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Using Speaker Source Code for Dating

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Alvin Ward (music_al)
Username: music_al

Registered: 08-2010
Posted on Wednesday, August 25, 2010 - 09:36 am:   

If you are not comfortable in taking your chassis apart to look for dates on your Music Man Amp, there is an easier way to get a good idea of when it was built. If the Amp still has the original Eminence speaker/speakers, then you can get a good idea of how old your amp is from the Speaker Source Code. This will be a 6 digit code which is inked stamped on the bell housing of the speaker. You should be able to look in the back of your amp ,and with very little effort, spot this code. The code will look something like this example: 67.7731 The first two numbers 67 indicate the source code for Eminence Speakers, while the last four numbers 7731 are for the date. The 77 is for the year and the 31 is for the 31st week of production. Therefor, this example would have the speaker dated at around the beginning of August in 1977.
Using the Eminence Speaker Source code should give you a reasonable idea of about how old your amp is, but remember it has to be the original speaker or speakers.
Bill Traylor (bozzy369)
Username: bozzy369

Registered: 02-2008
Posted on Wednesday, August 25, 2010 - 11:21 am:   

well i have a head so no luck there ,i looked inside anyway,but this kind of dating is really a wide guesstimate.that chasis could have just been built and that speaker a year ago or vise versa,throwing off the dating by a year.
Alex H. (alex_h)
Username: alex_h

Registered: 07-2007
Posted on Wednesday, August 25, 2010 - 03:03 pm:   

Don't know if this works for MM amps, but many 70's Fenders used transformers with a 606 source code, so looking to see if the transformers start with 606 is another option.
Alvin Ward (music_al)
Username: music_al

Registered: 08-2010
Posted on Saturday, August 28, 2010 - 09:22 am:   

Yes, you can use the power transformer as another option for dating your Music Man Amp if the original Eminence speaker has been replaced. You also don't have to remove or get into the chassis to find the transformer, and as mentioned earlier with speakers, this needs to be the original transformer and not a replacement. There should be a code stamped into the metal case on the transformer that looks something like this: EIA606-813. The EIA stands for Electronic Industries Association and the 606 is the source code for the manufacturer, which in this case is Woodward-Schumacher. Apparently Music Man used the same source for it's power transformers as did Fender back in the 70's, because my MM also has the 606 source code. Now, we come to the last three digits of the code with the 8 being the last digit of the year, and in the case of Music Man Amps this would have to be 1978, as the amps were only built from 1974 thru 1984. Finally, the last two digits of the code 13 would stand for the 13th week of the year.

If your amp is all original, you might find that the dates on the speaker and transformer can vary by several months, so I would probably be inclined to use the later date when trying to date the amplifier since the later dated parts were probably installed last in the manufacturing process.
Bill Traylor (bozzy369)
Username: bozzy369

Registered: 02-2008
Posted on Saturday, August 28, 2010 - 02:20 pm:   

I'm sorry guys,but this thing is getting silly,I'm not sure about all models but my head is like 4 screws.and its open,that is the best precise way to date your head .
Brian M. Watson (mrroundel)
Username: mrroundel

Registered: 06-2007
Posted on Thursday, September 23, 2010 - 07:01 am:   

FWIW: I removed the chassis on my 210HD130, and looked everywhere for a date stamped, written, etc., but found nothing. The speakers were from '78, the serial was in the B5300 range. However, the 212 I just bought did have a date written on a circuit board showing late 1978. This coincided with the speaker dates.