100 (prototype):1954
110: Dec 1954-early 1955
111:1955
112:1955-6 (later ones use 112A amps; all use side pedals)
112A: 1956 (production is simultaneous with later 112's)
120: very late 1956 to 1961 or early 1962
700 (console version of 120): Mid/late-1957 to 1961 or early 1962

There is usually a conventional, if abbreviated, date stamp on the wood of the action of the 110 through 112. (There is sometimes a M-YY) date stamped into the SIDE of the lowest key on early models)  With the 120 and 700, the most consistent dating I've found is a piece of handwritten masking tape hidden on the back of the reed bar.  There may be other stamps on the wood or electronics (esp speakers) in certain cases.

Then the 8-digit code begins.  The early-mid 1960's models:
140/145/720 (no "A" or "B" in model number....aka "pre-A"): 1962-3
140A/145A:1963-4
720A: 1963-1965 (there are two distinct variants--the 1965 instruments are basically a console 145B)
145B: late 1964-late 1965
140B/146B/146: 1964-1968
720B/726B/726: late 1965-1968 (maximum range presumed, very little data)

200 (no A) series, including 203W/207V/214V and 106/106P: late 1968-late 1974
200A series, including all other 2xx model #'s with an "A", plus 205, 210, 215, 270, and 200B: late 1974- May 1983.

The German 201 and 300 were made in the early 1970s.  They have date stamps on them, especially on the keybed under the keys, but don't follow the 8-digit code.


Exceptions:
***On earlier 1962 Wurlitzers, there is an 6-digit stamp. This is YWWxxx.  So a stamp of 228093 means the 28th week of 1962, or July 9-15, 1962.

***Very rarely, you may find an anomalous code.  For example, the second and third digit should only have a range of "01" to "12",  The 4th and 5th digit should be a number from "01" to "31" that would correspond to the number of days in the matching month. 

Keep in mind that these numbers were on stamps that would be seen backwards by the people setting them up.  It wouldn't be too difficult to flip a few digits.  In the cases I've found one of these codes, it's usually decipherable by checking the other date codes on the piano.

Here's an example: 
http://ep-forum.com/smf/index.php?topic=9359.msg51349#msg51349

All other date stamps indicated this was a September-October 1967 instrument, but there was a stamp of "13907."  It appears this was DD-MM(backwards)-Y.  Human error.

***In addition, there is a range of early 720's from 1962 where the keystamper seemingly didn't understand the new 8-digit coding system, and used "YYMDDxxx" in bright red ink.  (Such a system would have become unworkable in the later months of the year).  On these, "62813208" probably means August 13, 1962.  (In fact, both examples I've seen of this share this code, and have an October 1962 code on the action/main rail, still using 6-digits.)

***Instruments with date stamps that differ by more than a year have probably been Frankensteined together.  It is easy enough to replace a keybed.  In one case, I believe I found a 1970 main rail screwed into a 1962 model 140, with all the original action parts replaced.


************************
Some more info:

The 200 series instruments from 1968 to 1972, that do not have an "L" in the serial number, have an additional date that is THE most accurate date you are going to find.    It's a handwritten month and day on the lowest key, under the amp rail, accompanied by the initials "CM" (usually) or "RT" or "RP".  I call it the "CM number."  It's always the latest date on the intrument (unless something was switched-out later).  Combined with the year that you will find on the other parts, you can nail the month of production from this date.  Unfortunately it's only there in that 6-year window.  Apparently, when they moved operations to Logan, Utah (the meaning of that "L" as far as we can tell), "CM" didn't go.

It's also good to learn to read the date code on your speakers.  They are sometimes the latest part code on your instrument.  In general, it's best to get as many date codes off an instrument as possible, as there is little rhyme or reason to which part will have the latest date.

[Tonewheel]

Very interesting and helpful thread!

My 200A has A-60-5 and 60914282 stamps.

Would this make it Tuesday, September 14, 1976? The serial number ends with L, suggesting Logan, Utah.

Thanks

[DocWurly]

You got it.  That's the ballpark, based on the action rail assembly or inspection date, though the final assembly date of the whole instrument would have been a little later.  You can also triangulate with the transformer and the 8-digit stamp on the keys, and get a more accurate reading.

What's the serial number?  I have a surprisingly scant amount of data on Wurlies from that year.  I'm gonna guess that the first three digits are 106 or 107.

[DocWurly]

Some other things to look for:

*The capacitors of mid-60's Wurlitzers, specifically with 140 or 140B amps, have pretty clear coding of YYWW.  So a capacitor reading 6650 would have been from late December 1966, and the keyboard is probably from early 1967.  Sometimes these dates are surprisingly close to the other dates you'll find in a Wurlitzer.

*Speakers can give you a hint.  In the 1950's Wurlitzers (specifically the 120 and 700), the speaker is sometimes the latest easy-to-locate source of a date on the thing. The first line will be a part number, and the second line will include the date. If you find the number "232 933" on the back bracket of a 700 speaker, "232" is the company code, and 933 means "33rd week of 1959."  In the later 720 and 720A series, however, they were using up the 12" speakers from the 700's, and you might easily find a 1960 speaker in a 1964 instrument.  So these are only very rough guides. (On the other hand, the speaker dates are sometimes the latest dates in a 1962 Model 140 and a 1968 Model 140B!)

*On a 120 and 700, the other best clue as to the date of the instrument is usually a piece of masking tape hidden on the back of the reedbar, with handwritten scribbles on it.  And the serial number will give you an idea of whether it is an earlier (circa 1957 for 120, circa 1958 for 700) or later (circa 1961) instrument.

[izzythecat]

One thing that was not mentioned - tube codes.

I recently acquired a pristine example of a 720a. I disassembled it to clean out the 5+ decades of dust and to check the condition of the mechanicals. As I cleaned the dust off the tubes, I noticed they were all branded Wurlitzer, original equipment. All the silk screened print was clear and complete.

As I am a tube aficionado, I easily found the date codes on the tubes. The preamp tube 6K11 was built by GE during the 22nd week of 1965. The rectifier tube, the 6CA4 is an RCA produced during the 17th week of 1964. The power tubes, 7868, were twins, manufactured by RCA during the 9th week of 1965. (Date codes can be deciphered here - https://www.tubemuseum.org/)

The 8 digit stamp on the keys had the first numeral smeared, both on the bass side of the keyboard and the treble side. The stamp reads X0421370.

The speaker only had a part number and manufacturer code stamped on it, the manufacturer being Carbonneau. I suppose I could pull the pots to see their date codes but that will be for a later time.

With the preamp tube being the youngest of the bunch, I think I can confidently say that this is a 1965.

[cinnanon]

The 8 digit stamp on the keys had the first numeral smeared, both on the bass side of the keyboard and the treble side. The stamp reads X0421370.

My 8 digit stamp code was 40422442 (1964) but the action is stamped 50304055 (1965). Your keys are probably 1964 also.

The speaker only had a part number and manufacturer code stamped on it, the manufacturer being Carbonneau.

My carbonneau speaker reads 651109-1, 719, 417 which probaly 1965 also. What's yours say?

[DocWurly]

My carbonneau speaker reads 651109-1, 719, 417 which probaly 1965 also.

Not quite.

651109-1 is the speaker part number.  Most part numbers from 1962-1964 Wurlitzers read something like "65xxxx".  At some point in 1965 they switched to a part system where everything began with "11", a dash, and 4 more digits (11-xxxx).  This was retained with the 200 series, until they switched to a system where everything began with "20xxxx".

"719" is the EIA (Electronic Industries Alliance) speaker manufacturer code for the Carbonneau company. https://www.tedweber.com/more-codes/

This leaves "417" as the date stamp.  So it means "the 17th week of 1964."  April 20th to 26th.  https://www.epochconverter.com/weeks/1964

It so happens that Mark and I have discussed this instrument of his, and it is indeed from 1965.  .  But we know this because the action rail stamp is 50304055-- that means March 04, 1965.  The key stamp on that instrument is from a full 11 months earlier, and most of the electronic parts are from 1964.  So that goes to show that it's important to consult multiple date stamps on an instrument.

[DocWurly]

One thing that was not mentioned - tube codes.

I recently acquired a pristine example of a 720a. I disassembled it to clean out the 5+ decades of dust and to check the condition of the mechanicals. As I cleaned the dust off the tubes, I noticed they were all branded Wurlitzer, original equipment. All the silk screened print was clear and complete.

As I am a tube aficionado, I easily found the date codes on the tubes. The preamp tube 6K11 was built by GE during the 22nd week of 1965. The rectifier tube, the 6CA4 is an RCA produced during the 17th week of 1964. The power tubes, 7868, were twins, manufactured by RCA during the 9th week of 1965. (Date codes can be deciphered here - https://www.tubemuseum.org/)

The 8 digit stamp on the keys had the first numeral smeared, both on the bass side of the keyboard and the treble side. The stamp reads X0421370.

The speaker only had a part number and manufacturer code stamped on it, the manufacturer being Carbonneau. I suppose I could pull the pots to see their date codes but that will be for a later time.

With the preamp tube being the youngest of the bunch, I think I can confidently say that this is a 1965.

That's a nice catch, the tube codes!  If the 8-digit key stamp is smeared, the other one you want to check is the 8-digit stamp on the back of the action rail.  What does that one read?

While we are at it, what is the serial number of that 720A?  This would be helpful data for my research.  Feel free to PM me.  The 720A is a very interesting and uncommon model, usually in gorgeous shape.  It's really _two_ models in one, as they kept making them into the "145B" era; the later (1965) ones have the damper arm upgrades of the 145B's, and the fixed reed screws.  Basically, they kept making 145B's and 720A's until the stock of tube amps ran out, sometime in the fall of 1965.  At that point they seemingly introduced the 720B, which was a console that had the 140B amp (which had already been in use for a year or so in the portable 140B instrument), and a smaller speaker (which seemed to work just fine, basswise, perhaps because of the furniture body resonance).  The 720A's usually used leftover stock of the 12" speakers that had gone into the earlier 700 consoles, so a 1964 instrument might well have a 1960 speaker in it.

[jam88]

Threads on this topic:

http://ep-forum.com/smf/index.php?topic=9303.msg50803#msg50803

http://ep-forum.com/smf/index.php?topic=9359.0
  ...With the 120 and 700, the most consistent dating I've found is a piece of handwritten masking tape hidden on the back of the reed bar.  There may be other stamps on the wood or electronics (esp speakers) in certain cases...

Hi Guys, can you help?

I'm trying to date my Model 120, and approximate the serial number.  I've owned my 120 for 52 years. Many years ago, the serial number plate went AWOL.

There are some numbers stamped here and there. (See pictures)—

Key #1 has a faint stamp that appears to be "2  560  20", but could be "2  569  20"—Thoughts?

Key #3 is stamped "[C]OMPO", anybody know what this means?

Key #57 has a stamp on the underside. Using some imagination, it LOOKS like a 1960 date stamp. The stamp style is like the date stamp in the attached 112 picture. Thoughts?

(Key #4 has a Pratt-Read [not Wurlitzer] patent number; this number also stamped on the action rail. The patent was issued Dec 30, 1958, so I guess the action was shipped from Pratt-Read no earlier than January 1959.)

Ink stamp on back of the speaker "600141"—does that mean anything?



Here's what I DO know about my piano: it is a 'later' 120, that had the...
  --Painted lid, not textured film
  --Simple (not the ornate) Wurlitzer decal
  --Incandescent (not neon) lamp
  --Two-hole (not four-hole) nameplate--Does anybody know the highest serial number that used the four-hole plate, or the lowest S/N with the two-hole plate?
  --Amplifier S/N 18628. I seem to remember that the amp serial number about 2000 higher or lower than the S/N on the piano's nameplate. Do any of you know this spread on YOUR 120's or 700's?

[DocWurly]

It's possible that "600141" is the part number of that speaker.  It's also possible that "600" is the EIA company code, in which case "141" would mean "41st week of 1961."  Which would be very late indeed for a 120, but possible.   But I suspect that's a part number, as I know of no speaker manufacturer with code "600," and a lot of part numbers associated with this model begin with "600."  You might find some good data underneath that tape on the speaker.

I don't know anything about those key codes.  Can you supply a photo of the stamp on the bottom of #57?

A late-period 700 amp is 1200-1, so it's interesting that the amp model here is 1200-2.  That would make sense.  There are slight differences in the wiring of the octals and speakers of the amps in the two models of that era (120 and 700).

I know of a 700 with a spread between amp and body serial number of 1805 numbers.  Amp being the earlier number.  So, yes.  Perhaps your serial number was around 20733?  The latest 120 I know of has a serial number of 22728.  (and there could be later ones.)

It would be great to have good photos of the outside and inside of the amp, and of the instrument as a whole.  Does your reed/input cable have a capacitor and resistor mounted right onto the reedbar?  I would love to see the undersides of the dampers--do they have wodden spacers above the damper felts, on any or all of the keys?

The most surefire way to date this thing, given all the other mysteries, is by looking on the tubes in the amp.  If any of them are the originals, the years and weeks of year will be on those tubes.  The transformer might have a date code on it, too.

You sure you have no serial badge?  It would be on the back of the instrument.

[jam88]

...The most surefire way to date this thing, given all the other mysteries, is by looking on the tubes in the amp.  If any of them are the originals, the years and weeks of year will be on those tubes.  The transformer might have a date code on it, too...

You're right! PAYDIRT! Thanks, DocWurly. The (original?) Wurlitzer-labeled GE rectifier tube is dated 43rd week of 1959.

So between (1) the rectifier tube's date code, (2) the assumption of a serial number around 20700, and (3) an optimistic interpretation of the ink stamps on the keys, maybe the piano is early to mid 1960? 

The output transformer has two row of numbers neatly pressed into the metal:
     600613-C
      813939
Any idea what these numbers mean?

(FWIW, the RCA 6V6's are date code 'AT' [Sept 65], so guess these are replacement tubes installed around 1965-66.)   

[DocWurly]

600613-C is probably a part number

Are you sure it's 813 and not 831?
"831" means "Better Coil & Transformer", who did a lot of Wurlitzer's transformers.  939 means "the 39th week of 1959."

[jam88]

Are you sure it's 813 and not 831?

Oops, it's '831'. The '939' lines up with the 1959 date on the rectfier tube. Thanks again, DocWurly!

[TimeAndTineAgain]

Hey all, finally made an account.

Thanks to Doc being extremely helpful outside of the forums as well as inside them, I got my Wurlitzer 700 all cleaned and spiffed up, date July 57'

Unfortunately a particular "vintage" company sent me damper felts for a 112/120 when I specifically wrote a note saying it was for a 700 (same damper felt sizes) so I had to make due with what I had on those last 12 treble dampers 

I've got a couple other keys I need to deal with or I'd be all over the 700. Got it tuned up nice, she barks when she wants to and twinkles at night, ever flutter the "soft" pedal for a vibrato like effect? Haha

Matt

[DocWurly]

?  A 700 should have the exact same damper felts as a 120.  Do you have something other than cut-away damper arms and a sustain brick on the top 11 notes?  This should be a separate thread.  Glad I could help.  Start a new thread and show us more of your instrument, please!

[TimeAndTineAgain]

If you re read my comment it's about the size of the damper felts and not the amount of them.

[cinnanon]

I think therein lies the confusion. You should have received some narrower damper felts for the higher notes. The website states Mid Felt: Keys 1-46, Treble Felt: Keys 47-55

What did you receive (or not receive) exactly?

[DocWurly]

My article on finding dates in your Wurlitzer is on this page:

https://www.drwurly.com

[christine1117]

OMG! when I saw the title I was thinking of  something completely different!

[DocWurly]

I don't check this board too often. 

My updates on this topic will always be found in the link below. I appreciate the ongoing great ideas and input of others--I'm certainly not offering the final word. I'm a learner like everyone else here.  For example, Matt of this thread offered a great insight into dates found on keys in some 120's and 700's. And Izzythecat had that great insight about tube codes, which remains of the best ways to date a 120 or 700.

https://docwurly.com/wurlitzer-ep-history/the-date-of-your-wurlitzer-electric-piano/