Detecting Originality

When buying a vintage amp, you have to determine whether you are buying for tone or collectability (or both). For tone you may not care about total originality; for collecting originality matters. Most of the time, changed parts will be noted by the seller so the correct price can be ascertained. The more things have changed, the lower the price should be.
But once in a while it happens. You find an amp you think you want. It looks great. It sounds great. You have to have it. Everything looks original and the seller doesn’t say anything that leads you to believe anything is not original. You buy it and go on your way, skipping like a kid who just got an ice cream cone. After a while you notice something amiss or someone mentions that the grill cloth looks changed. You look into it further and lo and behold, they’re right. Many times there is nothing you can do because too much time has lapsed. If this has never happened to you, great. If it has, take it as a lesson on how to detect originality. Here are some tips to avoid buyer’s remorse:
Covering (Vinyl, tweed, tolex, etc). The covering on old amps was usually attached with hide glue. If the amp is old, the glue will be totally dry and flaky. If the amp has been recovered, the glue will give it away. It will be gummy and soft to the touch.
Grill cloth. Look at the staples. Are they new or old? If old, are there other staple marks under the grill cloth? On Fender amps, the speaker is mounted with screws that come through the baffle from front to back. The usual way to get them out is to take the grill off.
Transformers. There is a lot of information about original transformers on the Internet. Most have number stamped or printed on them. Fender and Marshall are well documented. You’ll have to search harder for info on most other brands. Look closely at the images on line and compare to what you have or are thinking of buying. Check out http://marstran.com/Historic%20Data%20Base.htm and http://www.svvintageamps.com/dating.php
Capacitors and resistors. Look on-line for amps of the same vintage and compare the boards. Do the resistors and caps look similar? Look for a few examples especially as they varied from year to year especially with the amps made in the UK.
Counterfeit money, counterfeit art, counterfeit antiques, counterfeit guitars, counterfeit handbags, and believe it or not, counterfeit amps.
Incredibly so, there is/was a well known vintage dealer in the UK who has built Marshall copies (and probably others like VOX and HiWatt) and sells them as original. They recreate and relic cosmetic parts. They find old parts by gutting less valuable vintage amps. This has been going on for so many years and they are so good at it, that many times it is difficult to tell the real thing from the copy. If you are in the market for a vintage Marshall, beware. Buy from a reputable dealer or a good friend who really knows. Get a second opinion, especially if it looks unusually clean. Here are some of the tell tale signs (besides the info above).
Marshall amps with brown pinstripe grill cloth. This is so rare that I’ve never seen an original. About 15 years ago, around 20 or so vintage Marshall amps became available with the rare brown pinstripe cloth. Somebody (cough, cough) found a roll of this rare grill cloth and put it on real and/or fake Marshall amps.
Check the piping, grills, and other cosmetic parts.
Check the glue. If it is a newly made cabinet, the glue will not be totally dry.
Marshall 18 watt combos built from original 10 watt amps.
On Fender amps, check the texture of the tolex and compare it to one that is totally original. For example there is current available brown tolex that looks old and slightly discolored. The back has a thin fabric lattice. The original doesn’t. On blonde tolex, the new stuff is thicker than the original.
The smell test. “Is something rotten in Denmark?”