Concertape was a budget brand of tapes that were very popular due to their low pricing, sold exclusively through Radio Shack stores. There is a lot of history with this brand. We have identified many versions of this tape, and many of them – but not all – are unusable. Hopefully this guide can help you determine which tapes you have, and whether you can play them .

Notes:

• At first, a complete line of tapes was available, with a full range of reel sizes and lengths. The early series of tapes look like they were supplied by multiple vendors including Audio Magnetics and Audiotape / Audio Devices. These early tapes provide acceptable performance and do not have sticky shed.
• Later, only the 1800ft version on a 7″ reel was produced.
• Later generations of tapes were reject Ampex stock typically sold as “031” for 1200 ft. and “041” for 1800 ft. as sold also under their budget Shamrock brand. The Ampex hold-down tabs marking the tape type made their way to all Concertapes accordingly.  We have identified the following back-coated Concertape / 041 formulations under that brand – and have also discovered that some of them were sold spliced from the factory (most likely under the Shamrock brand):
  1. Early generation acetate / Mylar tapes are based on the standard (type 1) tapes sold by Ampex in the 1960s and early 1970s, without back coating. These are still playable and have no sticky shed. You can identify them through their oxide color (brown) and that they have no back coating. These are the most reliable Shamrock tapes, and we offer the mylar versions as refurbished with their formula called out (Shamrock/Concertape Type 1: Ampex Ferrosheen Brown Oxide). These were sold in both 1200ft and 1800ft as Concertapes.
  2. Grey oxide tapes based on Low Noise formulations, also without sticky shed or back coating, in 031, 041.  These were sold in both 1200ft and 1800ft Concertapes. Early batches of grey oxide tape might have been sourced from Audio Devices / Audiotape, who made early Realistic tape. It is hard to tell the difference between that tape and the grey oxide tape labeled as 031. As of this writing, we are still evaluating whether these can be sold as refurbished.
  3. Grey oxide tapes without back coating WITH sticky shed, we did not play or test these tapes but discovered them during our processing
  4. Grey oxide tapes with back coating, without sticky shed – these tapes have a slight brown tint. The quality is OK on these. As of this writing, we are still evaluating whether these can be sold as refurbished.
  5. Brown oxide tapes with a graphite backing, tape otherwise used for 8-track cartridges. They do not have sticky shed and can be played without problems. We also offer these as refurbished with their formula called out, as some people want the tape to load into their 8-tracks (Shamrock/Concertape Type 5: Ampex Graphite Backed Brown Oxide / Cartridge Tape).
  6. Back coated master tapes with brown oxide in 031 and 041, especially popular in Europe as they were sold alongside BASF tapes in European department stores through the 1980s. We haven’t found any of this stock packaged as Concertape but it *might* be out there, given the history.
  7. Back coated instrumentation tape sold as 041. This has a shiny grey oxide, and the tape is thinner – you can identify this tape in that it looks like the reel is not filled with tape. This tape suffers from sticky shed. Also, it has a very low output and a strange bias characteristic that made it good for 3-3/4 ips and a noise reduction system at the time. This formulation was commonly found in mid-1980s Concertape. Unfortunately none of this tape is usable today without baking. There are some rare batches of this tape without back-coating, and we found it suffers from Sticky Shed, too.
  8. Back coated grey oxide tape sold as 041 with a more favorable performance characteristic, but similar sticky shed properties. These tapes are identifiable in that they almost fill the real, unlike type 7. They also have a distinctive pungent smell. This formulation was also commonly found in mid-1980s Concertape. Unfortunately none of this tape is usable today without baking.
• DO NOT PLAY OR WIND STICKY SHED TAPES BEFORE BAKING. Unless baked first, winding them can cause the oxide to be stripped from the polyester base material, essentially destroying them.  In fact, many batches cannot even be WOUND without baking as the oxide can be stripped off and the tape permanently destroyed. We have encountered some tapes that are less sticky than others, but there is no way to tell as the sticky shed condition seems to be dependent on the humidity of the environment they were stored in…and it has been over 40 years. If there is any valuable program material, these tapes need to be baked first.
• Available Refurbished: We do sell select types of Shamrock / Concertape that has passed our tests. Right now we are offering Type 1 (brown oxide) and type 5 (graphite backed brown oxide) in our store, as we have tested these and have found them to be reliable.